Aquatic Ape ‘theory’… again.

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There is a popular fringe theory about human evolution that claims we went through an aquatic phase.


Today we're going to point the skeptical eye into the world of anthropology, and shine the light of science around to see what we can learn about one of the fringe theories put forth to explain human evolution. It's been promoted on the stage in a 2009 TED talk; it was the underlying theory of Animal Planet's 2011 documentaryMermaids: The Body Found; and it was even described in Desmond Morris' famous 1967 nonfiction book The Naked Ape. It is the aquatic ape theory, an idea first widely publicized by marine biologist Alister Hardy in the 1930s. Its intent is to explain the reason humans are so different from the other great apes. While the other great ape species stayed on land and retained their fur, their knuckle walking, and their lean mass, humans became hairless, upright, and fat as an adaptation to being — for some two million years — an aquatic mammal.

The aquatic ape theory was an attempted explanation for why humans differ so much from the other great apes. Hominids all diverged from common ancestors, butHomo sapiens more radically so. We walk upright all the time, we don't have fur, we have bigger brains and are less robust, and so on. A number of people throughout history have noted that there must have been some evolutionary pressure on our line that wasn't on the others. Hardy was among the first to point this out at length, and his notion was that all these major differences are best accounted for if the Homogenus (after our evolutionary split from chimpanzees) went through an aquatic, or at least amphibian, stage. The idea's principal proponent since Hardy has been British screenwriter Elaine Morgan, who has written at least six books promoting the aquatic ape theory as a valid, if not superior, alternative to the standard model of human anthropology which has found that the Homo divergences are the result of adaptations for moving from the trees to the savannah.

Written By: Brian Dunning
continue to source article at skeptoid.com

28 COMMENTS

  1. I wonder if C-tactile nerve fibres (which are present in mammals where hairy skin exists) may explain the loss of hair in curiously patchy places on humans?

    These nerve fibres are the leisurely deliverers of the sensual pleasures of grooming and most probably developed to encourage self and mutual grooming in the hairy mammals, the mechanical stimulation of hair literally leveraging the sensitivity.

    However as with all evolutionary fixes secondary effects come along. These sensual nerves are also prone to deliver pain (or at least accentuate it in a neuralgic form) under certain circumstances. It may just be possible this neuralgic response led us to lose hair (or at least hair length and its mechanical transforming effect) after the adoption of wearing animal skins and the like.

    Hair would thus be lost from shoulders (but not underarms) and anywhere else neuralgic irritation might occur. The remainder of pubic hair may have its downside overridden by serving its original encouraging function, where the hunt for lice suddenly takes a turn for the procreative.

  2. I seem to recall having heard Elaine Morgan and David Atenborough discussing this idea on BBC Radio 4 many moons ago, and although I don’t know if he fully concurred with the idea, the “good Knight” was certainly sympathetic to it.

      • In reply to #13 by bluebird:

        In reply to #2 by Stafford Gordon:

        I seem to recall having heard Elaine Morgan and David Atenborough discussing this idea on BBC Radio 4

        Elaine Morgan’s TED talk was posted on old RD.net with _lots _ of comments…

        Goodness that old thread was good. Thanks for the reminder.

        Steve Z and Decius did a sterling job knocking the AAH into touch.

    • In reply to #2 by Stafford Gordon:

      I seem to recall having heard Elaine Morgan and David Atenborough discussing this idea on BBC Radio 4 many moons ago, and although I don’t know if he fully concurred with the idea, the “good Knight” was certainly sympathetic to it.

      That programme is here Note it gets called the AAH, not AAT there.

      I get the impression it was reasonable to think it might be true a while back, that there isn’t really evidence to support it, and that there are some people who are emotionally over-attached to it, some of whom apply conspiracy-theory style thinking and a feminist narrative to explain why it hasn’t been adopted.

  3. What bothers me is this hypothesis is usually dismissed with a contemptuous sniff, never even one argument against it. I have always been puzzled what the trouble with it was. To a lay person it seems plausible.

