General Problems with the AAT/H

The method of the Aquatic Ape Theory (AAT/H)

In this section I try to present, as simply as possible, the problems with the way the AAT/H is argued, broadly divided into basic problems with the use and misuse of evolutionary principles by AAT/H proponents, and the many logical fallacies that AAT/H accounts typically fall into. Later sections deal more with examples of specific errors.

Problems with the idea itself

The most basic problem with the AAT/H is that it uses extreme environmental determinism. The proponents do this apparently thinking they are using the quite legitimate evolutionary principle of convergent evolution, but they do so in a very mistaken manner which suggests they really don't understand it. I have a short explanation of convergent evolution here. It seems as though they've picked up the term without understanding what it actually means; most specifically they shy away from the fact that convergent characters are similar in function as well as in structure. That is, convergent features are similar in structure because they are similar in function due to environment , not simply similar in structure due to environment. In doing so AAT/H proponents commit a logical fallacy, the fallacy of explanation called "limited depth". Stephen's Guide to the Logical Fallacies describes this: "Theories which do not appeal to an underlying cause, and instead simply appeal to membership in a category, commit the fallacy of limited depth." They also expect this similarity to happen without regard to relatedness, which means that -- bizarrely -- they ignore the central element in evolution: phylogeny, relatedness, and descent with modification.

This is very bad, frankly -- no regard to phylogeny, no regard to function, just an expectation that environment should, somehow, cause all creatures within that environment to solve physical problems in the same way. Holding this view requires one to not just ignore basic evolutionary principles, but ignore the fact that animals in the same environments very often exhibit different adaptations to solve the same problem. Ignoring basic scientific principles is bad, certainly, but ignoring facts is arguably worse. And expecting this extreme environmental determinism, and particularly adaptation to a particular environment, is an especially bad idea when trying to explain the evolution of an environmental generalist, and humans are one of, if not the, supreme environmental generalists in the animal kingdom.

They make the mistake of supposing that even very distantly-related animals in a common environment should evolve the same mechanisms for dealing with any given problem, for instance, believing that if hominids had a land-based transition they would've have used the same form of thermoregulation as "the wild ass and the camel" (that example is from Elaine Morgan, in her 1990 book, The Scars of Evolution:  "On the supposition that man's ancestors moved out from the trees to open ground and needed sweat-cooling, they might be expected to have followed the example of the wild ass and the camel in adapting their apocrine glands for that purpose."). This idea -- suggesting that developing an adaptation is like catalog shopping -- is an odd and non-evolutionary idea, which not only ignores the role of phylogeny in evolution (the core idea in evolution, actually) but also ignores the fact that animals in any given environment often develop many different mechanisms to deal with common problems. This often leaves AAT/H proponents in the odd position of being surprised that humans most closely resemble our primate relatives (for instance in sweat-cooling via eccrine glands rather than apocrine glands) instead of distantly related ungulates.

The AAT/H method also includes an ironic double standard: for instance, while the observation that non-human savannah mammals don't predominantly walk bipedally and predominantly cool by sweating via eccrine glands is considered devastating evidence against a terrestrial divergence for our ancestors, but the fact that no non-human aquatic mammals do so is simply ignored. And asking why humans are so incredibly different from aquatic mammals in the actual traits which are ubiquitous in such mammals is also apparently a no-no. So while expecting a fantasyland version of environmental determinism, it doesn't accept convergent evolution due to water in demonstrated, actual aquatic features -- just non-demonstrated, or not-really-the-same superficially similar features, or completely "false fact" features.

In every version of the AAT/H at least since Morgan, environmental determinism is paramount. This is the assumption that evolutionary changes are virtually always driven primarily by environment. Evolutionary change being driven by environment can happen but doesn't necessarily happen, especially with animals which are generalists, as hominids are -- in fact, humans are perhaps the supreme generalists of the animal kingdom. Over the past decade or so, nutrition specialists Michael Crawford and Stephen Cunnane have introduced what amounts to a subset of environmental determinism, dietary determinism. This use of determinism has led to AAT/H proponents using a badly flawed understanding of convergent evolution, which is a terrifically useful concept when used accurately but which begets nonsense when used inaccurately.

