Thylacoleo carnifex, ancient Australia’s marsupial lion

31 08 2007

My home state of New Jersey is the epitome of suburban sprawl, McMansions and cul de sacs being about as common as the White-Tailed Deer that take advantage of the grass and brush on the side of the Garden State Parkway year round. There is seemingly no place you can go in the state where the rumble and roar of traffic cannot be heard, although the sprawling network of impervious surface does allow for easy travel to almost anywhere in the “Garden State.” On these roads, usually on warm summer nights, you’re likely to see what appears to be a large white rat shuffling across the lanes. While there are no hackneyed jokes that I know of about the Virginia Opossum crossing the road (“To eat your garbage” would be the most realistic answer), the critters turn up as roadkill quite often, not a very dignified end for the only marsupial mammal to live north of the Rio Grande in North America. While the scruffy Virginia Opossum represents the whole of marsupial mammals in the U.S., it has many close relatives throughout South America (Order Didelphimorphia), and is a bit more distantly related (but still close) to the Australian “possums” (Suborder Phalangeriformes), the marsupial forms of “the island continent” being perhaps the most familiar and oddly charismatic of any members of the Infraclass Marsupialia.

Kangaroo
A Red Kangaroo (Macropus rufus) at the Philadelphia Zoo (taken in February, 2007). The Red Kangaroo is probably the world’s most recognizable living marsupial mammal.

Much like any group of living mammals, however, the fossil record of marsupial mammals is full of bizarre forms that have left no living descendants. We should not regard such lines of extinct fauna as somehow inferior or flawed, however. As famed paleontologist Stephen Jay Gould once wrote in his book Wonderful 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.

I can scarcely think of a better example of this notion of the spectacular diversity of past life than the extinct marsupial Australian Megafauna, and the carnivorous Thylacoleo carnifex would remind any fossilist that just because an animal is extinct, such status does not imply that it was not a terror in its heyday. Deemed the “Marsupial Lion” Thylacoleo carnifex developed many of the predatory adaptations we seen in living big cats (hence the “leo”, meaning “lion”, in the genus name), and despite the superficially rodent-like appearance of it’s front teeth, it was certainly a powerful predator.

In order to understand why Thylacoleo was such a formidably hunter we first need to understand something about living Carnivora (civets, otters, cats, dogs, bears, etc.) and the way their teeth were arranged. While their have been many large carnivorous mammals since in the past 65 million years, carnivores are set apart by their carnissal, or “scissor”, teeth. If we look at the massive skull of the predatory mesonychid Andrewsarchus of the Eocene, for example, the front teeth appear useful for piercing but the teeth further back in the jaw a large and a bit blunted. While useful in tearing flesh from bone and crushing, they were not especially well-adapted to cutting slicing flesh and such creatures probably ate a fair amount of bone (and possibly had problems with bone splinters in their gastrointestinal tracts) as well.

Andrewsarchus
The only known skull of Andrewsarchus, on display at the American Museum of Natural History in New York City. Note the large, blunted teeth towards the back of the jaw.

The likely ancestors of today’s extant carnivores had their start long before Andrewsarchus was roaming what is present-day Asia. Miacids were weasel-like mammals and are known from the Paleocene and Eocene epochs, and are the first mammal group known to have teeth called “carnissals.” These are the teeth that group all living carnivores together, robust and pointed teeth that seem to be essential to consuming flesh. Another group of mammals, the creodonts (the first of which were discovered by E.D. Cope), also possessed carnissal teeth, but their line died out about 8 million years before the present. Still, the success of the carnivorous mammals seemed to depend on the specialization of the some of the premolar and molar teeth into a sharp, cutting edge, commiting many of the group to a strictly carnivorous lifestyle. Cats are the most specialized today, as they have lost some teeth in the front of their jaw in order to allow their dagger-like canines to have the maximum effectiveness and they no longer have flattened molars at the back of their jaw like canids (dogs) have, allowing those animals a little bit more of a diverse diet in tough times. Indeed, overspecialization in a predatory niche, called “hypercarnivory,” can often put a species at risk if they cannot effectively process other food sources if prey stocks dwindle (such a hypothesis has been put forward about the recent “bone-crunching wolf” discovered in Alaska).

Thylacoleo
A replica of the skull of Thylacoleo, on display at the American Museum of Natural History.

Thylacoleo, however, was an entirely different branch of the mammalian tree, but it seems that its skull and jaws were adapted to similar ends (although arguably were more extreme in their modifications). As easily seen from the skull of Thylacoleo, this marsupial predator was adapted to have it’s own fearsome shearing teeth. The premolars essentially became laterally-compressed blades, more high-ridged and pointed at the front, yet still sharp all the way down their length. These teeth in the upper and lower jaw even helped to sharpen each other as they slid past, allowed the predator to retain a sharp edge. Flattened teeth that might be useful for grinding or processing other foods are entirely absent behind the premolars, showing the Thylacoleo was a specialist of the highest order, having much more scissor-like teeth than the placental carnivores on other continents. Such a gape would have been absolutely fearsome, as exemplified by this recent reconstruction by Jeanette Muirhead;

Thylacoleo
Thylacoleo carnifex, used with permission of artist Jeanette Muirhead.

