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.

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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.





Tuesday book notes

21 08 2007

I usually read one book at a time, straight through, but this past week I’ve been in a sort of funk about my current reading material. I’m compelled to finish it all, although I haven’t exactly been impressed with my recent spate of books. Here’s the rather lack-luster summation so far.

A Field Guide to Evangelicals and Their Habitat by Joel Kilpatrick

I read this satirical “field guide” in the course of a few hours on the day I got it, and I probably read it too-close to The Sinner’s Guide to the Evangelical Right. Many of the jokes are the same, and Kilpatrick’s book takes itself a bit more seriously than Lanham’s, and so it didn’t get many laughs. Some bits are funny (especially the last few chapters about evangelical sex, parties, and decorating), but if you’re familiar with such satire on the topic of evangelicals you’ve probably heard it all before and it doesn’t get especially funnier. This isn’t a bad book, it just isn’t a terribly funny one.

The Naked Ape by Desmond Morris

If you’re looking for somewhat antiquated notions about human evolution, Morris’ book is the one to buy. Much like many modern books on human evolution and our relationship to extant apes, the focus is on behavior/psychology, with the fossil record summed up in a few pages and given little further thought. Indeed, although Morris’ book is vastly outdated (my paperback copy is from 1964) it does resonate with many modern writings, and although I would have to be a bit more research, it would seem that Morris’ book was one of the first to put forth notions that now fall into the categories of evolutionary psychology/sociobiology. What is most irritating about the book, however, is Morris’ insistence on ignoring Western society. Rather than looking at humanity as a whole, Morris insists that contemporary Western men are the pinnacle of human achievement, other world cultures (especially tribal ones) being aberrant and giving us no insight into our evolution as they are degenerates. How this book ever became a bestseller, I couldn’t imagine. Still, it appears that as wrong as Morris was his ideas were highly influential, especially in inspiring Elaine Morgan to put further ponder the Aquatic Ape Hypothesis, and it is for this reason that it was important for me to read.

The Third Chimpanzee by Jared Diamond

I’m not a little less than halfway through Diamond’s book and I can’t really say I’m enjoying it. Maybe it’s because I’ve loaded up on anthropology books as of late, but I usually find more to contest with what he’s saying than anything else. Especially bothersome is when he would put forth a list of various hypotheses, praising some for being more feminist and denouncing others for being too male-centered. Don’t get me wrong, the focus on “Man the Hunter” crippled evolutionary thought in terms of our own species for some time, but replacing that with equally extreme views based solely on the role of women doesn’t give us a complete picture either. This sociological back-and-forth in anthropology seems to be an important factor in which hypotheses are regarded as good or bad, and while both sides are right about some things, in the end I think focusing too much on the male or the female is a mistake. Again, the fossil record seems to be largely ignored in the book, most of what Diamond puts forward being based upon birds and a few living apes, which is another weak point of the book.

The Gorilla Hunters by R.M. Ballantyne

It was hard to find information about this late-19th century novel, and so when I received it I wasn’t sure whether I would be reading a true account or fiction. The prose quickly indicated that it was indeed fiction, but still it provides some insights into how gorillas (and Africa in general) was viewed at the time. From what I can understand, gorillas were very important when discovered as they seemed to be our closest relatives, even though their reputations were rather monstrous. Understanding how they were introduced to the public (and how that perception changed) is going to be important to my review paper. I should finish this rather racist and pompous novel this evening.

Where Darwin Meets the Bible by Larry Whitham

I generally avoid books about the evolution/creationism debate (being that I’m fairly familiar with it), but I decided to give Whitham’s book a try in case it contained information I had not heard before. In fact it does, spending much time on those who have tried to reconcile the Bible and evolution in America during the first part of the 20th century within the first 40 pages, but it largely reads like a list. The writing isn’t bad, but the first chapters of the book read like a chronological list of events and persons involved with the intersection between evolution and creation, the author never digging deeper into the issues during the time. This may be appropriate given that the book is supposed to be about more modern conflicts (i.e. after the 1960’s), but I do wish that authors writing on this subject would give the past a more thorough treatment, especially to show that the debate (and creationist arguments) are anything but new. While Toumey’s God’s Own Scientists was tedious at times, overall it gave the reader some insight into why some of the faithful find evolution so threatening (and why they have been able to co-opt the mantle of science without mastering it to further their cause). Whitham’s book, by contrast, is more of a summation of the history thus far, and I suspect, in the end, he’s going to advocate a NOMA-approach to the current debate, even though such an approach doesn’t work in real life. I’ll probably read another chapter or two of this tonight.

Anyway, that’s what I’ve been reading over the past few days, although I’m sure my enjoyment of some of the books is diminished by the horrible weather (it’s been grey and rainy for the past few days, temperatures stuck in the high 50’s to mid-60’s). Still, even though many of these books aren’t “fun” I am at least learning the opinions of the authors, and understanding the different standpoints will help in drawing up my review paper.





