I think my brain is full

6 10 2007

I just walked in the door from my long day at NYU (I woke up at 5:30 AM to make sure I made the train) and it was definitely worth the trip. The presentations were very interesting, even if I didn’t entirely agree with everything that was said. Unfortunately I have to run off again, but here’s a preview of some of the topics mentioned today that I’ll write some more about when I get a chance;

– Olive & Yellow Baboon Hybridization

– Monkeys that use their tails as tripods

– The role of populations and demographics in evolution

– The elusive Cross River Gorilla

– Alan Walker’s spear-throwing “fantasy”

– Non-adaptive speciation events (?)

I mostly remember the topics that made me go “I don’t think that’s right” more than anything else, but it definitely was a very informative conference and I’m glad I went. Tomorrow I’ll probably be away from the computer again until the afternoon and then I’ll be off to see the Walking With Dinosaurs Live show before it closes, but I’m hoping to have my new blog up and running for the beginning of the week (with lots of juicy new material, plus some older re-polished gems).





Apes aren’t the only primates to use tools

5 10 2007


A chimpanzee cracking open nuts placed on the ground with a large stone. Notice that a young chimpanzee is also present, learning this behavior. This is a sort of Type 1 tool use where a hammer (the rock) is used on another object.

“Tool use” was once considered one of the primary factors that made Homo sapiens distinct from all other animals, but Jane Goodall’s studies of Chimpanzees at Gombe and subsequent research among living apes has shown that the tool use of humans is differentiation of grade and complexity more than anything else. Tool use has now been extended to many other groups of animals, even outside the Class Mammalia, but it still is surprising to see some animals make use of objects in their environment in inventive ways. Indeed, while the idea that humans are distinguished by the possession of tool use is dead in scientific circles, it still is alive in the public mind (I recently had a friend tell me that we were “Man the Tool-User”), and genuinely impressive utilization of tools by other animals is often related to just be a sort of “trick” or purely instinctual mechanism (I’ll save the issue of animal cognition for another day).

Of the animals that use tools, however, among the most impressive are the Capuchin monkeys (Cebus sp.). Capuchins are platyrrhine primates (New World Monkeys) that inhabit the forests of South and Central America from about Honduras to Brazil. They’re generally familiar to everyone, the proverbial “organ grinder’s monkey,” a common household pet (until recently), and a regular in film roles that required a primate (i.e. Marcel from the show Friends). Indeed, Capuchins are easy to train and highly intelligent, but despite their close proximity to people they’ve generally been overlooked as “just monkeys” for a very long time. Recent research, however, has shown that they can tell us much more about the development of intelligence and human evolution than previously thought.

]

Capuchin monkeys cracking open nuts. Note the similarities between this footage and the film shown above.

The fact that chimpanzees have the highest brain-to-body size ratio out of all the African apes is well-known, but few people know that Capuchins exhibit brains of similar proportions. Such a fact is readily apparent (or at least easily researched) but Capuchins have generally been ignored because while they are primates they are not as closely related to humans as Chimpanzees, Bonobos, Gorillas, or Orangutans, but fortunately this has changed. While they can be difficult to study in the wild despite their inquisitiveness/ease of acclimation to human presence, Capuchins are primarily arboreal quadrupeds, able to run through the trees as fast or faster than researchers can make it over the forest floor. This may result in some behaviors being missed, and oftentimes studies are carried out in the dry season when foliage is a bit more sparse and allows for a better view of the monkeys. Why are such considerations important? Because the tool-use in Capuchins I’m about to discuss is more often seen in captivity than in the wild, and it’s important to consider what you may not be seeing when dealing with animals in their natural habitat.

Much of the work on Capuchin intelligence has been carried out in labs by researchers primarily interested in psychology, and as my professor once remarked when considering some of the studies, the background of the researcher can be significant as to what it studied, how it is studied, and how the results are interpreted. Be that as it may, studies in captivity involving Capuchins have shown that they can use tools and that they use tools in a variety of ways depending on the circumstances. Anyone who has used a hammer or other tool to make something recognizes that the way you grip an object has a lot to do with how effective it is going to be; it probably wouldn’t be very effective (or safe) to grip a hammer with the fingertips of both hands and try to use it to bang in a nail. Likewise, when Capuchin monkeys are given a stone and expected to throw the stone into a tub of peanut butter (as in one experiment) they need to choose a grip to accomplish the task, and while there are a number of different variations of grips they usually fall under the category of power grips or precision grips. The names belie what they are used for, and in the throwing experiment I had just mentioned the most popular grip used was called the “jaw chuck,” where an object is held in the palm of the hand with all the fingers holding it in place. The jaw chuck grip was not the most effective in this experiment, however, one monkey having better success during its attempts using a precision grip (the “cup grip,” where an object is held in a cupped hand with the fingers providing support) even though it did not catch on with the other individuals.

In a different experiment, where a tub of peanut butter was covered by an acetate barrier and stones with one sharp edge were placed in the cage, the jaw chuck was even more popular than in the throwing trials, even though similar “power grips” were used as well. Indeed, while the monkeys did use (experiment?) with a number of precision and power grips, the jaw chuck was the most popular overall. Another set of tests, however, showing that monkeys might not use tools at all if they don’t have to. When a tub of peanut butter was covered in 5cm of soil and the monkeys were provided with sticks, the monkeys simply dug with their hands (like baboons do) if the soil was loose. If the soil was hard, however, some of them used sticks, even modifying the sticks by removing leaves and biting off little bits, to reach their prize. This is significant because some people like the !Kung San of the Kalahari use sticks to dig for roots and tubers today and the ability to dig for food underground is considered to be a very important factor in human evolutionary history.

As seen in the video above, however, digging in the dirt isn’t the only thing Capuchins do. They also crack open nuts in a way very reminiscent of Chimpanzees, although not all Chimpanzees exhibit this behavior. Some, like the ones in the Tai Forest do use tools to open nuts (as do other populations), but some populations don’t use tools and some don’t use them in the same way. As I mentioned in my post about Mt. Assirik chimpanzees, the chimpanzees there use the large Baobab tree limbs and trunks as anvils to crack open the fruit of that tree, using a level of tool use lower than that of other populations that put a nut on an anvil and then use a hammer (the Mt. Assirik chimps are just using the tree as an anvil). Again, as described in my earlier post about the Mt. Assirik chimpanzees, tool use can evolve given the proper ecological opportunities and cognitive steps, going from simply using a hammer or anvil on an object to using two tools (hammer and anvil) to open an object to the production of more complex and specialized tools under the proper conditions. In the case of the Capuchins, the monkeys have been known to bang stones together (holding one in each hand), use stones to crack nuts, throw stones against the ground, and hit stones with other stones making a “bipolar” object (it flakes on two sides if held on a stone anvil). Unfortunately I don’t know what becomes of these objects as it seems that Capuchins do not keep or further modify tools they make when they are finished using them, but it could represent the beginnings of tool manufacture, the behaviors requiring the cognitive leap to move ahead.

The cognitive abilities of Capuchins is one of the ways that they differ from Chimpanzees, in fact. While Chimpanzees often recognize themselves if presented a mirror, Capuchins do not (although some have used mirrors to look around objects for hidden food). Capuchins also fail some cognitive tests passed by Chimpanzees, and it seems that while both primates exhibit some similar behaviors the convergence is even more striking because Capuchins are different in terms of their intelligence. Still, the fact that Capuchins can use tools and show convergences with chimpanzees shows us that certain “milestones” that were once considered hallmarks of human evolution can show up multiple times in multiple lineages, recalling the “branching bush” of evolution rather than the orthogenic line.

There are problems with the lab studies, however, and more study needs to be undertaken of wild populations to determine how tools are being used (or even made) in natural groups rather than animals in cages. The behavior of the captive animals will only make sense in terms of evolution when compared to that of wild groups, and it would be a mistake to assume that everything Capuchins do in captivity they must also be doing in the wild. Perhaps they are and we haven’t seen it yet, but perhaps it’s a matter of ecology. If a Capuchin lives in an area with lots of soft fruit and food that does not require tools, they’re not likely to turn to tools to solve some of the problems presented by their environment. If the environment is harsher, however, and the monkeys are not naturally well-equipped to crack open nuts or get the most flesh off bone possible (because Capuchins do eat meat when they can get it), tool use is much more likely to emerge if the cognitive connections can be properly made. Some are more proficient than others, and it make take a while for certain behaviors to become established, but the tool use of Capuchins teaches us some important lessons about evolution and how it is never finished shaping life in the most surprising ways.

References;

Visalberghi, E., and McGrew, W.C. “Cebus meets Pan.” International Journal of Primatology, Vol. 18, No. 5, 1997

Westergaard, G.C. “What Capuchin Monkeys Can Tell Us About the Origins of Hominid Material Culture.” National Institute of Child Health and Human Development,1998.

Westergaard, G.S., and Suomi, S.J. “Capuchin Monkey (Cebus apella) Grips for the Use of Stone Tools.” American Journal of Physical Anthropology, 103: 131-135 (1997)

Westergaard, G.C., and Suomi, S.J. “The Production and Use of Digging Tools by Monkeys: A Nonhuman Primate Model of a Hominid Subsistence Activity.” Journal of Anthropological Research, Vol. 51, No. 1 (Spring, 1995)





The Chimpanzees of Mt. Assirik

25 09 2007

When chimpanzees (Pan troglodytes) appear in documentaries they are often shown inhabiting relatively dense tropical forest, their lives taking place within the green refuge of the forests. As with any other species that is spread over a considerable distance, however, different populations of chimpanzees have different habits, and one of the most remarkable populations are those around Mt. Assirik. Located in the southeastern part of the Parc National du Niokolo-Koba in Senegal, the chimpanzees in this area have to deal with a local ecology that is drier and more open than some of their relatives elsewhere, and their behavioral adaptations to the environment is of great interest to those study human origins.

The Mt. Assirik study area is remarkable in that 55% of the habitat is open grassland, only about 37% being woodland of varying density and only 3% being more dense forest (the remaining area being made up of bamboo forest and isolated trees). Such open spaces allow some of the major Carnivora of Africa to live in close proximity to the chimpanzees; Lions (Panthera leo), Leopards (Panthera pardus), Wild Dogs (Lycaon pictus), and Spotted Hyenas (Crocuta crocuta) are all frequently seen in the area. As if having so many predators at their doorstep were not enough, the Mt. Assirik area seems to have fluctuations of food that aren’t correlated with seasonal changes, and in the dry season water is the most prized of any resource. The apes are not entirely helpless in the face of such pressures, however, and they’ve been behaviorally adapted in some very interesting ways.

Given a choice, the Mt. Assirik chimpanzees prefer to spend their time in the denser areas of forest, but shifting food resources sometimes require them to move across large expanses of open grassland in order to find nourishment. Wandering out onto the open plains alone is so dangerous as to nearly be suicidal, and the apes form large mixed groups when they have to move across the plains. During this time they are at their most vulnerable, especially since they would be unlikely to outrun any of the major predators (especially those that hunt in packs), and they are extremely alert when undertaking such a journey. What is perhaps most striking of all, hearkening back to Raymond Dart’s “Savanna Hypothesis,” is the fact that the chimpanzees sometimes stand up to get a better look at their surroundings, potentially spotting predators before they get too close, although such an observation should not be taken as a sweeping vindication of Dart’s ideas of human evolution.

The presence of just one tree or a few trees spaced far apart doesn’t help the chimpanzees much either; mothers with children and individuals spent much less time in the sparser woodland areas than in the forest, mixed groups seemingly having to issues with the woodlands. Why should this be so? Well, leopards can climb trees (and often do so to stash their kills), as well as lions, and so simply climbing a tree does not equal escape. Lone chimpanzees are far more comfortable in a habitat where they can climb a tree and move through the canopy out of reach of their assailants, something that is not possible in woodlands. The predators may also have another effect on the diet of the chimpanzees; the Mt. Assirik chimps do not seem to eat young ungulates or monkeys, although such behaviors have been made famous where it has been observed (i.e. Gombe). This may be due to some competition, but it may also be due to the restricted forested habitat and the fact that chimpanzees would have to enter the habitat of the carnivores in order to capture young ungulates, predators being likely to quickly learn about any kills that had been made.

Indeed, the Mt. Assirik population is remarkable in that it often moves long distances in order to obtain food as it becomes available, relying on numbers and vigilance to protect itself from predators when it’s habitat only offers a few isolated islands of relief. Although humans did not evolve from modern chimpanzees, this population may give researchers some idea of the behavior patterns of our ancestors when faced with similar constraints when forests became sparser and the plains were filled with predators. Such social behavior is not the only thing that makes the Mt. Assirik chimpanzees stand out, however; they also make use of Baobab trees in a very interesting way.

By now many people are familiar with the ability of chimpanzees to use a piece of wood as a hammer to break a nut placed upon an “anvil” of rock or tree root; such footage has been shown in television programs again and again. Such behavior did not come out of nowhere, however, and the way Mt. Assirik chimpanzees open nuts may represent a stage of tool use that precedes the hammer-and-anvil technology. While it had been disputed for some time whether the Mt. Assirik population used hammers and anvils or just anvils, recent studies have shown that they are cracking open the hard nuts of the tree on branches and not using a hammer. While we might think of an “anvil” as something that can only be used in conjunction with a hammer, mechanically this isn’t necessarily so, and the Mt. Assirik chimpanzees bang the hard nuts they collect on the branches of the tree (therefore staying aloft, not coming down to use stones or the roots of the tree), the tree itself being the anvil.

Given the basal usage of anvils by the Mt. Assirik chimps and the use of hammers and anvils elsewhere, it becomes possible to hypothesize about the evolution of stone tool use in our own ancestors. The starting point was likely similar to what is exhibited by the Mt. Assirik chimpanzees, banging hard nuts on trees or rocks in order to open them (thus preventing damage to the teeth, if it even would be possible to open the nuts using their jaws). The next step would be adding a hammer, possibly wooden (as seen in some groups today) or possibly stone. At this stage any combination of wood or stone hammers and anvils could be used, but tool use would probably not progress until a population was using stone hammers and stone anvils to open foods. In such a scenario, the apes would sometimes miss their targets and flake off bits of stone, an accident that would shape the tools. When a certain cognitive leap was made, the apes could then move from accidentally flaking their tools to doing it intentionally to truly be making tools rather than making use of naturally occurring bits of wood and stone. The reality of the situation may be forever lost to us, ancient tool use before the knapping of stone became prevalent being notoriously hard to discern, but such a line of behavioral descent is not unreasonable and seems to allow further development merely by chance combinations of naturally occurring resources.