What is even more surprising than the blade-like teeth of Thylacoleo, however, is how strong its jaws were for a creature of its size. A recent study by Wroe, McHenry, and Thomason found that Thylacoleo, a predator that was less than four-feet long and probably weighed only 220 pounds, had the a bite force equivalent to a modern lion twice its size. The unusual dental arrangement of its jaw might have mitigated this somewhat and technical trials still have to be carried out, but if what the researchers found holds then Thylacoleo could probably have preyed upon most animals living in its range up to sub-adult size on its own, perhaps being the fiercest mammalian predator ever known.

How did Thylacoleo attain such high bite forces? The answer might have to do with the brain and skull differences between marsupials and placental mammals. Many carnivores have relatively large brains in comparison with marsupials, lessening the amount of bone they can devote to massive muscle attachments to enhance bite force. Thylacoleo, by contrast, seems to have had stronger muscle attachments and a smaller brain, and it’s skull superficially resembles that of a big cat. While canids often have elongated skulls, cats have foreshortened ones, and oddly enough Wrote and his colleagues seem to have found that carnivorous mammals that are known to be bone crunchers (primarily dogs or dog-like carnivores) appeared to have overall weaker bite forces than those that did not have the same osteophagous tendencies. This may have to do with the actual killing of prey, big cats and similarly-designed predators depending on strong bite forces in order to choke their prey to death or tear out a large chunk of the prey’s neck with a jugular bite. There are exceptions to this, the bite of saber-toothed cats often being calculated as relatively weak, but overall it seems that a shorter skull with a deep mouth is better of achieving high bite forces than a longer and narrower one. Hence, Thylacoleo actually is not a bad name for the “pouched lion”; it seems to share a large amount of convergences with its modern-day namesake, although it may have been less bright (and less sociable) with a more powerful bite.

Thylacoleo
Ventral view of the skull of Thylacoleo. From E.D. Cope’s “The Tertiary Marsupialia” in The American Naturalist, Vol. 18, No. 7. (Jul., 1884), pp. 686-697.

The predatory affinities of this animal did not always seem so obvious, however. Paleontologist E.D. Cope, in a paper entitled “The Tertiary Marsupiala,” recaps some of the controversy about the feeding habits of Thylacoleo that formed in the late 1800’s;

The discussion between Professor Owen on the one side, and Messrs. Falconer, Krefft and Flower on the other, as to the nature of the food of Thylacoleo, is known to paleontologists. From the form of the teeth alone, Professor Owen inferred the carnivorous nature of the food of this genus, while his opponents inferred a herbivorous diet from the resemblance between the dentition and that of the herbivorous Hypsiprymnus. I have pointed out that the comparison of Thylacoleo with Hypsiprirnnus is weakened by two considerations :

First, the cutting teeth in the two genera are not homologous ; second, the grinding series of molars, complete in Hypsiprymnus, is almost wanting in Thylacoleo. It evidently does not follow that because Hypsiprymnus is herbivorous Thylacoleo is so also. Professor Flower refers to the reduction of the molars in Thylacoleo as slightly complicating the problem, and concludes that the food of that animal may have been fruit or juicy roots, or even meat. It is difficult to imagine what kind of vegetable food could have been appropriated by such a dentition as that of Ptilodus and Thylacoleo. The sharp, thin, serrate or smooth edges are adapted for making cuts and dividing food into pieces. That these pieces were swallowed whole is indicated by the small size and weak structure of the molar teeth, which are not adapted for crushing or grinding anything but very small and soft bodies. It is not necessary to suppose that the dentition was used on the same kind of food in the large and the small species… In Thylacoleo carnifex it might have been larger eggs, as those of the crocodiles, or even the weaker living animals. The objection to the supposition that the food consisted of vegetables, is found in the necessity of swallowing the pieces without mastication. In case it should have been of a vegetable character the peculiar premolar teeth would cut off pieces of fruits and other soft parts as suggested by Professor Flower, but that these genera could have been herbivorous in the manner of the existing kangaroos, with their full series of molars in both jaws, is clearly an inadmissible supposition.

