Re: Why is Homo sapiens hairless?

Newington Reference Library (fp96@dial.pipex.com)
Thu, 31 Oct 1996 15:07:42 +0000

John Waters wrote:
>
> Rohinton Collins <rohinton@collins.prestel.co.uk> wrote in
> article <01bbc6a7$0c67fc00$LocalHost@dan-pc>...
> >
> > > When a baby is carried in its mothers arms, there is a
> > > change in its effective surface to mass ratio.
>
> > Relative to what? To the baby floating in mid air?
> Certainly not to a baby
> > lying on the floor.
>
> JW: Relative to a baby hanging on to its mother in the way
> that ape infants hang on to their mothers. In the case of
> ape species, the young infant generally hangs underneath
> its mother when being transported. Air can circulate right
> round the infant's body, which allows its body heat to be
> transmitted to the outside air.
> >
> > Ever heard of thermoregulation? Anyway, the fur would
> insulate the baby.
>
> JW: Fur has very little insulation value per se. It is the
> air trapped in the fur which provides the insulation. When
> a baby hominid was carried in its mother's arms the fur
> would be flattened, thus losing most of its insular
> qualities. Theroregulation would have been limited because
> early hominids would have been unlikely to have had any
> more sweat glands than present ape species.
> >
> > > the
> > > core temperature continues to rise the baby could die
> of
> > > heat-stroke. Fact.
> >
> > Fact? Again, ever heard of thermoregulation?
>
> JW: Even today, babies left in unventilated cars have died
> of heatstroke in hot summers. Remember, early hominids
> lived in hot semi-equatorial conditions.
> >
> >
> > What 'areas' of the female body' ? Again, fact? As far as
> I was aware, the
> > only areas where *extra* or *additional* subcutaneous fat
> is laid down in
> > female humans is on the hips, bottom and thigh.
>
> JW: Yes, plus the breasts. In other words, where the baby
> comes into direct contact with the mother when carried in
> her arms, (normal when the baby is very young). Older
> infants are carried on the mothers hips, where they come
> into contact with the waist, bottom and thigh. Well done
> Roh, you're getting there.
> >
> >>
> > > The subcutaneous fat of the female leads to
> evolutionary
> > > pressure for less body hair in the female. This is the
> > > present
> > > situation. Fact.
> >
> > Just quit saying 'fact' will you? There is absolutely no
> flow of logic in
> > your last statement.
>
> JW: Sorry about the facts Roh. Perhaps I am wrong about
> this one. According to my information, females generally
> have less body hair than males. It seems to me perfectly
> logical to equate this lack of body hair to the fact that
> females have 12 to 15 percent more subcutanous fat than
> males.
>
> >
> > > In Chimpanzee and Gorilla species, the juveniles stay
> with
> > > their
> > > mother and share her nest until adolescence. After
> > > maturity, the
> > > young males are driven out by the alpha male. Fact.
> >
> > Untrue. Chimpanzees enjoy a multi-male polygynous social
> structure where
> > the males are related to each other.
>
> JW: I think you have misunderstood my meaning. I know all
> about female exogamy, but that is not the point I was
> trying to make here. What I was trying to say is that the
> juvenile males can share family nests with their mother.
> This happens with both Gorilla and Chimpanzee species.
> After puberty, the males do not share the family nest with
> their mother. Young males are also low ranking, and are
> kept away from the females by the Alpha males.
>
> In many hunter gatherer tribes the young males are
> similarly prevented from sharing living quarters with the
> females. In this sense, there is a parallel situation. As
> they cannot gain warmth from close contact, this could
> explain why the young males grow body hair after puberty. I
> accept this is pure speculation, but it seems a reasonable
> proposition.
>
> John.