Re: Is the AAH a legitimate hypothesis? Of course it is.

From: Algis Kuliukas (algis_at_RiverApes.com)
Date: 01/02/05 

Date: 1 Jan 2005 22:34:02 -0800

jae@ucdavis.edu wrote:
> Algis Kuliukas wrote:
> > Jason Eshleman wrote:
> > > In article
<1104480636.626415.104550@c13g2000cwb.googlegroups.com>,
> [snip]

First of all, thanks for such a full and intelligent response, Jason. I
note that you actually replied to my point in full in your last posting
too and thanked you for that, but this is an even better response, full
of balanced critical opinion. But I stand by my earlier criticism that,
until that posting, you had been rather evasive. Water under the bridge
now, though.

> > I have a tendancy to be sceptical of non-adaptationist arguments,
be
> > they Panglosian spandrels, ontogenic side-effects of Hox-genes or
> > whatever. As Dawkins might put it, 'they are not helpful'. At best
> they
> > provide mechanisms for increasing variation within population. But
if
> > they generate a phenotype that is weak, natural selection is
clearly
> > the force that will eliminate them. The fact humans swim better
than
> > chimps really must be due to natural selection because the weakest
> > phenotypes in that medium are clearly exposed to heavy selection.
>
> [note: my text following is largely text composed following a comment
> RW made to AK in another thread. I apologize for the macro-ish
nature
> of this repost and am doing it here rather specifically because I
> believe the same reply is warranted in this case as well.]
>
> Dawkins is wrong.
>
> The premise of Algis's question is that the difference is
significant,
> that it means something about our natural history and the natural
> history of chimps since the bifurcation of our lineages where in one
> lineage increasing abilities in water led to greater survival. This
> *could* be true, but it isn't necessarily true as Algis seems to
> indicate.
>
> Consider these possibilities:
>
> 1) The difference is trivial. This is a null hypothesis of sorts.
> Between any two species the abilities to move in any medium are
either
> exactly identical or they are different and this is true regardless
of
> whether or not selection made them different. I'd suspect that the
> overwhelming number of cases of "same" occur when ability is zero in
> both cases, like an armadillo and a zebra's ability to fly. If there
> were an actual ability to do something though, I'd suspect that
> completely identical abilities are less common. Is a peguin a better
> runner than a pelican? Is this a direct result of selection for
> running favoring one over the other? When comparing humans and
chimps,
> even if there's no evolutionary significance to this in the time past
> the bifurcation of our lineages, one is likely to be a "better"
swimmer
> as a pure product of chance. This is just the logical truism that if
> things are not equal, then they must be different and this is true
> independent of any cause or lack of cause of the difference.

Fair point. But...

1) I did try to remove such unrealistic permutations (armadillos versus
zebras at moving through the air) from my 'odds' calculation.

2) The pelican v penguin on the ground point is a good example of where
the difference might be seen, at first sight, as trivial. But I put it
to you that in such cases, even a slight increase in scrutiny would
reveal that there was, clearly, a great deal of selection that had
taken place. In this example, for instance, if we qualify the substrate
to 'moving on ice' I'm sure the penguin would come out on top and
no-one would doubt that it was due to selection. If it was moving at
higher speeds over short distances on hard-flat ground, I suspect the
pelican would come out on top for similar reasons.

3) Unlike the ability of birds to waddle around on the ground, even
slightly greater swimming abilities are clearly a potential life saver
and so even slight differences between humans and chimps (although I
doubt they're at all slight) are likely to be the result of selection.

> 2) The difference is not trivial with respect to a selective
difference
> in the lineages. This can be broken down into two general categories
> though:
>
> i) Selection for an ability
> ii) The difference is a biproduct of selection for some other trait,
or
>
> iii) a lack of selection against the loss of an ability.

True.

> AAH would argue the former (i.) and posits that there's evidence that
> humans have had a uniquely "more aquatic" existence where our
abilities
> to swim were refined.

Not necessarily. Option (iii.) is also a strong posibility. If the LCA
of all African hominoidae was an 'aquarboreal' (wading-climbing) ape it
is likely that it was rather adept at swimming too. That is my favoured
position, actually. The fact that gorillas do swim, as do humans, seems
to indicate that the most parsimonious explanation is that the LCA of
Gorilla-Pan-Homo could swim. Since that LCA, it seems that Pan lost
this ability, Gorilla retained it, whilst Homo enhanced it slightly.

