Jim Moore's "AAT Sink or Swim?" Web Site
The AAT Characteristics List
This page appears to be dedicated to an infamous leaflet about the AAT and an apparently damning list of characteristics claimed to be evidence for an aquatic past contained within it. Moore writes "I assume it was written by Elaine Morgan" and claims that she gave it out "at talks" but doesn't give any accurate reference to it other than saying that "her grandson posted it on his site soon after." Even this web site link is not given so again we just have to assume what Moore is telling us is correct.
Putting to one side the importance or otherwise of this 'leaflet' it is illuminating to analyse Jim Moore's counter-arguments and his methods to see if they hold any water. You will find that overall his counter-claims are weaker than the claims themselves. He does make one good point: The argument that the descended larynx happenned relatively recently and therefore contradicts Hardy's (1960) original proposal of an early, pre-Homo, aquatic phase appears sound. His arguments against such traits as loss of vibrissae, ventro-ventro copulation and psychic tears are also reasonable but, in my opinion, it is a mistake to consider these traits pivotal in the debate. On the traits important I consider to be important Moore seems to misunderstand and misrepresent the AAH argument.
On at least two occasions he is factually incorrect. For example on 'skin-bonded fat deposits' Moore dismisses the table as wrong, suggesting that our fat deposits are like other primates. Montagna (1985:p14) wrote "...human skin acquired a hypodermal fatty layer (panniculus adiposus) which is considerably thicker than that found in other primates, or mammals for that matter." And Moore's claim that hymen are only found 'only in fin whales' among the aquatics is directly contradicted by Fichtelius (1991).
The authority of this leaflet has to be questioned from the start but Moore's critique, even of this, ican be seen to be severely lacking in scholarly rigour and objectivity.
Details follow below.
This is the original table Moore critiques: Out of Eleven characteristics, he judges only one to be correct (bipedalism) one to be 'highly misleading' and the other nine simply wrong.
Moore agrees that this is "a pretty impressive list" but argues that it is only impressive to the uninformed. When one is informed, he claims, one then realises that the similarities listed in the list are bogus. Then, he claims, "explaining why they exist is impossible -- they aren't real."
His argument seems to be based upon the comparison (in this table) of savanna and aquatic mammals with humans. Moore claims that this is an example of 'special pleading' because the analogies with aquatics are open to all kinds of mammals from different sizes, habitats etc whilst the savanna animals are a small subset of terrestrial mammals.
Moore then goes on to list the table out again with a column entitled 'reality', where he points out the anomaly of the AAT leaflet's claim.
Hardy wrote "Wading about, at first paddling... He would naturally have to return to the beach to sleep and to get water to drink; actually I imagine him to have spent at least half of his time on the land." (Hardy 1960,p644).
The claim that AAH proponents would have to conceded that there was no evidence to back up the wading argument is not true, although Moore's web site was probably written before most of the recent papers (e.g. Doran & McNeilage 1997; Parnell et al 2001; Tutin et al 2001; Kuliukas 2003) documenting the clear tendency for bipedalism in extant apes when wading through shallow water came out.
But, clearly, Moore is missing the point. The aquatic argument here has always been that when one finds an odd trait in a species that is hard to explain, one looks for analogies in other species.
This was the subject of the first chapter of Desmond Morris' book 'The Naked Ape' (Morris, 1967). He wrote "Staring at this strange specimen [Homo sapiens, the naked ape] and puzzling over the significance of its unique features, the zoologist now has to start making comparisons. Where else is nudity at a premium? The other primates are no help, so it means looking further a-field. A rapid survey of the whole range of the living mammals soon proves that they are remarkably attached to their protective, furry covering, and that very few of the 4,237 species in existence have seen fit to abandon it." And, having considered a few examples (e.g. bats denuding their wings), he concludes "At this point the zoologist is forced to the conclusion that either he is dealing with a burrowing or an aquatic mammal, or there is something very odd, indeed unique, about the evolutionary history of the naked ape." Morris (1967:p11)
Of the eleven probable evolutionary occurrences of nakedness in the mammalian order, at least four may be attributable to aquatic forces (Sirenia, Cetacea, at least one Pinniped - the walrus, and Hippopotimidae); two may be attributable to large size (elephants and rhinoceroses); two for burrowing (naked mole rat and armadillos/ pangolins) leaving two: some pigs and humans. Assuming that our ancestors were never so large as the rhinoceros or took to a subterranean life style, aquatic factors do seem to offer a rather likely clue as to what may be behind our nakedness. There is also a distinct possibility that elephants (See e.g. Gaeth 1999), rhinoceroses and pigs all share a more aquatic past too.
