When I first heard of the Aquatic Ape Theory as a teenager, I had a good laugh. By the 1980s, we had alot more fossils to look at than Max Westenhöfer had had in 1942 or Sir Alister Hardy had had in the 1960s, and the perceived gap they sought to close in the human fossil record had by that time been found to be virtually non-existent. In the 80s and 90s, AAT seemed like something made up by people who really wanted to believe in mermaids.
But since then the AAH theorists have become alot less radical in their views, and with all the evidence of marine exploitation and coastal/riverside expansion in our fossil and archeological records, it would probably be unwise to discount any possibility at all that a temporary waterside existence influenced a stage in the evolution of mankind.
Most explanations provided by modern AAH thinkers can be explained more logically by other mechanisms, as pointed out by Jim Moore's website "Aquatic Ape Theory: Sink or Swim?"
John Hawks points out that most of these theories require terrestrial stressors for hominids to keep the traits they supposedly aquired in a water environment, therefore showing that these stressors could have caused the adaptations that AAH attempts to explain in the first place.
However, Phillip V. Tobias , one of the most respected anthropologists of the past century, stated before his death in 2012 that there are certain aspects of AAH that are "that seem more difficult to reason away." He also noted in a 2012 paper that rejection of the AAH has led to stigmatization of a whole spectrum of topics related to the evolution of humans and their interaction with water.
Hominids spread out over the Earth along coasts and river routes, and kitchen middens go back at least 164,000 years, so I wouldn't discount that at least some of the traits we've aquired over that time may have resulted as a result of a coastal existence. It is understood that the traits we've aquired over the past 164,000 years are all pretty minor traits considering the span of hominid evolution, but they are all traits that separate us from some of the other archaic hominids that were around at that time, and they are traits that separate us from one another "racially."
But there seems to be one demographic of extant homo sapien sapient that has evolved ever-so slightly more than the rest of us towards a maritime existence. These are the so-called "sea-gypsies" of southeast Asia. Conveniently, they are precisely the people that Oppenheimer, Solheim, and Manansala have identified as remnants of the "Nusantao Maritime Culture" which they theorize is one of the major impetuses of the Neolithic revolution and the spread of civilization around the world.
The ancestors of these people. the proto-Nusantao, are also likely the source of elongated carnial deformation practices, mummification, and circumcision, according to the views of those authors.
What's more, the Nusantao or proto-Nusantao are the most likely spreaders of Microcephalin D, which entered our genome 30 thousand years ago from an extinct hominid that is not neanderthal or denisovan, and most likely not "the hobbit" either.
We will call this ancestor Hominid X.
Hominid X had split off from the ancestor of homo sapien sapient at least 1.7 million years ago before it's genes reunited with us again in the late Pleistocene. We assimilated his Microcephalin D and seem to have bred out all of his other genes since then.
The "unknown hominid" component in the Denisova gene is probably a branch of this same unknown hominid's genome that spread from SE Asia into China. Either this hominid lived in South Asia or Sundaland up until at least 30 thousand years ago, or a "sister race" of anatomically modern humans akin to "Mungo Man" which had already assimilated Microcephalin D did, or it wouldn't be present in 90% of non-sub-Saharan Africans today. We had to assimilate it from someone, and the best match for a location of that hybridization is SE Asia with South Asia coming in a close second.
The Nusantao or pre-Nusantao are also the most likely spreaders of ASPM-D, a new allele that arose a mere 11 thousand years ago in populations with Microcephalin D and has since spread to 70% of non-sub-Saharan Africans alive today.
Microcephalin D, incidentally, is inherit in 90% of today's population. In a very general sense, wherever you don't find Y Haplogroup F you don't find Microcephalin D....and wherever you don't find F's descended Y Haplogroup K you don't find ASPM D.
The highest frequencies and diversities of both these genome sweeping alleles are found in Papua New Guineans, South East Asian Sea Gypsies, and Kalash...basically pointing to a spread from the center of Southeast Asia.
Did the Nusantao bind their heads to emulate their Hominid X/Homo sapien hybrid ancestors who gave them Microcephalin D?
Was Hominid X the descendent of homo erectus soloensis, which has recently been tentatively redated to 260,000 from a previous date of 27 thousand years ago?
How long did Hominid X live a maritime existence in the fluctuating sea levels of SE Asia over the past 1.7 million years, if at all, and how much did it change them?
How long did the proto-Nusantao or proto-Australasians live in this environment before spreading civilization and these sweeping Microcephalin and ASPM genes to the mainland?
Was it long enough to give them other traits that can be associated with a maritime existence, and did any of those traits make a sweep of the human genome as well?
I know hairlessness took a long time in marine mammal evolution, but I still don't quite buy that our lack of hair is all because of sweating. Horses sweat but are still alot hairier than us, and Nusantao y haplogroup O is alot less hairy than I am across the board.
Were my ancestors even hairier before the Neolithic revolution and the influx of Sundalanders into mainland genes?
Is 1.7 million years of seaside existence long enough to contribute to the developement of that kind of adaptive trait, or any of the others mentioned by AAH theorists?
And someone please give us a counter vs. AAH theorists as to why we alone among terrestrial mammals have that nasty gross stuff all over us when we're born, just like the marine mammals.
As Stan Gooch taught us long ago, it is always valuable to wonder, "What if they are all right?" when faced with seeming contradictions from various camps in interdisciplinary studies, especially in human origins.
So this year I will not be throwing the baby out with the bath water like I did the first time I encountered AAH, but will consider whether parts of the more plausible modern theories of it's supporters might be partially correct or even totally correct for a particular sub-species which contributed to our current genomic make-up.
And the questions put forth above will be further explored along with other reconsidered theories, such as partial multi-regionalism, Stan Gooch's "Double Helix" hypothesis, Paul Bahn's paleolithic horse domestication, even aspects of Gene McCarthy's Macroevolution, and many others.
Even the whacky-ass Urantia book predicted that chimps evolved from humans, which seems like it might kinda sorta be the case! Amazingly, the current mainstream is of the notion that the great apes descended from a fully bipedal ancestor which they shared with man!