So points (i.) and (iii.) are consistent with the AAH, whereas the
aquasceptic argument relies on option (ii.) For the AAH to be wrong,
our increased swimming abilities *must* be the result of some
side-effect and/or pure serendipity. Of course this is possible but, I
put it to you that it is by far the least parsimonious because we do
have a whole cluster of traits which also indicate some consistencies
with some more aquatic mammals.

> This too is possible (but it's again not the
> only possibility) though actually demonstrating that selection
occurred
> is not by any stretch a trivial problem to come to this direct
> conclusion and it's further difficult to distinguist between (i) and
> (ii).

I disagree. If humans have more anatomical traits consistent with (i.)
than with (ii.) then I think it's rather clear what has happenned. I
suggest that our general nakedness, increased adipocity, increased
webbing between digits, more streamlined bodyline, the ability to
rotate the metacarpals allowing hands to be cupped, facial traits such
as hood-shaped nose with downward-poointing nostrils with a rather
keel-like nasal bridge, a hair line on the scalp that generally follows
the water line whilst swimming, eye-brows and eye-lashes which deflect
water from they eyes, descended larynx enabling large mouth breathing
gulps of air to be inhaled, apparently greater breathing control etc
etc are all absolutely consistent with (i.) but hardly with (ii.) which
has to come up with a combination of bizzare set of just-so stories and
sneering ridicule to promote them.

> Also plausible is (iii) that the difference is not a result of
> selection for the ability in the more recent evolutionary past of
> humans, but due to a loss of ability in chimps due to relaxed
pressure
> to retain this. It seems that the bulk of mammals can swim and do so
> without training. Further, the "dog paddle" that describes more or
> less what dogs, cats (even those with an extreme distastes for the
> water), rats, and many other mammals appears to be the de facto
> movement of the "water babies" indicating at least to me that if
there
> was some selection for swimming, it well could have happened a long
> time ago, way back in the history of mammals. I'd go further that
the
> lack of an "aquatic" past in the majority of mammals who swim, and
who
> I'd suspect are more likely to not drown if dropped in water for the
> first time without any training or assistance than a human is
*counter*
> to the claim that water was somehow so incredibly important in our
> lineage. I also know we're able to swim in other ways than the dog
> paddle, but these ways seem to be taught rather than innate and that
> the modern strokes have "evolved" so radically in recorded history
> further convinces me of this though I know of no way to directly
> address this.
>
> More remarkable that that we can swim though is that chimps
apparently
> don't swim as well as the basic mammal. (I say 'apparently'
> because I don't know what to believe as far as the "evidence"
presented
> by AAHers is concerned. I once heard claims that chimps
categorically
> can't swim, later amended to that some could. But after a recent
> re-read of Morgan's first book, I've noticed that huge pieces of
> her "evidence" have been thoroughly shown to be radically false.
> I've noticed similar things here in usenet where wet-apers have made
> overreaching claims about hairlessness in seals-the vast majority of
> whom have fur-and noticed that revising the data seldom leads to any
> changes in the claims about the overall plausibility of AAH ideas
among
> its proponents. That the fervor with which the AAH is presented
seems
> largely independent of the current state of the evidence for it is a
> mark of pseudoscience.) A plausible alternative to our lineage being
> uniquely adapted to water post bifurcation with the chimp lineage is
> that the LCA could swim and could do so because it's a trait acquired
> from a much more primitive mammal and it is the chimps who have
> changed, having lost the ability.
>
> Traits can be gained and they can be lost, especially if there's no
> need to retain them. In absence of selection, evolutionary change
> actually speeds up considerably over situations where there is
> selection present, but it does so in an unpredictable fashion.
> Selection much, much, much more often than not puts brakes on change
> rather than speeding it along to some adaptation. Remove selection
and
> change proceeds at its most rapid rate without selection removing
> variation. If the chimp lineage didn't need to swim, the ability
could
> be lost or diminish greatly by drift without selection to *maintain*
> the trait. In two lineages that both began with a trait, bifurcated
> and neither needed them, it's actually unlikely that if one began to
> lose it the other would lose it in similar time or fashion, as drift
is
> by its nature random. That apparently gorillas can swim is more
> consistent with this than that swimming ability evolved independently
> in various lineages.

I have no big problem with that. Clearly chimpanzees have lost some
swimming abilities which has further emphasised the gap between them
and humans.