The AAH argument here is merely to suggest that if you take mammalia as a whole and ask Morris' question 'Where else is nudity at a premium?' the strongest answer most likely to be applicable to humans is clearly the ones that favour moving through water. Drag reduction is clearly reduced by shaving body hair, as any competitive swimmer will tell you, and as the Sharp & Costill (1989) paper clearly demonstrated. It is therefore not clear as to what Moore's objection could be to this particular argument.
Skin-bonded fat deposits
Moore is quite explicit here. He writes, of the AAT claim that this is found only in man and aquatics: "Wrong: Our fat deposits are like other primates and very unlike fatty aquatic mammals, both in pattern and life history."
Moore, as usual, does not provide any reference to back this claim up but if one looks up for papers in reputable journals on the subject of the evolution of human skin and the comparative anatomy with primates, it is possible to find them.
William Montagna, arguably the world's leading expert in mammalian skin, writing in the Journal of Human Evolution in 1985 completely contradicts Moore's claim. He writes "Together with the loss of a furry cover, human skin acquired a hypodermal fatty layer (panniculus adiposus) which is considerably thicker than that found in other primates, or mammals for that matter." (Montagna 1985:p14).
It seems that here it is Moore, not the infamous AAT leaflet, which is just plain wrong.
Personally I have never considered this 'trait' as being a direct consequence of increased aquaticism but rather a secondary effect of it due to our bipedality.
Diminution of apocrine glands
Montagna (1985:p17) says "apocrine glands are more numerous than eccrine sweat glands in gibbons and orang-utans but the opposite is true in chimpanzees and gorillas.. This state of affairs makes it comfortable to explain that man, with the fewest apocrine glands and most eccrine sweat glands over his general body surface is the latest model in evolution."
So, although the table was probably being too simplistic to apply a simple Yes/No attribute to such a variable, it would seem fair to conclude that the human condition of apocrine glands is diminished compared to apes (including gibbons and orangs). Moore's point, agreeing with Montagna, that humans follow in the progression of the great apes, does not contradict the assertion that in humans the apocrine glands have diminished the most.
Fichtelius (1991:p289) writes "The vagina of toothed whales, seals and dugongs is long and winding, and has a better developed hymen than is found among land mammals. These arrangements presumably function as a barrier, preventing water from entering the vagina." So not just fin whales then.
Moore is right to point out that lemurs also have this trait. Of this Fichtelius (1991:p289) writes "The hymen occurs in humans and prosimians, but not in monkeys or apes."
His conclusion was "the primal function of the hymen bears a relation to the seasonality of sexual activity; in the guinea-pig and some other small mammals it reseals the vaginal opening after each reproductive period. In Homo is is unlikely to relate to this function, considering the all-the-year rounds state of receptivity in the adult female. The presence of a well developed hymen in large, unrelated aquatic mammals suggests that in an aquatic medium it serves a different function. It would appear, therefore, that the labia and the vagina of the human female are in several respects better designed than those of the ape for keeping out water and water-borne impurities."
Once again, it would appear to be Moore, not the unknown AAT advocate who wrote the leaflet, who appears to be incorrect.
