Re: Sleeping on the ground
- From: "Paul Crowley" <slkwuoiutiuytciuyik@xxxxxxxxxxxxxxxxx>
- Date: Wed, 13 Jul 2005 18:29:40 +0100
"Jim McGinn" <jimmcginn@xxxxxxxxx> wrote in message
news:1121239778.515741.179010@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> Paul Crowley wrote:
> > At some point in our evolution, our ancestors
> > stopped sleeping in trees. This represented a
> > major change in niche.
>
> Why do you assume this?
I don't assume this. I stated the reasons for
proposing it. To restate: Unlike their chimp-
like ancestors, ground-sleeping hominids
could live in places where there were no
available (or suitable) 'sleeping-trees'.
Numerous other factors (such as the ability
to retain tools and weapons) allowed for the
occupation of an entirely different niche.
> > Sleeping on the ground brought in sets of new
> > and entirely different problems. Firstly, the
> > hominid territory had to be effectively free of
> > nocturnal predators.
>
> Why do you, once again, assume this?
I don't assume this. I stated the reasons for
proposing it. Ground-sleeping hominids,
especially young hominids, would not be
able to resist nocturnal predators -- if any
were in proximity of their sleeping site.
> Hominids on the ground
> > at night, especially hominid young, are
> > extremely vulnerable. The initial hominid
> > population must have evolved in a predator-
> > free location (probably an island). Later, once
> > they began to exploit typical mainland locations,
> > one of the principal functions of hominid adult
> > males would have been to keep their territory
> > clear of predators by constant patrolling, and
> > then killing or harassing any they located.
>
> What about this scenario is distinctive from the lifestyle of apes?
Everything.
> Let's keep in mind that we're supposedly looking for a hypothesis that
> explains the selective factors that underly the *differences* between
> hominids and apes.
I've set it out.
> > Sleeping on the ground would have made the
> > sexual dominance by an alpha-male of a harem
> > impossible.
>
> Okay, Paul. You just put your big foot into your big mouth. There are
> hundreds of examples of terrestrial (non arboreal) (and not aquatic for
> that matter) mammals of similar size that maintain harems domnated by
> alpha males.
Are there? Can you name any, apart from
horses? Also (unlike chimps and hominids)
nearly all mammals are male-exogamous, where
females allow certain males to join their band,
giving the females a much greater say
generally.
> So where do you get off declaring it to have been
> impossible?
Non-primate mammals do not have colour-
vision. Nor do they generally sleep at
night (i.e. they are almost entirely nocturnal).
They have long (i.e. over about 200 million
years) been adapted to moving around at
night, and using other senses, especially
smell, to detect and keep track of other
animals, of their own species and others.
If necessary, they can shepherd those
members of their harem (which are in heat)
into locations where they not approachable
by other males.
Alpha-males often have a problem making
sure that they are the only ones to mate
with their females-on-heat. Chimps achieve
it (substantially) by watching during the
day and sleeping below them at night. The
problems for an alpha-male hominid would
usually be too great, for such a system to
work.
> However,
> > females and their young would have been
> > vulnerable in the dark to attack by stranger
> > males, as well as in danger from other hazards,
> > such as smaller predators like jackals (on
> > babies). Monogamy would have come in at
> > this point, partly to help minimise these
> > problems.
>
> Monogamy minimizes jackal attacks?
The mother would be concerned about
such attacks on her infants, and would
welcome (and often need) the level of
protection available only from a person
with a strong genetic interest in the
survival of the infant.
> > For some strange reasons (probably mostly
> > historical) standard PA fails to recognise the
> > enormity of the changes brought in by the
> > switch to sleeping on the ground.
>
> Nonsense. It's obvious why hominid began sleeping on the ground. The
> earliest hominids were communal/situated. This type of habitation
> greatly reduced night predation simply due to the multiplication of
> eyeballs.
Primate eyeballs (and primate levels of
olfaction) are next-to-useless at night --
against nocturnal predators. But, even
more to the point, primates have no means
of defence at night against such predators.
> And, sure, this might have brought them to more often sleep
> on the ground. But they still used trees to evade predators, nighttime
> or daytime. Especially during the depths of the dry season.
Ridiculous. When did you last sleep in a
tree? When did you last hear of a human
family -- with a baby and other small infants
-- sleeping in a tree?
Like standard PA (which you follow so
much) you are reluctant to face up to the
fact that there was a drastic change in
niche, and that it could only have taken
place when the move was made to the
ground -- i.e. to sleep on it.
> > Defecation (of faeces or urine) by an infant
>
> Useless speculation.
You mean that it's something with
which you don't (or can't) deal?
For you (as for standard PA) infants
don't exist. The species consists
only of adult males.
Paul.
.
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