If chimps lost it since the bifurfaction and humans didn't. It begs the
question: *Why* didn't we lose it too? The simplest answer has to be
that, like most terrestrial animals, there was some selection involved
in keeping it.

So even there on your fullest point here against the AAH, if humans
have *not* lost those traits, whereas chimps *have*, then this clearly
also argues that water has acted as an agency of selection in our
evolution more than it has in the evolution of our chimp cousins since
the LCA with them. So your best point is actually still pro-AAH.

> So with the evidence at hand is there reason to favor any of these
> scenarios? I realize that a disciple of Dawkins who searches first
and
> foremost for the pan-adaptationist explanations will likely tend
> towards positive selection rather than relaxed selection or the null,
> but this indicates a grand neglect for all possibilities.

That's a little unfair, Jason. I've not neglected the other
posibilities. As I've said here, even option (iii.) is still pro-AAH.
The aquasceptic response *relies* on it being option (ii.) I reject
that hypothesis on the grounds that we have just too many anatomical
traits which indicate that our ancestors had greater aquaticism in the
past, not just as compared with chimps, but also with gorillas too.

> Whether or
> not Dawkins views non-adaptationist explanations as being "helpful"
> isn't relevant. Natural selection is not a synonym for evolution,
> but is merely one of the mechanisms for evolutionary change. If
> Dawkins doesn't appreciate this, he too is incorrect, lofty
> credentials and powerful book sales not withstanding. The relatively
> more "helpful" adaptionist story doesn't indicate that it's
> true.

I am comforted to note that, at this point in time, we see the
aquasceptic argument clearly siding with non-adaptationist arguments
about evolution in order to try to fend off it's main thrust. It has
always been my view that the AAH is absolutely neoDarwinist and here
Jason appears to be confirming that. I am very happy to be on the
neoDarwinist side of the fence here.

There are several mechanisms for 'change' and for increasing variation
but natural selection has to be the main force working on those changes
to drive evolution. Maybe it's not synonymous with evolution but it has
to be by far the biggest part of it.

> Considering this then, is there enough evidence to make a case for
any
> possibility? I for one am not impressed with our 'remarkable'
> swimming ability in comparison to chimps, as swimming is most
generally
> an acquired characteristic, learned.

This is a very weak point because:
1) Human bipedalism is learned.
2) Swimming in aquatic mammals is learned.
3) Human neonates, even before any learning could have taken place, are
more likely to survive in water than chimp neonates, if only due to
their increaesd adipocity.

> This is my impression and not
> anything quantifiable but certainly our most prodigious swimmers in
> terms of endurance have done so through considerable learning and
> training. Endurance swimmers do not exhibit their abilities
innately.

Perhaps not, but if Ian Thorpe had been thrown in a swimming pool the
second he was born, I expect he'd be far more likely to survive than
any chimp neonate, assuming their mothers were around to attempt to
rescue them. Heck, he might have even been born in the water! I don't
think many chimps have been.

> The strokes used by most swimmers are learned and have been greatly
> modified during the lifetime of everyone posting on usenet, not by a
> process of biological evolution but through human innovation.

Sure but look at how many different strokes are open to us - over half
a dozen. Just because swimming coaches have worked out how to perfect
these strokes in recent years it doesn't mean that our distant
ancestors didn't also learn how to do them long ago. No-one would claim
that humans had never sprinted or threw big long sticks before the
Greek Olympiads but, somehow, when it comes to swimming, we've managed
to convince ourselves that it's a purely modern phenomenon.

> Our
> swimming speed is further not terribly remarkable when compared to
any
> creature that has to swim regularly as part of its general lifestyle.
> Similarly, most semi-aquatic creatures are better able to accelerate
in
> the water and change direction in the water readily. We do neither
> much better than the host of non-aquatic mammals who can swim. If
> selection made us swimmers, it didn't go much further than is seen in
> a host of other non-aquatic animals.

I note here your deft switch to comparing humans to semi-aquatic
mammals. Let's stick to apes though, shall we? There's no doubt humans
swim far better than Pan. No doubt at all. I'd suggest that the
evidence seems to indicate that we're also far, far more versatile that
gorillas. Adult gorillas, to my knowledge, have been reported swimming
something like the breast stroke but I know of no reported incident of
an infant gorilla swimming or any gorilla swimming back-crawl,
front-crawl, side-stroke, doggy-paddle etc, not to mention diving under
water. Orang-utans and gibbons, note also, do not swim either.

