Re: In Lice, Clues to Human Origin and Attire


"Paul Crowley" <slkwuoiutiuytciuyik@xxxxxxxxxxxxxxxxx> wrote in message
news:dHaIh.18475$j7.368786@xxxxxxxxxxxxxxxxx
"pete" <vincent@xxxxxxxxxxxxxxx> wrote in message
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on Thu, 08 Mar 2007 17:57:45 GMT, Roger Bagula <rlbagula@xxxxxxxxxxxxx>
sez:

Lots of great stuff here. Hairless by 3Mya, clothes by 110kya.

But WOW!!! One of the few times we get ANY kind of dating of a soft tissue
event... I think this is a beautiful bit of science and hope to see it
"repeated" and perfected. WOW! I am loving it... hope the rest of you
folks on sap like it too...
Also of major interest is the possibility that we became hairless right
after the apith fossils. This is causing me a bit of head scratching,
because I "previously" believed that hairlessness (or relative lack of hair
growth, if you will) could be very recent in our species... less than 200
kya for example... like the clothing estimate....
--chap


The obvious criticism is the inconsistency of suggesting the
ur-species divided into two 13Mya in order to specialize in
different parts of the body on a fully hirsute ape, yet
claiming that acquisition of the pubic louse demonstrates
isolation of the pubic hair from the rest of the body hair
due to a mostly hairless body. Why not say that gorilla
separated from pan/homo at 13Mya and the lice speciated
as a result? I guess it conflicts with molecular estimates
of the gorilla divergence.

These 'divergence dates' estimated from DNA
have to be taken with more than a pinch or
two of salt. There is also a certain amount
of nonsense in the speculation.

||> Probing back even earlier in louse evolution, Dr. Reed and his
||> colleagues report that the two species of primate lice, Pediculus and
||> Phthirus, probably diverged from each other on an ape host 13 million
||> years ago. The divergence may have happened after the lice started to
||> specialize in different parts of the body.

This is crazy, in that a fully-furred animal
will not have room for two species of louse.
One will drive out the other.

||> Some seven million years ago, this ancient ape species split into
||> gorillas and the ancestors of humans and chimps, with both lineages
||> infected by both species of lice. But Pediculus then fell extinct in
its
||> gorilla hosts, according to Dr. Reed's reconstruction, and Phthirus
||> vanished from the chimp-human ancestor.

It is more likely that (working with the
divergence dates we are given) between
13 mya and 7 mya one of the louse species
(probably Pediculus) lived on some isolated
hominoid population -- not unlike modern
bonobos, or modern mountain gorillas.
When that merged back into the parent
species (or was wiped out by the parent
species) its louse found itself able to out-
compete that of the parent species.

...I guess I'll buy the clothes argument a lot more readily than the
hairlessness argument.

Human hairlessness is such a distinctive,
and peculiarly limiting characteristic that
it clearly dates back to the origin of the
taxon -- around 6 mya.

||> Next, chimps and humans
||> diverged, and their joint louse diverged with them into Pediculus
||> humanus and Pediculus schaeffi.
||>
||> The last event in this history of human-louse cohabitation was the
||> transfer of the gorilla's Phthirus louse to people.

The 'head louse' would be better described
as a 'child louse' -- it proliferates among
children as they bring their heads together.
Adults don't usually do that -- or do so to
a much lesser extent. Children don't, of
course, have pubic hair and when the
head louse happens to infest adults, it has
no good reason to find its way to such
locations.

The 'pubic louse' is an 'adult louse'.
It found an unexploited niche.


Paul.





.

Relevant Pages

  • Re: In Lice, Clues to Human Origin and Attire
    ... if you will) could be very recent in our species... ... of the gorilla divergence. ... The divergence may have happened after the lice started ... will not have room for two species of louse. ...
    (sci.anthropology.paleo)
  • Re: In Lice, Clues to Human Origin and Attire
    ... if you will) could be very recent in our species... ... of the gorilla divergence. ... The divergence may have happened after the lice started to ... will not have room for two species of louse. ...
    (sci.anthropology.paleo)
  • Re: In Lice, Clues to Human Origin and Attire
    ... These 'divergence dates' estimated from DNA ... will not have room for two species of louse. ... But Pediculus then fell extinct in its ...
    (sci.anthropology.paleo)
  • Re: In Lice, Clues to Human Origin and Attire
    ... In Lice, Clues to Human Origin and Attire ... louse, right, and the gorilla louse, left, diverged 3.3 million years ago. ... The divergence may have happened after the lice started to ...
    (sci.anthropology.paleo)