NEANDERTHAL: NO RELATION
By Sean Henahan, Access Excellence
Park, Pa. (10 July 1997) New evidence from mitochondrial DNA
analyses indicates that the Neanderthal hominid was not related to
Using refined and expensive genetic techniques, U.S. and German researchers
extracted mitochondrial DNA from Neanderthal bone. These studies showed
that the Neanderthal DNA sequence falls outside the normal variation of
"These results indicate that Neandertals did not contribute mitochondrial
DNA to modern humans," says Dr. Mark Stoneking,
associate professor of anthropology at Penn State. "Neandertals are not
The findings will cause of reconsideration of the current consensus
that Neandertals became extinct only 30,000 years ago and co- existed for
some time with modern humans in Europe. The new research indicated
that Neandertals and modern humans diverged genetically 500,000 to 600,000
years ago. While the two species may have lived at the same time, Neandertals
did not contribute genetic material to modern humans, the researchers report.
The team analyzed bone from a Neanderthal specimen found in the eponymous
valley. This is the first time researchers have been able to extract useful
DNA fragments from such a specimen.
"The ability to extract DNA from ancient bone is dependent on many factors,
including preservation, temperature and humidity," says Stoneking, a faculty
member in Penn State's College of the Liberal Arts.
The researchers devised an innovative technique using overlapping short
strands of DNA to obtain a mitochondrial DNA sequence of 378 base pairs.
The researchers ran multiple extractions and amplifications. to ensure
that errors caused by damaged DNA were not incorporated into the sequence
and that modern human DNA did not contaminate the samples. At the same
time the researchers ran a parallel extraction and amplification of the
To begin amplification, the researchers used two human primers -- small
pieces of DNA that match the beginning of the sequence to be amplified.
"The first two human primers we chose worked," says Stoneking. "It turns
out this was a lucky choice."
To check that the amplified DNA was really Neanderthal, the researchers
prepared primers based on their extracted sample and ran them on numerous human DNA samples.
"The Neandertals primers did not amplify any human DNA," says Stoneking.
"Most human primers would probably not work on Neanderthal DNA."
The researchers compared the Neanderthal sequence with 2,051 human sequences
and 59 common chimpanzee sequences. They found that the differences in
Neanderthal DNA occurred at sites where differences usually occur in both
humans and chimps.
"The changes reflect the evolutionary pattern typical of mitochondrial
DNA sequences of living humans and
chimpanzees, not that of random damage or degradation," says Stoneking.
When the researchers looked at the Neanderthal sequence with respect
to 994 human mitochondrial DNA lineages including Africans, Europeans,
Asians, Native Americans, Australians and Pacific Islanders, they found
the number of base pair differences between the Neanderthal sequence and
these groups was 27 or 28 for all groups.
"While Neandertals inhabited the same geographic region as contemporary
Europeans, the observed differences between the Neanderthal sequence and
modern Europeans do not indicate a closer relationship to modern Europeans
than to other contemporary human populations," says Stoneking.
The researchers used phylogenetic tree reconstruction -- a method that
uses mitochondrial DNA to place
individual groups in relative relationship -- to check the results
of their pair- wise DNA comparisons. The trees
show that the Neanderthal sequence branches before the divergence of
the various human mitochondrial DNA
lineages, but after the split from chimpanzees.
This phylogenetic tree also shows that the first three branches of humans
are of African origin, with only the fourth branch showing non-African
"The branching pattern indicates that the ancestor of the mitochondrial
DNA gene pool of contemporary humans lived in Africa," says Stoneking of
"I really looked for holes in the methodology, but I just couldn't find
any. It seems to be an authentic sequence and certainly as far as I can
tell the most rigorous ancient DNA study I've ever seen," says evolutionary
biologist and ancient DNA researcher Blair Hedges of Penn State.
The researchers caution that the current results are derived from only
one individual and note that DNA may be difficult to extract from other
specimens. Even if theNeanderthals did not contribute mitochondrial
DNA to modern humans, it is still possible that they contributed other
genes, they emphasize.
The research appears in the June 11, 1997 issue of Cell.
Related information on the Internet
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