Such a discussion is only a brief sketch based upon what I have only recently learned myself, but I hope that it has been at least somewhat informative. Different populations of chimpanzees show different behaviors and live in differing ecologies, and it would be a mistake to assume what the famous Gombe chimpanzees are doing holds true for all the other populations. Another population that I soon intend to write about spends time in caves, probes trees for bush babies, and may even have the beginnings of a fire culture; others do not show the same exact behaviors, but they have their own cultures and reactions to the local ecology. While we should be careful in analyzing the living populations of chimpanzees and their perceived similarities to humans, it would be foolish to think that they can tell us nothing of our own past, and if very well may be that some of traits (behavioral or otherwise) they now exhibit were present in our own lineage, vignettes of evolutionary history being replayed with different actors in our own time.





A peek at my homework

19 09 2007

Here’s the summary that I’ll be giving today in my Topics of African Prehistory course pertaining to the assigned reading Wrangham, R. 1987. “The Significance of African Apes for Reconstructing Human Social Evolution.” In Warren G. Kinzey (Ed.) The evolution of Human Behavior: Primate Models. It’s long by summary standards, but when have I been known to be succinct? In fact, I would have loved to make this even longer, but I don’t want to talk my classmates to death.

Summary

“Life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress. Most people may know this as a phrase to be uttered, but not as a concept brought into the deep interior of understanding. Hence we continually make errors inspired by unconscious allegiance to the ladder of progress, even when we explicitly deny such a superannuated view of life.” – Stephen Jay Gould, Wonderful Life, 1989

On June 30, 1860, “Darwin’s Bulldog” T.H. Huxley met Bishop “Soapy Sam” Wilberfoce in a debate on one of the most hotly contested topics ever to be put before mankind: are we evolved, or are we divine creations? While no one is quite certain as to the outcome of the debate, it is perhaps one of the most celebrated events in the history of the evolution idea, for when the Bishop rhetorically asked whether it was through his grandmother or grandfather that he was descended from a monkey, Huxley delivered this devastating rejoinder; “If then the question is put to me would I rather have a miserable ape for a grandfather or a man highly endowed by nature and possessing great means and influence and yet who employs those faculties and that influence for the mere purpose of introducing ridicule into a grave scientific discussion – I unhesitatingly affirm my preference for the ape.” Such wit did not halt the debate then and there, but as Huxley’s work Man’s Place in Nature, Darwin’s The Descent of Man, and various cartoons from Punch at the time make clear, it could no longer be denied that Homo sapiens had very close relations to the living gibbons, orangutans, gorillas, and chimpanzees, their lives providing insight into our own.

The relationship between men and apes is now taken as a “given” (and rightly so), but the question of just what living apes can tell us about our past must be asked. While the fossil record seemingly refused to give up hominid remains for some time, there is today a greater diversity of fossil hominids now known than in Huxley’s time, and what we know about living apes must be reconciled with these discoveries if we’re to accurately portray what our ancestors (even our common ancestors) may have been like. Indeed, we should not forget that our own species did not evolve from chimpanzees or gorillas but rather shared common ancestry with them in the past, and they have been evolving since the time of their separation just as we have. As Richard Wrangham rightly criticizes the approach of trying to crown a living species as the archetype for our ancestor, noting “The ideas these models generate are plausible and even thought provoking, but their value is limited by their initial assumption: they assume that the social organization of human ancestors was similar to that of living species.”

Given this potential pitfall, Wrangham suggests a behavioral sort of cladistics, surveying the social behavior of extant gorillas, chimpanzees, and bonobos in order to find the presence (or absence) of shared social behaviors. If certain behaviors exist within all the groups mentioned, then there would be reason to believe (at least in terms of parsimony) that such behaviors were inherited from a common ancestor rather than evolved multiple times. Concerning the closed or semi-closed social groups detailed in II A 2. (Grouping Patterns) of the outline, it appears that humans, chimpanzees, and gorillas all have closed or semi-closed social groups, making the behavior a shared trait that may have been shared by the common ancestor of all the groups. On the other hand, however, we have the data presented in II B 4. (Male-Male Interactions) where the variety of interactions precludes us from being able to tell what sort of behavior pattern our common ancestor exhibited in terms of male interactions.

Now that we understand the application of Wrangham’s methodology to living primates, we should consider the overall strengths and weaknesses it may have. One of its strengths may be the ability to recognize the possession of common behavior in the apes despite different ecologies. If humans, chimpanzees, bonobos, and gorillas all share certain behavioral characteristics despite living in different habitats or inhabiting different niches, the overall case is stronger for that trait being inherited from a common ancestor rather than convergent evolution. Convergent evolution can be problematic, however, as it sometimes seems to defy parsimonious explanations. Perhaps the common ancestor did not exhibit the behaviors now expressed as much carry a capacity for them through variations in populations (being that it is populations that speciate and change, not an entire species as a whole), and being that we are dealing with behavior and not morphology in this case, it might be easy to accentuate some similarities/differences while hiding others. For example, if we undertake cladistics in the traditional sense, let’s say describing a skull, the process is relatively straightforward; either a structure or trait is present or it is not. Behavior, however, can be more variable, and even in Wrangham’s description of Group Patterns there can be seen some potential for disagreement. Indeed, is there are large significance between a closed group and a semi-closed group? Again, given that we’re talking about behavior and not a morphological trait that is usually clearly present or absent, researchers would do well to be mindful of how they delineate what they consider significant behaviors and how they are measured in terms of this method.

Wrangham does not hold his method up as the one and only answer, however, and he concedes that it is more of a “quick” and “weak” starting point to determine possible similarities rather than a way to obtain ultimate answers. In fact, as he notes in the introductory paragraphs, the study of behavioral ecology weighs heavily on the issues herein discussed, although it is a discipline still in development. Even beyond modern ecology, paleoecology will have a very significant role to play in determining what our ancestors were like, especially because habitat does much to shape the bodies and behaviors of organisms through evolution. Indeed, living species can give us valuable insights into our past, but if the information gleaned is determined to be the product of convergence or is found not to be consonant with the data from the fossil record, developing understanding will have to accommodate such discoveries. Ultimately, the discovery and determination of our common ancestors with chimpanzees and gorillas will weigh heavily on this issue, but at the present time the information is overall insufficient and (as ever) there are more questions than answers. For the present, however, the behavior of living African apes can provide a sufficient framework for comparison, and Wrangham’s methodology provides a quick way to spot potential similarities that can then be checked through the study of ecology and the fossil record.





Photos from the Philadelphia Zoo, Pt. III

10 09 2007

Here’s the last set of the photos from this past weekend, and as soon as I get the entire set uploaded to Flickr I’ll let you all know.

Gorilla
One of the gorillas at the Primate House. I only saw two while I was at the zoo, so I assume that most of the rest of them were inside or in an area out of view.

Grevy's Zebra
A Grevy’s Zebra (Equus grevyi).

Prairie Dog
A Prairie Dog (Cynomys sp.) having a snack.

African Elephant
The only visible “enrichment” the African Elephants had was a naked metal chain, and the elephant that I was told was named “Petunia” couldn’t stop fiddling with it. I have to wonder if some of this was a way to comfort herself or divert unease, as just before this picture she was driven out of the shade by the two other elephants she shared her habitat with, and overall she seemed to be restless/ill at ease the entire day.

Puzzles
This is “Puzzles,” the Reticulated Giraffe (Giraffa camelopardalis reticulata). I don’t know why the zoo staff has not operated on this animal, and the plaque outside the enclosure is a bit shore on details. Perhaps the condition is inoperable, and it doesn’t seem to visibly inhibit the giraffe, but I do feel sympathy for Puzzles.

Pygmy Marmoset
The most deadly of all creatures, the Pygmy Marmost [Callithrix (Cebuella) pygmaea]. Don’t let their cute appearance fool you; they can deskeletonize a cow in seconds… or is that piranhas…

Sable Antelope
A Sable Antelope (Hippotragus niger) rests in the shade. It’s hard to tell from this angle, but this one has asymmetrical horns.

Squirrel Monkey
A Squirrel Monkey (Saimiri sp.) enjoying some fruit.

Tree Shrew
A Tree Shrew (Tupaia sp.), sitting still long enough for me to squeeze off a shot (albeit a blurry one).

Galapagos Tortoise
One of the Galapagos Tortoise (Geochelone nigra) taking a dip.

Aardvark
A pair of Aardvark (Orycteropus afer) having a snooze in an artificial cave.

Gibbon
“Solstice,” a female White-Handed or Lar Gibbon (Hylobates lar). She shares her habitat with her partner Mercury (who is black rather than blonde) and an Orangutan (Pongo sp.) pair.

Gibbons
Solstice makes her intentions clear; she wants to be groomed by Mercury.

Gibbon
Mercury seemed more interested in grooming his male orang friend than his partner Solstice.

Orang
The male Orang was very shy, and carried a cardboard box on his back like a shell/shade everywhere he went.

Orang

And that’s it. Hopefully I’ll soon upload all my photos (there are thousands of them) onto Flickr soon, but I hope that you’ve enjoyed the ones I’ve put up here.





Scuttling the Aquatic Ape Hypothesis

29 08 2007

On our occasional trips to the New Jersey shore, my wife is always the first one in the water. While I’m cautiously wading in, dreading that final slap of cold water just below my waist, she’s already frolicking in the waves, egging me on to just jump in and get it over with. Eventually I too become submerged (either willfully or by force of a wave I never saw coming), salt water inevitably shooting up my nose. Don’t get me wrong, I do enjoy warm days at the beach, but on each visit it seems that I as an individual, if not a representative of a population or species, am not well-adapted to a near-shore marine existence. Followers of the Aquatic Ape Hypothesis* (AAH), however, beg to differ.

[* I say “hypothesis” and not “theory” (AAT) because the writings of Elaine Morgan and others do not have enough supporting evidence to garner it the more prestigious title of “theory.” Given the current paucity of evidence and research, the Aquatic Ape Hypothesis is precisely that and no more.]

Before discussing the current manifestation of the AAH, we need to go back to a time when the truth of evolution had yet to fully take hold in the minds of scientists and philosophers. The Ionian philosopher Anaximander (610-546 BCE), student of Thales, suggested that the world first existed in an entirely aquatic state, the recession of the globe-consuming waters creating life. In From the Greeks to Darwin (1905), famed American Museum of Natural History president Henry Fairfield Osborn described the views of Anaximander as follows (a similar treatment is given in Osborn’s Man Rises to Parnassus, as well);

He conceived of the earth as first existing in a fluid state. From its gradual drying up all living creatures were produced, beginning with men. These aquatic men first appeared in the form of fishes in the water, and they emerged from this element only after they had progressed so far as to be able to further develop and sustain themselves upon land. This is rather analogous to the bursting of a chrysalis, then to progressive development from a simpler to a more advanced structure by a change of organs, yet a germ of the Evolution idea is found here.

We find that Anaximander advanced some reasons for this view. He pointed to man’s long helplessness after birth as one of the proofs that he cannot be in his original condition. His hypothetical ancestors of man were supposed to be first encased in horny capsules, floating and feeding in water; as soon as these ‘fish-men’ were in a condition to emerge, they came on land, the capsule burst, and they took their human form.

Like the works of many Ionian philosophers, the ideas and opinions of Anaximander do not seem to have taken hold (Aristotle ultimately becoming the preferred scientific and philosophical source for further consideration in Europe in centuries to come), and not much of his work remains. It is curious to note, though, that wrong as Anaximander was about the origins of humans, the reasons he uses to support his ideas (as relayed by Osborn) are very similar in approach to those of Elaine Morgan and some modern-day AAH adherents, as we shall soon see.

To the best of my current understanding, the hypothesis that man was a product of the sea did surface again until 1942 when Max Westenhofer of the University of Berlin published the book The Unique Road to Man. According to Donna Kossy’s book Strange Creations, Westenhofer’s treatment of an aquatic origin of mankind consisted of little more than mention of it as a promising hypothesis, however, and the outbreak of war prevented the professor from pursuing the line of inquiry further. The hypothesis would have to wait until March 5, 1960, when marine biologist Sir Alister Hardy presented a lecture on “Aquatic Man: Past, Present, and Future” to the British Sub-Aqua Club. The address caused quite a stir and led Hardy, who had been inspired by the layers of sub-cutaneous present in humans and some marine mammals he had seen skinned on a journey to the Antarctic in 1927, to write a series of articles in the magazine New Scientist to clarify his position on the subject. Kossy relates the words of Hardy from an April issue of the magazine (although the year is not specified);

My thesis is that a branch of this primitive ape-stock was forced by competition from life in the trees to feed on the seashores and to hunt for food, shell fish, sea-urchins, etc., in the shallow waters of the coast. I suppose that they were forced into the water just as we have seen happen in so many other groups of terrestrial animals. I am imagining this happening in the warmer parts of the world, in the tropical seas where Man could stand being in the water for relatively long periods, that is, several hours at a stretch. I imagine him wading, at first perhaps still crouching, almost on all fours, groping about in the water, digging for shellfish, but becoming gradually more adept at swimming. Then, in time, I see him becoming more and more of an aquatic animal going further out from the shore; I see him diving for shell fish, prising out worms, burrowing crabs and bivalves from the sands at the bottom of shallow seas, and breaking open sea-urchins, and then, with increasing skill, capturing fish with his hands.