If we remember to keep our comparisons with the hominoidae (in fact
even if we relax it a little to include all the primates), we see that
humans are, in actual reality, far better adapted than any of our
clade. If, on the other hand, we allow our minds to wander 'off topic'
and start making comparisons with other aquatics and semi-aquatics, we
can easily delude ourselves into thinking that humans are really poor
swimmers when compared with some arbitrarily chosen threshold of how
aquatic we think we *should* be, if the AAH were true.

> I'm also not impressed with the so-called adaptations we possess for
> swimming. Our hairlessness is rather incomplete. That shaving can
> marginally improve swimming speed and at least preliminarily there
> doesn't appear to be any relationship between hair *reduction* and
> improved speed indicates that if selection played a part, it did a
real
> lousy job. It also left us with hair atop our heads that, despite
> claims otherwise, drags in the water at the interface of water and
> surface in just about any swim stroke. This interface is actually
> where the bulk of drag occurs. Swimming fully submerged is faster
than
> swimming at the surface.

The fact is that two studies have demonstrated that shaving body hair
either reduces drag and one that is improves speed in water *somehow*
in competitive swimmers. There clearly needs to be more studies into
the quantitative relationship between the amount of hair removed
compared to the body size of the swimmer and the amount of drag
reduction. It remains a clear, falsifiable prediction of the 'Nakedness
for Drag Reduction Hypothesis' that there should be a clear and
unequivocal positive correlation there. The jury's still out on that
though.

The border of the scalp hair generally forms a continual line with the
water line for a typical swimmer. As such it is further evidence in
favour of the nakedness for drag reduction hypothesis.

> I'm not impressed that we're all that
> streamlined, certainly not when compared to the vast majority of
> creatures who depend in part on aquatic foraging.

Oops, slipped back to aquatics/semi-aquatics again. Compared to a
chimpanzee, I'd suggest that we're *very* streamlined.

> If such a case did occur where swim speed was a factor, we'd have to
> have some rather significant (yes, a nebulous term significant, but
> since a host of creatures occasionally have to cross bodies of water
> and show no clear special adaptations analogous to those seen in
> aquatics, it's got to be more than these forays) exposure to the
> selective environment to affect this change.

Drifting time and time again, to comparisons with aquatics/semiaquatics
is an instinct aquasceptics find hard to resist. (It's one of the very
few arguments they have.) But everyone should know that every time they
do so, they are simply grossly misrepresenting the AAH. This is a
tactic of pseudoscientists and creationists.

> But we seem to have at
> least a few physiological signs that we didn't spend such
> considerable time in the water. Somewhat paradoxically, being in the
> water stimulates the kidneys and dehydrates as many a scuba diver
> considering taking a leak in their wetsuit can attest to.

Why is this paradoxical? If you're in fresh water it makes good sense.

> We should consider seriously if there are actual predictions that
> follow from a more aquatic lifestyle, one involving a need to swim.
> Does it predict hairlessness? Not really. While there are hairless
> aquatic mammals, this is not a rule by any stretch. Highly aquatic
> seals, creatures completely dependent on water for their food,
> generally retain fur. Most of the mammalian lineages with swimming
> ability far surpassing our own do indeed retain hair. And there are
> similarly hairless mammals that are not aquatic. Hairlessness is not
> something *predictable* from being "more aquatic" on its own, but
> is rather something used in analogy to a specific subset of highly
> aquatic mammals. It is perhaps consistent with being aquatic, but
this
> is not the same thing as being a predictable outcome from being
> aquatic.

This is a rather facile point. The fact that a majority of
aquatics/semiaquatics have retained (increased, even) their body fur
can be explained, although the explanations are not absolutely simple.

1) Size-bouyancy factors. Small semi-aquatic mammals actually gain
bouyancy from retaining their fur as the hairs trap air close to the
skin. A small naked mammal would have to put on a vast percentage of
fat to gain the same amount of bouyancy. For larger mammals the balance
switches the other way. A human sized mammal is likely to gain more
buoyancy from being that bit fatter than from being very hairy.

2) Moving through abrasive substrates. Clearly having a pelt provides
protection from moving through abrasive substrates. Most semiaquatic
mammals, as they are not bipedal, are unable to avoid significant
abrasion with dense thickets, rocks etc. Aquatic/semiaquatics that do
not often move against abrasive substrates (e.g. cetaceans, sirenians,
hippos) tend to lose their pelts. If human evolution passed through a
late coastal foraging phase or any more open habitats at the water's
edge, as we were already obligate bipeds it is likely that skin
abrasion ceased to be a significant agent of selection too.

