Friday, September 27, 2013

The Aquatic Ape Hypothesis and the 'Wet Look'

An Aquatic Ape
An Aquatic Ape
I think the strongest 'circumstantial evidence' supporting a partial form of the (controversial) aquatic ape hypothesis* is something I don't think I've seen mentioned before: The simple fact that we find wet Homo sapiens sexually attractive. If you think about it, doesn't it seem a bit arbitrary? E.g. would gorillas find other wet gorillas sexy, or would rats find other wet rats sexy? How universal is this?

If we consider the concept of sexual choice** in evolution, then if our ancestors were once partially evolving "in that direction", then we might expect that they may have felt a mate choice preference for the entailed characteristics of a hypothetical "aquatic ape" (such as the 'wet look', as well as finding smooth, hairless skin comparatively more attractive, as we do).

To consider this argument, look at a picture like the one above (or thisthisthisthis, or this) ... then (for men now) tell me you don't perceive any vestigial sense whatsoever that our genes might have picked up some disposition toward aquatic-ape-like qualities somewhere along the way.

If you were a rat, would you find this sexy?
(Image credit: Rheaver)
This idea is comparable to how a peahen 'feels attracted' to peacocks with large tails - and crucially, the sense of attraction itself could even hypothetically have been a primary driver for such an evolutionary direction even in the absence of any external selection pressures - i.e. simply because our ancestors "liked it", and expressed that preference through mate choice.

The 'evidence' then might be retained within our 'genetically programmed' sexual choice preferences (i.e. 'finding wet humans sexy') - a kind of 'genetic leftover' handed down from a time when the relevant hypothetical evolutionary selection pressures peaked.

Another Aquatic Ape?
If the aquatic ape hypothesis had any truth to it, men would probably find images like this appealing.

Speculatively, one could imagine plausible scenarios in which the sense of attraction could have predated, and thus "caused", the evolutionary direction, particularly if characteristics of the look represented 'proxy characteristics' of qualities that might well have implied survival advantages in real terms - e.g. being near water = being near food sources - thus genes conferring mere predilections to 'being near water' could enhance survival even if indirect. The former could exist 'side by side' with conventional selection criteria, e.g. fish in our diet possibly conferring actual survival advantages or possibly carrying us through other evolutionary bottlenecks, though this wouldn't strictly be necessary - all that would be required is an increased likelihood of reproduction for those exhibiting characteristics that a hypothetical 'aquatic ape' might.

A female Homo sapiens that appears to exhibit characteristics that one might expect to be hypothetically indicative of evolutionary selection of an aquatic primate.
Of course this is all speculative, and more 'circumstantial' than strictly 'scientific'.

* This article assumes some familiarity with the the aquatic ape hypothesis, but in brief, it is the idea that humans might once have partially evolved in the direction of either becoming aquatic, or acquiring some 'aquatic qualities' for living in or near water. Of course, we have never been entirely aquatic, such a claim would be silly.
** See this book for a good introduction to the core idea of sexual choice as it might apply to humans; in brief though, the idea is that "advanced" human qualities such as appreciation of music might have evolved not necessarily primarily as a result of specific survival advantages 'per se', but rather, because our ancestors might have been (through their mate choices) essentially 'active agents' in selecting these criteria for their offspring in mates, i.e. by finding such qualities attractive (in a very loose sense, "designers" of their own offspring).


  1. "Men find wet young women sexually very attractive" looks like an excellent pro AAT argument to me, but I have no idea whether women find wet men more attractive. In any case, biologically, the "littoral" or "coastal dispersal" theory (better terms than "aquatic ape") is a lot more realistic than the usual plans running models (eg, running kudus to exhaustion...). Pleistocene Homo apparently spread along the coasts (possibly during the glacials over the then exposed continental shelves) & from there inland along the rivers as far as Java, Flores, China, the Cape, Angola & England. For recent insights in this theory, google, eg, "econiche Homo", "Laden misunderstandings Verhaegen" or "Vaneechoutte Rhys Evans". --marc verhaegen

  2. FYI, Human Evolution soon publishes the proceedings of the symposium on human waterside evolution ‘Human Evolution: Past, Present & Future’ in London 8-10 May 2013:
    SPECIAL EDITION PART 1 (end 2013)
    Introduction - Peter Rhys-Evans
    1. Human's Association with Water Bodies: the ‘Exaggerated Diving Reflex’ and its Relationship with the Evolutionary Allometry of Human Pelvic and Brain Sizes - Stephen Oppenheimer
    2. Human Ecological Breadth: Why Neither Savanna nor Aquatic Hypotheses can Hold Water - JH Langdon
    3. Endurance Running versus Underwater Foraging: an Anatomical and Palaeoecological Perspective - Stephen Munro
    4. Wading Hypotheses of the Origin of Human Bipedalism - Algis Kuliukas
    5. The Aquatic Ape Evolves: Common Misconceptions and Unproven Assumptions about the So-Called Aquatic Ape Hypothesis - Marc Verhaegen
    6. The Epigenetic Emergence of Culture at the Coastline: Interaction of Genes, Nutrition, Environment and Demography - CL Broadhurst & Michael Crawford
    SPECIAL EDITION PART 2 (begin 2014) with 12 contributions

  3. I read in the book "The Passionate Ape" by Craig Hagstrom, that human brain cells are fattier than chimpanzee brain cells, and that this enabled heads to float more easily. Brain size was limited by pelvic aperture, so there was a limit. Human babies are much fatter than chimp babies, and have much more subcutaneous fat. Human babies can float on water immediately after birth on their own, unlike all our nearest related ape cousins. AAT must therefore have some irrefutable validity.