Thus the more familiar image of the amorphous “Aquatic Ape” was born, wading out into the surf and feeling in the shallow sands for food. The early stage of such a transformation is awfully raccoon-like, as raccoons have incredibly sensitive hands that they use to feel about in streams and shallow waters for mussels, crayfish, and other morsels without being driven to become fully aquatic themselves. Nevertheless, the idea that man had his origins in a shallow sea rather than on a hot and brutal savanna was certainly controversial. Ever since Raymond Dart described the skull of the Taung Child in 1925 (shifting attention away from Europe and Asia for the origins of man) and the fossil assemblages of the South African caves were discovered, humans were thought to have evolved through a hunting culture, nearly every specialization that separates us from living primate relatives being due to our meat-craving societies. Indeed, the remains of Australopithecus found in South African caves (especially the jaw of a 12-year old child whose jaw appeared to have been fractured by a direct and accurate blow) like those Makapansgat suggested to Dart that these “proto-men” were not only skilled hunters, but also murderers and cannibals. Even though our understanding of these assemblages has greatly changed since Dart’s time (see C.K. Brain’s The Hunters or the Hunted?), the overall image of human evolution being intricately linked to meat-eating and hunting has dominated the discussion of our origins. Even more specifically, the considerations of our ancestors have nearly always focused on the male of the species, and even Hardy’s early ideas of an aquatic ape focused primarily on males.

In 1964, zoologist Desmond Morris published the bestseller The Naked Ape. Today the book is nearly useless outside of understanding the history of thought about human evolution, but when it was first published a short discussion of the AAH caught the attention of a woman named Elaine Morgan. On page 37 of the 1967 paperback edition, Morris states;

Another, more ingenious theory is that, before he became a hunting ape, the original ground ape that had left the forests went through a long phase as an aquatic ape. He is envisaged as moving to the tropical sea-shores in search of food. There he will have found shellfish and other sea-shore creatures in comparative abundance, a food supply much richer and more attractive than that on the open plains. At first he will have groped around in the rock pools and the shallow water, but gradually he will have started to swim out to greater depths and dive for food. During this process, it is argued, he will have lost his hair like other mammals that have returned to the sea. Only his head, protruding from the surface of the water, would retain the hairy coat to protect him from the direct glare of the sun. Then, later on, when his tools (originally developed for cracking open shells) became sufficiently advanced, he will have spread away from the cradle of the sea-shore and out into the open land spaces as an emerging hunter.

Unfortunately, [searching for fossils in marine or fluvial deposits or further research into the AAH] has yet to be done and, despite its most appealing indirect evidence, the aquatic theory lacks solid support. It neatly accounts for a number of special features, but it demands in exchange the acceptance of a hypothetical major evolutionary phase for which there is no direct evidence. (Even if eventually it does turn out to be true, it will not clash seriously with the general picture of the hunting ape’s evolution out of a ground ape. It will simply mean that the ground ape went through a rather salutary christening ceremony.)

[Emphasis mine]

Elaine Morgan read the brief treatment and qualifications (some of which has been omitted here for the sake of brevity) and wanted to know more about the possibility of our ancestors going through an aquatic stage of evolution. No information seemed to be available, and so Morgan wrote to Hardy in 1970, and he encouraged Morgan to push ahead with her research and desire to write a book about the AAH. The result was the bestselling The Descent of Woman, published in 1972. My copy is a little bit newer than that, being the Bantam 1973 edition, and featuring what appears to be a nude mother and child on the cover. Closer inspection reveals that something isn’t quite right, however; the mother I previously assumed was a representative of Homo sapiens looks like she’s been hit in the face with a frying pan. I didn’t know it at the time, but the text would reveal that the plump, nude, and long haired female on the cover was not drawn from life, but rather was Morgan’s idea of the Australopithecus specimen “Lucy” as Aphrodite.

Morgan’s first book is certainly a unique one, weaving in between “Just-so story” type paleo-fiction and long arguments about the female orgasm, including it’s fallacious mythical status. Indeed, the AAH only seems to occupy the first 1/3 of the book, only cropping up here and there in the following chapters, and receiving only a brief mention in the conclusion. Still, the way Morgan structures her argument in her first book will tell us much about her later works and the rise of the AAH as a popular idea. Early on in the work, we are introduced to a hypothetical female ape, not unlike Proconsul, living in Africa sometime during the Pliocene (~5.3-1.8 million years ago). During this time a hard life trying to find food and avoid predators was becoming even harder, Morgan hypothesizing that a terrible heat wave would change the way of life for many populations of these unnamed apes (from what I understand, however, the climate of the Pliocene began to approach our own and became cooler, drier, and had more seasonal distinctions rather than being a global hot-house).

Morgan’s ape was in a bit of a jam, that’s for sure. The water holes are said to be stalked by hungry cats and food was becoming scarce, and the imaginary female was not as fearsome or powerful as the males in her group. Eventually she was chased into the water by a large cat, and decides that, despite her distaste for water, “the seaside not at all a bad place to be. She found to her delight that almost everything on the beach and in the water was either smaller or more timid than she was herself.” Indeed, Morgan’s ape appeared to have found paradise. While other animals cooked during the “dog days of the Pliocene”, her ape (and by extension the population of apes) found what seems to be a sheltered and peaceful lagoon devoid of predators, scavengers, or other threats from either land or sea. “Leopards don’t come so far into the sea, nor sharks so near to the land,” we are told, and while leopards may not be attracted to water, sharks are well-known for their shallow water hunting habits. Crocodiles are not even considered, nor are stingrays, poisonous urchins, jellyfish, disease, infection, or any of the other biological problems that may come with an aquatic existence or change in ecological setting. The new home of the apes sounds better than Club Med, a watery Eden lacking in devious serpents and forbidden fruit.

As suggested by Morris and Hardy, the population of apes gets by on a diet of shellfish and relatively stupid sirenians that happen to come by, males making short work of the water-going creatures with rocks found along the shore. Given the amount of time that the apes would be spending in the water (they couldn’t have just subsisted by wading in or eating what washed up, or at least this is what is implied), bodies started to change. Males are paid little attention by Morgan, and the warm relationship between mother and child takes center stage. While most of the hair on the body would be lost as an adaptation to water (an odd conclusion given that otters, seals, and sea lions all are covered in hair), the hair on the head would be allowed to grow long, the water babies being able to curl their fingers into it and stay close to mom for a nap when they got tired of exploring off on their own. Conversely, breast feeding would still have to take place on shore, but the upright posture of the females (acquired from so much time in the water) would require the baby to be held at an awkward position in which they could not reach their mother’s nipples. This was solved by developing larger “hemispherical” breasts to reach down to the infant, even though larger breasts may cause infants problems when they try to get their mouths on them to breast feed (if the breast is so large that the infant’s nose is covered by it, breathing and feeding becomes difficult).

In searching for an aquatic example of such a striking characteristic, Morgan turns to the Florida manatee and other sirenians, many who have seen females with young noting the presence of “breasts” on the aquatic mammals. Interestingly enough, however, the manatee shares it’s ancestry with living elephants, the females of which also exhibit some rather sizable swellings when lactating. Robert Sapolsky, in his book A Primate’s Memoir, describes seeing such an unexpected shape on the chest of a female elephant for the first time;

Did you know that female elephants have breasts? I do not mean rows of teats, a mama elephant lying on her side with dozens of little piglet elephants nursing with their eyes still closed. I mean breasts, two huge voluptuous billowy mounds, complete with cleavage. I bet you had no idea, did you? Nor did I – it is a subject rarely broached in our public schools. I’m out in the bush that first month, armed with binoculars and stopwatch and notepad, spending the days carefully watching baboons mating left and right. And then, suddenly, some pachyderms come cruising past, and I see some elephant with these, well, breasts. And the natural first reaction is to think, Oh, great, I’m such a horny lascivious pathetic adolescent that after a mere month of isolation in the bush I’ve already cracked, I’m hallucinating breasts the size of Volkswagens on the elephants. Horrors, to have one’s psychotic break occur so soon, and to have it take the form of a puerile sexual obsession many embarrassing steps below gawking at National Geographic nudies. I was greatly relieved to eventually discover that the elephant’s breasts were real, that I was not having some Marlin Perkins wet dream.

It should be noted, however, that Morgan attributes an aquatic origin to elephants as well, primarily based upon their ability to shed tears (and therefore salt), as well as the ability of living Indian elephants to swim long distances in the ocean. Such considerations are a side trip from the main thrust of her argument, and no detail is given as to when, where, why, or how elephants arose from a water-dwelling species, only that a few characteristics in living animals point to an Aquatic Pachyderm Hypothesis.

Going back to the AHH, given about 10 million years in the water Morgan’s ape is substantially different than the one that was first driven into the waves by a predator. Referring to her as “Mrs. Australopithecus,” Morgan paints the following portrait (the artistic manifestation of which is found on the cover of the book);

So our hominid has a nose. I have no doubt that she also had fleshy nostrils, but considerable doubt that they evolved to make sex sexier for her mate. I think she was by no means the simian, cadaverous, lipless creature that artists sometimes reconstruct by covering her dug-up skull with a tightly fitting layer of hairy skin. The layer of fat which was rounding out her arms and legs and adding bulk to her breasts was also filling out her cheeks, and her nostrils, and her earlobes, and everting her lips… We would not have accounted her beautiful, with her low forehead and prognathous jaw, but the chances are that she was a chubby little creature with several superficial features resembling our own more nearly than they resembled any ape’s. And as for the expressions that flitted across that prehistoric countenance, her millions of years in the water had certainly left their mark on those also.

This is quite a different picture of “Lucy” than is often seen, but is there anything to it? Part of the advantage of the AAH is that Morgan doesn’t specify her ideas down to a scientific level, allowing her to poetically play with her ideas in any way she wishes, the female becoming more beautiful while the men continue to try and kill dugongs with rocks. This type of feminist reaction to the “Man the Hunter” narrative is the main connective feature throughout the book, and Morgan’s writing is far more concerned with the more graceful and beautiful evolution of woman, with sex ultimately bringing “sin” into the Garden.

In Morgan’s story, the genitals of the ancestral females went from facing backwards (making rear-mounting positions by the male easy) to facing downwards, a position that Morgan insists will not work for males, face-to-face mating being adopted as a must. Morgan’s reasoning for the change is that aquatic animals often undergo this type of genital shift (cetaceans are her primary example), but she generally ignores why the genitals should be shifted in the first place. In terms of cetaceans, the ancestors likely had their anal-genital openings in the position typical for quadrapeds; facing backwards at the location of the pelvis just under the tail, usually being at the most distal end of the body. As they evolved, the archaeocetes lost their hind limbs and their spines elongated, being the main source of propulsion, so rather than keep moving backwards with the spine the genitals stayed in the pelvic region “settled” on the ventral side of the body; where else they would have gone, I do not know. Given this morphological necessity, face-to-face mating became the only way cetaceans could copulate. Seals and sea lions, on the other hand, still have their anal-genital openings near the distal most parts of their bodies because that is where the pelvis is and there was no need to change mating styles, and males still mount females from behind. Even beyond such considerations, I do not see how the rear-mount strategy can be dogmatically ruled out, and I have a feeling that because such a position is considered “kinky” by some it was essentially ruled not to have happened. In fact, the retention of rear-mounting with the shift in female genitals could help explain elongation of the penis in males (they’d have to extend a bit farther), although this matter is far from settled. Curiously, Morgan generally ignores the bonobo and it’s face-to-face mating habits, even in her later books. She’s clearly aware of these apes (she does mention them and one graces the cover of The Descent of the Child), but they are conspicuously absent from discussions about sex.

Still, if we are to follow Morgan’s model, the apes would have to switch from mating using a rear-mount position to face-to-face (the males, we are told, couldn’t penetrate any other way), such a position causing much trauma for females. Males wouldn’t know how to calm the female for a face-to-face encounter, and it essentially led to either rape or an unfruitful attempt to mate. Morgan describes such a scene;

The primate was a totally different shape. Her new aquatic streamlining had been unable to prevent her becoming lumpy in the middle, and as a littoral biped her legs were developing in the opposite direction from the seal’s – they were becoming not smaller and thinner but farther apart, but longer and thicker and closer together. The seal’s solution was impossible for the aquatic apes. Their dilemma was unique.

So we left her on her back, kicking and struggling and frightened out of her tiny anthropoid mind, with her mate beginning to get irritated. When she saw him snarl and bare his canines she was finally convinced that he wanted her for dinner, and that her last hour had come. Further resistance was useless. She stopped fighting and signaled her submission, defeat, and appeasement as strongly as she could with so little room for maneuver.

Immediately, the incident was over. The male was a properly programmed animal, and it was impossible for him to go on clobbering a member of his own species that was giving clear indications that it had stopped fighting back. He moved a little way off, wearing a puzzled expression. He had thought for a moment that he was on to a good idea, but obviously there was a snag to it.

Such events removed us from our Eden along the shores, males taking up hunting on the plains soon after the eviction. Rains that quenched the African drought allowed the apes to leave the habitat that they had become so accustomed to (it seems like the males led the charge, being sick of their prolonged day at the beach), moving on to evolve in ways that fit the scientific orthodoxy of the times a bit more closely. Even so, Morgan suggests that women have retained the peace, beauty, and grace of their aquatic origins while males are more shaped by violence and hunting, her parting words being;

He is the most miraculous of all the creatures that God ever made or the earth ever spawned. All we need to do is hold out our loving arms to him and say: “Come on in, the water’s lovely.”

Oddly enough, such arguments seem more specific and in-depth than those in Morgan’s later works The Descent of the Child (1995) and The Scars of Evolution (1990). The Descent of the Child can largely be ignored, being that it’s primary focus is on doing for human babies (from conception through early childhood) what The Descent of Woman did for women, all-in-all being a string of facts presented to the reader in an easy-to-digest manner but without much further discussion. In covering past evolution, the “savanna hypothesis” and “man the hunter” are both alluded to or pointed out to be wrong, although no rigorous refutation is made. Instead the reader is referred to the earlier The Scars of Evolution for the “scientific” argument, but Morgan’s earlier poetry contains far more detail than the 1990 work. I breezed through the 178 pages of the book easily enough, but there was little positive evidence within it’s pages for the AAH. Certain physiological systems were pinpointed and deemed to be of aquatic origin since Morgan deemed no other hypotheses to be adequate (which, of course, assumes that all possibilities have been discovered and have received proper consideration).

I actually would love to write up a longer discussion of The Scars of Evolution but there is surprisingly little actual AAH evidence to be considered, and Morgan even makes some fairly basic mistakes about fossil preservation. Early on in the book she writes;

So if the prospecting had started in the north [of the Rift Valley] and worked down, popular illustrations of groups of Australopithecus would have shown them reclining under a shady tree at the water’s edge, living perhaps on fruit and greenery and fish. Instead, they are depicted as shaggy creatures trekking through parched grass and a scatter of stunted thorn bushes, turning to scavenging and hunting to supplement their diet.

