Musings on the Aquatic Ape Theory

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The Aquatic Ape Theory is being discussed over at Pharyngula. As PZ points out, an excellent resource on this idea is Moore’s site on the topic. Here, I just want to make a few remarks about it.

The Aquatic Ape Theory (AAT) is a human evolution Theory of Everything (TOE) and thus explains, as it should, everything. That is a dangerous way for a theory to act, because if it tries to explain everything then it is going to be wrong in a number of places, and it is going to seem (or even be) right in a number of places but only by chance. (Unless, of course, the TOE is totally rad and really does explain everything.)

For these reasons, a human evolution TOE will generally evolve into a zombie that won’t die and can’t be killed, potentially eating the brains of science geeks and graduate students for decades. Another example of a human evolution TOE is bipedalism. Here, the idea is that bipedalism explains everything. For a long time that TOE ate the brains of graduate students and the general public and even senior scientists. It no longer does for this reason: We now know that bipedalism evolved millions of years before many of the key human traits that we wish to explain. But the zombie is not completely dead. Many human evolutionists still make the claim that bipedalism was a very important step in human evolution, even though a) we can’t explain why it happened and b) there is no solid link between bipedalism and anything else. The fact that we are increasingly realizing that bipedalism evolved in many hominoid lineages may make this TOE go away eventually. So, for now, the Bipedalism Zombie doe not consume brains wholesale. It just scoops out a tablespoon here and a tablespoon there now and then.

The AAT is different from the Bipedalism TOE for a couple of reasons. For one, it was rejected a long time ago by almost all serious paleoanthropologists. It is quite possible that the fact that the theory was being promoted (but not originally generated) by a Welsh non-academic female and that she was being aggressive about it probably influenced more scientists (negatively) than many aspects of the theory. That would be unfair, and it probably was unfair. But after a while, the AAT began to demonstrate other reasons for its rejection.

The AAT, in its various forms over time, has addressed almost every general aspect of human anatomy and behavior and made the claim that an aquatic ancestry is the best explanation for that feature. Some of these claims were absurd. For instance, the “fact” that females have long hair was an adaptation to living in the water, where the long flowing locks of females would be used as life lines for her babies and toddlers (‘paddlers’?) floating around her.

One of the best possible forms of evidence for an aquatic phase would be to find other mammals that are not presently especially aquatic (or at least no more than humans), look for physical evidence of that adaptation, and then check for that evidence, surviving as physiological atavisms, in humans. Not finding such atavisms is meaningless, but finding them would be spectacular evidence.

For example, elephants may have gone through an aquatic stage, and this is in fact seen ontogenetically in their kidneys. Do human kidneys also show this kind of evidence? Well, no, sorry, they don’t. The fact that elephants would have gone through their aquatic phase much longer ago than humans does not help the AAT here.

When the AAT was first proposed, we had a murky view of human evolutionary history. At that time it was possible to suggest a single phase of evolution during which certain conditions prevailed, and from which a long list of human traits emerged. But since that time our understanding of human evolution has become more detailed and many of the human traits are now seen as having emerged at very different times over a multi-million year period of time. For the AAT to continue to explain all of these traits (hairlessness, bipedalism, large brain, head hair, body fat distributions, body size, leg length and form, atavistic webbed feet, seafaring, intense use of coastal resources such as shellfish, etc. etc.) it would have to be the case that our ancestors were ‘aquatic’ for millions of years.

For the entire time that the AAT has been extant, the theory itself has been rather murky. Just how aquatic? Were the babies born under water or on land? Was mating done under water? Was aquatic lifestyle facultative or did all hominids do this? All day every day? Was all the food aquatic? On top of this, only a few of the usual candidates for typical mammalian aquatic adaptations are seen in humans. Hairlessness and subcutaneous body fat were, of course, considered early on to be hallmarks of the aquatic adaptation. The fact that aquatic mammals do not vary in hairlessness (very much) and humans do is a problem. The fact that body fat distributions are sexually dimorphic seems to have been missed by the AAT. Or maybe not. Maybe there is a version where the females are aquatic and the males are not. They meet on the beach for romance. Thus, the link our species makes, psychologically, between beaches and romance!!! Aha!!! It explains everything!!!!!