3) Thermoregulatory factors. Many semi-aquatic mammals which have pelts
live in temperate zones where having a thick dry coat of fur at night
is of clear adaptive benefit. Humans almost certainly evolved in
coastal equatorial habitats where this simply would not have been the
case.

> Similarly, obligate bipedalism is not a prediction that
> follows from wading, though it may be consistent with it. Without
> cause why a facultative biped would be at a selective disadvantage
over
> an obligate biped when wading and without solid cause why there was
an
> increase in wading in one lineage over the other, it seems again at
> best something that is consistent with, but not predicted by being in
> the water.

It is not so much a question of why an obligate biped would have an
advantage over a facultative biped, but as to which traits of *two*
groups of facultative bipeds are most likely to be selected for in apes
that regularly waded? And, more importantly, would these traits be of
benefit as a preadaptation to facultative bipeds that then started to
move bipedally on the ground too? Indeed, a third question might be:
And could they be such that they actually *preclude* quadrupedalism and
hence act to convert a terrestrial facultative biped into an obligate
one?

> Turning observations of consistency into "predictions"
> is not a mark of science, but of pseudoscience.

Where did I do that? You can criticse me for doing that, if we have
unequivocal evidence that it is no longer a prediction, but then you
shouldn't question the evidence any more. It seems to me that you like
to have it both ways.

> It's also worth
> noting that things that appear far more predictable results of
> aquaticism, webbed appendages and more fusiform torsos, are not seen
in
> our species, things that would better qualify as predictions since
> they're far more universal than hairlessness or bipedality.

Back to arguing against what traits we *should* have if we were as
aquatic as some preconceived notion, as opposed to comparing the traits
we *do* have, compared to apes. This is again a misrepresentation - the
mark of pseudoscience.

Fusiform torsos are the hallmark of true aquatics. No-one has suggested
humans were ever that aquatic. It is a gross misrepresentation to imply
otherwise.

Compared to chimps humans hands have greater webbing between the
digits.
Compared to chimps human feet are shaped more like a paddle.

> Perhaps
> some phylogenetic inertia or constraints imposed by our earlier
history
> as brachiators made this less possible, but nonetheless, it does seem
> peculiar that we have such a hodge-podge of analogies with aquatic
> creatures, most of which are not the most universal traits.

It only seems peculiar if your benchmark is an aquatic/semiaquatic
mammal. If you stay focused and keep comparing us only with other
hominoidae, then it's clear that we're far more aquatic and have the
traits to prove it.

> None of what I'm saying is new. It's nothing I've not voiced in
> some form or another before, but since Algis is fond of saying that
> "aquasceptics" are evasive when it comes to explaining why the fact
> that humans can swim better than chimps isn't a clear sign that
> selection was responsible for it, here it is. Further claims that
> it's being avoided will be treated with appropriate scorn.

You have been evasive on this point, Jason, until your last posting
before this one. Why did you finally answer my question after the tenth
time of prompting you, if you didn't agree?

The individual points you have written here are not new, I agree,
although you have, perhaps for the first time, provided a strong
argument, stitching these points together in an intelligent way.

However even this, the best posting from the best aquasceptic poster on
this newsgroup, falls clearly short of a rebuttal for the AAH.

The way you have to keep changing the subject to aquatics/semiaquatics
is the weakest part of your argument. It's just a misrepresentation.
I've asked you not to do this for years and yet here we are, in 2005,
and it's still a major pillar of your argument.

Take that away and what do we have left?: Merely that a strict
neoDarwinist adaptationist approach doesn't provide all the answers.
Well, maybe it doesn't, but I'm happier now that the AAH ship is now
more clearly recognizable than ever by having the flag of neoDarwinism
visible raised high and that it's been distinctly lowered on the
aquasceptic one. Next to come: the white flag of surrender!

So, unless you dispute the neoDarwinist adaptationist program, I think
we can conclude that the fact that humans swim better than chimps is as
near to proof as one could get that the AAH has been right all along.
So, come on everyone, it's time to move on. Aquasceptics swallow your
pride and accept that a mild form of the AAH (defined here:
http://www.riverapes.com/AAH/AAH_Def_Detail.htm) is basically right.
Then we can finally report back to Joe Public that this matter is now
solved and that progress has finally been made.

Algis Kuliukas

Relevant Pages

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