This conclusion comes from Morgan’s assertion that some specimens of Australopithecus are found associated with fossils like crocodile remains and turtle eggs, suggesting an aquatic habitat. This largely ignores taphonomy, however, and an animal that dies in or near water being much more likely to be preserved and fossilized than one that drops out on the plains, the body undoubtedly being ripped apart by scavengers and leaving little or nothing to the fossil record. Most of the rest of the book covers material already mentioned in The Descent of Woman, like the fallacious notion that pheromones are essentially nonexistent or non-influential in humans because we went through an aquatic phase of evolution where scent wouldn’t have counted for much. Also curious is one of Morgan’s final statements about how evolution works, especially in regards to water. Rather than gaining specializations mentioned in so many of her works (i.e. the ability to cry and remove saline from the body, nostrils with possible flaps to keep water out, enlargement of the female breasts), a kind of de-volution of our ancestors is favored;

Conceivably, a species finding itself in a radically new environment (such as water) begins to shed the more advanced features which fitted it for its old environment. It back-tracks to a more unspecialized foetus-like form, before re-adapting to the new habitat. If that were the case, then our own ancestors, having moved from the land to the water and subsequently from water to land, would have been subjected to an impetus towards neoteny on two successive occasions. It would explain why in our case the trend was unusually powerful.

In all, Morgan’s work seem to be lacking of any rigorous research or hypotheses, and it led me to wonder why the AAH will simply not go away. Perhaps some of it is the mental appeal and the common error of linking correlation in evolutionary convergence to causation, working backwards to whatever ideal we hold most dear. Even if I’m incorrect as far as social motivation goes, the AAH has shown up in the scientific literature in the past few years, and it’s primary advocate seems to be Marc Verhaegen. Although the majority of his papers seem to be currently unavailable online, there is no name that more frequently appears in terms of AAH literature in scientific journals, giving the hypothesis some visibility (and credibility, as far as AAH advocates may be concerned). Some of the papers published on the AAH I could find are;

Bender R, Verhaegen M, & Oser N. “Acquisition of human bipedal gait from the viewpoint of the aquatic ape theoryAnthropol Anz. 1997 Mar;55(1):1-14.

Cunnane, S.C. “The Aquatic Ape Theory reconsideredMedical Hypotheses Volume 6, Issue 1, January 1980, Pages 49-58

Ellis, D.V. “Wetlands or aquatic ape? Availability of food resources.Nutr Health. 1993;9(3):205-17.

Rhŷs Evans, PH. “The paranasal sinuses and other enigmas: an aquatic evolutionary theoryJ Laryngol Otol. 1992 Mar;106(3):214-25.

Vaneechoutte, M. ” Report of the Symposium ‘Water and Human Evolution’, Gent, Belgium, April 30th 1999Human Evolution. 2000 Volume 15, Numbers 3-4

Verhaegen, M.J.B., Puech, P.F., & Munro, S. “Aquarboreal ancestors?Trends in ecology & evolution (Amsterdam). 2002 Vol. 17, Issue 5, page 212

Verhaegen, M.J.B. and Puech, P.F. “Hominid lifestyle and diet reconsidered: paleo-environmental and comparative dataHuman Evolution. 2000 Volume 15, Numbers 3-4

Verhaegen, M.J.B. “The Aquatic Ape Theory and some common diseases”. Medical Hypotheses
Volume 24, Issue 3, November 1987, Pages 293-299

Verhaegen, M.J.B. “The Aquatic Ape Theory: Evidence and a possible scenario
Medical Hypotheses Volume 16, Issue 1, January 1985, Pages 17-32

Verhaegen, M.J.B. “Aquatic ape theory and fossil hominidsMedical Hypotheses Volume 35, Issue 2, June 1991, Pages 108-114

Verhaegen, M.J.B. “Aquatic ape theory, speech origins, and brain differences with apes and monkeysMedical Hypotheses Volume 44, Issue 5, May 1995, Pages 409-413

[And for an opposing view see Langdon, J.H. “Umbrella hypotheses and parsimony in human evolution: a critique of the Aquatic Ape HypothesisHuman Evolution. 1997, Volume 33, Number 4, pp. 479-494(16)]

As is immediately apparent, the great majority of the papers have appeared in one journal (Medical Hypotheses) and can be attributed to one author, Verhaegen. Judging from what I was able to find, many of the arguments that Verhaegen employs are very similar to those of Morgan, working backwards from somewhat contested or enigmatic human features to an aquatic origin to the exclusion of other hypotheses. Where Verhaegen differs, however, is that his aquatic hypothesis is far more broad than that of Hardy or Morgan. While Morgan implied that the aquatic apes were an isolated group that ended up leading to man (what happened to populations elsewhere is never spelled out), Verhaegen suggests that the last common ancestor of living gorillas, chimpanzees, bonobos, and humans was at least semi-bipedal and semi-aquatic, likely living in a habitat like a mangrove swamp. From the paper “Aquaborel ancestors?”;

A vertical posture and an ability to climb with the arms raised above the head could have helped a wading primate to enter or leave the water by grasping overhanging branches or waterside vegetation, and to grasp fruits above the water. Body enlargement and tail reduction would hinder agile arborealism, whereas a larger body is more easily supported in water and helps reduce heat loss (explaining why aquatic mammals are larger than related terrestrial forms). Tails would be of little use for a wading and/or swimming primate and would cause both drag and heat loss.

Thus Verhaegen attempts to separate New and Old World monkeys from apes by making the ancestors of all living apes at least partially water-bound, standing up to wade through water. Ultimately humans would have stayed in the pool while gorillas and chimpanzees got out, although gorillas, chimpanzees, and bonobos do not seem to show the same signs of being adapted to water that are often associated with humans under the AAH. Of further note is the fact that living primates like baboons, macaques, and proboscis monkeys have been known to swim and stand upright in water, although none seem to show signs of becoming exclusively adapted to an aquatic lifestyle. In the recent BBC series Planet Earth, baboons of the Okovango Delta in Botswana were shown wading through the water;

The baboons are not especially comfortable in the water, just as many other animals in the delta like cheetahs and lions don’t especially like crossing the waterways. Indeed, crocodiles are the primary danger in the water, and many animals seem to know of the threat all too well (but must cross from time to time, anyway). Such modes of moving through water, also seen in chimpanzees (see the final episode of the BBC’s Life of Mammals, entitled “Food for Thought”), seem to constitute the “weak” version of the AAH, and isn’t entirely unreasonable in explain possible motivation to become bipedal. It does require a certain ecology, however, (i.e. flooded plains, a swamp, shallow mangrove forest, lagoon, etc.) and has little explaining power out of such a context. Still, there are even more aquatic primates that were also featured in Planet Earth; the crab-eating macaques.

If we’re looking for a model of what an aquatic ape would look and act like, surely these monkeys would be it, and Morgan does note some of the aquatic habits of macaques (especially the behavior of washing food in water, as seen in Japanese Macaques). The problem is that macaques are monkeys, not apes, although they seem to get along in the water just fine. Unfortunately the adaptation of these primates to water is going to be slow and take many generations, but the study of these animals could give us some clues as to what the AAH can and cannot explain, although it seems that many of the features explained by the AAH don’t fit with what we see in the macaques. Looking at the underwater behavior, it would seem that the monkeys would be adapted to swim in a matter similar to that of quadrupeds rather than to start wading in, becoming bipedal, and then doing a breast-stroke. Indeed, the video shows that becoming bipedal is not a necessary precursor to being able to swim or becoming semi-aquatic, and it is quite possible (even probable) that primates could abandon the upright stage altogether. Standing upright seems to be generally uncomfortable for many primates, and it’s hard to see how primates introduced to a fruitful aquatic habitat would want to stand up before just jumping in if there was really nothing to fear in the waters. Even in the weak version of the AAH, it is hard to see how standing upright while crossing a river would have selected for bipedalism as it seems that many primates are capable of doing it over short periods and it does not hold any strong advantage that would relate to mating success or overall survival. Unless the hypothetical apes lived in an area constantly flooded, requiring them to stand up much of the time, it is difficult for me to imagine how water could have helped to select for an upright posture.

The overall problem I have with Morgan’s hypothesis about apes becoming almost exclusively aquatic is that it forces us to make a choice of one habitat or another. Mentions are made of Proboscis Monkeys and Macaques enjoying a swim, washing off food, or living near water, but they don’t seem to be bent on the same path as the one Morgan proposes. Organisms certainly are plastic, and they don’t rigidly abide by the “rules” set down by those that describe them as to where to live, what to eat, and how to act properly. In fact, it seems more reasonable to me that primates past and present would take advantage of an aquatic resource if readily available, but still maintain their terrestrial life unless they were so isolated that they had no choice for food other than the water. Time will tell if some of today’s semi-aquatic primates ever become more fully at home in the water, but I see no reason to believe that our ancestors decided to take a prolonged summer vacation on the beach, proceeding in a way that just so happened to explain everything neatly (if un-parsimoniously).

The AAH hinges on apes willingly going into the water for safety from predators, but this is only a Just-So story without the details. It also ignores the fact that the water can be almost as dangerous, if not moreso, than the land, and there are predators in the water just as there are in terrestrial habitats, not to mention rip-tides and other problems inherent to the ocean itself. While Morgan, in The Descent of Woman, states that newborns could be left to paddle about on their own while mom went about her own business, such maternal inattention doesn’t seem like it would be especially effective in making sure that young made it to adulthood. Only the calmest, most sheltered, and safe of lagoons would have allowed for this. If the AAH is to be taken seriously in whatever form, it is going to require rigorous ecological study, and so far it seems that it relies far more on post hoc arguments than actual evidence.

While Jim Moore has already done a fantastic job dismantling the various problems with the AAH, I hope I have helped to illuminate the overall lack of evidence for the idea. As an idea it’s not a bad one, but it seems to have never gone beyond hypothetical situations and Just-So stories, and most of the ideas associated with the AAH seem to be criticisms of other hypotheses, therefore leaving the AAH as the only alternative. While I can certainly appreciate the frustration Morgan and others must have felt (and even still feel) towards a male-dominated field in science and consideration being mainly given to the strong, archetypal male, I feel that the AAH is taking things too far in the other extreme. It is hard to ignore the feminist underpinnings of Morgan’s writing and the overall disregard for the big picture in order to bring women and children into closer focus. Combating a hypothesis you don’t like with an equally narrow one, just reversed, is not the way to bring greater understanding of our evolutionary history, and given that hominids and apes are so close to us, it’s easy to fall into trapping of preference. Being that I am no expert on the matter, however, I will close with T.H. Huxley’s final words from his work Man’s Place in Nature, as they seem to resonate with the big questions about our origins that remain unknown;

Where, then, must we look for primeval man? Was the oldest Homo sapiens pliocene or miocene, or yet more ancient? In still older strata do the fossilized bones of an Ape more anthropoid, or a Man more pithecoid, than any yet known await the researches of some unborn paleontologist?

Time will show. But, in the meanwhile, if any form of the doctrine of progressive development is correct, we must extend by long epochs of the most liberal estimate that has yet been made of the antiquity of Man.





Seeing red pink

21 08 2007

Update: I guess all those cranky folks who said that Led Zepplin were girls because of their long hair were right; click here to see Plant and Page in pink. Oh, and I hear that Aerosmith is quite fond of pink too…

Everyone knows that blue is for boys and pink is for girls; everything from the color of baby clothes to the paint on the walls of elementary school bathrooms reinforces this point. Even though it hasn’t always been this way (it used to be that pink was for boys and blue was for girls), there is no mistaking the trend that girls in some technologically advanced societies prefer pink hues and boys prefer blue, and a recent study has attempted to explain why this might be. In the most recent issue of Current Biology researchers Hurlbert and Ling published the study “Biological components of sex differences in color preference,” and it certainly has caused quite a stir on the internet, yet I’m not so sure that the author’s “confirmation” of cultural expectations is entirely accurate.

The people studied in this survey were Chinese and British, two cultures that have been culturally/technologically/etc. advanced for some time. Thus, there is certainly an issue of “nature v. nurture” that cannot be avoided. Colors carry any number of cultural connotations, varying from one society to another, and so there may be an inherent bias for or against certain colors. The researchers even recognize this, writing;

In China, red is the color of ‘good luck’, and our Chinese subpopulation gives stronger weighting for reddish colors than the British.

Still, they say, there is a biological (even evolutionary) basis for the preference of reddish colors among women. Before I go on further, I should probably state what the authors found and propose. After testing 208 subjects (171 being from the UK) from two cultures, the authors found that while both sexes seemed to like the color blue, females preferred reddish/violet hues much more than men. Looking at the graphs, however, this disparity is much more marked in the UK than in China, and this is probably because (as the authors mentioned) red is considered to be a “good luck” color in that culture. Assuming that these preferences do have a biological basis, however, how can they be explained? The authors look to the hunter/gatherer dichotomy of ancient peoples (and I would assume some hominids, by extension);

The hunter-gatherer theory proposes that female brains should be specialized for gathering-related tasks and is supported by studies of visual spatial abilities. Trichromacy and the L–M opponent channel are ‘modern’ adaptations in primate evolution thought to have evolved to facilitate the identification of ripe, yellow fruit or edible red leaves embedded in green foliage. It is therefore plausible that, in specializing for gathering, the female brain honed the trichromatic adaptations, and these underpin the female preference for objects ‘redder’ than the background. As a gatherer, the female would also need to be more aware of color information than the hunter. This requirement would emerge as greater certainty and more stability in female color preference, which we find. An alternative explanation for the evolution of trichromacy is the need to discriminate subtle changes in skin color due to emotional states and social-sexual signals; again, females may have honed these adaptations for their roles as care-givers and ‘empathizers’.