I have to agree with Cope; it is hard to imagine what sort of vegetable matter Thylacoleo would be eating with its specialized dentition. It would have been able to chop plants, surely, but whatever food was not inside the mouth would fall into the ground, that inside the mouth would have to be swallowed whole. This would results in Thylacoleo chewing much more low-quality plant food than other animals with teeth adapted to herbivory, and I doubt that Thylacoleo had a caecum or a habit of swalling smooth stones to aid in the digestion of the hypothetical greenery. Even in 1969, however, there seemed to be some doubt as to whether Thylacoleo was a herbivore, an omniovore, a carnivore, or a hypercarnivore. Leigh Van Valen, in the paper “Evolution of Dental Growth and Adaptation in Mammalian Carnivores”, wrote;

The jaw musculature of Thylacoleo was generally similar to but more powerful than that of Trichosurus, but whether all this increase was an adaptation to greater size is unknown. The question of the diet of Thylacoleo is unresolved. If Thylacoleo was carnivorous, it was in several respects a relatively inefficient carnivore. However, large carnivores were rare in Australia, and the condition of Thylacoleo is what would be expected if a Trichosurus-like phalanger became carnivorous. But the herbivorous diet advocated especially by Flower, Krefft, Lydekker, Charles Anderson, and Gregory remains a real possibility. A decision on this matter will probably not be possible until there is adequate knowledge of the appendicular skeleton.

The initial descriptions of Thylacoleo by Richard Owen were more certain of the carnivorous habits of the marsupial, however. One December 16, 1858, Owen’s paper “On the Fossil Mammals of Australia. Part I. Description of a Mutilated Skull of a Large Marsupial Carnivore (Thylacoleo carnifex, Owen), from a Calcareous Conglomerate Stratum, Eighty Miles S. W. of Melbourne, Victoria” was read before the Royal Society. It states;

The evidence of a large carnivorous marsupial, from pliocene formations in Australia, reached me not many years after my determination of the still larger herbivorous marsupial, Diprotodon australis, which first suggested the idea of the coexistence. The evidence was received in the year 1846…

Thylacoleo
The fragmentary skull of Thylacoleo from Owen’s paper “On the Fossil Mammals of Australia. Part I. …”

The initial fragmented skull of Thylacoleo carnifex (Owen), pictured above, was obtained and sent to the great naturalist by Dr. Hobson of Melbourne. Upon receiving the fossils, it seems that Owen almost immediately recognized the convergences in the skull with modern carnivores, the extant lion (Panthera leo) being his foil for the characters in the new skull. Owen describes the deterministic state and characters of the skull as follows;

The ‘skull’ consisted of the cranial part, similar in size and in the development of the temporal ridges and fossae to that of a Lion. The ‘incisor’ was a large tooth with a trenchant or incisive crown, implanted, with a small tubercular tooth, in a portion of the right superior maxillary bone, including part of the orbit and lacrymal bone. The latter specimen gave decisive confirmation of the carnivorous character of the fossil, the ‘incisor’ tooth answering in shape and function to the great sectorial or ‘carnassial’ and the tubercular tooth to the small tubercular molar of the Lion; being situated, as in that animal, on the inner side of the back part of the sectorial tooth.

Indeed, the bladelike teeth alone were enough to convince Owen of the ferocious nature such an animal must have possessed, writing;

In existing carnivorous mammals the ferocity of the species is in the ratio of the ‘carnassiality’ of the sectorial molar, i. e, of the predominance of the ‘blade’ over the ‘tubercle;’ and this ratio is shown more particularly in the upper sectorial, in which, as the tubercular part enlarges, the species becomes more of a mixed feeder, and is less devoted to the destruction of living prey. From the size and form of the carnassials of Thylacoleo, especially of the upper one, we may infer that it was one of the fellest and most destructive of predatory beasts.

Thylacoleo
A second, more complete skull of Thylacoleo carnifex, from Owen’s paper “On the Fossil Mammals of Australia. Part II. Description of an Almost Entire Skull of the Thylacoleo carnifex, Owen, from a Freshwater Deposit, Darling Downs, Queensland”

Owen’s assertions did not go unchallenged, however. In a later 1886 paper “Additional Evidence of the Affinities of the Extinct Marsupial Quadruped Thylacoleo carnifex (OWEN),” the anatomist includes a quite humorous remark in response to one of his critics. As noted before, some scientists believed that Thylacoleo was essentially a living Cuisinart specializing in cutting up fruit, no more terrifying than some of the arboreal relatives of the Virginia Opossum noted above. Owen, in classic style, writes;

These eminent authors received the support, in reference to objections to my conclusions, of the (then) Curator of the Australian Museum, Sydney, Mr. GERARD KREFFT, who, in his contribution to the ‘Annals and Magazine of Natural History,’ series 3, vol. 18, 1866, p. 148, records his opinion that “the famous marsupial Lion was not much more carnivorous than the Phalangers of the present time.”

The species of carnivorous Phalanger is not named. No evidence of such by fossil specimens has reached me, nor have I found such exceptional habit of an existing species of Phalangista elsewhere noted.