Oh, sorry, … I’ve got control now, didn’t mean to go off like that…

So, you can see where the theory goes, and how in fact it can’t be stopped. The AAT is a zombie theory, untestable because so much of what it proposes has not been framed in a testable way. The AAT remains capable of consuming many more, still untapped “connections” and “explanations.” The AAT has consumed many brains, and not all of them particularly susceptible. Just recently, I heard from an excellent, unimpeachable source that a very famous person whom you have heard of is an AAT ‘believer.’ I found it hard to believe, but it is apparently true. Some day I hope to have a little conversation with this person!

AAT: The theory that keeps giving. And eating brains.

UPDATE: See this video just in.

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38 thoughts on “Musings on the Aquatic Ape Theory

  1. Funny. And I’m glad you mentioned the sexism around the negative view many have of AAT: while it’s a load of crap, it wasn’t a load of crap because Elaine Morgan championed it for a time, it’s a load of crap for the many other reasons you nicely outlined.

    I have a hypothesis, which is probably testable through literature review/surveys of scientists, that underrepresented and/or oppressed scientists sometimes, in order to get the attention of the white men who are turning their noses up at them, create or champion TOEs at a higher rate than those not in oppressed groups. It’s only one of several strategies, mind you; others include fitting in with the dominant behaviors, keeping your head down, leaving the jerks to themselves, etc, but it could be a strategy for a minority of these folks. Right now Margie Profet and Elaine Morgan come to mind, as do a few others that I’d rather not name for pseudonymity purposes. As a female scientist who found throughout graduate school and sometimes even after I was done that when I said something no one heard it, and when a man said the same thing everyone would nod like it was brilliant, I certainly wanted to wave my hands and shriek at times.

  2. Now and not… too dissimilar in meaning to be so close in spelling. Such things should not be aribrary! (Clearly, language evolved and was not designed.)

  3. Perhaps this explains mermaids:p A fully adapted aquatic hominid:p Urf! Urf! Hack! Sorry. Hairballs.

  4. For instance, the “fact” that females have long hair was an adaptation to living in the water, where the long flowing locks of females would be used as life lines for her babies and toddlers (‘paddlers’?) floating around her.

    They don’t actually try to make the distinction between male and female hair length do they? Did Aquaman have hair clippers? I sure hope that it is understood that head hair length differences in the sexes is a social thing, and that’s another discussion…

  5. Maybe there is a version where the females are aquatic and the males are not. They meet on the beach for romance. Thus, the link our species makes, psychologically, between beaches and romance!!! Aha!!! It explains everything!!!!!

    Mermaids? Ooh la la!

    But seriously, what the hell is so romantic about finding sand in crevices you didn’t even know you had a full week after the escapade? ๐Ÿ˜‰

  6. jj: Yes, they did, briefly. There is a phrase in the literature somewhere … “The reason for long hair in women is…”

    Robert: Mermaids are to the AAT what bigfoots are to regular human evolution, I suppose.

  7. I highly doubt that mating was done in the water. Anyone who has attempted this knows how difficult it is to thrust correctly without just pushing your partner away. It’s much easier to do on land.

  8. Gav, sorry, I totally neglected to mention Elaine Morgan’s name. In my little world she is well known and so closely linked to the AAT that I just (incorrectly) assumed.

    (Sorry Elaine!!!)

  9. Not wanting to support a TOE, but is the traditional “plains ape” any better supported than “waterside ape” (or, for that matter, “forest ape”)? Even if the Olduvai area was plains at the time (was it really? all of it?) that doesn’t tell us much; fossils form where they can, not necessarily where the most specimens died.

    I see the visceral reaction as, in part, another example of scientists taking their own discomfort at being obliged to maintain two equal theories as itself evidence against the less historically familiar one. If, for personal reasons, scientists need to keep just one default theory in the absence of evidence one way or another, “waterside ape” seems as good as any. It seems to me a good thing, then, for some fraction of anthropologists to hold it that way, while others relax with “plains ape” and others again with “forest ape”. Maybe some real evidence will come along to favor one or another, someday.

  10. Plains? I don’t like plains, and I never did. Hominids would never have been common, say, on the Serengeti plains. The evidence suggests that early hominids (australopiths prior to erectus) liked wooded savannas and were tethered to water. There is a lot of evidence for that, yes.

  11. The behavior of AAT advocates exposited on Moore’s site seems sufficient to justify a visceral reaction, particularly after decades.

    I do wonder about taphonomy, though. If we did have coastal-ape or riparian-ape ancestors in addition to the wooded-savanna dwellers, could the evidence of it survive?