One example of this -- and a real roadblock for AAT/H proponents' understanding of hominid evolution -- is the way they mistakenly assume that environmental determinism is the normal method within paleoanthropology. Of course paleoanthropologists examine environment in human evolution, especially since one of the central questions in human evolution has always been how we came to be able to use so many different kinds of environments while our closest relatives, the apes, are stuck being able to use only a very few. But the mainstream theories of human evolution typically deal with social interaction and food-getting, not environment, as drivers of selection. It is true that many of these theories are interested in how our ancestors were able to make changes that allowed them to live in more and more open savannahs over the years, because these savannahs were getting more widespread and because we always have wanted to figure out how hominids went from being forest-dwelling animals to an animal that can live pretty well anywhere. We're by far the most widely ranging mammal with the possible exception of the rats and mice that have followed us around the world.

AAT/H proponents seem not to understand this, as can be seen in the way they refer to mainstream paleoanthropological ideas as "savanna theory" or "terrestrial theory" or "mosaic theory". Contrast those terms to the actual theories used for many decades, even the discredited "killer ape", or others like the "hunting hypothesis", the "seed-eating hypothesis", the "gathering hypothesis", the "food-sharing hypothesis", or even hypotheses that deal with individual features such as the "radiator hypothesis". Note that most of these theories deal heavily with food, food-getting and sharing, and social interaction, and only tangentially with environment. Environment is mentioned, of course, and there's a big interest in figuring out what environment(s) we evolved in, and also of course any theory concerning human evolution must look at how we, as a species, managed to deal with a wider and wider variety of environments. It's one of the key differences between us and apes -- we did so much better at it; they managed only a few different environments, and not all that different when you compare to what we managed even through the time of Homo erectus. But the basic ideas generally concern behavior rather than environmental determinism, important since rather obviously it doesn't make sense to look for an environmentally deterministic solution to how an animal became more and more unconstrained by their environment. So, whether mistakenly or deliberately, AAT/H proponents build a strawman of normal paleoanthropological theory, and whenever normal paleoanthropological theorists mention environment, as they naturally do, AAT/H proponents typically assume they're using environmental determinism just as the AAT/H proponents themselves do.

So from its earliest iterations, the predominate method used in constructing the AAT/H consists of this environmental determinism with an extremely heavy reliance on this flawed understanding of the evolutionary concept of convergent evolution as a mechanism and an equally extreme adaptionist view, along with a "pick and choose" browse through what I think of as "The Big Book o' Adaptations" much like you see done way too often in the poorly done forms of sociobiology (cause it's easier than doing it right). In this "pick and choose from the Big Book" method, evolution is like catalog shopping and animals get to ignore basic evolutionary principles and simply grab any feature they like from any animal.

Indications that, in Morgan's case at least, this problem is due to a severe lack of understanding of the basic principles involved, are that in the last 10 years (after decades writing on the subject of AAT/H-style evolution) she mistook the concept of "homoplasy" -- which is the umbrella term for both convergent and parallel evolution -- for a new term even though it's over 150 years old; and that she has claimed that convergent evolution in arctic animals are convergent in a "single shared feature" (white coloration -- several posts in 1995-6 in the sci.anthropology.paleo newsgroup, including Aug 01, 1995, Jan 25, 1996, Feb 01, 1996, as well as in her 1997 book), when anyone who does the slightest study of convergent evolution should know that arctic animals -- which are indeed a classic case of convergent evolution -- typically also have very short ears, shorter legs, and fur or feathers which insulates the bottoms of their feet (all to conserve heat). She also, in her Jan. 25, 1996 post, suggested changing the established evolutionary term convergence to one of her own devising, which is a strange bit of business one usually sees only in pseudoscience crackpots -- I am not saying she is one, mind you, but picking up their habits is a very bad idea for someone who wants to be taken seriously in science, as she clearly wishes. (Perhaps even odder is that she said she wanted to change the term "convergent evolution" because it didn't lend itself to being an adjective, when convergent is an adjective -- and she's a graduate with a literature major from Oxford, one of the world's best universities. Talk show host Arsenio Hall used to have a segment in his monologue, "Things that make you go hmmmm....").

Another argument common in AAT/H circles provides a good example of how a melange of errors can be involved in creating one false argument. This is the question of "hairlessness" or "relative hairlessness" and what it means in evolutionary terms. The usual category set up of "hairless" or "relatively hairless" mammals suggested by them contains humans, naked mole rats, and aquatic mammals. Because of their use of radical environmental determinism, this, they say, means that "hairlessness" or "relative hairlessness" is somehow due to either "aquaticness", "semi-aquaticness" or subterranean living (the naked mole rat), and since humans obviously are not rodentlike burrowers, and since no one argues they ever were, they must have been "aquatic" or "semi-aquatic". (Sometimes they include "wallowers" in the above categories, which adds the ridiculous implication that wallowing in mud is in some degree "aquatic" -- it gets worse than that; I've seen suggestions that damp ground or even humidity constitute an "aquatic" environment -- let's be kind and ignore those ideas).

