31 July 2009

Is the aquatic ape hypothesis fringe science?

I admire today’s TED talk by Elaine Morgan as a great presentation, but I have reservations...



Morgan promotes the “aquatic ape” hypothesis. This suggests that the many anatomical features that distinguish humans from chimpanzees and bonobos were due to humans being aquatic at some point in their evolutionary past. It is not a loopy idea by any means, and is quite an interesting explanation.

Unfortunately, some of Morgan’s claims of why this hypothesis hasn’t got traction are very close to the sort of rationalizations that all manners of denialists use. Rather than admitting there are any weaknesses in the evidence, she instead chalks up resistance of the hypothesis to vague and shadowy forces of vested interests: “academia” and “paradigms”. She doesn’t call it a conspiracy; Morgan is clearly too sophisticated for that. (And I don’t mean that in a derogatory “Oh, she thinks there’s a conspiracy but just doesn’t use the word” way; I think her view is more smart and subtle than most wacky conspiracy “theories.”)

In that sense, yeah, I think the aquatic ape hypothesis is fringe science. Sorry, Elaine.

Human paleontology is its own very specialized field, so I make no claims of expertise here, but it seems to me that what is missing from the aquatic ape hypothesis is that it hasn’t been able to generate predictions. Pretty much every piece of evidence advanced for an aquatic past is, “Here is a distinctive anatomical feature that we already know about, and it makes sense if we had an aquatic past.” In other words, it’s always retrospective and ad hoc evidence – another warning sign.

One logical prediction to me would seem to be, “If we had an aquatic past, then we should routinely find hominid fossils associated with ancient lakes, rivers, and other water bodies.” To the best of my knowledge, that hasn’t been the case. When the aquatic ape hypothesis starts making useful testable predictions, it’ll move into the mainstream.

Additional: After writing this, I found AquaticApe.org, which indicates much the same thing. I admit confirmation bias may be playing a role here, though.

3 comments:

AK said...

IMO another big problem with the aquatic ape hypothesis is that none of the "explanations" are really any better than the alternatives, one by one or all in a group.

On that subject, are you familiar with Dr. Aaron G. Filler's "Upright Ape" hypothesis? The suggestion that the ancestral Great ape already walked upright, with the brachiating adaptations of Orangs and Chimpanzees/gorrillas being secondary? This does make testable predictions, including that we should be able to find fossil offshoots of our lineage with signs of upright posture going all the way back (to the branching point perhaps 20MYA).

I suspect that by hindsight, a decade from now, Filler's hypothesis won't turn out to be "fringe science".

w said...

Zen said:
One logical prediction to me would seem to be, “If we had an aquatic past, then we should routinely find hominid fossils associated with ancient lakes, rivers, and other water bodies.” To the best of my knowledge, that hasn’t been the case.

Actually, that is exactly the case. Pretty much ALL of the hominids fossils found in Africa are found associated with river or lake environments. Lucy, for one, was found associated with turtle eggs, alligators and other aquatic animals. The thing is, a wet environment is very favorable for making fossils in the first place. The savannah doesn't preserve fossils - bones get scattered and eaten. Rainforests don't preserve fossils well. I think they are too acidic. Rivers, lakes, bogs, perfect. Bones get buried quickly in sediment. So the question is: are all the fossils found in places were there was lots of water because that's the only ones preserved or because that's were the creatures were always hanging out? Impossible to say. But as I say, we definately routinely find hominid fossils associated with ancient lakes and rivers. By homo erectus time, cut marks on bones of river animals like hippos and crocodiles become common.

Marc Verhaegen said...

Humans didn’t descend from aquatic apes, of course, although our ancestors were too slow & heavy for regular running over open plains as some anthropologists still believe. Instead, Pleistocene Homo populations simply followed the coasts & rivers in Africa & Eurasia (800,000 years ago, they even reached Flores more than 18 km overseas), google “econiche Homo”.
–eBook “Was Man more aquatic in the past?” introd.Phillip Tobias
http://www.benthamscience.com/ebooks/9781608052448/index.htm
–guest post at Greg Laden’s blog
http://scienceblogs.com/gregladen/2013/01/30/common-misconceptions-and-unproven-assumptions-about-the-aquatic-ape-theory