    • In reply to #3 by Roedy:

      What bothers me is this hypothesis is usually dismissed with a contemptuous sniff, never even one argument against it. I have always been puzzled what the trouble with it was. To a lay person it seems plausible.

      It seems entirely plausible to me. It seems that it also has the evidence in its favor. It would be nice to troll the ocean floor off the coast of Africa.

  4. The idea seems interesting to explore, but without any strong empirical data to back up the claim, it remains unvalidated. The article makes a few good points and my only complaint is the author’s decision to group it in with the ridiculous Mermaid special.

    Just because the idea inspired a laughable narrative about mer-apes doesn’t mean that the hypothesis promotes that view. There are plenty of other unfounded scientific claims that seek to disrupt the public’s conception of theory and they deserve this kind of degradation.

    This fringe idea in no way threatens any established paradigm. In fact the evidence for the development of bipedalism is utterly vacant and all attempts remain hypothetical in nature. People have unique ideas and those ideas should be explored and rigorously challenged. One should not group in such ideas with pseudo-scientific nonsense.

  5. If humans look so different from chimps and bonobos because we spent more evolutionary time on the savanah, should we not have convergently evolved to look more like baboons, rather than the way we do?

  6. Interesting to see this topic resurface. I’ve always liked the story (not even calling it a hypothesis), and I know that “liking” is not science, so don’t bother telling me.

    As I began to read, I didn’t mind if this interesting and likable story was about to be proven wrong. But it wasn’t, was it? The article did a good job of showing why it is a superficially attractive story, but the debunking that followed was somewhat too glib for my taste. I see some of the comments on the original article also point this out.

    So, why the disdainful dismissal? Not Invented Here Syndrome, because it came from amateurs, not the academically trained specialists?

    Is it hard to get grants for studies that put the aquatic notion to the test? I mean, compared to other studies aimed at filling out some details of the as-yet-incomplete story that is the “conventional” hypothesis?

    I hope to hear more about this topic, and not just from fringe sources.

  7. Morgan’s “Scars of Evolution” reads like a religious apologetic. I keep a copy of on my shelf as an example of failing to respect Feynman’s overarching principle (however tempting, you mustn’t fool yourself).

  8. Besides the debunking above, the main reason I am especially skeptical of it was because I first heard of it, the reason presented for it not being taken seriously was male chauvenist scientists. This was from, I believe, the woman who is pioneering the hypothesis now. Because of that, I can’t help but put it into the same catagorey of claims that are ‘rejected because of western imperialist science!’.

    Ultimately, the hypothesis is interesting, and really wouldn’t change anything for most people if true or false. I have nothing against the idea that it were true, it’d be interesting, but wouldn’t really DO much, except for specialized experts in the field of humans and other primates. So if most (qualified) scientists came forward and said this is probably what happened, I’d think it was cool, maybe check out the work done (if it was simple enough for me to understand), and get on with my life.

    Until then though, this hypothesis will be linked with woo in my mind. Not on the most well grounded of basis, I know, but I’m fighting against the limitations of a brain evolved from my tree or seaweed dwelling ancestors :D

  9. Sadly, my theory for hairlessness fails due to studies of human louse evolution which suggests we may have been hairless three million years before adopting clothing this latter possibly about 100,000 years ago. This hairlessness would rather trap us in location of high ambient temperatures, the sheer energy wastefulness of running around without our hair on being paid for by a corresponding reduced energy demands at other times.

    Timing for both has come from louse evolution studies, reported on here.

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3248486/

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2687769/

    I may have to reduce my claims about C-Tactile nerves. Maybe they just started a second wave of hairlessness perhaps, reducing some of us from a “Mediterranean” level of hairiness closer to true body baldness?

  10. I had a student who researched the idea last year for an IB project. She looked at the diving reflex in humans, and the suppression of heart rate and breathing rate as the face and nose are submerged, relating it to different water temperatures. It does appear to be an autonomic response, and interesting to try and link it to the aquatic theory. Needs more work, but I’m not writing it off just because it goes against perceived wisdom.