Thylacoleo
Lower jaw (outside view) of Thylacoleo carnifex, as seen in Plate I of Owen’s “Additional Evidence of the Affinities of the Extinct Marsupial Quadruped Thylacoleo carnifex (OWEN)”

Indeed, armed with a more complete lower jaw of the animal, Owen even further extrapolated its carnivorous habits, postulating that it had been the “check” on the large herbivores known from the same period in Australia. All the large forms, in Owen’s view, ceased to exist when “bimanous” forms came to the continent, either eliminating Thylacoleo or putting it out of a job through competition, although the wholesale slaughter of Australia’s megafauna by the people who would become the Aborigines is not an open and shut case. Even beyond the skull, Owen was provided with a claw complete with retractable teeth, now known to occupy the “thumb” position of this carnivore. Some have speculated that its size, ferocity, and retractable claw allowed it to climb trees like a leopard, although others have doubted this an account of how robust Thylacoleo probably was (being twice the weight of modern leopards), which 1) would have made it difficult to climb trees, and 2) would have allowed it to chase off most of the competing predators/scavengers of it’s day. I doubt that there were many creatures that would have crossed the path of Thylacoleo and survived if the “pouched lion” was hungry or territorial.

Despite it’s fearsome reputation, Thylacoleo seems to have disappeared from the land “down under” around 40,000 years ago, probably the very last of its lineage. Indeed, while I have primarily focused on Owen’s T. carnifex here, there were many other earlier species and related genera, each showing different aspects of the skull and form. Why these bizarre creatures, once so prominently disputed, have disappeared from the public understanding of paleontology I cannot say, but it is probably to the relief of living kangaroos and other Australian fauna that they are long gone.

Thylacoleo
Partial skull elements, most notably the incisors, from Owen’s paper “On the Fossil Mammals of Australia. Part IV. Dentition and Mandible of Thylacoleo carnifex, with Remarks on the Arguments for Its Herbivority”





Icon of Delusion: Jonathan Wells

31 08 2007

If ever there were an unsavory, real-life creationist character that should be cryptically referred to as “You Know Who” as in the Harry Potter series, it would have to be Jonathan Wells. While I have not actually tested this as yet, the very mention of his name seems to make my blood pressure rise, and perhaps his goal is to be so annoying and deceitful that evolutionary scientists all die of stress-induced heart attacks because they can not even stand the mention of his name. If this is indeed the plan, then Wells has certainly taken another step towards its fruition. On the dubiously titled “Evolution News & Views” blog run by the Disco. Institute, Wells has issued a rather hateful screed about the terms “Darwinist” and “Darwinian.”

Starting out with a rather hateful attack on the quality of The Seattle Weekly, stating that “as [a source] of news [it's] probably about as reliable as Minju Choson, the official organ of the Democratic People’s Republic of [North] Korea. But homeless people make good use of [it],” Wells quotes a recent article in the paper in which Eugenie Scott of the NCSE as saying “a real follower of modern science would never call himself a ‘Darwinist’,” because “evolutionary biology has advanced way beyond Darwin’s 19th-century tracts.” This is rather strange, especially the quotation marks that Wells decided to “helpfully” insert as they do not appear in the original article. The original sentence reads as follows;

Scott isn’t buying it, not least because she says evolutionary biology has advanced way beyond Darwin’s 19th-century tracts, so that a real follower of modern science would never call himself a “Darwinist.”

Sounds more like the reporter, Nina Shapiro, tried to condense Scott’s argument down into a shorter sentence and was not quoting Scott directly, so once again Wells has shown us that he is either being deceitful or ignorant of how to properly use the copy-paste function on a computer. Still, he uses his doctored quote as a set-up to try and muddy the waters with cherrypicked examples from historical science, and Wells misses the entire point of the now outdated term “Darwinist.” Wells writes;

The reason that “Darwinism” and “Darwinian” – even “Darwinist” – are used by modern evolutionary biologists is that they are more precise than “evolution” and “evolutionist.” The latter have many meanings, most of them uncontroversial. For example, “evolution” can refer simply to change over time, something no sane person would deny. Or it can refer to minor changes within existing species, which breeders have known about for centuries.

Actually, the reason why “Darwinist” was the most popular term in years past is because Darwin’s mechanism of natural selection (and later sexual selection) proved to be the correct one. Prior to Darwin and even during his time “transmutation” of species was a hot topic, and there were various schools of thought as to how creatures evolved. Thus a more exact term for the school of evolutionary thought Darwin founded, “Darwinism,” was necessary to distinguish it from the competing hypotheses of Lamarck, Agassiz, the thoughts put forth in the popular book Vestiges of the Natural History of Creation by Robert Chambers, and the later criticisms of Darwin put forth by the likes of St. George Mivart. In fact, especially in America, evolution by natural selection was not immediately and fully embraced, the famed scientist Louis Agassiz being a critical of Darwin so vociferous that even Wells would have been likely to get his admiration. Even the noted paleontologist E.D. Cope ascribed to Neo-Lamarckian ideas of evolution, a evolutionary framework that has been long known to be insufficient.

