Re: Why is Homo sapiens hairless?

Susan S. Chin (susansf@netcom.com)
Thu, 14 Nov 1996 08:29:59 GMT

: In article <susansfE0qpt3.6M7@netcom.com>
: susansf@netcom.com "Susan S. Chin" writes:

: > . . Once this bipedal ape was out in the
: > open, not necessarily a savannah, but not a covered arboreal setting
: > either, the need for heat loss was such that selection favored loss of
: > hair which apes living in forrested environments still have. Makes sense
: > to me...

Paul Crowley (Paul@crowleyp.demon.co.uk) wrote:
: why should the need for heat loss be so compelling?
Most people would agree that humans sweat more while exposed to the sun
than while doing similiar activities in the shade. A primate aboreal
ancestry isn't disputed by most. Hominids are the exception of the
Hominoids (Great Apes and Hominids) in having left the covered arboreal
environment. This hair loss, to repeat from above, was *gradual* over the
entire prehistory (possibly since I wasn't there) of the hominid lineage.
I'm not saying I think this is what happened. But makes more sense to me
than most other explanations.

: What was waddling little Lucy doing that needed such energy?
Well if you insist on calling Lucy a waddler, maybe she needed the extra
energy to sustain life other than her own? There is no evidence for this
of course, but I'd feel better calling her a waddler if it were the case.
There is no functional anatomical reason for A.afarensis to waddle. And the
Laetoli footprints proves this.

And some more questions:

: Why is it retained on the head?

I believe Roh answered that in his post better than I could. I might add,
though there are exceptions, hair on the head also serves to protect the
organ(s) underneath the head. The brain, spinal column, arteries and
veins in the head. (and no, I don't know why some males of our species
lose theirs, though recently there are studies relating estrogen to this).

: Why do males have more body hair than females and children?
I'd love to say Testosterone, but that is already being used for another
hypothesis in s.a.p.

: Why do babies have virtually none at all?
Where is this going... that babies have less hair than adults...how does
this relate to the idea above that hair loss is associated with change in
environment over a long period of time in the human lineage? Babies also
have less teeth. Is that significant?

Susan

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                                             susansf@netcom.com