For many people who don't know a lot of relatively arcane facts about many different mammals (which is most people, after all) this can sound convincing, but it's actually a number of "false facts" along with several logical fallacies (the second part of this page deals with some of the many logical fallacies that AAT/H proponents trip over regularly). First of all, the vast majority of aquatic mammals are neither "hairless" or even "relatively hairless" -- in fact this is only true of a very few fully aquatic mammals: whales and sirenia (manatees and dugongs) and one very large pinniped, the walrus. For the majority of these aquatic mammals the reason for their hairlessness (or relative hairlessness in the case of the walrus) is rather clearly the same as the widely accepted and well supported reason for relative hairlessness in elephants, rhinoceros, and hippopotamus -- it's their size and proportions.

All animals have to dissipate heat, and this is easier for animals which have more surface area for their volume. This is just like a radiator; if you look at one you see it is designed to have a great deal of surface area for its volume (if you look inside your computer you'll find this principle in use in heat sinks on heat producing components -- it's a general law of physics). An animal like an antelope has relatively long legs and neck, and therefore a lot of surface area for its volume compared to an elephant; the elephant therefore has more trouble getting rid of heat. The elephant has little hair for this reason (and tends to habits that don't build up heat as readily too) and as further proof that this is the reason, one can look at prehistoric elephants (and rhinos) which lived in much colder regions -- they were covered with hair, because they didn't have the heat load that their tropical cousins have to deal with.

The very large aquatic mammals have an even more difficult problem with surface area, because they don't have as long limbs as the very large terrestrial mammals. Now although most cetaceans are very large, there are some smaller versions (dolphins and porpoises) but besides some effect of volume vs. surface area there are two other likely reasons for hairlessness in their case. One is that they are very swift swimmers, with highly specialized shapes for high speed swimming. The other may be simple phylogeny -- it may be that they are hairless because they had larger ancestors (early whales) who were hairless, and the modern dolphins and porpoises had to deal with this as best they could, just as every animal is to some degree a "victim" of their ancestry.

Then there's that naked mole rat; does it give some support for the idea that hairlessness is somehow, in some unspecified manner, due to environmental determinism as the AAT/H view would have it? Well, you can test that idea by wondering if they're simply an unusual curiosity among burrowing mammals. You could look at gophers, ground squirrels, and moles, or any number of burrowing mammals (all quite hairy except for the naked mole rat) but you don't even need to look that far afield, because there are 5 closely related species of mole rats, all with similar burrowing habits and habitat -- and the naked mole rat is the only one which is hairless. So what we see is that relative hairlessness is not environmentally deterministic as the AAT/H insists, not related to habitat but is instead an unusual feature with a few scattered species exhibiting this odd characteristic for idiosyncratic, species-specific reasons -- with the exception of those very large mammals with thermoregulation problems, a well known and well established solution to a problem of heat and body size vs. surface area.

But the AAT/H tries to explain this feature instead by first incorrectly describing it, then ignoring alternative explanations which make sense, then finally inaccurately shoehorning all these different beasties into a category and claiming the category makes the reason. This is a number of errors followed by the use of a classic logical fallacy (mentioned above and described further below), the fallacy of explanation called "limited depth".

Other problems with the AAT/H are that the supposed degree of aquaticism is rarely explained or defined and is never enough to account for the features mentioned -- since the features mentioned are typically those of seals, whales, and sirenia -- and that it doesn't account for continued existence of extreme deleterious features which should have been selected against. I mention these in more depth as part of the next section.

Problems with the presentation and argumentation of the AAT/H:
Logical fallacies

ad hoc ZING!ability:
AAT/H proponents (most at least) use an awfully "fluid" set of claims about aquaticness -- what I've called ZING!ability -- to go wherever and be whatever the proponents say it should be at any given time, dodging this way and that in internally inconsistent ways so they can answer any critics in an ad hoc fashion. Critics talking about swimming -- ZING! -- it's a wading and shorewalking creature... talking about walking along the shore and not swimming -- ZING! -- it's a creature capable of long distance open sea swimming. You can see this in the past on the subject of sweat and other matters -- the AAT/H has always had this trademarked ZING!ability, the ability to ZING! in and out of watery environs as much as they need to dodge criticisms. So when any difficulty arises with one of their claims, or a critic appears -- ZING! -- off the creature goes to the shallows or the shore, and the critic is accused of malfeasance.