  12. Edge ape? Lived in the edge of the forest so can use plans and forest habitat as needed like many good generalists.

  13. Couple points. My web site is just a web site, not a blog. (I don’t have the energy to write a blog :)) Elaine Morgan is Welsh, not Scottish.

    And the emphasis on savannas among the supporters of the aquatic ape idea doesn’t really mesh with what the prominent theories about human evolution have been saying for decades. Those theories tend to be about food-getting and social interaction, and deal with environment only in describing where those activities happened. Those ideas are not environmmentally deterministic as the AAT/H proponents seem to think, and as the AAT/H is. Hominids used a variety of environments, judging from the fossil sites, which is what you might expect for a creature on its way to becoming perhaps the world’s supreme environmental generalist. (Is there any other animal, of any kind, which managed, even before modern technology, to use so many different environments while remaining one species?)

  14. Greg

    Excellent, devastating post. I despair when this “theory” crops up on the Science or Discovery Channel, which, alas, it often does.

    Maybe you could have a look at Bernd Heinrich’s Why We Run as another inflated TOE in need of balloon bursting.

  15. Thank you, Mr. Moore. My information was evidently badly out of date.

    Somebody should tell Brad Delong to stop referring to himself and his colleagues as “east-african plains apes”. Suggestions for the replacement? “Pan-african ground apes”? Is our wide range of habitats our defining characteristic, as apes? Macaques seem pretty versatile.

  16. Macaques do pretty well on the versatility scale, but we shot past them a million years ago and never looked back.

    I didn’t register your question though: “I do wonder about taphonomy, though. If we did have coastal-ape or riparian-ape ancestors in addition to the wooded-savanna dwellers, could the evidence of it survive?”

    I think this is something that also hurts the aquatic ape idea badly. The areas they suggest our ancestors be in are the areas we’d expect to see loads of them fossilized; so how come we have relatively few hominid fossils and from such a range of environments? They only spots where they have claimed for this semiaquatic phase that might not leave lots of fossils is the beach or tidal saltwater areas, and they’ve pretty much dropped that idea because of the salt load problem and the fact that our reactions to salt are those of an animal which evolved in a salt-deplete environment. Of course that doesn’t stop them from sometimes suggesting the fellows were here for this problem and then, when you point out the problem with that they whip them off to another spot entirely. I refer to this ad hoc method as ZING!ability.

  17. The AAT is a zombie theory, untestable because so much of what it proposes has not been framed in a testable way. The AAT remains capable of consuming many more, still untapped “connections” and “explanations.”

    Surely it’s not worse than evolutionary psychology for generating untestable “connections” and “explanations”?

  18. Humans seem far better adapted at long-distance running than surviving in an aquatic environment. It still seems surprising to me that we can outrun any animal, given a long enough distance.

  19. I’ll go for “edge ape” too. I edge away from water all the time. But my wife loves it. In our early days she introduced me to snorkling. Now we have kids we don’t bother.

    “Honeymoon Aquatic Apes” ?

    “Maybe there is a version where the females are aquatic and the males are not. They meet on the beach for romance. Thus, the link our species makes, psychologically, between beaches and romance!!! Aha!!! It explains everything!!!!!”

    Curiously among Tasmanian aboriginals (original southern coastal route Out of Africa Culture???) men were not allowed to go into the sea, mostly I suspect because this was women’s work (gathering crayfish, abalone, other shellfish), men would even be pushed across on boats to islands that the women pushed while swimming (apparently). (Scalefish were not eaten at the time of British colonisation, possibly taboo. Scalefish bones are in the archeological record of middens but not after about 4000 years ago. Some hunter-gather political dispute no doubt. Tim Flannery says they just forgot but I reckon it was political, everything is.

  20. Elaine Morgan’s doctorate is an honorary doctorate from the University of Glamorgan. The university’s guidelines for proferring these honors are:

    Where the contribution is in a field related to an academic discipline, a specific Doctorate (e.g. DSc, DLitt) will be awarded; in other cases, a Doctorate of the University will be awarded.

    Morgan’s honorary doctorate was a DLitt (Doctor of Letters) indicating they gave it to her for her literary work rather than her aquatic ape work. Not that she’s trying to put one over on anyone. ๐Ÿ™‚ She does have several honorary fellowships as well.