But if Darwin was right, why would Eugenie Scott say his “tracts are outdated”? Well, Darwin was right in terms of his big ideas of natural & sexual selection (as well as many other points), but he did get some things wrong. Heredity was vastly unknown during his time, and even Darwin threw in a pinch of Lamarckism into his writings. In the 2nd edition of The Descent of Man, Darwin wrote the following in the preface;

I may take this opportunity of remarking that my critics frequently assume that I attribute all changes of corporeal structure and mental power exclusively to the natural selection of such variations as are often called spontaneous; whereas, even in the first edition of the ‘Origin of Species,’ I distinctly stated that great weight must be attributed to the inherited effects of use and disuse, with respect both to the body and mind. I also attributed some amount of modification to the direct and prolonged action of changed conditions of life. Some allowance, too, must be made for occasional reversions of structure; nor must we forget what I have called “correlated” growth, meaning, thereby, that various parts of the organization are in some unknown manner so connected, that when one part varies, so do others; and if variations in the one are accumulated by selection, other parts will be modified. Again, it has been said by several critics, that when I found that many details of structure in man could not be explained through natural selection, I invented sexual selection; I gave, however, a tolerably clear sketch of this principle in the first edition of the ‘Origin of Species,’ and I there stated that it was applicable to man.

And so I still cringe when I heard scientists refer to themselves as “Darwinists” (or even worse, “orthodox Darwinists,” as I once heard Ken Miller opine). The term is no longer necessary or even accurate because in scientific understanding Darwin’s big ideas won the day ages ago while some of his subjects he did not fully understand have become better known, the science we now have being based on Darwin but not adhering only to the thoughts within his published works. If we’re going to start tagging schools of thoughts with names, we could very well have “Gouldists,” “Dawkinsists,” “Simpsonists,” “Mayrists,” “Morganists,” “Copeists,” “Agassizists,” etc. etc. etc. The distinction that the term “Darwinist” used to have is now largely lost because of our greater understanding, time proving Darwin to be the victor in the battle that took place in evolutionary through between the late 19th and early 20th centuries, but I know of no scientists who holds On the Origin of Species by Natural Selection who holds the great work to be a holy book that may not be added to or contradicted in any fashion whatsoever. Just like paleontology requires a historical understanding and a long-view of the subject at hand, so does the topic of the evolution of how we think about biological evolution.

After some more jabs at Scott and confusion of the origins of the words he’s talking about, Wells concludes;

So rather than learn Scott’s word games, biology students should begin by learning to distinguish “evolution” from “Darwinism” and “evolutionist” from “Darwinist.” Or “Darwinian” – it’s one and the same.

I assume that he’s not suggesting that school boards should hire Neo-Lamarckian staff to “Teach the Controversy!” about evolution. I think a biology class would largely benefit from understanding the historical aspect of the evolution idea, starting with the Ionians like Thales and Anaximander and working through Darwin and the Modern Synthesis to today. That way it can be clearly seen that there indeed was a time when evolution did not necessarily mean “natural selection, common descent, etc.” in the minds of some notable scientists, and how eventually their ideas (often influenced by their adherence to religious doctrine) came crumbling down. “Teach the Controversy!” seems like it could have just as well been the battle cry of Louis Agassiz or St. George Mivart as that of current ID thinkers, but apparently they cannot be bothered to go back and try and uncover the history of the evolution idea.

To put it concisely, Darwin was a highly intelligent man who uncovered the beginnings of one of nature’s greatest mysteries, but we would be fools to think that he was somehow all-knowing or that no data would later be found that would clarify or possibly refute his ideas. Nearly 150 years after On the Origin of Species by Natural Selection was published, however, natural selection working on variations in organisms is still a major mechanism of evolution, exemplified by Stephen J. Gould in his coral-branch analogy in The Structure of Evolutionary Theory. Can we expect any scientist never to make a mistake or never have their ideas overturned? For every important idea that has been put forth by great minds, how many ideas ended up being stillborn or eventually refuted? Are we to remember scientists for their failures only, disregarding their successes? To do so would mark us imbeciles, and we would pay a heavy price for judging those who strove to bring enlightenment to the work by sharing their ideas. Darwin was one of those great minds, and even though “the long argument” will likely continue, I see no reason why we should exhume the corpses of long-dead competing hypotheses of evolution when Charles so eloquently put laid to rest.





Amalgamated Friday Notes

31 08 2007

So here we are, the last day of August. This morning when I stepped outside to drop the mail into the corner box, the orange light struck the trees and small flocks of chickadees pecking at the sidewalk just right, a few crickets continuing on the evening chorus of chirps. No one was around despite the relatively late hour and I had the sidewalk to myself, reminiscing about such morning in Florida, a place I am much more fond of. Still, it was not a bad moment to part with my summer, and I’ll be counting the days until it comes again.

Indeed, this is the last weekend before school starts, and I’m pretty tied up for most of the weekend. I hope to get some writing done, but I have no idea how much. On the book front, I’ve been trying to get through as many books as possible before school starts. The other night I read T.H. Huxley’s Man’s Place in Nature and it was an utter delight. Some parts were a bit dry, but when let loose from measuring skulls, feet, or hands to pontificate upon the subject of the book named in the title, Huxley is at his best. I am sorry I had not read it sooner.