  11. On a slight tangent here: I’m not even sure how to frame the question properly, but I’ll try.

    Since our ancestry diverged from the other primates, what was the smallest size of our ancestral gene pool? Meaning, there was a time when there weren’t many of our ancestors around. Many that could interbreed, that is. Is there work in this area, and has it found anything definite? I’m just wondering how large would have been the population during the period of greatest change – losing hair, walking upright and so on.

    Badly asked. Hopefully there’ll be those among you who know how to relay what answers are known. Thanks.

    ps: 2 is not the right answer, so Adam & Eve can stay out of it.

    • In reply to #15 by OHooligan:

      On a slight tangent here: I’m not even sure how to frame the question properly, but I’ll try.

      Since our ancestry diverged from the other primates, what was the smallest size of our ancestral gene pool?

      I remembered something when reading this question (pretty sure it was in a bit of the Ancestor’s Tale), so I looked it up. The human population has been estimated to have shrunk to around 10,000 about 70,000 years ago. I don’t know if any evolutionary milestones can be traced to this period, but it seems to me that a population crash and subsequent growth is a quick way to spread genes that happen to be advantageous at the time.

      70,000 years ago is pretty recent though…could it have given a kick start to language?

    • In reply to #15 by OHooligan:

      On a slight tangent here: I’m not even sure how to frame the question properly, but I’ll try.

      Since our ancestry diverged from the other primates, what was the smallest size of our ancestral gene pool? Meaning, there was a time when there weren’t many of our ancestors around. Many that could in…

      I think humans were reduced to several thousand people around 60-80,000 years ago by a supervolcano and its aftermath. But that’s just one of many theories.
      There’s been a bottleneck according to genetic evidence, maybe as small as 2,000 people – but certainly not 2 ;)

  12. How about parasite theory? I remember Stoneking’s group in Germany sequenced DNA of lice in on human head and body and found some differences. They suggest that humans shed body hair to get rid of parasites.

  13. I would like to suggest a book to you, The Descent of Religion, in which the author presents a sweeping view of human evolution – both physical and social that is strongly influenced by the AAH. The book covers many topics such as the pressures on physical development that would occur if forced to live in a partially aquatic environment. The author also discusses the development of language, migration patterns, as well as many others including evolving hominid social behaviours, development of communities and the “glue” that held them together – the myths, rituals, ideals and guidelines (eventually called religion). The last two chapters discuss the last 7,000 years or so and the disastrous effects of theist religions and other hierarchical social institutions on society. I found it a very well researched, logical and convincing narrative.

      • In reply to #21 by This Is Not A Meme:

        In reply to #20 by This Is Not A Meme:

        oops, truncated my post.. I was just gonna complain about String “Theory” being taken more seriously than Aquatic Ape.

        I’ve heard that Rope Theory is much stronger.

  14. I suspect this is politically incorrect, but, I’d like to promote this item as indirect supporting evidence of the AAH:

    scientific american article on the secrets of the phallus

    What’s not to like about this Ancestor’s Tale: an endless beach party where the females copulate with multiple partners in quick succession. Maybe the big strong guys pushed to the front, but it’s the one who came last who passed on his genes. Enough of the time to make the difference. So, we have a particular anatomical shape, and overall more brains than brawn.

    Ah, the good old days.

  15. How many other mammals (let alone primates) are hairless outside of domesticates, burrowers, wallowers and of course semi-aquatics/aquatics? Are we the only other ones to make life difficult for the lice?

    Interesting how so often you get guys with big brains who know everything there is to know about a small field, say the DNA of lice, they have this ah-ha moment and try to apply their deep but narrow expertise (specialisation) to fields where shallow but broad expertise (multidiscipline) is better suited. Where even, dare I say it, talented amateurs like the proponents of AAH might be better suited — at least initially.

