Darwin-L Message Log 7:62 (March 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.

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<7:62>From LANGDON@GANDLF.UINDY.EDU  Fri Mar 18 08:18:53 1994

Date: Fri, 18 Mar 1994 08:18:53 -0600
From: "JOHN LANGDON"  <LANGDON@GANDLF.UINDY.EDU>
To: darwin-l@ukanaix.cc.ukans.edu
Subject: Re: Time article

In message <Pine.3.87.9403171520.A7368-0100000@husc8.harvard.edu>  writes:

> The date makes ABSOLUTELY NO DIFFERENCE WHATSOEVER as far as the African
> vs multiple origin debate goes.

I disagree; the new date pushes the debate slightly in favor of a later African
origin for modern humans. I say this because I feel that the debate has come
down to a shouting match in which the determining factor for each scholar is
his/her gut feelings about which model seems more compatible with his/her
understandings of evolutionary processes. (I expect future evidence to change
this.) In this context, a 1.8 Myr date for Java is significant.

Under the previous consensus (0.8 Myr in Java), the differences between the
earliest African and eastern/southeastern Asian forms of H. erectus could be
readily explained as chronological differences and all were comfortably lumped
into the same species. Some researchers, to be sure, expressed discomfort about
lumping. If, however, African and Asian forms are really contemporaries, there
is less room in the taxon for the observed variation and there is less time
depth for the origin of a recognizable Homo erectus that could then have spread
across the Old World. The possibility that African forms are not erectus is
increased and the chance of maintaining genetic contact for 1.6 Myr instead of
6 Myr is less. This is not conclusive, but I feel that it undermines the notion
of multiregional speciation through gene flow.

> 	It puzzles me greatly as to why _Time_ chose to make such a big
> noise about it. I'm afraid it's a sort of tabloid stunt.

Many other interesting questions arise from the new date. When did hominids
leave Africa? The 2.0 Myr faunal date from 'Ubeidiya in Israel suddenly looks
more plausible. What species first left Africa? Instead of erectus, we are now
forced to consider something more along the lines of ergaster or habilis. We
now have a  new missing link between the early African Homo and Asian erectus.
I think the question of where in Africa Homo arose is more open than ever. The
Rift Valley dates now seem too recent. Very likely the focus on the Rift Valley
has been only an artifact of sampling.

> 	Of course the Chinese 200ky "H.s." skull is mixed up in all this
> but it's never made clear that this skull looks like erectus with a big
> brain -not like you and me and the African _H.s.s._ fossils.

I agree with this criticism. I think it got into the Time article because it
also was a recent development involving human evolution and for no other
reason. I don't think it carries the same weight as the Java date.

JOHN H. LANGDON                email   LANGDON@GANDLF.UINDY.EDU
DEPARTMENT OF BIOLOGY          FAX  (317) 788-3569
UNIVERSITY OF INDIANAPOLIS     PHONE (317) 788-3447
INDIANAPOLIS, IN 46227

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