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Theory that humans spent part of our recent evolutionary history living by (and largely in) the sea. Hence many adaptions which are odd for land animals, and hard to explain (eg. loss of fur while gaining layers of subcutaneous fat, salt tears, upright walking) are more common in aquatic mammals or easy to understand in the context of a litoral lifestyle.

Explanation :


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Amazing how many people I keep bumping into who espouse this theory. I recently met a distant relative-in-law who told me he was writing a book of semi-fictionalised essays highlighting our aquatic nature as it has developed through the ages.

Do you have a view on this Phil?


I really like the theory. I hope its true. For all kinds of reasons. (Not least because I love living by the sea.) I like ElaineMorgan's orginal book "The Descent of Woman" very much. It's a) very radical, and b) very funny. (I tried to get a dance company I know to use the story as the basis of a dance piece.)

I'm not bothered by a lot of the criticism that Morgan is "unscientific". As I read it, her way of operating : ie. picking the current "best" theories and criticising them, is almost identical to KarlPopper's presentation of the pre-socratic philosophers (Thales, Anaximander, Anaximenes) which he holds up as the paradigm examples of critical / scientific tradition.

Having said that, I think her critics, linked above, also raise important questions : the predation by crocodiles thing, the degree of difference between human hair-loss patterns and other marine mammals. I don't think they succesfully answer all the questions she raises, but in some cases, they raise counter-issues that are as awkward for her as anything she uses to criticise the "Tarzan" theory.

So basically, I think it's one hell of a bold conjecture. Even if it's wrong, the work done to answer the questions it raises and find what's wrong with it, is very useful work for the reconstruction of early proto-human life. And it should be taken seriously. I'm not knowledgable enough to judge exactly where all the detailed evidence points. But I haven't been persuaded by the anti-story that it can't be true. Though it certainly might not.

The other problem, of course, is that it does resonate with a lot of new-age stuff about the sea, which I have no interest in. I can see that there are plenty of people willing to both praise or damn by association with that. (As I suppose, many political left-wingers want to criticise Tarzanism for the macho, competitive story it tells.)


Quora Answer : How likely is it that the aquatic ape hypothesis is true? What are some good arguments for or against it?

Aug 23, 2013

You want a probability between 0 and 1? Not possible really.

Instead, let me take you through a reasoning process.

As far as I can tell, the enmity against AAH is largely motivated by

a) dislike of Elaine Morgan (for being an outsider, for having political motivations, for just banging on about it for so long (somehow being persistent is meant to be a negative thing in her case))

b) conservatism. It conflicts with a lot of assumptions that people have picked up at college so they assume it must be weird and wrong. The funny thing here is that this is one of the most speculative, unsubstantiated areas of science, riddled with wild guesses and assumptions, but mainstream scientists who wouldn't bat an eyelid when someone conjectures that the size of the human brain is due to runaway sexual selection (something that's extremely hard to corroborate in the archaeological record) suddenly gets hot under the collar about bad science when someone else conjectures it might be due to fish-oil in the diet.

c) Some specific hypotheses have been naive and shown to be wrong.

OTOH there's a MASSIVE question to answer about the evolution of humans. We are very distinct from our nearest relatives in very specific ways. It's very hard to tie those differences to savannah living.

An ape evolved for the African savannah runs fast, on four legs, and has big teeth.

Our nearer ape relatives (the ones that look and act more like us) all still live in forests. NOTHING else on the savannah has the kind of human characteristics that impress AA hypothesists. And it's very hard to tie those characteristics to the ecological niche of savannah life.

Which is why ALL the anti-AAH people find such a big role for sexual selection. Sexual selection is a kind of get-out-of-jail-free card for evolutionists that can't match an adaptation to a practical use. They say "this feature must exist because the other sex just happens to like it."

So human fat is sexual. Human hair is sexual. Human brain development is sexual. Human spoken language is sexual. (And not about communication in water where smells don't stick and reflected sunlight gets in the eyes.) Etc. etc.

Another thought. Even without wild animals, before the advent of farming, few humans seem to have chosen to live on the savannah. Indigenous tribes have tended to live in the forests and on the edge of rivers. Places where there is more, and more varied, food. Savannahs and grasslands dry out for parts of the year and are only really good for hunting or herding grazing animals. Modern humans only really colonize them when they've managed to domesticate animals and are taking horses across the steppes or nomadically wandering the semi-desert with their cattle.

Read the Wikipedia article on Aquatic ape hypothesis the Langdon critique ( Umbrella hypotheses and parsimony in human evolution: a critique of the Aquatic Ape Hypothesis if you can get it from behind the paywall) and the Reply to Langdon

Now, I'm unashamedly a sympathizer with the AAH, even as I recognize that it's controversial and might well be wrong.

I'm betting that the most likely result will be that there's a gradual accommodation of the claims of AAH into the mainstream. Those who are anti-AAH will increasingly admit that early hominids lived alongside rivers and around lakes and the sea; that much of their activities and lives were oriented around the water (foraging for shell-fish etc.) but they'll continue to sneer at the AAH as "the mermaid hypothesis" and assume that it claimed humans were fully aquatic.

They'll continue to make grandiose claims about the philosophy of science and pontificate on exactly how science ought to be done and how an elderly Welsh woman who wrote popular screenplays couldn't possibly be doing it right. And they'll quietly forget all the equally outrageously unjustified speculative presumptions they made about how life on the savannah was organized and sexual selection that had to be quietly dropped in the firming up of contemporary models. (This will probably happen once aquatic claims start being championed by younger, maler, and less witty thinkers than Morgan.)