  21. OK, I changed scottish to welsh a while back (I am a typical confused American who makes silly mistakes like calling Elizabeth the Queen of the British and so on) and I meant non-academic as a compliment, really.

  22. “They are really similar in the way they are untethered to actual research questions with empirical anchors.”

    Well composed sentence there, Greg, but entirely untrue. Without supporting AAH or any other theory, I’d like simply to point out that indeed, AAH definitely has REAL ACTUAL QUESTIONS (which the theory is “tethered” to) that it hopes to answer with EMPIRICAL (observed) ANCHORS (information).


    Why are we hairless? (Actual Research Question)
    Empirical Anchors:
    1) sometimes aquatic and subterranean mammals lose much of their hair during evolution because it can no longer thermoregulate temperature properly
    2) those same mammals also sometimes evolve subcutaneous fat because it does regulate properly

    Valid, actual, empirically driven hypothesis: Maybe homo sapiens are hairless because we evolved in a semi-aquatic environment! Eureka!

  23. ahuman: Not really. Most of the aquatic ape ‘hypotheses’ started out as interesting ideas (naked mammal, subcutaneous fat) but when examined more closely and broken down into ontogenetic, functional, and phylogenetic components they don’t hold up. For instance, consider the functional aspect of naked skin and subcutaneoius fat. Two problems emerge right away. 1) aquatic mammal surfaces to get naked and underlain by fat, but that skin also covers a body with shortened appendages and other shape changes. The functional shift of interest is adaptation to an environment where the matrix sucks away heat. Changes in body shape are far more important than hair, for instance, yet they don’t happen. In other words, functionally, the human skin adaptation is not even close to being explained as an adaptation to spending hippo-amounts of time in the water (to make an appropriate direct comparison).

    2) Subcutaneious fat distribuiton, if for thermoregulation, would be distributed uniformly or greater over heat loss surfaces. But in fact, they are distributed (in humans) the exact OPPOSITE way, as would be predicted by an alternative hypothesis: Food storage without losing high thermal LOSS abilities (not retention, as a mammal would require spending a lot of time even in warmish water).

    Fat and hair are interesting, but on very preliminary examination it becomes clear that the actual adaptation is heat LOSS (and that also wipes out your naked fossorial mammals from the equation, by the way) for aquatic mammals not just nakedness or having extra fat.

    In other words, it’s like saying a “long appendage” is good for seeing father away or eating leaves off the top of a tree) like a giraffe) but the appendage you are looking at is a tongue (as in woodpeckers, for probing).

    Untethered. Way.

  24. In response to Greg Laden:- Those seals which lost their fur and went the subcutaneous fat route have little fat on their flippers (“heat loss surfaces”) – increasing SQ fat makes things rounder and round hands / flippers would be tough to swim with.
    The endurance issue is important – I have seen it used to explain our need for nakedness – so that we wont overheat and can run down animals over long distances in the hunt. This is unlikely. On the Savannah, predator/prey chases are all over in a few seconds. Large predators hunting us can all outrun us over short distances – so we would never get the chance to show how well we can run marathons. Lion /leopard/hyena and Usain Bolt and he is just lunch (don’t even think about the cheetah).Similarly, even San (“Bushmen”) hunting must slow down their prey with poisoned arrows to be able to catch them. It is not possible to run down (while tracking) a healthy plains antelope. On the other hand, a semi aquatic ape which does not have the ability to endure while swimming will simply drown. It is far more likely that we evolved the physiology of endurance (which is far more than just the ability to keep cool) in response to the challenge of swimming than of hunting. Our ease on two legs running now (compared to swimming) should not fool us into believing it was always so. Certainly at first we would have been as clumsy and slow as a chimp on two legs. So what was the immediate one step benefit for doing so? We cannot argue that we started walking on two legs because we knew that in a few thousand generations we would get good at it. Walking in water and keeping your nose out of the water by standing on your hind legs is just such a one step benefit.
    If comparing how well and with what enthusiasm humans swim compared to run, we should also compare how well chimps run and swim. Clearly we are relatively hugely better swimmers and they are better runners.

  25. Greg, I don’t think you even understand what these ideas are. The “aquatic ape” is a misnomer. It’s not one idea, it’s several. It’s not arguing that our ancestors were “aquatic” in any commonly accepted sense, just more aquatic than the lineage leading to chimps/bonobos/gorillas since the split. It’s not necessarily suggesting that this “more aquatic” pressure only occurred as apes, but could also include relatively recent human ancestry.

