AAT/H claims and the facts:

Below are some key AAT/H claims juxtaposed with the relevant, and contrary, facts. Most also have either references or links to more information on these facts or in-depth examinations of the claims (more will be added as I complete them):

Claim: Human hairlessness is explained by an aquatic past

Fact: Humans' relative hairlessness is unlike aquatic mammals, because A) most aquatic mammals aren't hairless; and B) those few that are have skin that's radically different from humans (there's a link for this in the seal skin and sweat section below).

Claim: The pattern of human hair alignment is strikingly different from apes and indicates streamlining for swimming.

Fact: The pattern of human hair alignment is only very slightly different from apes. Also, in order for this pattern to indicate streamlining for swimming we would have to be swimming with the crown of the head facing straight forward and your arms held at your sides. Just take a look. This is so easy to see, you've got to wonder how AAT/H proponents can make the claim, or why it's swallowed so uncritically. There's also the problem that humans are not even close to being fast swimmers to whom streamlining therefore might help (more info in the "hairlessness" link above).

Claim: The human body responds the same to the act of standing up as it does to surgery or massive haemorrhage but this reaction doesn't occur when standing up in water.

Fact: Ooh, this is a thorny thicket; neither part is true but are misrepresentations of facts twisted about to make a point which isn't true sound true. To see how and why, you'll have to read this link on aldosterone and bipedalism.

Claim: Only humans and marine mammals shed salty tears.

Fact: All primates shed salty tears (see tears link below).

Claim: Only humans, Indian elephants, and aquatic mammals cry emotional tears.

Fact: Humans are the only mammals proven to cry emotional tears. There are no animals other than humans which have been scientifically proven as having emotional tears. However, there are unproved accounts of many other mammals crying emotional tears, but these are not just aquatic animals; they include dogs and wolves, seal, sea otter, lab rats, cats, cows, pigs, lambs, horse, a kangaroo and a gorilla.

Claim: Only marine reptiles and birds have salt glands.

Fact: Salt glands are found in many non-marine reptiles and birds, including ostriches and other birds, and many lizards, including iguanas, chuckwallas, and others.

Claim: The human response to salt indicates we evolved in a salt-water environment.

Fact: Human responses to salt are similar to terrestrial mammals, including chimps. Mammals which live in salt-rich environments do not exhibit these responses as humans do. Our salt mechanisms indicate a terrestrial past with a large herbivorous component to our diet, unlike the AAT/H claims.

Claim: Human infants naturally swim while other non-aquatic mammals' infants can't.

Fact: The infant "swimming response" has been found in all mammals tested.

Claim: Only humans and aquatic animals exhibit the "diving reflex".

Fact: The "diving reflex" is found in all mammals.

Claim: Only humans and aquatic animals can hold their breath.

Fact: Non-human, non-aquatic animals can and do hold their breath (refs in diving reflex link above).

Claim: The descended larynx of humans is like that of aquatic mammals, and must have arisen in an aquatic environment. Although it's necessary to make all the complex sounds we use in speech, it cannot have arisen for that purpose, because it wouldn't be useful for that purpose in its initial stages.

Fact: The descended larynx of humans is not particularly similar to those which are found in (only a very few) aquatic mammals (refs and info in diving reflex link above). Previously here I'd said that the evidence from the fossil record also indicates that this feature developed several million years after the purported aquatic period, but research on the larynx over the past shows this is actually a far more common trait than previously thought, and is primarily because of vocalization (see the "descended larynx" section of the breathholding, descended larynx, and diving reflex link).

Claim: Non-human primates have nostrils that point forward, unlike humans.

Fact: What can I say; Old World primates are in fact called Catarrhine primates precisely because their nostrils face down. Morgan likes to try to have this one both ways; while she claims that forward-facing nostrils are detrimental to aquaticism, and that we had a human-like nose several million years before the bones on our ancestors' faces indicate they did, she takes the nose of both male proboscis monkeys (with its downward-facing nostrils) and of female and juvenile proboscis monkeys (which face as much forward as other Old World monkeys) as aquatic adaptations. (Scientists who study these monkeys' behavior say it's sexual selection, as is true of all sexually dimorphic traits which aren't due to differences in use.) She even has a drawing of a juvenile proboscis monkey swimming in her latest book which, according to her theory, should have water shoved up his forward-facing nostrils. Why, if it's no problem for a monkey, would it be such a big problem for hominids as to force a massive change? Morgan doesn't see the contradiction.

Claim: Our ancestors wouldn't have changed from quadrupedalism to bipedalism, because initially bipedalism would be less efficient than quadrupedalism.

Fact: Actual tests of chimpanzees by Taylor and Rowntree in 1973 (Science 176: 186-187) has shown that bipedalism is no less efficient for them than quadrupedalism. It wouldn't be for our ancestors, even if they evolved from knuckle-walking apes such as chimps. Also, the consensus over the last few decades has been that the LCA was far more likely to have been a brachiating (swinging from branches) ape rather than a knuckle-walker, which makes it even less of a problem to be bipedal. In fact, brachiating apes -- such as gibbons -- virtually always walk bipedally when they are on the ground.

Claim: Proboscis monkeys use bipedalism more often than other primates and often walk bipedally as "merely an alternative locomotor mode of getting from A to B."

