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Sunday, 1 May 2011

Were our ancestors aquatic apes?

This is not a question I would have ever thought of until I was followed today on Twitter by the intriguingly named @AquaticTheory.

When I clicked to see their tweets, I saw an array of superficially plausible contentions to support the proposition that we are, indeed, descended from apes that wallowed in water; it would explain our mainly hairless bodies, and so on.

I also saw that others dismissed the views completely.


I realised this was a moment where I could incur the infamous wrath of skeptics and Neo-Darwinist.

I knew that, if I said anything which seemed not to accord with the official version of human evolution, I could just be dismissed as a crank and a quack.


Or would those who promote an evidence-based approach and critical thinking welcome a different point of view, and perhaps constructively show me the errors in this interesting theory?


There is one way to find out, and so I ask the readers of this blog: are we the successors to aquatic apes?

And does it matter?


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22 comments:

junklight said...

I came across this some years ago and found it very compelling. However further research and reading showed that there are some gaping holes in the theory.

However sadly I can't remember any of the details. Having been pretty convinced that the theory is wrong I am not prepared to do all the reading and research again for a comment on your blog post. I do remember that there was a pretty decent overview somewhere on the web with lots of references so perhaps another commenter will turn that up.

Interesting theory but I don't think the evidence stacks up too well.

grb26 said...

It would explain why I quite like fish.

Matthew said...

It's an interesting idea that, I think, gets dismissed partially because of the word aquatic, this implies an animal spending most of it's life in the water rather than, for example, a beach dwelling one.

Perhaps the term littoral ape would be better?

JFDerry said...

@JFDerry: Aquatic Ape is not new http://bit.ly/jtjKk6 - predates Morgan RT @DavidAllenGreen ...Were our ancestors aquatic apes? http://bit.ly/if75ux

Cathyby said...

I've read two of Elaine Morgan's books. Basically the hypothesis says brain size and bipedal walking (along with other traits) evolved through apes living in water. This at least cannot be true, since early bipedal fossils without larger brains have been found. Equally the other traits she examines could have arisen in a different way and are not as exclusive/similar to aquatic animals as claimed.

Got to say though, the claim that face to face sex evolved because "doggy style" became anatomically difficult is my favourite flaw with the theory. Unfair to mention it maybe but I did find it funny.

Tony Lloyd said...

I read Elaine Morgan's "The Descent of Woman" a while ago and thought it a nice, elegant, theory. There were a few silly bits (the theory that we have sex face to face because "doggy" is too difficult.) but the theory seemed to have a lot of explanatory power.

Unfortunately it doesn't seem to stack up.

"(D)oes it matter?"

No, not really. What probably does matter though is wasting time on a theory once it's shown to be untenable. Science can't prosper unless it can dump the stuff shown not to work. It's dumped astrology, homoeopathy, creationism etc. which would be fine except for the fact that astrology, homoeopathy and creationism will not stay dumped. The astrologers, homoeopaths and creationists keep on clamouring for attention for their theories and stop science doing what it should: dumping the rubbish and getting on.

An understandable irritation at people who waste everyone's time by hanging onto refuted theories may be behind the ill temper with which some address the aquatic hypothesis.

Grumpy Bob said...

I think the key is succinctly said in your own words:

"...an array of superficially plausible contentions..."

Superficially plausible, particularly to non-biologists!

David Jarman said...

There's a lovely TED talk on this; I'm sure a quick web search would find it - I'm tapping into my phone, otherwise would do so myself.

Anonymous said...

Enjoyed reading the books; certainly a very plausible theory. I don't know enough about the ins and outs of evolutionary theory to be able to say for definite one way or the other whether it's a good theory or totally way out. I note though that David Attenborough write the forward to one of the books. I would like to think that he wouldn't put his name to a totally crackpot idea!

JRevell said...

I think not, and its because I don't see much in the way of good evidence to support the theory. What looks superficially like good evidence seems to be to be largely cherry-picking.

For example, we are largely hairless, and so are aquatic mammals. But the kinds of aquatic mammals that are hairless also have many other features we don't. For the absence of hair to really make a difference to an aquatic mammal it would have to be in the water an awful lot - and we don't have webbed feet, closable nostrils, or features of that sort, which you otherwise might expect. Even seals and otters have fur, after all (as do the vast majority of aquatic mammals), and rhinos, for example, don't.

Has your skin ever wrinkled after you've been in the bath? If so, does that really seem like a great adaptation to an aquatic environment?