This is connected with the last item in this list, the Fallacy of Ambiguity.

Strawman Argument
Definition, from the Talk.Origins Jargon FAQ: "Strawman Argument: Stating a misrepresented version of an opponent's argument for the purpose of having an easier target to knock down."

This is -- judging from its continual and widespread usage -- another essential AAT/H technique. An example is the assertion, echoed by almost all AAT/H versions, that paleoanthropologists claim that early hominids lived on "the arid savannah", which AAT/H proponents typically -- and inaccurately -- characterize as a waterless, treeless plain. The AAT/H is then said to be the only sensible theory, since early hominids were probably not well adapted for surviving on a treeless, waterless arid grassland. But paleoanthropologists don't make this claim; they actually refer -- quite clearly -- to an early hominid habitat consisting of mixed vegetation: trees, bushes, and grass (and some say the earliest hominid habitats were likely denser forests). Although online, and in her latest (1997) AAT/H book, Elaine Morgan has derided this correct version as some new idea -- a sort of last ditch desperate act by weaselly scientists to dupe their students and try to keep hominid evolution on land -- this is the definition of savannah which has been used for about a century.

Promoting their idea by tearing down another (strawman) idea:
This is a combination of the Strawman and False Dilemma logical fallacies, and is a mainstay of pseudo and fringe science of all stripes.

This is a very unscientific method; even if you could tear down another idea, it doesn't make any competing idea correct, and doesn't even bolster the competing idea. Let me illustrate by assuming that some incorrect idea is generally accepted -- let's say the idea that 2+2=7. Advocates of a competing idea say that 2+2 actually equals 9 -- even if they successfully show that 2+2 does not equal 7, it still won't mean that 2+2=9, and it won't even make it more likely that 2+2=9. Only showing that their idea is correct can prove their idea. I know it seems like this should be obvious, but for some reason it often isn't, especially when the competing ideas are not so obviously shown to be correct or incorrect as in basic addition.

And this would be a problem even if they accurately described the mainstream idea instead of using a strawman, and even if they accurately showed that mainstream idea to be wrong -- in fact they do neither, and that makes this an even bigger error on their part.

I think this one would be Irrelevant Conclusion (ignoratio elenchi):
Definition, from Stephen's Guide to the Logical Fallacies: An argument which purports to prove one thing instead proves a different conclusion.
This one is just plain saying that an appropriate expert said the opposite of what they actually said. Morgan has done this a number of times, one is her use of Derek Denton's work on salt. Citing Denton as her source, she said that in humans, innate physiological reactions to salt had been lost, and that this was a "specifically human characteristic -- the fact that we have no instinctive awareness of the state of the sodium balance in our bodies", while Denton actually said the exact opposite, that "in the human case, the cultural influences are acting in the context of an innate propensity", and that this was an "overall innate organization dedicated to salt ingestion along with the elements determining appetite response to sodium deficiency and to the hormones of the reproductive process."

Special Pleading:
This is holding another idea to a very different standard of evidence than your own, and is also a mainstay of pseudo and fringe science of all stripes. There are many instances of this shown on my site, but perhaps the classic example in the AAT/H is the proponents' common use of a double standard as they argue that the idea of hominids evolving bipedality in a terrestrial setting is badly damaged by the fact that no non-human terrestrial mammal is predominantly bipedal, yet the fact that no aquatic mammal is bipedal is brushed off as irrelevant.

A variation of this fallacy is using the ad hoc "not enough time" excuse for features or problems they don't want to explain, but plenty of time for bizarrely different features to appear, and sometimes disappear later without a trace:

actual ubiquitous aquatic features = "not enough time"

wading bird style long legs = "enough time"
shorter legs as seen in actual mammalian semi-aquatic adaptation = "not enough time"

"straight pelvis" = "enough time"
narrow pelvis as seen in actual semi-aquatic adaptation = "not enough time"

non-mammalian-style salt excretion system = "enough time"
kidney changes to deal with salt as seen in actual mammalian aquatic and semi-aquatic adaptation = "not enough time"

Fallacies of explanation: Limited Depth: Definition: "Theories explain phenomena by appealing to some underlying cause or phenomena. Theories which do not appeal to an underlying cause, and instead simply appeal to membership in a category, commit the fallacy of limited depth."

