Re: Homo erectus

HARRY R. ERWIN (herwin@osf1.gmu.edu)
7 Jul 1995 13:30:52 GMT

Alex Duncan (aduncan@mail.utexas.edu) wrote:
: In article <herwin-2906952204200001@192.0.2.1> Harry Erwin,
: herwin@gmu.edu writes:
: >Probably, although the KBS tuff is at 1.88 MYr, and there's some
: >post-cranial stuff below it that may be H. erectus.

: Since we aren't sure what the postcrania associated w/ the various
: habiline species looks like, it would be premature to assume that
: postcrania older than 1.88 Myr necessarily belongs to H. erectus. It may
: be that the larger habiline taxon had a more modern postcranial skeleton
: that would be difficult to distinguish from H. erectus. Yes, the stuff
: MAY BE H. erectus, but I won't be satisfied until it is associated w/
: cranial or dental remains.

Alex, I think I agree. My database seems to indicate that the
habilis/erectus transition involved three or four major feature sets:
1. A change in diet, with a remodeling of the masticatory apparatus,
2. A change in sexual biology, with less differentiation between male
and female roles and less sexual dimorphism,
3. Loss of arboreal adaptations and gain of adaptations for the open
savannah, with concomitant size increase, particularly in females, and
4. Some cranial remodeling and brain size increase, _but not a change in EQ_.

Features 2, 3 and 4 seem to be inter-related, so that the emergence of
feature 3 probably created selective gradients on features 2 and 4.
Feature 1 seems somewhat independent and later. I believe even H. habilis
was an exploiter of patchy resources, and these changes simply carried the
pattern further.

1470 appears to be evolved in this direction (feature 4 and perhaps
elements of feature 3), and 15000 appears to be a good example of the
character set that eventually emerged. The time range of H. habilis is
about 2.4 to 1.5 MYr and that of H. erectus starts at 1.5 MYr. 1470 is
dated to 1.89 MYr. That suggests we will not find H. erectus predating
1470 by much, and that we will find two stages for the evolution of H.
erectus--a period of large-jawed, primarily vegetarian open-savanna
dwellers with relatively modern social behavior that evolved during
2.0-1.75 MYr BP, and a further period of mostly behavioral evolution
(1.75-1.5 MYr BP) that led to a small-jawed H. erectus that had moved
further up the food chain to exploit higher quality but even patchier food
sources.

BTW, I suspect H. erectus could talk, but had not developed symbolic
communication (which seems to be very late in emerging in H. sapiens).
Complex vocal communication would have been adaptive in the exploitation
of patchy resources.

--

Harry Erwin

Internet: herwin@gmu.edu 

Home Page: http://osf1.gmu.edu/~herwin (try a couple of times)

PhD student in comp neurosci: "Glitches happen" & "Meaning is emotional"