Hello enki
For me, one of the more astonishing claims of the programme came from a few supporters of the theory who were prepared to suggest that the aquatic ape period was much more recent than the 5-7 million to 3.5 million b.p. period that Hardy and Elaine Morgan had suggested. One hypothesised its occurring during the time of Homo Erectus (1 million years ago?), and another during the early years of the establishment of our own species, Homo Sapiens - maybe 100,000 years ago at most. I would certainly think that such recent estimates must be precluded by any reputable evolutionary theory. Nonetheless, aren't we still very much in the dark about the rates of evolutionary change? Isolation of an animal group has been suggested as a principal cause of speciation, but I believe Darwin himself (despite his Galapagos observations) was reluctant to claim this as the only cause of dynamic evolutionary change. (In this respect, I think E.M's idea of hominids isolated on an island is speculative in the extreme.)
Enter Stephen J. Gould, and his Punctuated Equilibrium. He was prepared to accept that from his observations of the fossil record that stasis over vast aeons is a pretty common phenomenon, but interspersed with periods of very rapid evolutionary change. I have to admit that I don't have the in-depth knowledge or indeed full understanding of what Gould was arguing to be able to suggest why such rapid evolutionary change might occur under certain conditions, but I think he might have thought that 3.5 million years was enough to effect a few bodily modifications in a hominid. We're not talking about a creature becoming fully aquatic here (as in the case of the cetaceans that you cite) - simply spending a lot of time in the water in search of the most readily available food supply.
The question of food supply is of course the clincher to several aspects of the argument. Was it not posited that lypids * found in abundance in aquatic animal tissue, but not so abundant in terrestrial animals, was an essential element in the preservation of healthy human organisms? And that these substances for long periods of the year were extremely meagre in animal prey, but always in high amounts in marine life? Those that had the healthier marine diet would certainly be the 'fittest' to survive. It was also argued that these substances were essential for the massive growth of the human brain, and that those creatures deprived of such essential ingredients never develop large brains. Thus, the propensity to develop larger brains would be intrinsically dependent on consistent supplies of the chemicals in question over possibly a few million years. And that would certainly give the hominids involved an evolutionary advantage.
*Not sure if these were the substances mentioned. I'm not a biochemist 
Hi Dicky,
Morgan regards the crucial gap between Ramapithecus at 9My and Australopthecus at 3.7 My(Morgan 'The Aquatic Ape Hypothesis') and refines the precise period between 8 and 6 My. Of course ramapithecus is now regarded as being part of the orangutan group and is not a viable ancestor for the hominid line. It is interesting that in her earlier book, she considers that there were 'ten or twelve million years in the water'(Morgan 'The Descent of Woman')
Stephen Gould's (and others) hypothesis of punctuated equilibrium mainly deals with the idea of the problems related to stasis and the sudden appearance and disappearance of species, as we see it in the fossil record. It is proposed that it is usually the result of rare and geologically rapid events, allowing new morphologies to form quickly.
I'm not sure that this helps explain the AAH though. Surely Ockham's Razor suggests that with a terrestrial antecedent and a terrestrial descendent shortly(geologically) thereafter, the evolutionary trajectory would be through terrestrial intermediates. As regards the coastal theory of the aquatic/semi aquatic ape, it is surely true that hominids have occupied a successful niche in mosaic/savannah habitats, even with the suggested aquatic changes of, for instance, bipedality, the descended larynx, sweating(involving salt and water loss) and subcutaneous fat. So, why did these proto-hominids desert such a rich and productive niche for the rigours of the savannah? After all the Miocene cooling provides the necessary pressure to justify a savannah/mosaic woodland explanation whilst the coastal aquatic scenario would seem a more stable environment, leading to increasingly more well adapted aquatic/semi aquatic hominids better suited to survival, maybe leading to a population explosion. Their subsequent disappearance is surely a problem for those who suggest that coastal waters was where they originated. A tsunami, perhaps?
Your point about the marine food supply and the enlargement of the brain is an interesting one. This is largely founded on the fact that omega 3 fatty acids are required for brain growth, and that omega 3 is abundant in fish in particular. First of all, Morgan argues that there is no evidence that the savannah requires more intelligence to exploit than the ancestral forest.(Morgan 'Descent of the Child'). Of course she is correct, but fails to consider other factors whichare often cited as leading to larger brains, such as socialization and co-operation. Also, although some cetaceans can be generally considered to have large brains, and good EQs, what about other marine species, especially intellectually challenged fish?
Greater encephalisation, of course, is shown in both homo habilis and homo erectus rather than the australopithecines, and these are clearly associated with a terrestrial environment as witnessed by stone tools and bones.
As regards the omega 3 fatty acids, we don't really need loads of it as(apart from infants) we can synthesize it from vegetable oils and meat sources, as well as the seashore. Indeed, if you move back say two hundred years(or before dietary supplements and mass food availability) plenty of people with normal brains existed on diets which didn't have marine elements. Also the idea that rich sources of omega 3 would, in some way, kickstart larger brains is postively Lamarckian in its intent. Evolution doesn't work that way. If it did, why haven't fish eating species such as herons, diving ducks, otters, seals developed much larger brains?
Finally, whilst scanning Ch 9 of Gould's 'The Structure of Evolutionary Theory'(which was a bit like wading through treacle), I did come across this quote. I hasten to add that he was not talking about the AAH at all, but, for me, this quote is entirely apposite.
He mentioned G.K.Chesterton, who wrote that all art is limitation. He then goes on to say:
The same principle operates in science, where claiming too much, or too broad a scope of application, often condemns a good idea to mushy indefiniteness and consequent vacuity
I think that the AAH had a kernel of a good idea, I'm not against it, but Morgan tried to encompass too much in her enthusiasm to put it across. It does seem now to have reached a point however, that in a much more watered down form, the idea of the waterside ape can be looked at with new eyes.