This is seen in the common AAT/H use -- or rather misuse -- of convergence and those characteristics they claim we have in common with other, generally unspecified, animals. Since they don't want to admit those animals are highly specialized aquatic animals which have been aquatic for tens of millions of years, they use phrases like "aquatics" and "where do we see" [these characteristics]. This is also an example of the fallacy called Coincidental Correlation, and is generally linked, in their work, to the next Fallacy of Definition.

Fallacies of definition: Too Narrow:
As seen, for instance, in the AAT/H Leaflet, they use any aquatic or semi-aquatic environment, yet try to restrict their critics to using one and only one specific terrestrial environment -- a strawman version of the savanna which includes only a limited number of actual savanna environments, and of course an even more limited range when you consider all terrestrial environments.

Appeal to Pity (argumentum ad misercordiam):
This is a bizarre (to my mind) and rather sad method, most often seen used by AAT/H proponents when talking about critics of Hardy or Morgan, although Morgan has used it in referring to herself. The critic is asked to think of the age, or sometimes the grandparent status, of the AAT/H proponent and to therefore not be so critical. Mistakes are excused by referring to the proponents' ages and/or supposed enfeebleness.

Ad hominem:
The most widespread use of ad hominem by AAT/H proponents is the careful creation -- particularly seen in Morgan's writings and career -- of the myth of the closed-minded academic establishment closing ranks against the embattled AAT/H proponents merely because they are outsiders, not because the proponents make poorly thought out and poorly supported arguments. The Attenborough BBC radio show I critique on this site used this method rather heavily, taking up something like 15 or 20 minutes of the first half hour segment with this technique.

"Argumentum ad Assertion Repetitio ad Nauseam":
Although used to some extent by other AAT/H principles, this is Marc Verhaegen's baby, perhaps his most common online method (other than simple abuse directed toward his critics).

Appeal to Authority (argumentum ad verecundiam):
First, there are authorities and authorities, so to speak. For an authority to be properly used, that authority needs to have some validity as an expert on the subject at hand, and even then it's better -- far better -- to use someone's study or data rather than just quote them as an authority. It also helps, to say the least, if that authority actually says what you claim they say. For instance, if you were thinking of using Phillip Tobias as support for the AAT/H (as has been done, fairly frequently), you might want to reconsider since he has stated that he does not support the AAT/H.

Anonymous Authorities:
An example here would be Morgan's use of Daniel Dennett's anonymous "distinguished biologists, evolutionary theorists, paleo-anthropologists, and other experts", or her 24 Apr 1995 sci.anthropology.paleo newsgroup posting "I could easily cite between a dozen and a score of cordial, even blushmaking, responses from reputable journals and academics. I won't do it on the Net." In online communications this is generally chuckled at as the "lurkers support me in email" defense.

Hasty Generalization:
Seen, for instance, in Hardy’s original seal comparison, variations of which have been made ever since by most if not all AAT/H proponents. Here a superficially similar appearance seems to show a similarity in traits, but only if you don't think at all about the massive differences in that feature between, in this case, seals and humans.

Fallacy of Exclusion:
Lots and lots of this; it is one of the most common methods used in arguing for the AAT/H. One example (of several on this site) are Morgan's mentioning anecdotal accounts of emotional tears in aquatic animals while burying such accounts of non-aquatic animals, even though both appeared in the same source (same book, same chapter) she used as a reference.

This can be done inadvertently, but is sometimes done deliberately as one-sided "lawyer-style" data mining, and sometimes you will even find pseudo and fringe science advocates admitting doing this without apparently thinking it's wrong. So ingrained can this habit become that it's possible for an advocate -- when seeing others not do this -- to think that the person not doing it can only be doing so "by mistake", as Algis Kuliukas did in my case regarding the conflicting data I found on hair and swimming speed.

For that matter, why, after making hair loss one of the cornerstones of the AAT/H for decades, supposedly as a convergent evolutionary feature due to water use, did none of the proponents bother to look for data on it -- why did it fall to me to do so? You just look it up at the library -- a couple of hours, tops -- why do they so often want others to do their research for them?