Sure, we have subcutaneous fat, but so do other mammals, and (unless you're really fat) we don't have actual blubber. Yes, we can hold our breath, but not in the same way that aquatic mammals do (by storing vast oxygen reserves in their blood), and certainly not as well as animals that really live in the water. Humans drown far more often and far more easily than otters, proportionally speaking.

Is it a serious theory? Yes, it was at one time, but there doesn't seem to be any good reason to suppose it's true. We have some features that certain other aquatic mammals do, but they're not unique. And we don't have many of the features that genuinely aquatic mammals do.

Might we, perhaps, be more water adapted than, say, chimps? Maybe, but that doesn't make us an 'aquatic animal' in any meaningful sense. The theory may not be outright ludicrous, but I can see no reason to suppose it is true, and plenty to suppose that it may not be.

Mammuthus said...

This is one of the main sites that critques aquatic ape theory:

http://www.aquaticape.org/

Largely speaking, AA discussion takes place outside the literature so this is the kind of place where much of the debate occurs.

In principal it's not a particularly crazy hypothesis. In practice, the evidence doesn't really stack up. However, water may have been important in early human evolution. For example as discussed in this paper:

Wrangham, R. (2009) Shallow-Water Habitats as Sources of Fallback Foods for Hominins. American Journal of Physical Anthropology, 140, 630-642.

This paper gives more credence to aquatic influences than most mainstream discussions. But it is plausible and shows where where real interest and debate may lie. This interest is unlikely to lie, however, in the more extreme claims put forward by AA proponents.

Naadir said...

I think Morgan's specific claims aren't correct because she's using the "Aquatic Ape" theory to explain a whole host of evolutionary changes that are likely to be unrelated.

As one author puts it [1]

"As for the aquatic origin, other terrestrial animals, like primates and kangaroos, use bipedalism, but they all remained hairy. In fact, human fat deposits are like those of hairy primates and not of aquatic mammals. Breath holding has been observed in many primates, but even in dogs. In addition, some pinnipeda maintained their fur (which, incidentally, is used by modern women) and modified their limbs. It would be curious if humans lost their hair while maintaining their limbs unchanged."


The Aquatic Ape in its fullness annoys the hell out of Greg Laden [2], because he calls it a "Theory of Everything," a single selection pressure that is supposed to explain every human evolutionary change. This is unlikely to be the case, because evolution hardly ever works like this. Movement along the line of evolution is a random, non-linear walk. Adaptations usually evolve in response to a specific ecological problem.

For a good round up of competing theories, see the review by Rantala [3]. The well known hypotheses can be summarised in the following ways:

1) A form of temperature regulation
Either, as we moved out of forests and into the savannah, or to become better hunters by cooling off from a run quicker.
Or, to keep ourselves warm because bipedalism meant there was less sunlight hitting our bodies.

2) It was a mistake, but technology (clothing / fire) meant that it didn't matter.

3) Sex. Better view of the sexual organs and fitness. This is an evolutionary psychology explanation based upon the "fact" that women shave. I'm generally sceptical of evopsych, so make of that what you will.

4) Response to parasites & their associated disease. It's an increasingly popular theory , what with advances in genetic sequencing and the comparison of the molecular clocks of humans and lice.

[1] http://dx.doi.org/10.1111/j.1365-4632.2009.04266.x
[2] http://scienceblogs.com/gregladen/2009/08/my_critique_of_morgans_aquatic.php
[3] http://users.utu.fi/mjranta/reprints/Rantala%202007.pdf or http://dx.doi.org/10.1111/j.1469-7998.2007.00295.x

Side note: I'd be slightly weary of Twitter accounts like this. They're usually trying to hawk a book. I note that Morgan's 2008 book, The Naked Darwinist is currently out of print.

Lord Snooty said...

I think genetic fingerprinting would give us a more than fair guess at our evolutional lineage.

Our closeness to Orangutangs, Chimpanzees and Gorillas seem well established and they are all pretty hairy.

Seems improbable

Science is never settled, just ask Al Gore

Stephanie Zvan said...

Greg's post is one of a pair and should probably be read with this one, which digs further into the TOE problem: http://scienceblogs.com/gregladen/2009/08/musings_on_the_aquatic_ape_the.php

rjh01 said...

This subject was discussed recently in the JREF forum. The answer was no we are not descended from aquatic apes.

http://forums.randi.org/showthread.php?t=149865

Anonymous said...

Via @pzmyers... Oh, no, not the Aquatic Ape hypothesis! : Pharyngula http://bit.ly/jChOTe

ian644 said...