First, for those unfamiliar with the term, trichromacy is the condition of having three different kinds of cone-cells in the eye, allowing animals that posses these three cone cells to see long (L, red), medium (M, green), and short (S, blue) wavelengths of light. Humans are trichromatic, as well as some primates, some marsupials, honeybees, and assorted other animals. Being trichromatic allows an organism to better distinguish colors, which is very important if you’re using plants for food (or live in a place with lots of strikingly colored insects, reptiles, and other creatures that advertise their poisons, or your species has evolved very colorful mating displays). Enter the hunter-gatherer stereotype. The hypothesis the authors put forth in the paper is hypothetical and relatively superficial, depending on woman only gathering and consuming the plant material and men only doing the hunting (and consuming the meat). No mention is made of food sharing, and the mistake of a female picking a poisonous fruit having implications beyond herself. Indeed, in many tribal societies today (i.e. the !Kung people) the men go out and hunt to procure the meat and the women gather roots, tubers, and plant material, all of which is shared. What people do today, however, isn’t a catch-all for ancient behaviors, but even if males were stingy with the meat, they would have likely shared with the females, the males also having to eat plant material as meat can be hard to come by (unless they were lazy and just made the females do all the gathering).

For a moment, however, let’s assume that females only gathered the food and ate the plants first, those picking poison fruits dying and other members knowing not to eat what that female just ate (this is already stretching things a bit, I think). Why should the ability to recognize ripe fruit vs. unripe fruit based upon the color red only be passed on to females? I’m not as well-versed with genetics as I would like to be, and obviously there are some traits that belong to females and not males, but if poisonous or un-ripe fruits created such a selective pressure why was it only passed on to the one sex? I would imagine that the trait for better red-detection would have to be X-linked and require a copy of it on each of the female X chromosomes (thus males, even if they carried one copy of the gene dictating this, would always be recessive and not express the trait). Perhaps this is possible, but the published work does not pursue the question into this area.

The second problem I have is the general “women are more empathetic and therefore have use to telling the detecting emotions.” If we’re talking about redness, we’re probably not talking about anything subtle, and it would be of an advantage for males to detect red just as much as females (especially if dealing with angry dominant males). Being flushed with red usually signals embarrassment, excitement, or anger, the physiological sign usually being accompanied by other behaviors, and so I don’t think the “empathetic woman” example proves the case here either.

In the end, I think the study has more sociological/psychological value than anything else. This should not stop further questioning in this area, however. Rather than testing people who have grown up in societies where there have been strong gender roles associated with blue and red, we should look to other cultures and perform the same test. The problem is that red is a very distinct color and will carry meaning wherever we may go for such a study, but a larger data set may show an underlying preference of women for red across cultural boundaries, at which point I’d be more likely to accept that the results are not the result of a particular culture or society. Differences in the color receptors in male v. female eyes should also be studied and if there is a marked difference, we should try to figure out where that difference stems from. In all, however, this study reminds me more of evolutionary psychology than anything else; picking behavioral/cultural traits or preferences present now and trying to trace them backwards in order to explain them, often (as in this case) built upon a huge heap of assumptions. There are certainly more questions in this case than answers, and I had hoped that such problems with the study would have been considered before it started showing up as the great confirmation of color-choices in various news outlets.

P.S.> I just occurred to me that the implications of this study aren’t so much about “seeing” red as preferring red. It could be relatively easily tested whether men or women can see shades of red/violet better and if the number of L cones in the eye differed between sexes. Instead, the study is attributing an affinity (essentially a behavior) as an acquired reaction to the environment, and it all seems a bit Neo-Lamarckian. I can understand a gene that allows for better detection of red, but that doesn’t automatically mean that the organisms that have that ability will have an affinity for red based upon fruit ripeness in their environment. The more I think about this study, the sillier it seems to get…

Refs:
Hulbert, A.C. & Y Ling. 2007. Biological components of sex differences in color preference. Current Biology 17, R623-R625.





Homo sapiens: The Evolution of What We Think About Who We Are

11 08 2007

[Note: I definitely didn’t expect the welcome reception this post has received from so many notable bloggers! Thank you all for your support and compliments. I took a few snapshots and have uploaded them, although I admit they are not of the best quality. I will come up with some better versions of these images when I have more time this week.]

Pondering
From the Wellcome Images Collection

How many ribs do humans have? Despite it being a fairly straightforward answer, you may get different replies depending on who you ask. Few people will know the exact number (12 pairs), but a surprisingly large amount of people might tell you that while women have a full set, men come up one short. Basic anatomy proves this to be wrong, but then again most people have not studied basic anatomy, so where would such an idea come from?

20: And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field; but for Adam there was not found an help meet for him.

21: And the LORD God caused a deep sleep to fall upon Adam, and he slept: and he took one of his ribs, and closed up the flesh instead thereof;

22: And the rib, which the LORD God had taken from man, made he a woman, and brought her unto the man.

23: And Adam said, This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man.

– Genesis 2:20-23

It almost sounds like a Neo-Lamarckian belief; that because God took a rib from Adam (whether it was just one or one pair, the book does not say) to make Eve in the second Genesis creation story, all men should inherit the trait of missing one rib. In fact, it is possible (even likely) that the “rib” taken from Adam was not one of the bones in his chest at all, but rather a mythical baculum (or “penis bone“), which is present in most mammals but missing in man and a few others. Despite the Bible being opaque on the topic of general anatomy, however, the belief that the number of ribs in men and women are different is widespread and I am often met with astonished faces when I tell people who accept the idea that there is no difference between the sexes in that respect at all. Outside of a widespread unfamiliarity with basic human anatomy, the belief shows us something else; that just as Homo sapiens has evolved, so too have our ideas about ourselves, and vestiges of past beliefs still remain in the skeletal structure of our understanding.

Skeleton
From William Cheselden’s The Anatomy of Bones. This image also graces the cover of my copy of William Paley’s Natural Theology.

Although the Genesis account of the creation of man is probably the most familiar, it is far from being original. The concepts found in the first chapters of the book of Genesis correlate surprisingly closely to earlier beliefs of the Chaldeans and Babylonians, from the differing orders of the two creation accounts to the dispersal at the Towel of Babel. Seeing that the myths from which the Genesis account derive no longer exist in their original form, however, we will start our intellectual foray with the set of beliefs that rails against science even to this day; that humans were specially created by God less than 10,000 years ago, from little more than some dirt and a rib. As alluded to before, the accounts of the creation of humans contradict each other and cannot be reconciled (as many apologists attempt to do) by saying that the account given in Genesis 1 is merely an overview or outline, with Genesis 2 filled in the details.

If we look at Genesis 1, God creates plant life (before the “lights in the firmament”), then life in the water and the air, then all the “beasts” and “creeping things” (of which there are many more than the beasts), and then both sexes of Homo sapiens simultaneously;

27: So God created man in his own image, in the image of God created he him; male and female created he them.

The God of Genesis 2 does things a little differently (perhaps even taking a more pragmatic approach). We are told that because there was “no man to till the ground,” there was no point in creating plants on earth before people. Thus God watered the entire face of the earth and then created man, “planting” the man in Eden. It might be impious to think this way, but whenever I read that verse (Genesis 2:8) I can’t help but imagine a gigantic hand picking up Adam by the scruff of his neck and literally placing him back down in the Garden. Imagery aside, God then populates the Garden with plant life (which in Genesis 1 was long established on earth before Adam came to be), and then decides that it isn’t good to have Adam wandering around Eden by himself. We are told that God then created all the “beasts of the field” and “fowl of the air” and had Adam name them (but neglected to form a proper system of taxonomy or systematics), but no “help mate” was to be found. Then comes to famous rib-story (see above), things finally being set right in Eden, at least until that whole forbidden-fruit business. Despite the strange inconsistencies, in both accounts humans are the crowning achievements of the Creation, told to “subdue” the planet and to reproduce in order to fill it. This idea of trampling nature beneath our heel has resonated with people for thousands of years, although theology has twisted various aspects of Genesis this way and that to suit certain needs.

Indeed, while Adam and Eve were supposed to be the ancestors of all humanity, some groups of people were left out of the picture. Just like certain lower classes of people in other cultures were said to be formed from the “dirt of the body” particular gods, denoting their inferior existence, people with darker skin were deemed to be bearing the “Mark of Cain” or to be “Sons of Ham,” in either case slavery being justified for the sins of the proginator of that line. Thankfully this view has now largely been abandoned, although vestiges of such superstitions remain today (and equality wasn’t even given to these people until the middle of the last century in the United States). Racism and the Biblical justifications for it is another complex issue however, and it is only mentioned here to elucidate the point that even in theology, the origins of man have not always been used for good or just ends.

Progress
The first section of the original “March of Progress” from F. Clark Howell’s Early Man

While basic researches into ancient Egypt and other cultures began to show that the chronology determined by Lightfoot, Ussher, and others was far too short to be accurate, our place as a special creation didn’t start to be truly challenged until the remains of ancient peoples unlike ourselves began to be discovered. Fossils found by many cultures had long been thought to be evidence of gods, titans, giants, dragons, and monsters (see Adrienne Mayor’s The First Fossil Hunters), but these remains seemed to be more curiosities or holy relics than the remains of people more ancient than anyone then conceived of. Andrew D. White tells us in his masterwork A History of the Warfare of Science With Theology in Christendom;

In France, the learned Benedictine, Calmet, in his great works on the Bible, accepted [“the doctrine that fossils are the remains of animals drowned at the Flood”] as late as the beginning of the eighteenth century, believing the mastodon’s bones exhibited by Mazurier to be those of King Teutobocus, and holding holding them valuable testimony to the existence of the giants mentioned in Scripture and of early inhabitants of the earth overwhelmed by the Flood.

Even in the 1854 edition of Gideon Mantell’s Medals of Creation, fossil remains of humans are not mentioned because they seemed to be conspicuously lacking. In the “Retrospect” of the book Mantell writes;

But of MAN and his works not a vestige appears throughout the vast periods embraced in this review. Yet were any of the existing islands or continents to be engulphed in the depths of the ocean, and loaded with marine detritus, and in future ages be elevated above the waters, covered with consolidated mud and sand, how different would be the characters of those strata from any which have preceded them! Their most striking features would be the remains of Man, and the production of human art – the domes of his temples, the columns of his palaces, the arches of his stupendous bridges of iron and stone, the ruins of his towns and cities, and the durable remains of his earthly tenement imbedded in the rocks and strata – these would be the “Medals of Creation” of the Human Epoch, and transmit to the remotest periods of time a faithful record of the present condition of the surface of the earth, and of its inhabitants.

This doesn’t mean that the remains of humans were not thought to be found, however. In an earlier chapter on reptiles (being that amphibians were included within the reptiles in Mantell’s work), the author writes;

A celebrated fossil of this class is the gigantic Salamander (Cryptobranchus), three feet in length found at Ceuingen, which a German physician of some note (Scheuchzer) supposed to be a fossil man!

Mantell
Scheuchzer’s tricky salamander, from the 2nd volume of Mantell’s Medals of Creation.

The view of fossils began to change, however, as creatures were found that could not simply be considered giants, gods, or heroes. A.D. White quotes Dr. Anton Westermeyer’s The Old Testament vindicated from Modern Infidel Objections as follows;

“By the fructifying brooding of the Divine Spirit on the waters of the deep, creative forces began to stir; the devils who inhabited the primeval darkness and considered it their own abode saw that they were to be driven from their possessions, or at least that their place of habitation was to be contracted, and they therefore tried to frustrate God’s plan of creation and exert all that remained to them of might and power to hinder or at least, to mar the new creation.” So came into being “the horrible and destructive monsters, these caricatures and distortions of creation,” of which we have fossil remains. Dr. Westermeyer goes on to insist that “whole generations called into existence by God succumbed to the corruption of the devil, and for that reason had to be destroyed”; and that “in the work of the six days of God caused the devil to feel his power in all earnest, and made Satan’s enterprise appear miserable and vain.”

Indeed, although the first known remains of Megalosaurus were confused to be the enormous testicles of an “Antediluvian Giant,” the rest of the skeletal remains found by Dr. Buckland (and those of Iguanodon found by Mantell) showed that these animals could not be considered to be characters introduced to us in the Biblical narrative of creation or history. While evolution or “transmutation” of species was not yet ready to make its full appearance on the scientific stage, some did recognize the fossils as representing animals long gone, and the concept of extinction that Cuvier did so much to establish became essential to scientific thought and was a great victory over the religious dogma that God would not create a “kind” of animals and then let them be destroyed. This does not mean that other explanations of these remains were not legion, however.

Despite his contributions to marine biology, Philip Henry Gosse published one of the most infamous attempts to reconcile the geologic column with a historically-accurate Genesis account in his 1857 book Omphalos: An Attempt to Untie the Geological Knot. Taking the reader on a painfully protracted tour of creation, the author introduces us to Adam, the prose suggesting that Gosse has persuaded Adam to sit down for a full anatomical evaluation. After detailing certain aspects of Adam’s anatomy (including the ever-problematic navel), Gosse tells us that every bit of Adam’s anatomy tells of a full human life, from gestation to birth to growth, but this is merely a set-up. Gosse writes;

How is it possible to avoid this conclusion? Has not the physiologist irrefragable grounds for it, founded on universal experience? Has not observation abundantly shown, that, wherever the bones, flesh, blood, teeth, nails, hair of man exist, the aggregate body has passed through stages exactly correspondant to those alluded to above, and has originated in the uterus of a mother, it foetal life being, so to speak, a budding out of hers? Has the combined experience of mankind ever seen a solitary exception to this law? How, then, can we refuse the concession that, in the individual before us, in whom we find all the phenomena that we are accustomed to associate with adult Man, repeated in the most exact verisimilitude, without a single flaw-how, I say, can we hesitate to assert that such was his origin to?

And yet, in order to assert it, we must be prepared to adopt the old Pagan doctrine of the eternity of matter; ex nihilo nihil fit. But those with whom I argue are precluded from this, by my first Postulate.

Gosse’s first Postulate being;

If any geologist take the position of the necessary eternity of matter, dispensing with a Creator, on the old ground, ex nihilo nihil fit, – I do not argue with him. I assume that at some period or other in past eternity there existed nothing but the Eternal God, and that He called the universe into being out of nothing.

All such considerations from Gosse, Mantell, and others seem to ignore that remains like, yet unlike, humans were already being discovered during the 19th century. While the most noted discovery of Neanderthals occurred 151 years ago this past week, fossils of hominids we now call Neanderthals were found in 1829 and 1848, A.D. White mentioning unspecified “human remains” being found “as early as 1835 at Cannstadt near Stuttgart” as well. Still, the remains of Neanderthals and stone tools seemed to be too close to Homo sapiens to dissuade advocates of special creation that man had evolved, although scientists were able to confirm that the origins of mankind were probably far older than anyone had previously thought.