At the moment I’m reading The Bonehunter’s Revenge aloud to my wife, and it is one of the most enjoyable popular science/history books I’ve come across as of late. The author, Wallace, gets some of his history muddled in only giving it a brief mention (he fumbles a bit in his discussion of Cuvier and Lamarck and at one point calls a titanothere a titanosaur), but overall the prose flows well and tells and exciting story, tying it all together with the famous feud between Cope and Marsh in the Herald. If you’re tired of simply hearing that Cope and Marsh had long-standing ill-will towards each other and want to know why, I highly endorse picking up a copy of this book (and if you like card games, check out Bone Wars, too!). Being that I have to wait until the evening to read Wallace’s book aloud to my wife, I spent most of yesterday evening reading the companion volume to the BBC series The Velvet Claw. I never got to see the series, nor am I likely to as it seems to never have come out on DVD, but the book is definitely a well-illustrated overview of living and extinct carnivorous mammals. It is a bit dated in some of it’s paleontology(Pakicetus was still thought of as a half-seal at this time), and it can be a bit dry at times, but it has been a very useful book.

In fact, The Velvet Claw and Jeremy’s recent post about the scent-marking habits of Binturongs has inspired me to write about something that I have not yet seen covered in full in the blogosphere; genital mimicry in cat-line carnivorans. Spotted Hyena are the most famous example, but they are not alone in appearing androgynous; Binturongs, Fossas, and some other living carnivores on the cat-side branch of the evolutionary tree also express genital mimicry (the parts of the females looking like those of the males), and upon learning this I definitely became more interested in just how widespread such a condition is among civets and their relatives. I’ll have to do a bit of research before I get churn that one out (I’m now even more thankful that I picked up Walker’s Mammals of the World), but hopefully I’ll have it done soon.

Like I mentioned earlier, this weekend sees me pretty booked up, but next weekend I hope to visit the Philadelphia Zoo (I’ve been waiting to go all summer, and other plans continually got in the way), so expect plenty of pictures of the various critters there. Hopefully I’ll snag some shots of the tiger cubs born this past spring, but if I’m going to do that I’m going to have to get there a bit early.

I should probably get back to work on my post about a certain killer marsupial that was roaming Australia until the end of the Pleistocene, though, and I hope everyone returning to school gets to enjoy the long weekend before the semester sets in full-force.

Update: I nearly forgot a few things I meant to add. First, my wife brought home a 6-bottle pack of Woodchuck Draft Cider last night and it was really good. I’m told that Woodpecker Cider is better, but I won’t complain about the Woodchuck brand, especially since it’s got the scientific name on the bottle.

Second, my wife is interested in the Carnivora as much as I am, and she definitely wanted to read The Velvet Claw. Being a bit tired, she picked up the book to flip through it, and when she had stopped I asked for it so I could start it. She held it close and got a distrustful look in her eye and said “Mine.” I replied “But you didn’t even know the book existed until I bought it.” She shot back “Just because I didn’t know about it doesn’t mean it’s not mine.” She soon relented and will start on the book soon herself.

Lastly, my wife related an anecdote to me of her trip to the liquor store to get the aforementioned Marmot Woodchuck Cider. Last night was the 1st football game of the season for Rutgers, so hordes of freshmen swamped the streets and stalls of local purveyors of alcohol. In one such establishment, a young man said to my wife (as related by her to me) “Hey, I’m totally, like, having a party later and you should, like, totally come.” My wife, clever as I know her to be, replied “Oh yeah? I’m having a party too.” The young man, somewhat expectantly said “Oh yeah? Really?”, my wife swiftly interfecting “Yeah, with my husband.” I am told that this attempted suitor was rather deflated upon hearing these words and did not utter any more until he had left.

And yes, I am fully aware that I took on a rather erudite tone in that last passage; perhaps I’ve been reading too much 19th century prose…





If I had known I would have baked a cake….

31 08 2007

Blog Day 2007

Happy Blog Day everyone! This is the 3rd annual celebration, and in keeping with the wishes set forth by those who’ve spread the word, I’ve picked five blogs that I regularly read and think you should, too. I was quite surprised to have been chosen as one of the five over at A Blog Around the Clock (thanks Coturnix!), and I’m going to carry on the meme in quite the same way by picking 5 of my favorites instead of just 5 “new” blogs. Envelope please…

Catalogue of Organisms – Chris admittedly has “An inordinate fondness for systematics,” and a wide range of interests that would have made E.D. Cope and other earlier naturalists proud. His posts are always well documented and researched, and it’s hard not to learn something new on any given visit. Plus, he was nice enough to tag me with the Thinking Blogger Award for a second time, so this is my way of saying “Thanks!”