Fact: Morgan bases this claim on several seconds of film taken by Japanese filmmakers, which showed several proboscis monkeys walking bipedally. On this subject, I just (August 9, '01) watched a TV program, "The Secret World of the Proboscis Monkeys", and over the course of the hour, those obnoxious primates simply refused to do any bipedal walking. Perhaps it was because it was French filmmakers this time, or maybe the anthropological conspiracy quashed all the bipedal episodes. Or, just possibly, it's what years of observations by primatologists tell us: Proboscis monkeys don't walk bipedally more often than other primates (all primates use bipedalism occasionally).

Claim: It was too dangerous for our ancestors to live on land during the transition from ape ancestor to hominid. The water provided safety from predators.

Fact: The water environment would be far more dangerous than the land environment; the predators there are more numerous and harder to deal with.

Claim: Our ancestors couldn't have dealt with predators on land, because the only way to do so is to run away, and we weren't fast enough and there were no trees to climb.

Fact: Not only were there trees in the hominids' environment (see savannah definition if you haven't already), but it is unlikely we would have been limited to running from predators. How we probably would have handled them is how chimpanzees handle predators now (see the predators link just above).

Claim: The body temperature of normal, healthy humans is the same as that of whales, rather than our primate relatives or other terrestrial mammals, and it doesn't fluctuate, while that of terrestrial mammals does.

Fact: The body temperature of normal, healthy humans is like that of our primate relatives, it does normally fluctuate, and it's not like that of whales.

Claim: Hymens are an aquatic trait.

Fact: Besides humans, hymens are found in lemurs (fellow primates, you'll note), guinea pigs, mole rats, hyenas, horses, llamas, elephants, rats, horses, and some species of galago, as well as in aquatic mammals such as toothed whales, seals, and sirenia. Among these, toothed whales, seals, and sirenia are aquatic. And note that the aquatic ones are fully aquatic, not casual dip in the water types; once again AAT/H proponents are comparing us to mammals which have been fully aquatic for tens of millions of years.

There's another thing: the hymen seems to vary an awful lot, so much that it doesn't look like you can make the easy comparisons across species the AAT/H relies on. For instance, guinea pigs' hymens are quite different from most others, and those in whales are apparently different enough that various textbooks refer to them as "vaginal bands" or refer to "a hymen-equivalent possibly present in juveniles" ("Reproduction in Marine Mammals" by Ian L. Boyd, Christina Lockyer, and Helene D. Marsh, in Biology of marine mammals edited by John E. Reynolds III and Sentiel A. Rommel, 1999).

Also, AAT/H proponents suggest that the reason for a hymen in humans was to seal off the female reproductive organs from waterborne parasites and such; but since the hymen is generally absent from the time of first intercourse (and very often before) this protection wouldn't be available for much of the female's lifespan.

Claim: Vibrissae (sensory whiskers) are absent only in humans and in aquatic mammals.

Fact: Among aquatic mammals, vibrissae are actually absent only in some types of whales (whales such as blue, fin, and humpback whales have them) and of course they are abundant and very sensitive in most aquatic mammals. They are, however, also absent in other, terrestrial, mammals, such as tree shrews and the monotremes (platypus and echidna). The great apes have few vibrissae compared to other mammals, and their absence in humans seems to be yet another of the "continuation of a trend" features we see in primates (hair and sweat glands are other such features). A few minutes search on the web (using the term "vibrissae" with either "primates", "comparative", or "whales") easily turned up this information. Why do AAT/H proponents not do even so easy and basic research as this before making their claims?

Claim: Human fat quantity and distribution is like that of aquatic mammals; it is adapted for insulation and swimming in an aquatic environment. Humans have subcutaneous fat which is bonded to the skin rather than anchored within the body, unlike non-aquatic mammals.

Fact: Human fat characteristics show no sign of any aquatic adaptation, and are radically different from the aquatic mammals AAT/H proponents say we resemble. Human fat deposits are anchored to underlying depots, just as those of all mammals are. Human fat deposits are found in the same places, and are anchored the same way, as those of other primates.

Claim: Seals sweat through eccrine sweat glands, like humans, because aquatic mammals lose their apocrine sweat glands.

Fact: Seals don't sweat via eccrine sweat glands, and in fact the sweat glands of seals are apocrine glands (refs in "skin" link below).

Claim: Human sebaceous glands waterproof the skin, like the sebaceous glands of seals (and that "Sebum is an oily fluid whose only known function in mammals is waterproofing the hair and skin.").

Fact: Sebaceous glands cannot waterproof human skin (which is why your skin wrinkles when wet). This is because human skin is very different than the skin of seals. And that's not the only evidence that human sebaceous glands are not an aquatic adaptation. The primary function of sebum, the output of the sebaceous glands, is to produce scent (generally as a sexual attractor). This is true of a variety of mammals, including humans. In some seals, sebum can also keep their highly specialized skin pliable as an aid in waterproofing (refs in "skin" link).

Claim: Aquatic mammals copulate facing each other, like humans do, while other terrestrial mammals don't.

Fact: This statement is at odds with the facts about mating postures.

Claim: Hominids couldn't have developed large brains without Omega-3 fatty acids (DHA) from a shore-based diet.

Fact: Simply untrue, and rather obviously as well. See brains and "brain food".

Feedback: E-mail me