The AAT/H has a long tradition of ignoring the problem of predators, very unlike traditional paleoanthropology -- this is another example of the Fallacy of Exclusion.

Another common use of the Fallacy of Exclusion in the AAT/H is that it doesn't account for continued existence of extreme deleterious features which should have been selected against; these include (but are not limited to) ear exostoses (which causes ear infections and can rob us of hearing, and which aren't limited to people who swim and dive but which AAT/H proponents such as Marc Verhaegen claim are); diving problems such as heart arrhythmias and blackouts -- these and other problems are well known and represented in medical literature about diving (in fact there is a branch of sports medicine which deals with the health problems resulting from swimming and diving); and food allergies to things like shellfish, which are some of the most common and severe allergies found in people.

How about this: GULP! why do we still -- mind you after supposedly millions of years of our population swimming and diving -- why on earth do we tend to inhale when we go under, with obviously unfortunate results. And how when we run out of air, we automatically fight to breath, even when we're underwater -- obviously an incredibly dangerous thing to do. Actual animals which evolved diving abilities (as most all the AAT/H accounts claim for us) have physical adaptations which eliminate the impulse to inhale underwater -- we, even after supposedly millions of years of our population swimming and diving, don't. They got these adaptations through convergent evolution, the kind of evolutionary change, in the kind of environment, that AAT/H proponents claims for us.

and related:

Why, even after supposedly millions of years of our entire population regularly swimming and diving, do we drown so readily?

Oddly enough, some of these deleterious conditions, such as ear exostoses and dangerous food reactions, have been presented as evidence for the AAT/H by some of the proponents, namely Verhaegen and Morgan. This is actually another logical fallacy, called Irrelevant Conclusion (ignoratio elenchi): Definition from Stephen's Guide to the Logical Fallacies: An argument which purports to prove one thing instead proves a different conclusion.

One other excluded item from the core of the AAT/H is taphonomy, the study of the distribution and numbers of fossils based on the rate of fossilization. This is a well established and understood principle and has been for many decades; one of the most common consequences is that animals and plants which live in water and along shorelines get fossilized at far higher rates than other organisms. This is where the AAT/H claims our ancestors lived: Why don't we therefore have lots and lots of hominid fossils? Why don't we therefore have many many more than we do?

Fallacies of Ambiguity:
The best example of this would be the AAT/H's definition, or lack thereof, of the degree of aquaticness they're talking about. The fact that this changes to suit any counter-argument makes it even more ambiguous. For instance:

The Aquatic Ape Hypothesis (AAH):
The hypothesis that water has acted as an agent of selection in the evolution of humans more than it has in the evolution of our ape cousins and that, as a result, many of the major physical differences between humans and the other apes may be explained, at least in part, as adaptations to moving (wading, swimming and/or diving) better through various aquatic media.

Elaine Morgan endorsed this definition earlier this year and I propose that this is what people use when discussing it from now on. If we do that, perhaps the next 44 years might be a little bit more productive in resolving this issue than the last.

Algis Kuliukas, 24 Aug 2004 sci.anthropology.paleo

In presenting this definition at several points during the early half of 2004, Algis made the following remarkable claim:

"To be fair to Hardy and Morgan they weren't really even at the stage to be able to define the hypothesis."
Algis Kuliukas, 24 Aug 2004 sci.anthropology.paleo
So here Algis claims (incorrectly, in my view) that even after decades of working on the idea, publishing account after account of the idea, and insisting that academics accept their idea, none of the idea's proponents had gotten to the stage of being able to define their idea!

If this were indeed true, it would be an incredible admission of incompetence, but in fact I think you can see pretty clearly in both Hardy's and Morgan's work what their idea was.

Besides the incompetence issue this claim raises, the two major problems you can see in this "mild" definition are:

  1. It's so vague as to be meaningless.
  2. Many of the major characteristics they claim arose in humans are found only in seals, whales, and sirenia, highly specialized aquatic mammals which have been aquatic for tens of millions of years, and not in any other aquatic and semi-aquatic animal, which indicates that it takes a long time and a lot of intensive, extremely specialized adaptation to an aquatic environment to develop these characteristics. Therefore, while it's certainly true that in order for a mammal to evolve these characteristics would take "more" water use than we see in apes, the "more" would be far more than any of the proponents want to accept; far "more" than anyone, even among the idea's presently (2006) living proponents, can see as even remotely possible. So much "more" that it makes the definition effectively meaningless.