Clastic Detritus – Brian is another good friend of mine who, in addition to just acquiring a spiffy new title and moving to wordpress, is the father of the new earth sciences blog carnival The Accretionary Wedge. He is far more well-versed in geology than I could ever hope to be, and I am glad that he is helping to lead the charge to get geo-bloggers more involved on the web.

Prehistoric Pulp – Walt reads ‘em so you don’t have to, or rather, Walt reads ‘em so you know which ones actually are pretty good so you know where to turn when you’re in the mood for some good paleo-fiction. Walt’s knowledge of the monsters (real and imagined) lurking in the pages of recent literature is encyclopedic, and his is a wonderful and well-written resource.

Thoughts in a Haystack – And I thought I spent a lot of time trying to understand the history of science. I have only recently discovered John’s blog, but it is an absolute treat to read and his writing is brimming with careful research, measured opinion, and an excellent sense of humor. If you’re not reading Thoughts in a Haystack yet, you darn well should be.

The Ethical Paleontologist – Where would I be without Julia? Outside of directing me to other people extremely helpful in my fields and interest and providing plenty of encouragement, Julia writes an excellent blog that ranges from her “Jurassic Garden” to songs about dinosaurs to her current journey to get her PhD. Her blog, simply put, is a must-read.

Also of note: My friend Zach’s blog When Pigs Fly Returns (if for no other reason that his excellent reconstruction of Arizonasaurus, and Pondering Pikaia, which was duly recommended by Coturnix and will likely be on many more lists.

So what are your five commendations for your readers? You can read all the “official rules” at the Blog Day website, but be sure to add a description as to why each of the blogs is so good. Go on, boost some egos and endorse good blogging wherever you may find it.

[Blog Day Technorati Tag]





The tooth is a big clue…

30 08 2007

It’s going to take a little while to get my latest paleo-post up and running, but in the meantime I thought I would put up a bit of a “teaser.” The following picture is of the remains of the skull studied and described by a persnickety British anatomist during the 19th century, and is the focus of my current project.

Skull

I can’t think of any sort of “prize” that I’d be able to give for anyone who correctly identifies the fossil, although the self satisfaction from figuring it out should be a pretty good ego-boost in-and-of itself.





It’s almost that time again…

30 08 2007

The next installment of the paleo-carnival The Boneyard is coming up this Saturday, and it will be hosted by my good friend Zach over at When Pigs Fly Returns. Be sure to send your submissions to him or to me by Friday evening if you want in on the osteological action.

Also, my friend Brian of Clastic Detritus (formerly …Or Something) has started a earth sciences-based carnival with the absolutely wonderful title of The Accretionary Wedge (it ranks right up there with Highly Allochthonous as a title). The first edition is all about how bloggers came to be interested in the earth sciences to begin with, so if you’re a geo-blogger be sure to contribute to this new conglomeration.

And, lest I forget, the anthropology carnival Four Stone Hearth is up at Hominin Dental Anthropology and Tangled Bank #87 is up at Balancing Life. I really need to get back on top of when carnivals are going up to get some more posts out there…





Waterlogged Weblog

30 08 2007

Evolutionary transitions into and out of the water (imaginary or real) have been a hot topic on this blog lately, so I thought I would provide the links to some of the posts from the past year on that theme. Hopefully I’ll be able to cover icthyosaurs, mosasaurs, plesiosaurs, and other critters in due time, but for now here are some aquatic-oriented works to keep you occupied;

Scuttling the Aquatic Ape Hypothesis

Everyone back in the pool!: From artiodactyl to cetacean

Protosuchus

Alligators? In the sewers?

A different kind of White Shark

Carnivory in Hippos

You can bring a Rhipidistid to land but you can’t make it walk

Idiocy beyond belief: Sharks don’t have webbed feet!

Bluffing in crayfish arm-wrestling

Skimming for supper, or not…

Giant Swimming Sloths of South America

An Iguanodon with flippers





School starts when?!

29 08 2007

Note: Thanks to the kind comments of people here and a relaxing evening reading some T.H. Huxley I’m feeling much better, although I’m sure putting out this little rant helped too. I’m going to try to make the best of the position I’ve found myself in, and hopefully I’ll move on to better things after I get my B.S. (both meanings apply) straightened out. Thanks to everyone who’s stopped in to show me some encouragement and support during this rough journey.

I’m not less than a week away from the start of the fall semester, and I’m definitely not done with summer yet (hell, I didn’t even go and get my first Rita’s gelati until Saturday). Still, I really need to buckle down and do well this semester as I’m essentially out of “last chances.”

Some of you might remember that I was considering switching into Evolutionary Anthropology. It appears that I cannot. Rutgers was recently restructured to consist of the School of Arts and Sciences (Busch, Livingston, Douglass, and College Avenue campuses) and the School of Environmental and Biological Sciences (Cook campus), and I have too low of a GPA and too many credits (121) to transfer into the program. Perhaps if things were as they have been for a number of years I could have made a case, but it appears that there’s a whole new set of rules and administrative B.S. and I do not have much hope for my appeal for a transfer. I stupidly painted myself into a corner academically, and now I don’t have much choice other than to finish up my current program and try to escape in one piece.