Personally, I have never considered this feature to be a very important one in the debate as emotional crying would appear to be, like language, a rather unique human characteristic. Morgan only really talks about it in the sense that it make be some kind of scar from our evolutionary past where, perhaps, salt excretion may have been aided by this method as with some sea birds.
vibrissae (sensory whiskers)
I am not quite sure why this trait was included in such a list of AAT traits, as pinnipeds certainly have very pronounced vibrissae, and do not really see the need to defend it.
Perhaps the table should have given a qualified 'No' for savannah mammals and apes, admitting that almost all land mammals also appear to have the ability to swim and therefore require some form of voluntary breath control.
It should be noted that Moore did not contradict the table's claim that apes do not exhibit eccrine sweating.
Hardy made it quite clear that his idea was that human ancestors were water-side dwelling and never more aquatic than an otter. It is a tropical water-side habitat where sweat cooling makes most sense as a supplementary thermoregulatory mechanism to 'going for a dip'. In this sense any attempt to compare eccrine sweating with true aquatics is bound to fall over.
There are two separate points here. The first is that, in comparison to aquatic mammals, the human larynx has a very different life history. If Moore is thinking of cetaceans (he doesn't make it clear), then clearly he is right. But whales and dolphins, as he points out himself, have been fully aquatic for tens of millions of years. The evolution of a blow hole has taken the larynx in a very different and specialised direction. The AAH claim is that only some, rather less aquatic mammals, such as the walrus, sealion and dugong have such an analogous trait. Moore does not contradict the table in its claim that apes and savanna animals do not share the descended larynx.
The second point Moore makes is that the larynx descended in humans relatively recently (as seen in the fossil record) and therefore contradicts the original Hardy (1960) claim that a specific 'aquatic phase' occurred since the last common ancestor (LCA) of Homo and Pan but before the evolution of the genus Homo as we identify it today.
On this point I agree with Moore. It is clear that a post-LCA, pre-Homo aquatic phase is not supported by the fossil record. However this does not contradict the alternative AAH view which argues that no such distinct phase occurred but rather that Homo has generally lived in water-side habitats more than the ancestors of Pan/Gorilla.
Fichtelius, Karl-Erich (1991). More Thoughts on the Aquatic Ape Theory: How the aquatic adaptations of man differ from those of the gorilla and the chimpanzee. In: Roede, Machteld; Wind, Jan; Patrick, John; Reynolds, Vernon (eds.), (1991). Aquatic Ape: Fact of Fiction: Proceedings from the Valkenburg Conference. Souvenir Press (London)
Gaeth, A P; Short, R V; Renfree, M B (1999). The Developing renal, reproductive and respiratory systems of the African elephant suggest an aquatic ancestry.. Proceedings of the National Academy of Sciences of USA Vol:96 Pages:5555-5558)
Hardy, Alister (1960). Was Man More Aquatic in the Past?. New Scientist Vol:7 Pages:642-645.
Kuliukas, Algis Vincent (2002). Wading for Food: The Driving Force of the Evolution of Bipedalism?. Nutrition and Health Vol:16 Pages:267-289
Montagna, William (1985). The evolution of human skin. Journal of Human Evolution Vol:14 Pages:13-22
Morgan, Elaine (1982). The Aquatic Ape Theory. Souvenir Press (London)
Morris, Desmond (1967). The Naked Ape. Vintage)
Parnell, Richard J; Buchanan-Smith, Hannah M (2001). An unusual social display by gorillas. Nature Vol:412 Pages:294
Sharp, Rick L; Costill, David L (1989). Influence of body hair removal on physiological responses during breastroke swimming. Medicine and Science in Sports and Exercise Vol:21 Pages:576-580
Tutin, Caroline E G; Ancrenaz, Marc; Paredes, Jorge; Vacher-Vallas, Myriam; Vidal, Carmen; Goossens, Benoit; Bruford, Michael W; Jamart, Aliette (2001). Conservation biology framework of the release of wild-born orphaned chimpanzees into the Conkuati reserve, Congo. Conservation Biology Vol:15 (5) Pages:1247-1257