    Admit it. You heard about this idea over a coffee or a beer when colleagues sneered at it and you’ve been sneering at it ever since, right?

    You say “… it was rejected a long time ago by almost all serious paleoanthropologists” so, ok, where was that rejection published?

    You mean John Langdon’s unscholarly, straw man portrayal that had no reply until recently? (See here for a discussion, with John, of my critique of his) Or Roede et al – where the decision “against” was rather marginal and even then the editors made it clear that (like you) they were considering a “full on” aquatic ape, not the concept that perhaps our ancestors were subjected to slightly more selection from wading, swimming and diving than the chimps?

    You mention the “bipedalism TOE” which, I agree, has been used to explain everything, but you fail to notice the overlap here – the wading hypotheses has to be one of the most obvious and plausible, and least anthropocentric, ideas on hominid bipedal origins.

    Perhaps in a future blog you might cite that paper where the idea was “rejected” by paleoanthropology because I’ve been doing a PhD on the subject for years and I cannot find one that so much as even discusses it specifically.

    Finally, you ape PZ’s incritical backing of Jim Moore’s masquerading web site and label it as “excellent”. I doubt either of you have even read it.

    If you had, you’d note the nauseating hypocrisy throughout – e.g. he criticises Elaine Morgan for not using page numbered citations when almost all of his gossip takes the form “aquatic proponents tend to say x about y” – with no citation at all.

    Normally, in science, we use the scientific, peer reviewed literature to refute ideas. Here, I note, the bar has to be lowered so much that the biased twistings of an ex-car mechanic without any academic training in science other than a nepotistic link to Nancy Tanner, can substitute with impunity.

    You, like Jim Moore, should be ashamed of yourself for trying to pull the wool over people’s eyes like this.

    Algis Kuliukas

  26. Algis, your uniformed hubris made me laugh this morning. Yeah, it was a lot like sneering at ideas over a beer but it was actually getting a PhD in the study of human evolution and stuff! But yes, there was sneering and there was beer.

    Hey, here’s a new bit of information: When we put my baby in te water, he sinks right to the bottom. He’s been taking swimming lessons or otherwise swimming with his grand dad or mom once or twice a week sine he was about 6 months old (he’s now 2 1/2). He still sinks right to the bottom if he is not being held or wearing a flotation device. I’m told this is normal for human children.

    Therefore your ideas are rong!!!!11!!

  27. I first heard about AAT in _Time Magazine_ in the early 70s. _The Descent of Woman_ was a delight to read, even if, as Steve Gould said about the Gaia hypothesis, “It’s poetry, not science.” (Personal communication, 1986.)
    I think in general that to avoid political confusion in the general American-speaking population, one should avoid the term “theory” except in cases when it is a proven hypothesis, such as gravity, relativity, and natural selection.
    Re: AAT: Do other species of great apes have a diving reflex? “I’m just askin'” (รข??the B-52s).

  28. The “Diving Reflex” is a mammal wide trait, it would seem, although no one has ever tested anything on all mammals, it is known in a wide variety of mammals. It is also found in many birds (I don’t know of any birds it is not found in, but again, no one has ever tested anything on every bird).

    It is activated by cold and not warm water, so I suppose one could wonder about the evolution of hominids in tropical regions vs. the cold-water diving reflex! In any event, the diving reflex is probably plesiomorphic for mammals, or vertebrates, or some other large taxonomic category, so it is not helpful in identifying the AT “theory/hypothesis” (both words have been used at different times by its proponents)

  29. Greg thanks for confirming that your bias against this idea is based on a sneering session and that you are somehow proud of this ignorance.

    Oh, so because your baby sinks (N = 1) suddenly that data must override everything else, is that it? Oh and you “were told this was normal for human children”? Brilliant! Kind of like the argument “well my grandad, who’s 75, smokes 20 a day, and he’s ok. I was told this was normal, so I’m skeptical about all that cancer stuff.”

    Blimey, Greg, with aquaskeptic arguments like this, who needs science?

    Your final point (it seems, made after a one too many of those beers) was damning…

    “Therefore your ideas are rong!!!!11!!”

    It’s the paucity of the arguments against waterside hypotheses – as you admirably show here (I note, not one word about Jim Moore’s masquerading web site – I bet you haven’t read more than a few sentences of it) – that most convince me that it is probably right to some degree.

    Algis Kuliukas

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