The publication of Charles Darwin’s On the Origin of Species by Natural Selection made evolution a scientifically credible and defensible idea, however, and while he generally avoided the evolution of humans in this work (it being more important to convince readers that evolution has in fact occurred rather than offending religious sensibilities of the time head-on), he later addressed the issue directly in The Descent of Man. Darwin writes in the Summary;

Man may be excused for feeling some pride at having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen, instead of having been aboriginally placed there, may give him hope for a still higher destiny in the distant future. But we are not here concerned with hopes or fears, only with the truth as far as our reason permits us to discover it; and I have given the evidence to the best of my ability. We must, however, acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system – with all these exalted powers – Man still bears in his bodily frame the indelible stamp of his lowly origin.

Mandrill
A Mandrill as it appears in the 2nd edition of Darwin’s The Descent of Man.

Darwin wasn’t the first to consider that men today had changed from earlier forms, although Darwin was much closer to the truth than other intellectual peers. The Ionic philosopher Anaximander proposed an idea that later would come back, in new form, as the Aquatic Ape Hypothesis. In his valuable book From the Greeks to Darwin, Henry Fairfield Osborn presents Anaximander’s thesis thusly;

He conceived of the earth as first existing in a fluid state. From its gradual drying up all living creatures were produced, beginning with men. These aquatic men first appeared in the form of fishes in the water, and they emerged from this element only after they had progressed so far as to be able to further develop and sustain themselves upon land. This is rather analogous development from a simpler to a more advanced structure by a change of organs, yet a germ of the Evolution idea is found here.

We find that Anaximander advanced some reasons for this view. He pointed to a man’s long helplessness after birth as one of the proofs that he cannot be in his original condition. His hypothetical ancestors of man were supposed to be first encased in horny capsules, floating and feeding in water; as soon as these ‘fish-men’ were in a condition to emerge, they came on land, the capsule burst, and they took their human form.

After evolution became established in both terms of fact and theory, the great fossil collectors of the late 19th and early 20th century began to come up with hypotheses as to from whence came Homo sapiens. In his Neo-Lamarckian 1896 treatise, Edward Drinker Cope proposed the following hypothesis;

The relation of this fact [“the high percentage of quadritubercular superior molars in the Malays, Polynesians, and Melanesians”] to phylogeny is to confirm Haeckel’s hypothesis of the lemurine ancestry of man. I have advanced the hypothesis that the Anthropomorpha (which include man and the anthropoid apes) have been derived directly from the lemurs, without passing through the monkeys proper. This close association of man with the apes, is based on various considerations.

Cope goes on to list some of the differences, focusing primarily on limbs and teeth, before coming to this passage;

Professor Virchow in a late address has thrown down the gage to the evolutionary anthropologists by asserting that “scientific anthropology begins with living races,” adding “that the first step in the construction of the doctrine of transformism will be the explanation of the way the human races have been formed,” etc. But the only way of solving the latter problem will be by the discovery of the ancestral races, which are extinct. The ad captandum remarks of the learned professor as to deriving an Aryan from a Negro, etc. remind one of the criticisms directed at the doctrine of evolution when it was first presented to the public, as to a horse never producing a cow, etc. It is well known to Professor Virchow that human races present greater or less approximations to the simian type in various respects… Professor Virchow states that the Neanderthal man is a diseased subject, but the disease has evidently not destroyed his race characters; and in his address he ignores the important and well-authenticated discovery of the man and woman of Spy. These observations are reinforced by recent discovery of a similar man by DuBois at Trinil in the island of Java [“Java Man,” otherwise known as Pithecanthropus erectus].

Progress 2
The second part of the original “March of Progress” from F. Clark Howell’s Early Man

Cope goes on to describe the fossils, noting that the remains DuBois had found do not seem to be of a Neanderthal, and Neanderthals are sufficiently far from humans that Cope finds the scientific name Homo neanderthalensis somewhat objectionable, the more defining characteristics of Neanderthals being found nowhere in the aboriginal peoples then known. Nowhere does Cope suggest an anagenic relationship of Neanderthals or “Java Man” as a direct ancestor, although their utility in showing evolution has occurred is invaluable. Still, the fossil remains of hominids (and in turn, their ancestors) were certainly wanting during Cope’s time, but in the first half of the 20th century some scientists became to come across some bonanzas in Africa. Raymond Dart was one of the most noted scientists to study the great fossil-bearing caves from Taung, Sterkfontein, and Makapansgat in South Africa. In the fantastic book The Hunters of the Hunted?, C.K. Brain shares with us this passage of Dart’s from his early discoveries in the caves;

The fossil animals slain by the man-apes at Makapansgat were so big that in 1925 I was misled into believing that only human beings of advanced intelligence could have been responsible for such manlike hunting work as the bones revealed… These Makapansgat protomen, like Nimrod long after them, were might hunters.

They were also callous and brutal. The most shocking specimen was the fractured lower jaw of a 12-year-old son of a manlike ape. The lad had been killed by a violent blow delivered with calculated accuracy on the point of the chin, either by a smashing fist or a club. The bludgeon blow was so vicious that it had shattered the jaw on both sides of the face and knocked out all the front teeth. That dramatic specimen impelled me in 1948 and the seven years following to study further their murderous and cannibalistic way of life.

As Brain then notes, such was the murderous Australopithecus of R. A. Dart; brutal savages and cannibals, making their tools and weapons out of the bones and horns of the animals that they managed to kill. Examinations of the cave after Dart, however revealed something incredibly different from the terrifying reign of the “protomen.” Humans were, in fact, prey for a long time, many remains attributed to cannibalism instead being signs that the caves once belonged to fearsome predators. One of the most famous evidences is part of a skull with two puncture holes, nearly exactly matching the canine teeth of a leopard. Indeed, the real story seems to be a struggle for existence among the hominids found in these areas, not being very advanced in hunting at all. Nonetheless, they eventually overtook the predators (when they weren’t stealing from their kills), and came to reside in the caves themselves. Such revelations, however, would have to wait until the 2nd half of the 20th century, and there were plenty more ideas about human origins prior to Brain’s 1981 book.

Despite the progress of science there have always been “fringe” hypotheses about humans and their place in the universe, and perhaps nothing fueled crackpot claims so much as the popularity of UFOs and the possible existence of aliens on Mars during the first half of the 20th century. Humans became the products of alien engineering projects, bizarre sexual encounters between aliens and early hominids, or even aliens themselves, having no remembrance of coming from a civilization on another planet. Racist hypotheses also abounded, and there were many odd amalgamations of cherry-picked scientific discoveries and superstition.

While some were content to conjure up ideas of aliens laying down with “Lucy”, scientists continued to attempt to determine not only from what ancestors man arose from, but where those ancestors may be. A.S. Romer, in the 1933 book Man and the Vertebrates Vol. I, supports H.F. Osborn’s view that man’s origins were likely to be found somewhere in Asia. Indeed, the famous 1923 expedition undertaken to the Flaming Cliffs of Mongolia by Roy Chapman Andrews that yielded Protoceratops and so many dinosaur eggs was intended to be a search for the ancestors of humans. Romer writes;

The fossil of Tertiary tropical life is, however, still comparatively unknown. It is not only possible but extremely probable that the Asiatic hills will, upon further exploration, give us the certain knowledge we desire of the primate ancestors of man.

Despite the lack of early ancestors, however, there was enough scientific understanding for Romer to close out the 1st volume with the following words;

Man has gone far and, we trust, may go still farther along the lines of evolution. But in his every feature – brain, sense organs, limbs – he is a product of primitive evolutionary trends and owes, in his high estate, much to his arboreal ancestry, to features developed by his Tertiary forefathers for life in the trees.

Romer’s diagram of human evolution varies from that described by Cope earlier, however. While Cope saw humans evolving directly from lemur-like ancestors, Romer created a diagram of extant primates (lemurs, tarsiers, new world monkeys, old world monkeys, great apes, and man) connected by one line, each of the groups branching off from the main line leading to man and seemingly having no relation to each other. This is part of the classic model of anagenesis that seems to suggest non-stop progress to man, almost as if a vitalistic force was setting humans on a fast-track (although I am not suggesting Romer had this view or advocated it; it merely seems to be an underlying theme in such illustrations). As G.G Simpson noted in the 1950 popular work The Meaning of Evolution, however, contentious fossil remains so close to humans can easily stir up trouble;

Primate classification has been the diversion of so many students unfamiliar with the classification of other animals that it is, frankly, a mess. It involves matter of opinion on human origins and, humans being what they are, such opinions are endlessly varied and not always distinguished by competence or logic.

Simpson
G.G. Simpson’s tree diagram of primate evolution, from the 3rd edition of The Meaning of Evolution.

Simpson’s diagram of primate evolution is a bit closer to truth than Romer’s from nearly 20 years earlier, as well. It more closely resembled the “branching bush” of evolution, groups linked by common ancestors with some lineages dying out and leaving no living descendants. Still, great apes are distinguished from “early man” and the genus Homo, and given that details are not given it can’t be ascertained whether Simpson held the view that all hominids discovered by that time were linked in a straight-line of evolution. Edwin H. Colbert (also of the American Museum of Natural History), put forth a similar view in his popular work Evolution of the Vertebrates, stating;

Even though human beings may not be descended from the australopithecines as we know them, it is very possible that man arose from australopithecine-like ancestors. The origin of the human stock probably occurred in late Tertiary times, for man is essentially a Pleistocene animal. Having become differentiated from his primate relatives, man evolved during the Pleistocene period along certain lines that made him what his is today. The evolutionary development of human beings was not of great magnitude within the course of Pleistocene history; rather it was a matter of the perfection of details that set man apart from all other primates, and from all other animals for that matter.

Colbert
The hominid reconstructions as they appear in Colbert’s Evolution of the Vertebrates.

This isn’t an especially profound statement, more along the lines of “Man is different from other animals, thus different things must have happened to cause his ‘perfection,'” but it does point towards the “ladder” view of human evolution. What Colbert is essentially saying is during the latest parts of human evolution, there was a refinement of types rather than major evolutionary change, and while he doesn’t line up a point-by-point lineage some of the pictures accompanying his text do suggest a sort of anagenesis from Australopithecus to Pithecanthropus to Neanderthals to Homo sapiens. Chris Beard, in his indispensable book The Hunt For the Dawn Monkey, attributes this view of human evolutionary “progress” to Sir Wilfrid E. Le Gros Clark, quoting Clark’s work The Antecedents of Man as follows;

Among the Primates of today, the series tree shrew-lemur-tarsier-monkey-ape-man suggests progressive levels of organization in an actual evolutionary sequence. And that such a sequence did occur is demonstrated by the fossil series beginning with the early plesiadapids [so-called “archaic primates” from the Paleocene] and extending through the Palaeocene and Eocene prosimians, and through the cercopithecoid [Old World monkeys] and pongid [apes] Primates of the Oligocene, Miocene, and Pliocene, to the hominids of the Pleistocene. Thus the foundations of evolutionary development which finally culminated in our own species, Homo sapiens, were laid when the first little tree shrew-like creatures advanced beyond the level of the lowly insectivores which lived during the Cretaceous period and embarked on an arboreal career without the restrictions and limitations imposed by… a terrestrial mode of life.

Potto
Skeleton of a Potto (a prosimian like a Loris) from the American Museum of Natural History

As Beard notes in his book, however, most of the hominid fossils then known were almost like bookends to a series, with the lemur-like ancestors (i.e. Notharctus from North America and Adapis from France) of later primates and the famous African and European hominids being the most well known. As countries became more open to science, however, more and more fossils came out of the ground, and Beard does note that while Africa may very well be the “cradle of humanity” in terms of hominids, if you really want to go back to the beginnings of prosimians Asia is the place to search. This somewhat vindicates those who thought that Asia would be the place to look for human ancestors, though not quite in the way they imagined. Even so, the ladder view seemed to be the favored one, at least for all fossil hominids younger than the Australopithecus. In his Vertebrate Paleontology (3rd Edition), A.S. Romer writes;

A word may be added here with regard to the nomeclature of human finds. We have freely used several generic terms for various early human finds. Such a usage implies that the forms differed widely from one another, had independent evolutionary histories, and did not interbreed – that the differences between them were not merely of species value but of such a magnitude as, for example, those between a cow and an antelope, a dog and a fox. This is absurd. Because they are so close to us, we tend to magnify differences. Actually, the differences between modern man and “Pithecanthropus” are, viewed impersonally, rather minor ones (particularly if we keep in mind the considerable variations found even today), and quite surely all types on the human line above the Australopithecus level pertain to our own genus Homo. Further, while communications between the various Old World area in which man was early present were obviously poor, and there presumably was little interbreeding and consequently (as today) a tendency for the differentiation of regional races, it seems fair to assume that throughout our long Pleistocene history, our human ancestors formed at all stages a single, if variable, group.

Despite this rather homogenous view of human evolution (the idea that Pithecanthropus falls within human variation being an idea that has reared its ugly head in modern creationism, as we’ll see later), Romer does make a distinction when it comes to Neanderthals. He writes;

A type of man definitely assignable to our own species, Homo sapiens, appeared in Europe well toward the end of the last glaciation, not more than 50,000 years or so ago. One would at first assume that he had arisen from his Neanderthal predecessor. But the contrasts are too great; there in (in Europe, at least) no evidence of transitional types; the appearance of modern man was, the evidence suggests, relatively sudden. There is every indication that the “modernized” invaders wiped out their predecessors (Tasmania is a modern parallel).