What we see is really not so much an attempt to define the idea as to "define away" any possible objections -- this is not an honest approach to science. Here's the biggest problem I see with that attempt (which has been done, in various forms, by other proponents, including Morgan). The claim that we became the way AAT/H proponents say we did (and they're incorrect on most of the specifics they give as examples) through just a bit of wading and swimming certainly seems more mild, and the way it's often worded as an opener (for instance, "that water played some role in our evolution" or "a sea-side lifestyle") is often so generally nonspecific as to be both meaningless and non-controversial. And even if they simply said that wading may have been one of the many factors involved in our ancestors' bipedality that too would meet with little or no objection. But that's not all there is to it, once you "dive in".

First, they just can't seem to let it be one of many parts -- it's got to be the main thing, the key factor, and in doing so they continually discount or downplay the many other things that we see bipedalism is good for, and is used for by present-day apes and other primates. They also vastly overstate the use of bipedalism when apes are in the water -- from their descriptions, you'd think it was virtually all the time, but it's not, and most of the time the bipedalism in the water is used during activities much like when it's used on land (for instance, during feeding on things which would otherwise be out of reach, or during displays). They sometimes also make the claim that bipedalism couldn't have arisen without the support of water, which has two major problems: one is that we know apes (and other primates) use it as part of their locomotor activities, some more than others; and there's the question, which never seems to get answered, of how wading in shallow water supports the weight of your body. And there's a contradiction if the AAT/H proponent claims (as they sometimes have) that we needed that water to support body weight for bipedalism, because we also see adaptations toward weightbearing in bipedality in hominids.

So this definition ends up bring most notable for its vagueness, merely suggesting "more" water use than apes as a definition. Contrast that with the explanation set forth in the "Methods" section of a 2001 paper by Bininda-Emonds et al. ("Flippers versus feet: comparative trends in aquatic and non-aquatic carnivores", Journal of Animal Ecology, 2001, 70:386-400): "We consider aquatic carnivores to be those species in which the aquatic habitat inevitably plays a key role in the life-cycle of an individual..." which they then compare to definitions as given by others as they discuss the strengths and limitations of their definition. And note that this more specific explanation is in a non-controversial academic paper rather than what is supposed to be a groundbreaking new idea. With an ultra-vague definition like the AAT/H one offered, note that you could make a similarly vague definition, using virtually anything instead of "water" and make a case for it.

The AAT/H definition suggested is not only so vague as to be virtually meaningless, it's notable that this is the first attempt since Hardy at such an explicit definition, and it's taken over 40 years to show up (while a normal paper in a typical journal, as seen above, warrants such a definition as an obvious first step). However, there has always been an implicit "how aquatic" definition in the AAT/H, ascertained by the characteristics the proponents have used to build their case. It isn't the definition Kuliukas offers, and it's not one AAT/H proponents like to mention, and they are generally mighty coy about mentioning just what animals they're saying we resemble (preferring to use a vague category instead), but nevertheless the implicit definition is there. The next section will get into that.

ZING!ability, the shifting target

Versions of the AAT/H have been developed, primarily by Marc Verhaegen and more recently by Algis Kuliukas, to attempt to counter this problem by declaring that the period of change due to some degree of aquaticism is essentially the whole of human evolution. These versions have some of these same problems -- for instance claiming that various features are shared with humans and aquatic animals even those features are not similar -- and introduce or accentuate others, such as the problem of describing how a claimed small amount of extra water (or just waterside) use by hominids provides selection pressure for convergence with highly aquatic mammals such as seals, whales, and sirenia (manatees and dugongs).

It is very true that they sometimes say one shouldn't compare humans to those animals, and that our ancestors were not even remotely as aquatic as any of those mammals, but the features they say we share are found only in those mammals, so they are actually comparing us with them, and since they use convergent evolution to explain these supposed similarities, that comparison also necessarily implies that our ancestors were that aquatic. Naturally, this is not what they say explicitly, but look at their comparisons.

And that's the central problem with the stated definitions of "how aquatic" offered by AAT/H proponents versus the implicit definition that can be seen by their constant comparison to features seen only in seals, whales, and sirenia -- there's an enormous disconnect. The two cannot be reconciled, which should -- but doesn't -- give them pause.

