Re: AAT Theory

Phil Nicholls (
Mon, 25 Sep 1995 04:35:01 GMT

VINCENT@REG.TRIUMF.CA (pete) graced us with the following words:

>J. Moore ( sez:

>`Let's see: humans have big heads and broad shoulders, long legs
>`(which create drag -- that's why aquatic mammals have short limbs);

>well, no. It would take a bit of time to dredge up the references,
>but as I recall, the optimum ratio of length (in the direction of
>motion) to width for travel in a fluid the viscosity of water, is
>about 15 to one. That's why all fast moving aquatic animals are
>the shape they are. Salmon, sharks, crocs, otters, whatever.
>To get that ratio, most of them grow long tails. Lacking tails,
>the next best thing would be long straight legs. Sorry, but if
>we're talking hydrodynamics, homonids have a considerable advantage
>over other primates.

Unfortunately, this only applies to MODERN hominids. Early
australopithecines had limb proportions that are very close to those
observed in some African apes. Arboreal, not aquatic.

Phil Nicholls
"To ask a question you must first know most of the answer"
-Robert Sheckley