Mingling key to modern man
Mingling key to modern man
By Robert Lee Hotz
March 7, 2002
Spreading out of Africa like
starlings, early humans conquered the world by embracing the strangers they
encountered around the globe, not by forcing them into extinction, as many
researchers thought, according to a new analysis of human genetic
In the textbook view, the founding fathers of modern humanity
emerged suddenly from Africa about 100,000 years ago and swept into oblivion all
other prehuman species -- Neanderthals, for example -- that they
A new and elaborate computer genealogy of 11 inherited
traits compiled by Alan Templeton at Washington University in St. Louis today
will present a very different slant on the origins of
Templeton's work, being published today in Nature, suggests
that "interbreeding, not replacement," was the rule for successive waves of
primitive humans migrating out of Africa. By mingling, these ancestral human
groups "strengthened the genetic ties between human populations throughout the
world," said Templeton, who studies the history and geography of
In his view, the ancient world was a vast melting pot in which
tribes of human ancestors scattered, rejoined and scattered again. As they did
so, they intermingled inherited traits across thousands of generations to mix
the palette of modern humanity.
Templeton's work is the latest riposte in
a 20-year-long debate in which anthropologists, archeologists, molecular
biologists and population geneticists have battled over human origins with
rounds of research papers scattered like hand grenades.
specialists in the field enthusiastically hailed the new study of evolutionary
parentage as "brilliant," while others briskly dismissed it as "hocus-pocus" and
For all their differences, both camps agree that the earliest
ancestors of humankind evolved in Africa about 2 million years ago.
Where the scientists part company is in deciding how those ancestral
groups gave rise to anatomically modern people -- with their small pointed jaws,
smooth foreheads, high rounded skulls and advanced mental
Frustrated by the ambiguous fossil record, researchers have
turned to the genes that code for growth and development to flesh out this
missing chapter of human evolutionary history.
To reach his conclusions,
Templeton combined published data on 11 parts of the human genome. He analyzed
mitochondrial DNA -- genetic material that each person inherits directly from
his or her mother -- as well as data from genes carried on the Y chromosome,
which is inherited only from fathers. He also looked at genes on other
chromosomes that can be inherited from either parent.
analysis detected considerable gene mixing and evidence of two separate waves of
migration out of Africa into Asia and Europe -- the first between 420,000 and
840,000 years ago and a more recent one between 80,000 and 150,000 years
Robert Lee Hotz writes for the Los Angeles Times, a Tribune Co.
Copyright © 2002, South Florida
Copyright © 2001, South Florida Sun-Sentinel