Indeed, the coming semester is not really going to be an enjoyable one, as many of the classes I have to take are basic courses that are required for students that I had not taken in my early years. This fall I’ll be taking;

Precalculus – I can’t put it off any longer; I must face the math demons and hope to come out in one piece. If I fail this course I’ll be prevented from taking other courses that are critical next spring and summer, and so the pressure is definitely on.

Computer Science 110 – Basic computers course on Excel, Word, etc. that everyone has to take. It’s not hard, but it’s mind-numbingly boring and I have little use for it. Still, it’s something I have to take care of.

Fundamentals of Ecological Modeling – I’m a few credits short of my requirement for ecological courses within my major, and this was the only one that fit in my schedule. The name just screams “Math!” at me though, and I don’t particularly have a good feeling about this one.

Soils and Society – I tried to take care of my “soils” requirement last semester, but I ultimately picked the wrong course. “Soils and Water” kicked my butt and now I have to take the easier version (which I wished I had found out about beforehand). I don’t think this one will be difficult, but I’d be lying if I said I was interested.

Living Primates – The one course I’m actually looking forward to. Even though I can’t major in Evolutionary Anthropology, at least I’ll have this one “fun” course to make things a bit more enjoyable and even out my GPA a bit (hopefully). I may have to drop this one though, especially if I’m struggling in more important courses or I need to work more in order to pay the rent.

I apologize for being such a sad-sack, but I simply am not looking forward to finishing out my degree. I need to have a degree in something, and past mistakes have led me down a path with no other choice. My wife opined that it would be wonderful if they just let me write a thesis and handed me a degree (you would figure I would have fulfilled the general requirements for some course of study by now), but such a fanciful notion will never come to pass.

What does this mean as far as blogging goes? I’ll still be on here, and I’ll still have something new up every day, but I don’t know how much I’ll be able to actually post. I actually usually don’t write during the evening as I read during that time, but even my reading is likely to be curtailed. I’m sure my attitude to this whole affair isn’t helping either, but in general I feel trapped into a course of study that doesn’t engage my interests during a time of year when I start to feel the effects of seasonal depression (I’m a warm-weather creature). Still, things as they are now are still better than the alternative of getting a minimum wage job at a retail store, and I’m not ever going to be happy or contribute anything if I don’t try and make it through this last year and a half of college.





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 Hypothesis" Human 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.





Pictures from Petsitting and the Delaware Water Gap

28 08 2007

These are a bit long in coming, but here are some photos taken while petsitting a few weeks ago and during the trip to the NJ side of the Delaware Water Gap. Unfortunately I’m not too familiar with fungi so I can’t say I know what many of the species pictured are, but many of them were impressive all the same.

Spider

This spider was busy building a web outside the house I was staying at a few weeks ago. I’ve never seen an abdomen on a spider like this one has.

Blue Jay

I usually only see Blue Jays during the winter (or at least only remember seeing them during winter), but this one stopped by the bird feeder.

Cardinal

A Cardinal pair also came by, although they were more skiddish and difficult to photograph.

Birds

Finches

Eastern Goldfinch and Cedar Waxwing were the most common visitors to the feeder, however.

Turkey Vulture

A Turkey Vulture also circled overhead for a while, although it didn’t find anything interesting in the yard.

Deer

White-Tailed Deer also came by many times during the day, although the amount of brush and shrubs made them a little hard to photograph.

Fawn

Fawn

Fawn

The second round of summer fawns also came by in the mornings and evenings, usually.

Katydid

A very large Katydid with a color pattern I hadn’t seen before also paid us a visit, albeid inside the house.

Now on to the photos from the hike along the Appalachian Trail to Sunfish Pond;

Harvest

Early on we came across these two fighting harvestmen (“daddy long legs”).

Fungi

Fungi

Fungi

Fungi

Fungi

Fungi

Fungi

Being that the ground was relatively damp, there was fascinating fungi everywhere. The last two shots are among my favorites, and could the “S” on that last one be intelligently designed? (If you are new here, sprinkle the last bit of that sentence liberally with sarcasm)

Frogs

Frog

Once we got up to Sunfish Pond, we were greeted by scores of Bullfrog and Leopard Frog young, which hopped, almost in unison, back into the shallows.

Toad

Toads were also present over the entirety of the hike. We counted at least 20 over the 10 miles.

Three Lined

Three Lined

We also saw two Five-Lined Skink (thanks for the correction, Lars) on a log and tree near the pond, the one on the tree have a brilliant blue tail.

Frog

Fish

Millipedes

Corn Snake

The area that we sat down to lunch at was absolutely full of life as well, from fish and frogs to a small snake that was getting ready to shed.

In all, I’ve been able to get more photographs of NJ wildlife this summer than I have in previous years, and I hope that next year I’ll be able to get some better pictures overall.








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