Progress 3
The third part of the original “March of Progress” from F. Clark Howell’s Early Man

Thus, during the 1960’s the evolution of man was rather ladder-like as it approached culmination, with relatively little radiation of types. The links to Australopithecus and Homo neanderthalensis as understood then were both doubted, although it was certain that humans had gone through a similar stage in the evolutionary process from the apes. Indeed, the ladder-view seemed to use representative types to show the gradation of evolution than linking all known hominids into a straight line (at least this is the impression from the popular works cited). Still, visual representations of human ancestry seemed far-more powerful than the actual text of many of these books, which brings us to the (in)famous “March of Progress.” The artwork, appearing in the 1979 Time-Life book Early Man by F. Clark Howell, certainly became iconic, and I am lucky enough to have a copy of the “Young Readers Nature Library” version of the book from my childhood. The “march,” with all members standing upright, carries this caption, and proceeds as follows;

The stages in man’s development from an apelike ancestor to the modern human being are shown in drawings on this and the following three pages. Some of the stages have been drawn on the basis of very little evidence – a few teeth, a jaw or some leg bones. However, experts can often figure out a great deal about what a whole animal looked like from studying these few remains. In general, man’s ancestors have grown taller as they became more advanced. For purposes of comparison, this chart shows all of them standing although the ones on this page [Pliopithecus through Oreopithecus] actually walked on all fours.

PliopithecusProconsulDryopithecusOreopithecusRamapithecusAustralopithecus africanusAustralopithecus robustusAustralopithecus boiseiHomo habilisHomo erectus – Early Homo sapiens – Neanderthal Man – Cro-Magnon Man – Modern Man

Progress 4
The final part of the original “March of Progress” from F. Clark Howell’s Early Man

Proconsul
Skull of Proconsul from the American Museum of Natural History

The inclusion of “Early Homo sapiens” before “Neanderthal Man” is a strange one, and even on the following pages australopithecines are shown living during the same time or exhibiting variation. While the author and artists of the book may not have meant to show that all the primates in their line evolved directly from their predecessors in line, the power of the image overwhelmed any explanation, and the image certainly became iconic. Evolutionary scientists did not sit idly by while a fallacious notion of human evolution was promulgated, however; Stephen Jay Gould opens his 1989 book on the Cambrian fauna Wonderful Life with his astonishment that his books, translated into other languages, bear the incorrect image. Gould writes;

The march of progress is the canonical representation of evolution – the one picture immediately grasped and viscerally understood by all. This may best be appreciated by its prominent use in humor and in advertising. These professions provide our best test of public perceptions. Jokes and ads most click in the fleeting second that our attention grants them. …

Life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress. Most people may know this as a phrase to be uttered, but not as a concept brought into the deep interior of understanding. Hence we continually make errors inspired by unconscious allegiance to the ladder of progress, even when we explicitly deny such a superannuated view of life. …

First, in an error that I call “life’s little joke”, we are virtually compelled to the stunning mistake of citing unsuccessful lineages as classic “textbook cases” of “evolution.” We do this because we try to extract a single line of advance from the true topology of copious branching. In this misguided effort, we are inevitably drawn to bushes so near the brink of total annihilation that they retain only one surviving twig. We then view this twig as the acme of upward achievement, rather than the probable last gasp of richer ancestry.

Gould as absolutely right; the iconic imagery of the “March” is so wrong, yet so easily understood, that it survives even when it is inaccurate. Creationists use it as a symbol of evolution (or, more often, mistakes evolutionary scientists have made), while satirists often use it to show the “devolution” of one group or another, and I doubt that the overall imagery will lose its utility anytime soon. If nothing else, the lesson we must learn from “The March of Progress” is that we are to use the utmost care in selecting visual representations of evolution, for one image can stay in the collective understanding (or misunderstanding) of a subject even when it’s accuracy has long passed the expiration date.

Going back to the thoughts of human evolution during the 60’s and 70’s, the life of earlier hominids was deemed to be a violent one, centering around man as the hunter. Without the ability to hunt as a group on dangerous African plains, we wouldn’t have advanced to our current state, requiring plenty of red meat to provide human ancestors more protein for their growing brains (or so was the logic, anyway). Some people, however, didn’t buy into this view that humans owe everything that evolution bestowed upon them to the Great Hunter, and so a feminist reaction was proposed; the Aquatic Ape Hypothesis. Centuries after Anaximander proposed his own views on the aquatic nature of man, Alister Hardy presented a lecture on “Aquatic Man: Past, Present, and Future” in 1960, and soon after he presented the idea to the public in a series of articles for New Scientist magazine.

The Aquatic Ape Hypothesis did not really take off, however, until a writer named Elaine Morgan published the book The Descent of Woman in 1972. Hardly a scientific work, the book focused more on a rejection of male-centered anthropology, and Donna Kossy provides an excerpt of Morgan’s prose in the book Strange Creations;

She knew at once she wasn’t going to like it there. She had four hands better adapted for gripping than walking and she wasn’t very fast on the ground. She was a fruit eater and as far as she could see there wasn’t any fruit… She never thought of digging for roots – she wasn’t very bright. She got thirsty, too, and the water holes were death traps with large cats lurking hopefully around them. She got horribly skinny and scruffy-looking.

…The only thing she had going for her was the fact that she was one of a community, so that if they all ran away together a predator would be satisfied with catching the slowest and the rest would survive a little longer.

What then, did she do? Did she take a crash course in walking erect, convince some male overnight that he must now be the breadwinner, and back him up by agreeing to go hairless and thus constituting an even more vulnerable and conspicuous target for any passing carnivore? Did she turn into the Naked Ape?

Of course, she did nothing of the kind. There simply wasn’t time. In the circumstances, there was only one thing she could possibly turn into, and she promptly did it. She turned into a leopard’s dinner.

With piercing squeals of terror she [a different ancestral ape] ran straight into the sea. The carnivore was a species of cat and didn’t like wetting his feet; and moreover, though he had twice her body weight, she was accustomed like most tree-dwellers to adopting an upright posture, even though she used four legs for locomotion. She was thus able to go farther into the water than he could without drowning. She went right in up to her neck and waited there clutching her baby until the cat got fed up with waiting and went back to the grasslands…

…One idle afternoon after a good deal of trial and error she picked up a pebble – this required no luck at all because the beach was covered with thousands of pebbles – and hit one of the shells with it, and the shell cracked. She tried it again, and it worked every time. So she became a tool user, and a male watched her and imitated her (This doesn’t mean that she was any smarter than he was – only that necessity is the mother of invention. Later his necessities, and therefore his inventiveness, outstripped hers.)

… She began to turn into a naked ape for the same reason as the porpoise turned into a naked cetacean, the hippopotamus into a naked ungulate, the walrus into a naked pinniped, and the manatee into a naked sirenian.

Morgan wrote other books on the subject and there still is a bit of a following to the idea that humans arrived in their current configuration due to an “aquatic stage” sometime in their history. Long hair on the head is for babies to cling to, large breasts float better than small ones, hairlessness makes one more streamlined, and nearly any part of the body that has been adapted this way or that, is potentially explained by life in or around the water, and even recent popular science books have taken a bit of a shine to Morgan’s hypothesis (like Survival of the Sickest). Despite the popular appeal, there is not much to the hypothesis, however, and no actual evidence to confirm it, fossil or otherwise. Indeed, it almost starts with modern female anatomy and works backwards, trying to find an explanation for this trait or that, based upon how we act in the water now, although if we were ever well-adapted to life in the sea we have lost such abilities. While Morgan was right to criticize the lack of attention given to women in terms of anthropology and evolution, her view is as extreme (if not moreso) than the one she was trying to replace.

And now we come to the present. The evolution of Homo sapiens from older species now extinct has long been established, the evolutionary history of hominids now understood to represent more of a “bush” than a ladder of progress. There are lineages that do show anagenesis or transitions from one species to another, but in the last few decades so many unexpected finds have come out of the ground that imagining human evolution to be a straight-line, deigned to produce us in our present form, is utterly ridiculous. There are still battles to be fought over which fossil fits where, what kind of dispersal early hominids had, what pressures led to our ancestors being obligate bipeds, but the competing hypotheses in such debates become more and more refined with every discovery, and the evidence supporting the fact that we have evolved cannot be overturned. This isn’t to say, however, that some trends in understanding ourselves or our ancestry haven’t changed. As I mentioned earlier, some of the diagrams of human evolution during the first half of the 20th century based themselves on living primates and prosimians, looking to them for the order in which we should place human evolution. There has been something of a return to this as of late, but in the area of evolutionary psychology rather than paleoanthropology. Chimpanzees and bonobos, after being confirmed as our closest living relatives, are often used as the two polar archetypes for our own ancestry; we were either violent like chimpanzees, horny bohemians like bonobos, or something in-between. While it is often noted that we humans have the ability to do good in spite of our evolutionary past, the authors of Demonic Males make their premise clear; all living male apes are exceedingly violent;

This helps explain why humans are cursed with demonic males. First, why demonic? In other words, why are human males given to vicious, lethal aggression? Thinking only of war, putting aside for the moment rape and battering and murder, the curse stems from our species’ own special party-gang traits: coalitionary bonds among males, male dominion over an expandable territory, and variable party size. The combination of these traits means that killing a neighboring male is usually worthwhile, and can often be done safely.

Frans de Waal, in Our Inner Ape, also recognizes our dark side, but is more of an optimist; he sees the sexual (and “peaceful”) culture of bonobos to be proof that violence is not pre-ordained for us. He writes;

That such a creature could have been produced through the elimination of unsuccessful genotypes is what lends the Darwinian view its power. If we avoid confusing this process with its products – the Beethoven error – we see one of the most internally conflicted animals ever to walk the earth. It is a capable of unbelievable destruction of both its environment and its own kind, yet at the same time it possess wells of empathy and love deeper than ever seen before. Since this animal has gained dominance over all others, it’s all the more important that it takes an honest look in the mirror, so that it knows both the archenemy it faces and the ally that stands ready to help it build a better world.

While chimpanzees and bonobos are our closest living relatives, we proceeded on our own line of evolution for at least 4,000,000 years, evolving on an apparently accelerated trajectory while our evolutionary “cousins” have not been adapted in exactly the same way. This is not an appeal to say that humans are so distinct that we should not look to living primates for answers about why we are as we are, but rather that we must also keep the long view in perspective. Exclusively using the behavior of living apes to work backwards to the behavior of our own ancestors treats the subject as if chimpanzees and bonobos our are ancestors, one of the biggest mistakes still made by people unfamiliar with how evolution works. Speaking of the “If we’re evolved, why are there still monkeys?” argument, it is now time to look at modern creationism and its view of human evolution.

As covered at the beginning of this post, the contradictory Genesis accounts tell of humans being created at some point in the past by the Judeo-Christian God, exactly when this event occurred being inferred from chronologies in the Bible. Still, how could such stories stand up to the weight of scientific evidence for our own evolution? The truth of the matter is that it cannot, but that has not stopped some from trying to bring us back to a reliance on Genesis. The first unsuccessful attempt to debunk human evolution I came across was in Jonathan Wells’ odious work Icons of Evolution, which bears a scaled-down version of the “March of Progress” on its cover. In the chapter discussing this particular “icon”, Wells notes that he is familiar with Gould’s rejection of the ladder-view of human evolution in Wonderful Life, but this does not seem to be sufficient for Wells. He engages in the following rhetoric in trying to make his case;

But how does Gould know that extinctions are accidents? On the basis of fossil evidence, how could he possibly know? Clearly, it takes more than a pattern in the fossil record to answer sweeping questions about direction and purpose – even if we knew for sure what those patterns are. And even if extinctions are accidents, does that rule out the possibility that evolution is goal-oriented? Everyone’s death is contingent; does that make everyone’s birth and life an accident? The continued existence of the human species is contingent on many things: That we don’t blow ourselves up with nuclear weapons, that the earth isn’t struck by a large asteroid, and that we don’t poison our environment, among other things. But it doesn’t follow that our very existence is an accident, or that human life is purposeless.

In this metaphysical muddle Wells offers up no evidence that extinctions have a purpose, that evolution is goal-oriented, or that human life has an inherent “purpose.” Indeed, he acts with such incredulity that he seemingly expects it to be contagious, luring the reader in with a string of absurd questions. There is no sign of evolution (or extinction) occurring as a part of a plan or having an ultimate goal and mind, and even if there was some sort of “directing force” to evolution it would seem to be an awfully wasteful process, never ensuring the permanence of a species (and would evolution, therefore, have an end?). What Wells essentially does is dress up Gould’s argument from Wonderful Life as a straw man, and apparently he doesn’t realize that Gould beat him to the punch about the famous illustration (and much more accurately, too) over a decade before Wells published his own book.

Young Earth Creationist ministries, like the well-known Answers in Genesis, take a slightly different approach; goading based upon the perceived authority of the Bible. In his tract The Lie, AiG leader Ken Ham includes cartoon after cartoon of the Bible being set up as the foundation for everything Christians believe, evolution being (often comically) set up as the origins of murder, abortion, and all sin. According to this view, even Old Testament figures like King David fell under the “evil influence” of evolution when they committed various sins, even though Darwin would not even be born until centuries later. The book states;

Society depends on moral foundations. By a mutual agreement which has sometimes been called a “social contract,” man, in an ordered and civilized society, sets limits to his own conduct. However, when such obligations are repudiated and the law collapses along with the order it brings, what option has the man who seeks peace? The psalmist is looking at the fact that whenever the foundations of society are undermined, then what have good and righteous men done to prevent its impending collapse?

Indeed, AiG sets the stakes high; nothing less than the existence of “civilized” and moral society rests on the battle being fought over evolution by creationists. Even those who accept evolution and are Christians are deemed to be compromisers, and generally looked down upon despite shared central theological beliefs. While the argument that there can be no morality without religion is certainly fallacious, it is a powerful concept, deeply tied to the evangelical desire to “save” those who have not accepted Jesus as God. What is even more surprising, however, is that creationists often state this weakness in their thought process up front; in the Young Earth Creationist view, nothing can contradict the Bible, and so anything that seems contradictory to accepted doctrine (which has, of course, been interpreted from the Bible by people) has to either be shoved into the Bible or dismissed as a lie or hoax. Case in point; AiG’s new geologist Andrew Snelling once tried to address the lack of human remains intermingled with those of dinosaurs and other fossil creatures from ages past (they should have been mixed together by the Flood) by stating that God made sure that no human remains survived the Flood so they would not be worshiped if found by subsequent generations of survivors. He wrote;

It would seem to us unloving of God to execute such relentless judgment, but such is God’s abhorrence of sin that its penalty must be seen for what it is—utter destruction and removal of all trace. If God cannot tolerate sin (His holiness cannot ‘look’ on sin), then all trace of sin has to be removed in judgment, which necessitates utter destruction. Should human remains have been allowed to survive the Flood as fossils, then there could also have been the possibility of such remains being worshiped and revered.