This is part of AAT/H theorists going in for a classic technique among marginal theories, the shifting target. This is specifically seen in the fact that the "aquatic apes" have become less and less aquatic over the years, from being fully acclimated to sea life, diving, etc., to seashore-dwelling waders, to denizens of the shores of streams and inland lakes. (This is the essence of the versions put forth by Verhaegen and Kuliukas, for instance, and Morgan has also gone along with this method.) In explaining (excusing?) this shifting target strategy, AAT/H proponents simply say their theory is adjusting to new evidence, as any scientific theory should. However, actions speak louder than words, and when we examine AAT/H proponents' actions, what we see are attempts to have their cake even after they've swallowed it.

As just one example, with the change in the AAT/H mentioned above (i.e., a less aquatic wading ape), the AAT/H claim that these hominids would not and could not evolve bipedal posture and locomotion without being in neck-deep water falls by the wayside... and yet they still use that claim. (Morgan has insisted that she has never made the claim that water was necessary for support despite having had her own works quoted with sections that said just that. There's more on this in the later section on "Aldosterone, water, and bipedalism".) 

And although you'll rarely see an AAT/H proponent state just what mammals they're talking about when they use (supposed but not accurate) similarities between humans and "aquatics", the characteristics they use show that the animals they are talking about are those highly or completely aquatic creatures, the seals, whales, and sirenia. But if it was unlikely that the original degree of "aquaticness" as suggested by Hardy would produce those changes in humans (and it was incredibly unlikely), to suggest these changes would happen with a much lesser degree of aquaticness is simply bizarre.

In essence, the AAT/H proponents want to have an aquatic mammal that isn't very aquatic, yet is forced to develop features seen only in fully aquatic mammals which have been aquatic for tens of millions of years. And even then, many of their claimed features are inaccurately stated; the features they mention are not actually like those of aquatic mammals. And even more telling, the aquatic features actually seen over and over in aquatic mammals due to convergent evolution -- which you would naturally expect to find in a mammal with an aquatic background -- are not seen in humans.

Sexual selection and the AAT/H

Sexual selection is interesting vis a vis the AAT/H because a surprising number of the traits that AAT/H proponents say are aquatic traits due to convergent evolution in response to the environment (and therefore selected via natural selection) are actually, and rather obviously, due to sexual selection. This is obvious because, typical of sexually selected features, they differ between the sexes and appear at puberty instead of at the age the animal would start using the aquatic environment.

We see this, for instance, in the lifespan history of fat in seals versus humans. Seals rapidly gain fat while very young, and at a very early age they are essentially like their parents in their fat distribution and quantity. We, on the other hand, start off fairly fat as babies, drop within a few years to the leanest condition of our lives as children, and then rapidly build up fat at puberty, with radical differences in quantity and distribution of fat between boys and girls, and to top it off, at middle age our fat distribution changes once again. Also, in humans fat distribution and amount is far different in males and females, while in seals the sexes are very similar. The same huge differences between aquatic mammals and humans that we see in fat we also see with our hair and sebaceous glands. AAT/H proponents say they are aquatic traits, which means they must be due to convergent evolution selected via natural selection, but they are actually obviously sexually selected traits.

Perhaps this is why AAT/H proponents like Morgan have made a habit, both in books and in online writings, of downplaying the role of sexual selection in the emergence of these traits. She's done this in several books, including her most recent, the 1997 The Aquatic Ape Hypothesis, where she spends some time in Chapter 7 poo-pooing it, along with a misuse of a quote from Darwin that's unfortunately reminiscent of the method that creationists often use with Darwin's words. I cover this in the section "A brief critique...".

Perhaps the oddest problem with AAT/H proponents' methods

The AAT/H is typically presented as a series of two-part claims, i.e.:
1. Feature A cannot have evolved on land.
2. Feature A is found only in humans and aquatic animals.
Therefore Feature A is evidence of an aquatic transition from LCA to hominid.
Many claims have been made in support of the AAT/H using this general form. However, the quality of the research that has gone into these claims has been poor. Many of these features are not unique to humans amongst terrestrial animals. Many of them are shared by only a few aquatic mammals. And those features which actually are ubiquitous amongst aquatic mammals -- and which therefore would be expected to be found in a mammal which evolved in an aquatic environment -- are (just by coincidence?) features which AAT/H proponents have consistently ignored, because none of them are seen in humans or our hominid ancestors.

So one essential technique of the AAT/H is, ironically, to ignore all actual aquatic features.

Feedback: E-mail me