Photo of the Day: Gorilla mother and babies

20 08 2007

Gorilla

I know I’ve posted this picture before, but it’s one of my favorites and I thought I would drag it back out to the top of the blog again. It probably has to do with my current dilemma of whether to stay the course in Ecology & Evolution to just “get it over with” or switch over to Evolutionary Anthropology to make the most out of my last year (as long as it won’t keep me back again). What to do, what to do…





Friday Book Notes

17 08 2007

Yesterday I wrote down a few thoughts on the first half of Jack Horner’s book Dinosaur Lives, and I can’t say the second half of the book was much better than the first. Decrying the current public misunderstandings about evolution, Horner tries to take on the subject himself, but the attempt doesn’t come off especially well. First, he attacks Eldredge & Gould’s idea of punctuated equilibrium, seeing it more as a theory that ends queries way too soon rather than an understanding of speciation and evolutionary rates. Horner also has issues with the Linnean system of taxonomy & systematics, preferring cladistics, but then saying that cladistics doesn’t have all the answers either. In this area I agree about some things (i.e. still using designations of modern species to keep related groups apart, like putting dinosaurs in “reptiles” while birds get a class to themselves despite being derived from dinosaurs), but overall no alternate system is proposed to fix problems based entirely based on extant taxa or morphology out of context with the stratigraphic record. Although Horner had been dropping species names left and right throughout the rest of the book, when he comes to the evolution of some centrosaurs he holds back on their binomials, instead calling them centrosaur I-IV, which makes that section more complicated than necessary (especially since it appears that Horner has put together a good case for the anagenesis of Pachyrhinosaurus within the Judith River Formation). This is followed up by some intellectual meanderings about souls and an afterword about commercial fossil collecting, but overall I can’t say I really enjoyed the book. It might serve biographers of Jack Horner well, but the actual findings about “Dinosaur Lives” seemed to be of secondary importance in the book.

The Third Chimpanzee by Jared Diamond

Last fall this book was recommended to me by a professor of mine, although I merely added it to my amazon.com wish list and forgot about it for a time. Finally having the chance to pick it up last week, I was looking forward to reading this one (despite the very “March of Progress”-like illustration on the cover). 50 pages in, however, I can’t say I’m exactly impressed. As I noted in my big post on how we think about human evolution, popular works about human evolution these days are far more focused on living apes (especially chimpanzees and gorillas) than fossil ones, many authors taking the behaviors/habits/morphology of living apes and extrapolating backwards, usually paying little heed to the fossil record. Diamond falls into the same trappings, opening the book with the genetic tests conducted by Sibley and Ahlquist showing that we share over 98% of our genetic code with chimpanzees. This difference, the author repeatedly states, is greater than the difference between White-Eyed and Red-Eyed Vireos, and in a perfect world chimpanzees would be called Homo troglodytes (bonobos being Homo paniscus). While Diamond evokes cladistics, however, this new plan seems to ignore evolutionary history, using the data from the tests conducted circa 1992 to rearrange the taxonomy. While there’s no doubt at all that chimpanzees and bonobos are our closest living relatives, I think there are more than enough differences between us to classify us as different genera, especially since we are on diverging evolutionary paths. Further, different tests for genetic similarities seem to have come up with different results, and while I don’t expect the overall “% relatedness” figures to drop drastically, I think as we refine our understanding of genetics and evolution we’ll be better able to put our finger on how different we are from living apes and why that is.

Diamond does wade into paleoanthropology a bit (although he usually calls is archeology), although his treatment here isn’t much better. Statements are rattled off quickly, everything we are told about ancient hominids being related to Diamond’s experience with people in New Guinea, who (according to the author), just stepped out of a “Stone Age” way of living. This problem of differentiating between possible correlation and causation (or other significant pattern) seems to be a recurring problem through the first section, and at some points the reader is simply told that this or that fact is true without any support. Considering whether the ancestors of modern day humans and Neanderthals interbred, Diamond relates the idea to a sexist adventure/time-travel novel, concluding;

Believe it or not, something like that experiment [sex between Homo sapiens and Homo neanderthalensis] actually took place. It happened repeatedly around forty thousand years ago, at the time of the Great Leap Forward.

No evidence is offered to support this view, and it seems that Diamond is merely arguing from authority or expecting the reader to believe the hypothetical situation because he wrote a book. When writers take such approaches, I don’t feel respected by the author, and there is no footnote or citation that would help the inquisitive reader find out more on the subject if they were so inclined. Perhaps later chapters of the book will be better (Diamond seems a bit out of his element in terms of paleoanthropology), but somehow I get the feeling that this book will be very much like de Waal’s Our Inner Ape and Peterson/Wrangham’s Demonic Males in that molecular studies and cultural anthropology will trump other fields more concerned with “dusty old bones.”