But what about the hominid remains that we do find? These are usually said to be “degenerate” people dispersed from the Tower of Babel, as God confused the languages of the people trying to build a tower to reach to heaven and dispersed them, feeling excessively threatened by the attempt for some reason (it is likely that those who wrote the Babel story thought God lived on the firmament in the vault of heaven, a place that actually could be reached if you just built high enough). It has even been argued that if you were to see a Neanderthal today on a subway, you would probably think them a boxer or wrestler, never being the wiser to the fact that you’re looking at another species. Generally members of the genus Homo are incorporated into such arguments, with the more basal Australopithecus and Paranthropus being relegated to merely being “apes.” In The Amazing Story of Creation From Science and the Bible, creationist-celebrity Duane Gish writes;

However, evolutionists’ faith in their theory makes it necessary for them to believe that a tooth, or a piece of skull, or a jawbone, or some other fossil bone came from a creature partway between ape and man. When all of the evidence is carefully and thoroughly studied by the best scientific methods, however, it turns out that these fossils were either from monkeys, apes, or people, and not from something that was part ape and part human.

This assertion is importance not only because it shows the YEC need to shoe-horn various hominids into the three categories mentioned above, but also because it involves one of creationism’s big tricks; trying to equate science with religion. If scientists can be said to “believe” in evolution, or have “faith” that more fossils will be found, then it becomes easy to make it sound like a parallel belief system to Christianity, evolution just being a secular creation myth. This, of course, is far from the truth, but many are easily drawn into this idea as all religions that are not Christian must therefore be incorrect by definition, once again putting the cart before the horse when considering the natural world. Young Earth Creationists aren’t the only ones attempting to refute evolution, however. Hugh Ross is a famous Old Earth Creationist, and his hypotheses are neither here nor there. Rejecting both evolution and the idea that the earth is less than 10,000 years old, Ross holds that Adam and Eve really were created by God just like the Bible says, only 7,000 to 60,000 years ago. As for other hominids, Ross puts them in a separate category with other animals, the primarily dividing factor being a lack of a relationship with God. In The Genesis Question Ross writes;

Although bipedal, tool-using, large-brained primates roamed Earth for hundreds of thousands (perhaps a million) years, religious relics date back only about either thousand to twenty-four thousand years. Thus, the anthropological date for the first spirit creatures agrees with the biblical date.

Thought most anthropologists still insist that the bipedal primates were “human,” the conflict lies more in semantics than in research data. Support for their views that modern humans descended from these primate species is rapidly eroding. Evidence now indicated that all bipedal primates went extinct, with the possible exception of Neanderthal, before the advent of human beings. As for Neanderthal, the possibility of a biological link with humanity has been conclusively ruled out.

Only such Neanderthal/Homo sapiens interactions, however improbable, haven’t been conclusively ruled out. There are strong arguments from both sides, and at present it doesn’t appear that we’ll be able to come up with a definitive answer. Still, Ross’ stance is just as silly as that of the YEC’s; he concedes scientific evidence for an old earth and universe, yet evolution is still too much of a detestable idea to be taken seriously. It’s not surprising that AiG issued a book, twice the length of Ross’ original, entitled Refuting Compromise, presenting a point-by-point breakdown of Ross’ arguments. All this is a great waste of intellect and paper, but I’m sure Jonathan Sarfati and Hugh Ross would say the same about what I’m doing here.

There is still at least one more trick in the creationist toolkit, however; bringing up past hypotheses that have been refuted or fossil lineages that have been changed and claiming that scientists are either ignorant or liars. Such is the setup provided to Jonathan Wells by the apologist Lee Strobel, who prides himself on being a “Devil’s Advocate” when he actually presents those he interviews with straw man after straw man. In the numbingly boring book The Case for a Creator, Strobel concocts a story of how he was convinced that evolution was true because of a reconstruction of “Java Man” (whom we’ve already met, see above), only to have Jonathan Wells crush his childhood memories of Pithecanthropus. he writes;

As I leaf back through my time-worn copies of the World Book from my childhood, I can now see how faulty science and Darwinian presuppositions forced my former friend Java man into an evolutionary parade that’s based much more on imagination than reality. Unfortunately, he’s not the only example of that phenomenon, which is rife to the point of rending the record of supposed human evolution totally untrustworthy.

I guess Strobel couldn’t be bothered to update himself on evolutionary theory between the time he received his World Book and when he met Wells, and if his “faith” in a topic can be so easily manipulated, I wonder why anyone considers him a good apologist. Still, creationists continue to bring up historical mistakes like “Nebraska Man” as if such errors were to strike terror into the hearts of scientists everywhere. Outside of the outright lies, however, Strobel’s prose shows us another important side to creationist tactics in trying to undermine evolution; science is not to be trusted at all. This strategy, like those mentioned before, works because it appeals to sentiments probably already held by many evangelicals, primarily that the Bible is the source of all truth and holds the answer to every conceivable question, any sort of knowledge or understanding produced by man being inherently flawed and untrustworthy. The fact that the Bible requires interpretation and that theology is constantly changing, however, does not seem to register, and so the evolution of humans is denied simply because the idea is unsavory.

And that, my friends, bring this post to a close. Despite the amount of resources I’ve used from my personal library, this is hardly an exhaustive study; I have largely ignored major fossil finds in order to focus on the ideas surrounding our own evolution, and any more detail would have greatly prolonged this post. What I hope to have shown, however, is that science does not crumble when taxa are reassigned or a new fossil shows up where it was not expected; it only furthers our understanding. If a hypothesis is shown to be false, then that is one more thing that we now understand to be wrong, therefore improving our knowledge and understanding. Some will continue to consider this a source of weakness, but as we are not gods, the constant desire to improve our understanding of nature is the best that we can hope for, and the correction of old ideas is what science thrives on. What would be the alternative? To hold on to favored ideas even when they’ve been proven wrong, hoping that the mere devotion to a notion would make it true? Such an idea is far from being unproductive; it is dangerous. Fossil finds will continue to be made, the genome will continue to be searched for clues to our evolution, and scientists will continue to ask questions, being both amazed but never satisfied by the latest information as to the history of life on earth.

Me
The author taking his place among the transitional forms in the branching bush that is hominid evolution, taken at the American Museum of Natural History.





Bluffing in crayfish arm-wrestling

26 07 2007

It’s expensive, and dangerous, to fight. While it’s easy to consider the jaws, claws, horns, etc. of male animals to be armaments used to beat conspecifics into submission in male v. male competition for breeding rights, the process by which one male is regarded as dominant is far from chaotic (see my post on deer antlers and sexual selection). In fact, sometimes it’s better to bluff, and that’s precisely what some crayfish appear to be doing. Apparent size/strength can go a long way in establishing dominance and keeping males from fighting each other, and usually observed fights amongst animals that undergo some sort of male competition are between males that seem to be equally matched in size (or in the size/prominence of the determining trait, in the case of the crayfish, claws), although as a new study in the journal American Naturalist shows, size or impressiveness doesn’t always mean the animals have the muscle to back things up.

In the paper “Dishonest Signals of Strength in Male Slender Crayfish (Cherax dispar)
during Agonistic Encounters
,” Wilson et al. find that male crayfish with larger claws are clearly dominant over those with smaller claws. When claw strength is tested, however, it was found that the males with larger claws weren’t significantly stronger than competitors with smaller claws, most of the energy going into building up claw size rather than strength. This makes sense if males with larger claws were always assumed to be stronger and allowed to be dominant; if other males did not contest those with a variation towards larger claws, then there would be no pressure to build up muscle mass instead of mere claw size. This is a classic bluff, although I would assume that at least some males with smaller claws would be able to mate in the wild, otherwise we would probably see runaway selection for increasing claw size. Indeed, when bluffing doesn’t work (which happens in the wild) the male with the stronger claws wins (the larger claws seemingly having no advantage other than intimidation), so the male with the smaller claws may very well win over the one with larger claws.

This isn’t all about the males, however; researchers found sexual dimorphism in the quality of claw muscles in the crayfish. Females, in fact, had higher quality claw muscle than males did, the males apparently investing more in growing larger claws (and probably replacing them when they are lopped off), whereas female claws are more of an honest display of strength as the females do fight for resources. While not quite as complicated or distinct as in my previous discussion about sexual dimorphism in deer, this shows that crayfish have differing needs based upon sex, and what makes a good male crayfish (ability to grow large claws while not reducing strength too much) is different from what makes a good female crayfish (strength regardless of claw size). Thus, if we’re to more fully understand these animals, we have to not only understand them on the species or population level but on the level of sexual distinction as well.

But what happens when these animals fight, and what makes “winners” different from “losers,” especially if some choose to disregard intimidations and fight? Bora has re-posted some wonderful information over at A Blog Around the Clock entitled “Influence of Light Cycle on Dominance Status and Aggression in Crayfish.” When studying the aggressive behavior of crayfish, Bora and then-undergraduate Amy Hughes found that aggressive interactions occurred most frequently during the first 3 hours of darkness (the crayfish being kept in a 12-hour day/night cycle). During these hours when aggression was highest, some of the crayfish became established in the hierarchy very quickly, but others (“about half”) did not become established in the hierarchy as quickly, leading to some shuffling around in the hierarchy. Bora writes;

Interestingly, more switches in social status occurred during the day than during the night. This can be explained in several different ways. For instance, a very high level of aggression may be necessary to trigger the changes in the brain, and such highly aggressive encounters are most likely to occur in the early night. Thus, encounters during the previous day were not intense enough to result in long-term changes in the brain. Further research needs to be done to study the rate at which an experience of victory or loss triggers permanent changes in the brain.

Part of this “confusion” may result from the fact that individual crayfish apparently cannot recognize other individuals as distinct individuals, and I would imagine that many crayfish that are of average strength/size/aggressiveness would have a difficult time finding a place in the hierarchy. Those that have some advantage, however, (i.e. greater claw strength or larger claws) are more likely the “winners” and experience increased amounts of serotonin in their nervous system, and melatonin is a metabolite of serotonin (which is, oddly enough, highest during the first hours of the night). As Bora notes, crayfish (like other crustaceans, such as lobsters) squirt urine at each other during fights or aggressive displays, and it’s highly likely that the chemical changes that come along with being a “winner” are expressed in the urine expelled at an opponent, helping to further establish hierarchies.

Indeed, as Robert Sapolsky notes in A Primate’s Memoir, aggression is an enigmatic subject, and why some creatures are more aggressive than others (and how they got to be that way in the first place) is a complicated subject, and perhaps that’s why it’s so intriguing. In terms of crayfish, aggressive displays for dominance likely have a lot to do with agonistic displays and the sexes involved, but also the different substances coursing through the crayfish’s bodies (some of which they shoot at each other). If I could, I would love to somehow merge these two ideas and see what differences there are (if any) between crayfish with smaller claws and bigger claws among males and stronger/weaker claws among females; I’m sure that claw size/strength and urine squirting are all factors, but just how important is each in a given fight? After all, I do have an extra 30 gallon tank that I’m not using right now in the apartment… hmmm…

Amy Hughes, Bora Zivkovic and Robert Grossfeld, Influence of Light Cycle on Dominance Status and Aggression in Crayfish (April 6, 2006), A Blog Around The Clock; http://scienceblogs.com/clock/2006/09/influence_of_light_cycle_on_do.php

Robbie S. Wilson, Michael J. Angilletta Jr., Rob S. James, Carlos Navas, and Frank Seebacher. 2007. Dishonest Signals of Strength in Male Slender Crayfish (Cherax dispar) during Agonistic Encounters. Am. Nat. 2007. Vol. 170, pp. 284-291.





New England Journal of Medicine Peddles Kitty Woo

26 07 2007

In the latest edition of the New England Journal of Medicine, out today, there is a new “Perspective Article” entitled “A Day in the Life of Oscar the Cat.” It is clearly a puff piece, describing how a resident cat named Oscar at Steere House Nursing and Rehabilitation Center in Providence, Rhode Island curls up to patients that only have a few hours to live. The tone of the article is a bit more mystic however, suggesting that Oscar sniffs the air in order to figure out when someone’s “time” is, acting like a feline Grim Reaper (although to the best of my understanding Death does not purr and nuzzle those about to die, despite his well-known fondness of cats).

Still, the fact remains that this particular cat has attended 25 people who died shortly after Oscar curled up to them, and the cat generally ignores other people. This has led Yahoo! to put the story “Oscar the cat predicts patients’ deaths” on the front page, referring to the NEJM article as if it were some kind of new paper or research. The only real rationality in the Yahoo! story is found in this quote;

Nicholas Dodman, who directs an animal behavioral clinic at the Tufts University Cummings School of Veterinary Medicine and has read Dosa’s article, said the only way to know is to carefully document how Oscar divides his time between the living and dying.

If Oscar really is a furry grim reaper, it’s also possible his behavior could be driven by self-centered pleasures like a heated blanket placed on a dying person, Dodman said.

Still, I’m sure plenty of people will latch on to the story as proof of psychic connections with animals, ESP, and other woo despite the fact that an observation has been made but no actual research has been done. I’m not even sure if there have been any studies about how animals react towards the sick or dying, although there is plenty of anecdotal evidence to suggest that pets can pick up on signs that we may miss (my parents’ dog knew my mother was pregnant with me before she did, at least that’s how the story goes). Hopefully someone will have a look at this case and determine what is actually going on, but I have the feeling that even if such a study was undertaken many people would ignore it in preference of ideas about special connections with animals.

Update the 1st: Aydin brings up something I didn’t think about at first; maybe Oscar’s actions are a variation on those of Clever Hans the horse. For more, visit Snails Tales.

Likewise, Julia pointed me to a BBC article where it states that Oscar becomes quite upset if he’s removed from the room. This is likely an important clue, and (as morbid as it sounds) maybe there is some sort of chemical/pheromone/scent or something else about the dying that attracts this cat. It would explain the behavior of selecting and being affectionate with those who are about to pass away. Hopefully someone will look into this, and I’d love to see if a reason could be found for Oscar’s behavior.