Jim Moore's "AAT Sink or Swim?" Web Site
Relevant Questions for the Aquatic Ape Theory
Jim Moore's web site has hardly started by setting glowing standards of scholarly robustness. The three pages of criticism of the AAH reviewed so far have not yet included a specific citing from any of Morgan's five books despite his initial characterisation of AAT proponents methods as being less than scientific and an early promise that you would not find similar methods here.
It's a poor start then, but although there is actually one full reference to one of his claims here, it gets worse.
Moore starts by stressing the importance the AAH places on the principle of convergent evolution. He claims that this is so important to the AAH that it uses it "to make statements which ignore the crucial role of phylogeny (relatedness) in evolution." He gives one, quite bizarre, example to back this up. He writes 'For example, the AAT says we did not evolve on land because some of our adaptations, such as our method of thermoregulation, are different from the methods used by other distantly-related-to-us mammals in that habitat, such as "the wild ass and the camel".'
It is difficult to know how to respond to such a gross misrepresentation but let's start with the most obvious and blatant one: 'The AAT says we did not evolve on land.' Apparently Moore now thinks that Hardy, Morgan et al are proposing that humans left the land and lived out to sea for a million years or so. If that is one's assumption of the AAH then it is not difficult to refute it. Of course Hardy and Morgan never proposed any such thing. Hardy stated unambiguously that he envisaged man never being more aquatic than a semi-aquatic otter (Hardy 1960:p643) and Morgan has often stated a similar line herself. For example she wrote "The AAT proposes that some of the indigenous apes living in that region [of a wide belt of tropical forest in East Africa] could have been cut off from the rest of the ape population and forced to adapt to a semi-aquatic life in flood plains or coastal marshlands or off-shore islands for up to a million years" (Morgan 1994:p158). The AAH clearly agrees that humans evolved on land, but land that was at the water's edge and that our ancestors, as a consequence, often had the need to move (wade, swim, dive) through water.
It is difficult to critique the quotation to the 'wild ass and the camel' because Moore gives no citation. Even assuming that Morgan, at some point in her books, did make such an analogy it is difficult to comment without knowing the context. As to the argument about the AAH using convergent evolution to the point where phylogeny is ignored, we shall see how completely wrong that idea is shortly.
Moore argues that even though the AAH uses convergent
evolution to back its arguments, it ignores many such examples in aquatic
mammals, which are not mirrored in humans. The page then goes on to ask nine
questions to AAH proponents, the first five related to aquatic features seen
in most aquatic mammals. The questions are largely facile and clearly show a
complete misunderstanding of what the AAH is proposing. Full answers will be
given here, nonetheless.
Questions for the AAH:
1. Why don't humans have really small ears (or no
external ears) like virtually all aquatic mammals?
The AAH proposes that our ancestors were more aquatic than the ancestors of our ape cousins, not that we were ever anywhere near as aquatic as those animals which have reduced their external ears.
The comparisons that matter are with our great ape cousins, the chimps and gorillas, not with very distant related aquatic mammals. (This is the point about phylogeny that Moore claimed the AAH ignored). In terms of external ear size, it would appear that humans have smaller ears than Pan but not Gorilla.
2. Why were our legs, unlike those of other aquatic
animals, exempt from convergent evolution?
The main difference between humans and the great apes is our elongated leg length which, presumably, is an adaptation for bipedalism. The AAH explanation for bipedalism is that it evolved at least in part as a consequence of the pressure for a group of apes to wade in relatively shallow water. Clearly, one would predict that leg length would increase, not reduce, under such pressure.
The answer is therefore very much the same as the previous one: Pressure for terrestrial bipedalism would have clearly acted against any counter-pressure from swimming for shorter legs. The AAH proposes only that selection for swimming and diving acted upon our ancestors more than it did the ancestors of apes, not that it did so as much as in aquatic mammals such as seals.
3. Why did the purported aquatic hominids change in
the opposite direction [in terms of their speed of developmental growth]
from other aquatic mammals?
Morgan wrote a short chapter on this subject (Morgan 1994:p21-24) and later, arguing about the increase in the size of human infants generally (and therefore their slow speed of development), wrote "only in an aquatic environment would a fat baby be less burdensome than a thin one, because one of the functions of fat in aquatic mammals is to give buoyancy." (p162).
My answer to Moore's question is this: Assuming that it is correct that aquatic mammals do develop more rapidly than terrestrial analogues (something I would need convincing of) one would have to postulate that it was a function of the danger of predation that resulted from marine life that would have driven their young to develop as quickly as possible. As the AAH proposes no such stage of marine life occurred, but rather one in a water-side and relatively nutritionally rich and predator free habitat, humans would be predicted to become more k-selected. Larger, slower developing infants make more sense in a water-side habitat than in arboreal or purely terrestrial ones.
4. Why are humans so unlike all marine mammals and
so like terrestrial mammals [in their milk composition]?
