Glenn Morton [<glenn.morton@btinternet.com> Sun, 18 Feb 2001 16:41:29
-0000, ASA list V1#2002] quotes Alan R. Rogers, "Order Emerging from
Chaos in Human Evolutionary Genetics," PNAS, 93(2001), 779-780 in
support of his argumentation for a very old humanity (>1 million years).
He continues with other literature, discussing old coalescence data.
Last November [<pruest@dplanet.ch> Thu, 02 Nov 2000 20:30:12 +0100, ASA
list V1#1859], I drew attention to 2 papers showing that coalescence
data are (1) very imprecise and (2) cannot be used to argue for an
equally old origin of the genes concerned. Bergstrom et al., "Recent
origin of HLA-DRB1 alleles and implications for human evolution", Nature
Genetics 18 (1998), 237-42 believe "...that most of the alleles at some
class II loci, such as DRB1 and DPB1, may have a more recent origin
[than previously believed]".
Alan Rogers (in the above paper quoted by Glenn) concludes that the
human genetic data are better interpreted as indicating a recent
population expansion (in the late Pleistocene), rather than natural
selection of advantageous mutations in a large, stable population. He
writes:
"Of the noncoding regions that have been studied to date, all of those
outside of functional genes show evidence of a population expansion, and
so do several of those from introns. Within coding regions, on the other
hand, no such evidence is consistently found... we should take seriously
once again the evidence for an expansion of human population size during
the late Pleistocene... we should take seriously the possibility that
geneticists from the 1930s through the 1960s may have been right after
all about the importance of balancing selection [eliminating deleterious
mutations]."
The Pleistocene dates from 1,640,000 to 10,000 years ago. Thus, "late
Pleistocene" may be pretty recently! By this, I am not implying that
modern humanity does not have any genes older than that. But a sudden,
late Pleistocene expansion of the human species may possibly be
interpreted as the dividing line between pre-Adamites and Adam.
Armin Held and I (PSCF 51 (1999), 231) argued from the Hebrew Genesis
text that Adam was not the first human being, but elected by God for a
specific task, and then, after failing, the representative head of the
fallen race, whereas genuine, created (pre-Adamite) humanity is much
older (our estimate then: by very roughly 100,000 years). We furthermore
indicated that we conclude from Gen.1 that biologically and
psychologically, humans descended from animal ancestors, but that their
becoming human was caused by God creating their spiritual dimension
(after God's image). Of course, science is unable to date this spiritual
event with any certainty.
As an aside to those who emphasize the theological content of Genesis 1,
as over against any historical information: I fully agree that the main
thrust of the text is exclusively theological. But why can't it have any
additional aspects, such as a consistency with real history? Certainly
God can reveal theological truths through fallible human opinions, if he
wants to do so. But he certainly is not incapable of revealing more than
that if he wants to. I don't want to try to press him into a fixed
scheme of "theology-only".
Glenn favors the multiregional origin of modern mankind, which implies
that modern humans descend from old Homo erectus populations in Africa,
Europe, and Asia. Glenn concludes that all forms of Homo back to at
least 2 million years ago were members of the same human species, and
that, therefore, Adam must be dated at least that far back (assuming
Adam was the first human). If the multiregional view is correct (rather
than the recent-out-of-Africa one), then presumably all members of the
genus Homo of a given time belonged to the same species. It doesn't
follow, however, that it was the same species throughout the 2 million
years: H. sapiens might well have been unable to mate with H.erectus,
even if he could have used a time machine. We cannot conclude, either,
that the first (biblically) genuine humans lived >1 million years ago -
and much less so for Adam.
Furthermore, Takahata N., Lee S.H., Satta Y., "Testing multiregionality
of modern human origins", Molecular Biology and Evolution 18 (2001),
172-183 concluded (on the basis of DNA sequence data from 10
X-chromosomal regions, 5 autosomal regions, 1 Y-chromosomal region, and
mitochondrial DNA) that the multiregionality theory is probably wrong.
Peter Ruest <pruest@dplanet.ch>
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