Re: AAT:A method to falsify

pete (VINCENT@REG.TRIUMF.CA)
5 Oct 1995 20:26:27 GMT

Phillip Bigelow (n8010095@cc.wwu.edu) sez:

[...]

` The question to ask is: "Is it even physiologically possible for a small,
`hairless hominid to be a ubiquitous-wader/occassional-swimmer, and not have
`problems with hypothermia?"
` A year or so ago, I posted a summary of body masses for all
`hairless-water-bound mammals (ie., the hippo and the entire group Cetacea),
`and found that the hairless-aquatic group was STRONGLY weighted numerically
`toward animals that were 250 pounds. The Bell-shaped curve also tapered off
`slowly toward higher-mass animals, but it tapered off SHARPLY toward
`low-mass animals.
` I recall that the smallest cetaceans were slightly less-massive than a
`chimpanzee, but these cetaceans have very low surface-area/volume ratios.
`Chimpanzees, humans and the purported "aquatic ape", if it were Lucy-size or
`smaller, would have much greater surface-area/volume ratios.
` A good test for some future researcher would be
` to predict how small a hairless hominid can get, and not
` be limited by thermodynamics.
`If even a FAT hairless primate of Lucy's mass could not be habitually a
`wader/swimmer without suffering from hypothermic effects (even in warm
`water), then the whole theory is essentially demolished.
`I predict the key to dismantling the theory will be surface-are/volume
`ratios, heat-retention, and metabolism.

This will not really resolve anything, except to put some limit on
the duration of excursions into the water. In warm tropical climate,
temperature can be easily regulated by shifting in and out of
the water. Even the marine iguanas use this strategy. They spend
no more than 20 minutes or so in the ocean, coming out quite
thermally depressed - they're quite small, after all - and then
lie more or less stunned on the rocks until the sun warms them to
the point where they can function again. This same tactic, though
obviously without the same extremes of temperature, is how most
humans cope with thermal loss in water.

In temperate climates, ocean water rarely gets to 18C, except on
the surface in sheltered areas. But generations of young children
(the size of adult hominid ancestors) have enjoyed full days at the
beach, spending at least 50% of their time in ~15C water, by
alternating periods of submersion with periods baking on the
rocks, where the temperature will be ~30C. Further note, that
this degree of aquatic activity is sufficient to qualify for
aquatic specialization, cf those iguanas.

--

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    vincent@triumf.ca   <== faster       %    Pete Vincent

    vincent@freenet.vancouver.bc.ca      % Disclaimer: all I know I

                                         % learned from reading Usenet.