Humans are evolved from apes, therefore one would
expect us to have milk composition that was closer to apes than to any other
animal. Human milk is, however, much fattier in content than our ape
cousins, (4.4% compared to 3.0%, Ben Shaul 1962, Tailor & Tomkinson 1975.)
This is to be expected as our infants are born much fatter than theirs
and continue to put on even more fat than theirs do in the first twelve
months of normal growth. The functional significance of this increased fat
is much easier to explain in the AAH than alternative hypotheses.
5. Why didn't we adapt as all marine mammals have
done, via a change to our pre-adapted kidneys?
Moore then suggests that the answer he usually gets to these questions is that "there wasn't time" and counters that by suggesting that the AAH is selective in arguing that there was time for other significant changes (e.g bipedalism) to have occurred in the same time frame.
This would be a reasonable counter, but I would suggest that the answer to the questions is not so much that there wasn't time, but that there wasn't actually very strong aquatic pressure. I would suggest that Moore, like most aquasceptics, have misunderstood what the hypothesis is proposing: that we were merely more aquatic than our ape cousins but that moving (wading, swimming and diving) more than they did was sufficient to cause our evolution to take a significantly different direction to theirs.
Moore then goes on to ask four more questions...
6. How did we swim, breath, see where we were going
in this [swimming with head held out of the water] position?
The fourth part of the question asked 'how did we swim fast in this position?' Clearly, as humans do today, any swimming hominid would adopt a variety of swimming strokes for different requirements... something akin to front-crawl for speed, something like breast-stroke for efficiency.
The fifth part of the question included a surprising addition - it actually contained, for the first time so far, a clear and unambiguous reference to the source of the claim. He wrote "The reduction of hair and its orientation has been said to be an adaptation for speed in the water to escape sharks (Hardy 1977, reprinted 1982); but while large land-based predators run approximately 3-4 times as fast as humans, sharks swim approximately 3-6 times as fast as the fastest Olympic swimmers. Why were we able to swim away from sharks but not run away from land-based predators?"
Hardy did indeed suggest that reduction of hair would
help increase swimming speed but it is an astonishing misrepresentation to
imply that he was claiming it would be sufficient to outswim a shark. Hardy
wrote "We can easily see how natural selection could lead to the reduction
of hair of it is reported that the Sydney University Swimming team shave off
all their body hair before a race and by this save a second in a hundred
yards swim; as groups of our ancestors swam in the tropical seas, chased by
sharks, it was the more hairy that tended to lag behind and so become a
prey to the voracious jaws." Hardy (1982:p150)
It should be clear
to anyone reading that, that Hardy was merely suggesting that in group
situations, the hairier members would be selected against. Animals that live
in groups are therefore not so much competing against their predators but
against each other to avoid them.
This idea was backed up by firm scientific data in 1989 when Sharp & Costill found significant reduction in drag in male competitive swimmers that shaved off body hair compared with with controls that did not.
7. How did the postulated aquatic transitional
population deal with common aquatic predators such as crocodiles and sharks?
It should also be noted that throughout our evolution our ancestors would have still be quite adept in trees and, although many land-based predators are able to climb trees there is yet to be a reported case of a crocodile or a shark doing so.
8. Hardy and others say that during this supposed
aquatic phase of the transition, we learned to make sharpened stone tools,
knives, and even spears, and to hunt and butcher large animals: why did we
quit doing these extremely useful things for the next 4-6 million years
after supposedly learning to do so?
9. Why haven't we developed a resistance to such
toxic reactions [Elaine Morgan apparently claimed that H. erectus
KNM-ER-1808 may have died after Vitamin A poisoning due to eating fish] to a
food which supposedly had been eaten regularly for approximately 4-6 million
years before that time?
Moore presumably thought that his nine questions were difficult to answer for a proponent of the AAH but, as we have seen they weren't. Instead, they illustrate rather clearly the kind of misunderstandings of Hardy's mild hypothesis that have been allowed to go on unchallenged.
In return, I have just one question to put to Moore and the aquasceptics:
If human ancestors did not live closer to water-side habitats more than did the ancestors of chimpanzees since the split, how come we are better able to swim than they are?
Hardy, Alister (1960). Was Man More Aquatic in the Past?. New Scientist Vol:7 Pages:642-645.
Hardy, Alister, (1977) "Was there a Homo aquaticus?", article originally appeared in Zenith, 1977, vol. 15(1):4-6. Reprinted in 1982 The Aquatic Ape by Elaine Morgan
Morgan, Elaine (1982). The Aquatic Ape Theory. Souvenir Press (London)
Morgan, Elaine (1994). The Descent of the Child. Penguin Books (London)
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
Tailor, J. A. & Tomkinson, M. (1975). A comparative study of primate breast milk. Reports of the Jersey Wildlife Preservation Trust, 12, 76-77.