Re: Hairlessness and sweating - tentative hypothesis

Robert, why construct far-fetched just-so "explanations" whereas simply
applying what we know on other mammals to humans would suffice?
Homo c 1.8 Ma had dispersed between Algeria in the West (Ain Hanech) & Java
in the East (Mojokerto). Every thing we know suggests this diaspora went
along the coasts (how else??). Now:
- furless: middle-sized tropical semi-aquatic mammals are furless, but have
localized hair distributions (babirusa) - why should we be an exception?
- sweating: requires lots of sodium & water, and is seen in overheated
furseals on land... - why not in our littoral ancestors?
I think it's time PAs stop treating humans as exceptions among mammals.

Marc Verhaegen

http://allserv.rug.ac.be/~mvaneech/Verhaegen.html

http://www.onelist.com/community/AAT

________




<robertleigh456@xxxxxxxxxxxxx> wrote in message
news:1115759490.555743.119750@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>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)
  • Hairlessness and sweating - tentative hypothesis
    ... without adapting in the ways that hominids are said to have adapted. ... The explanation I wish to advance for hominid hairlessness and sweating ... attacks by hominid hands with opposeable thumbs. ...
    (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)
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