Hairlessness and sweating - tentative hypothesis

I was looking at this ng to get an idea of the current state of the
aquatic ape hypothesis, having just read Daniel Dennett's suggestion in
"Darwin's Dangerous Idea" that it isn't as obviously wrong as is often
suggested.

I would like to propose an evolutionary explanation for hominid
hairlessness and sweating which does not depend on the geographic
location in which these characteristics evolved.

Both the AAH and the SAH (savannah ape hypothesis) start from the old
fashioned assumption that the environment (in the sense of the totality
of things which exert selective pressure on a species) consists mainly
of the geographic and climatic environment in which the species lives.
This is both wrong in itself, and unhelpful to their arguments because
other mammals have lived on the savannah and in or near the water
without adapting in the ways that hominids are said to have adapted.

The explanation I wish to advance for hominid hairlessness and sweating
is based first on the observation that hominids are highly social
animals and that a major part of their environment is not the sea or
the crocodiles in it, or the savannah and its lions, but the other
hominids in the same social group and in other local groups; and
secondly, that hominids are highly antisocial in the sense of being
given to lethal violence between individuals, families, groups and
tribes.

The hypothesis is this: that hairlessness and sweating evolved because
of the advantage these attributes confer in unarmed fighting between
hominids. A handful of fur makes a great handhold for a hominid enemy.
Once you start to lose the hair the slipperiness provided by sweat
becomes an additional advantage because sweaty hairless human skin.

The hypothesis assumes that early inter-hominid violence would take the
form of no holds barred wrestling. This assumption is borne out by
observation of present day hominids; real bar fights are not the
Queensberry Rules affairs they are in the movies but consist largely of
grappling, biting, gouging and kicking. Jane Goodall's descriptions of
violence among chimpanzees give the same impression of no holds barred
wrestling and routinely speak of victims being pulled, grabbed, lifted
and dragged. It would obviously be crucially helpful to know the extent
to which fur-grabbing featured in these fights.

The advantages conferred by sweating in intra-hominid fighting are well
illustrated by the rules of FILA (Federation Internationale des Luttes
Associes, the governing body for olympic wrestling). Chapter 2, Article
8 e) provides that: "It is forbidden to ... arrive at the mat
perspiring for the beginning of the match *as well as for the second
period*" (their emphasis; and their slight mistranslation of the French
original - *and also for the second period* is more accurate).
Sweatiness confers such an advantage in a wrestling match that the
rules permit no excuse for it - not even that one has just done a round
of olympic wrestling!

The hypothesis proposes a unique environmental cause for hairlessness
in hominids - the cause being the strong probability of being attacked
by other hominids. What makes the effect unique is that the strategies
of hairlessness and sweating are highly effective defences against
attacks by hominid hands with opposeable thumbs. They are useless or
worse than useless against attacks by tooth or claw since hair must
give some, if not much, protection against such attacks. Except for
hominids, no wild mammal has been in a position where it was so
overwhelmingly more likely to be attacked by hominid than non-hominid
predators that it was worth adapting to counter the hominid threat. The
hypothesis therefore satisfactorily establishes why there is no
similarity except on the most superficial level between the
hairlessness of hominids on the one hand and whales, elephants, rhinos
and naked mole rats on the other.

Objections to the hypothesis are 1. that it fails to account for the
persistence of facial and scalp hair both of which provide first class
hand holds for an enemy in a fight. This is a good point to which the
answer must be that pressures of sexual selection have overridden the
advantage which would accrue from beardlessness and baldness.

Objection 2 is that the hypothesis doesn't explain bipedalism, the
descended larynx, subcutaneous fat deposits, face to face copulation or
hominid noses. It isn't meant to. These are completely separate issues
on some or all of which the AAH or indeed the SAH may be absolutely
right.

.

Relevant Pages

  • Re: Hairlessness and sweating - tentative hypothesis
    ... > hairlessness and sweating which does not depend on the geographic ... > without adapting in the ways that hominids are said to have adapted. ... > attacks by hominid hands with opposeable thumbs. ...
    (sci.anthropology.paleo)
  • Re: Hairlessness and sweating - tentative hypothesis
    ... localized hair distributions - why should we be an exception? ... - sweating: requires lots of sodium & water, ... > without adapting in the ways that hominids are said to have adapted. ... > The explanation I wish to advance for hominid hairlessness and sweating ...
    (sci.anthropology.paleo)
  • Re: Sweating hominids
    ... the organism needs a constant ... In such cases the positive value of the other changes may trump any plus or minus benefits of a trait such as sweating. ... If such non-sweating hominids ever evolved, ... The habitats they exploited were too small or too dangerous, or did not provide the right kind of sustenance, or did not have enough stability, or had some other defect. ...
    (sci.anthropology.paleo)
  • Re: Sweating hominids
    ... > Perhaps sweating is the unintended consequence of genetic change ... > elsewhere in the organism. ... If such non-sweating hominids ever ... The habitats ...
    (sci.anthropology.paleo)