    Unfortunately the AAH may fail on closer examination of the facts – when specialists in adipose tissues and so forth are brought in to verify/falsify the theory. But it was a good hypothesis. Unlike the parasite theory which may fit one narrow set of facts about lice DNA but says nothing about bipedalism, big brains, tool use etc. etc.

    Typical theory goes like this. Why did we become bipedal? To leave the (shrinking) forests behind and venture forth onto the savannah. Ah, but that leaves us exposed to the sun. So we lose our body hair to keep cool. But we keep our head hair to keep the (tropical) sun off the top of our heads. And we sweat to keep cool. Too much, it’s hard to keep hydrated on the dry savannah, but let’s not explain that. And walking on two legs (at cost of back problems, hernias etc.) frees our hands to make tools to help us catch red meat, which we run after coz two legs are so much better for that kind of thing.
    I’m exaggerating, slightly, but many “scientific” explanations for human evolution are a lot like this. The AAH appeals because it at least sounds a sensible way to tie together a lot of features that need explaining; and it’s falsifiable; it might have been falsified. Unlike, say, the lice theory which sounds potty, and might explain hairlessness but doesn’t really offer anything about intelligence and bipedalism beyond taking them as givens around the time clothing was invented when the lice DNA evidence kicks in.

  16. Discussions on the so-called “aquatic ape theory” are often outdated, not considering the recent literature on the subject.
    Humans didn’t descend from “aquatic apes”, of course, although our Pleistocene ancestors were too slow & heavy for regular running over open plains as some anthropologists still believe.
    Instead, Homo populations during the Ice Ages (with sea-levels often 100 m lower than today) simply followed the coasts & rivers in Africa & Eurasia, eg, 800,000 years ago, they even reached Flores more than 18 km overseas.
    - google “econiche Homo”
    - google “aquarboreal” on ape & australopith evolution
    - eBook Was Man more aquatic in the past? introduction Phillip Tobias http://www.benthamscience.com/ebooks/9781608052448/index.htm
    - guest post at Greg Laden’s blog http://scienceblogs.com/gregladen/2013/01/30/common-misconceptions-and-unproven-assumptions-about-the-aquatic-ape-theory
    - http://greencomet.org/2013/05/26/aquatic-ape-the-theory-evolves/
    - Human Evolution conference London 8–10 May 2013 with David Attenborough, Don Johanson etc. http://www.royalmarsden.nhs.uk/education/education-conference-centre/study-days-conferences/pages/2013-evolution.aspx
    - M Verhaegen & S Munro 2011 “Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods” HOMO – J compar hum Biol 62:237-247
    - M Vaneechoutte, S Munro & M Verhaegen 2012 “Reply to John Langdon’s review of the eBook: Was Man more aquatic in the past?” HOMO – J compar hum Biol 63:496-503

  17. You say: “There is a popular fringe theory about human evolution that claims we went through an aquatic phase.”
    It’s not “fringe” (in fact, it’s the only serious theory left) although it’s not “popular”, at least not among paleo-anthropologists.
    And “aquatic” is not the best word: “littoral” would be a lot better. The remarkably “fast” diaspora of archaic Homo as far as Indonesia (Mojokerto & Flores), the Cape & England (Pakefield & Boxgrove) – BTW, at all these sites were coastal and had abundant edible shellfish – could only have happened along the coasts & from there inland along rivers.
    Obviously this littoral phase didn’t happen more than 5 million years ago as Hardy & Morgan (understandably) thought at the time, but instead during the Pleistocene: all Homo features that suggest a littoral phase appeared in the Pleistocene: brain expansion, external nose, pachyosteosclerosis, ear exostoses, association with marine shells, dispersal along Africa & southern Eurasia, small mouth & masticatory reduction (MYH16 inactivation cf soft slippery seafoods) etc.
    And – contary to what many paleo-anthropologists think – the littoral theory has nothing to do with australopithecines, google, eg, “common misconception aquatic ape.

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