I Created the @AquaticTheory on twitter,



May I first briefly describe what I mean by AAT (AAT various greatly from person to person). An aquatic ancestor is miss-leading. Much More appropriate would be semi-aquatic ancestor. Aquatic ape has unfortunately stuck when referring to this topic. Having said that some people do believe we had a fully aquatic ancestor, but there is no evidence for this and by far not enough time.

What I mean by semi-aquatic is that they lived on dry land (in the sense that breeding, sleeping and large parts of the day would have been spent out of water), however we would have spent time in the water, wading from dry land to dry land, perhaps in swamps or river system and finding food in the shallows. This period of semi-aquatic living would only have lasted a few tens to a couple of hundred thousand years, long enough for bipedal locomotion and hairlessness to be favoured.

I am currently finishing a much more detailed explanation on this and it will be available next week.

Catheyby: All the evidence does suggest bipedal walking did come much earlier than the vast increase in cranium size. This does indeed go against Elaine's initial work. The semi-aquatic stage would only have been a very small portion of the 6 million years or so since our split from our common ancestor with chimpanzee's. I believe Bipedalism came from wading were as brain size increasing was caused by a much later unrelated factor.

Jrevell: "Might we, perhaps, be more water adapted than, say, chimps? Maybe, but that doesn't make us an 'aquatic animal' in any meaningful sense"

Exactly! We are not fully aquatic and neither were our ancestors (in the period we are talking about) but we did evolve certain features due to spending a period of time in close proximity to and in water.

JRevell said...

ian: I think you're over-interpreting what I'm saying. It's not impossible that we have a degree of familiarity with water in our past, but it's important to remember that we don't appear to have evolved any features relating to this (lack of hair, for example, is irrelevant) so there's no reason to suppose it *is* true.

ian644 said...

Hello JRevell:


More research is of course needed before we can say for certain whether we went through a semi- aquatic stage.

However at the moment there is no solid evidence for human traits such as bipedalism and why we are hairless. There are of course a number of theories for both.

The Aquatic ape theory can explain both, as well as explaining many other human features which we do not share in common with our closest living relatives chimpanzees.

You mention hairlessness. What is wrong with suggesting that due to spending time wading through water we adapted accordantly and lost much of our body hair? It is exactly the same as speculating that we lost our body hair through sexual selection or from wearing clothes or from any other THEORY you care to mention.

Ian Love said...

To me the most interesting part is why JoK wrote this - liking a stir?
"I realised this was a moment where I could incur the infamous wrath of skeptics and Neo-Darwinist."....??

As often the easiest way to get some insight is google, and the website mammuthus cites, aquaticape.org is really good and has lots of details. There is even a nice summary of how the so-called evidence really stacks up

Anonymous said...

A falsifiability test seems reasonable, as it does for any highly speculative evolutionary theory. What evidence could convince aquatic ape proponents either (a) that no human ancestors ever had whatever degree of aquatic life it is they propose, or that (b) this exerted no significant evolutionary pressure on the traits they explain by it?

If the answer is "none", or at any rate "none that we're ever likely to find even if it existed", then the theory is unfalsifiable and hence to a sceptic it's irrelevant.

The same test of course needs to be applied to savannah theories. The latter are to some extent attempts to explain the fossil record which actually exists, so falsifying evidence would be "fossils inconsistent with the described evolutionary progression". To some extent they're no less speculative than aquatic ape theory.

Personally I have a preference for evolutionary descriptions based on fossil evidence, over descriptions based on what "best explains" modern phenotypes. Where we don't know it is *interesting* to speculate, if only because it informs the search for more evidence. But none of it is "truth". As long as it's taken in that spirit, there is no problem.

Steve said...

Sorry, I believe that Javascript problems caused my first attempt at this post to be completely anonymous. What follows is a repeat:

A falsifiability test seems reasonable, as it does for any highly speculative evolutionary theory. What evidence could convince aquatic ape proponents either (a) that no human ancestors ever had whatever degree of aquatic life it is they propose, or that (b) this exerted no significant evolutionary pressure on the traits they explain by it?

If the answer is "none", or at any rate "none that we're ever likely to find even if it existed", then the theory is unfalsifiable and hence to a sceptic it's irrelevant.

The same test of course needs to be applied to savannah theories. The latter are to some extent attempts to explain the fossil record which actually exists, so falsifying evidence would be "fossils inconsistent with the described evolutionary progression". To some extent they're no less speculative than aquatic ape theory.

Personally I have a preference for evolutionary descriptions based on fossil evidence, over descriptions based on what "best explains" modern phenotypes. Where we don't know it is *interesting* to speculate, if only because it informs the search for more evidence. But none of it is "truth". As long as it's taken in that spirit, there is no problem.