Re: Who Killed the Australopithecines?
HARRY R. ERWIN (herwin@osf1.gmu.edu)
2 Apr 1995 19:23:50 GMT
BARD (bard@netcom.com) wrote:
: In article <3lkim9$dmb@portal.gmu.edu>,
: HARRY R. ERWIN <herwin@osf1.gmu.edu> wrote:
: >Re: BARD's comments.
: >
: Re: Erwin's Comments
: Yeah, but, H. habilis minus H. erectus, equals A. species plus or
: minus an error factor of .05 MY.
: Get it?
No.
H. habilis appears to be descended from some subspecies at the base of the
robustus radiation. It showed an encephalization quotient about the same
as the low end of the erectus group and higher than that seen in the
Australopithecines. It shared a general landscape with A. boisei. It did
have a number of characteristics in common with the Australopithecines,
including faculative bipedalism, sexual dimorphism, and tree-climbing
adapations. It evolved into erectus via an intermediate stage that appears
to have been developing obligate bipedalism in response to a shift to a
hot treeless environment. The earliest erectus groups were specifically
adapted to that environment in much the same way the Turkana peoples are
today (tall and thin--great basketball players). Early erectus seems
fairly close to modern groups in gross behavior and anatomy except for the
brain, which had very weak frontal lobe development and no evidence for
speech and related adaptations. Apparently the move into the treeless
environment also triggered the development of the modern-style pair bond.
H. erectus infants had a sapiens-style period of extreme maternal
dependence.
The overall pattern is a beautiful example of patchy evolution.
: BARD
:
--
Harry Erwin
Internet: herwin@gmu.edu
Doctoral student in computational neuroscience
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