Just ran across a fascinating story on Prodigy. For those of you who want
more detail, check the Jan. 15 issue of _Science_ magazine. The original
2-page article may be found there.
--Liz
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Copied from the Science News section of the Prodigy service, without
permission:
Oldest Americans Descend From Small Band
The first people to arrive in North America may have included as few as
4 closely related women who came across the Siberian land bridge 21,000-
42,000 years ago, says research by Emory U geneticist Douglas Wallace.
The earliest anthropological, rather than genetic, evidence puts the
first humans on the continent about 12,000 years ago, says Science magazine.
Wallace and his team tracked the mitochondrial DNA (mtDNA) of 547 native
Americans from 24 tribes from Alaska to Argentina. His findings were
surprising.
All full-blooded native Americans carry 1 of 4 different rare variations
of the mtDNA that is also found in Asians. These variations are not found
in Europeans or Africans, says Wallace. This means that all native Americans
are descended from a small group of Asian "founding mothers," each of whom
carried 1 of the 4 mutant mtDNA variants.
MtDNA is passed along solely by the mother to offspring and does not
undergo the shuffling and mixing that can obscure the evolutionary trail
of other nuclear genes.
The mtDNA mutates more rapidly than the bulk of cell DNA and provides
more points for genetic comparison.
Relayed by Liz Pollard
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Elizabeth Pollard Bitnet: uahebp01@uahvax1
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