Re: Bipedalism and theorizing... was Re: Morgan and creationists

John Waters (
Sun, 28 Jul 1996 04:54:13 +0100 (HARRY R. ERWIN) wrote:

>And completely untestable without much better material than we have. I
>suspect body hair reduction occured with the emergence of H. erectus.

Gerrit wrote:

>That's what I suspect too,assuming that the reduction of bodyhair is
>related to thermoregulation and given the skeletal features that seem
>to indicate adaptation to deal with heatstress (high radial and crural
>indices,small bi-iliac breadth)
>It may even have occured in Homo rudolfensis but the association of
>cranial and postcranial material in this species is quite uncertain.

Have you considered a possible relationship between the evolution of
bipedalism and a reduction in the growth rate of body hair? Consider
also other effects of thermoregulation e.g. increased number of sweat
glands, the moulting of fetal hair, increased salt levels in the blood.
Think about surface to volume ratios. A baby carried in its mother's
arms experiences an apparent change in its surface to volume ratio. It
still produces heat at the same metabolic rate, but the amount of its
skin which is exposed to the air is reduced by as much as thirty
percent. Imagine the effect of the baby hominid's body temperature when
carried in its mother's arms for any distance. Imagine the long term
evolutionary consequences of this behaviour.

John Waters