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News: Scientists find big differences in Y chromosomes of men, chimps.

Von: Ye Old One (usenet@mcsuk.net) [Profil]
Datum: 14.01.2010 13:07
Message-ID: <o52uk5trsr06rso9mu3d1ibv5crrlpclqa@4ax.com>
Newsgroup: uk.singles
Scientists find big differences in Y chromosomes of men, chimps

http://blogs.usatoday.com/sciencefair/2010/01/scientists-find-big-differe
nces-in-y-chromosomes-of-men-chimps.html


Couples, not male harems, are a story of human evolution, suggests a
Wednesday study of the male chromosome.

Male children result from a father's male sperm carrying a "Y"
chromosome, resulting in the "XY" chromosome pairs that trigger
masculinity in offspring. In the journal Nature, a team headed by
David Page of the Whitehead Institute in Cambridge, Mass., compared
the male chromosome in men and chimps and finds "that they differ
radically in sequence structure and gene content, indicating rapid
evolution during the past 6 million years." In particular they find
the chimp Y chromosome is "considerably smaller and simpler than that
of the human."

Rather than shrinking over time, as some earlier studies suggested,
the human male chromosome seems to have been adding and deleting genes
regularly, according to the study. Chimps however, have been losing
chromosome genes not directly related to mating.  Many male apes mate
with one female in the species, leading to evolutionary success only
for those whose sperm out-impregnates others, a process called "sperm
competition" in evolutionary biology.  The human male chromosome, in
contrast, shows no evidence of such competition, according to the
study.

"Their findings, in essence, represent a tour de force of comparative
genomics," says bioscientist William Murphy of Texas A&M University in
College Station, who was not part of the study. "They convincingly
show that the evolution of long standing Y chromosomes is far more
dynamic than any other part of a genome, and that Y chromosomes are
constantly being reshaped," he says by email. The male chromosome is
the "most notoriously difficult region of any genome to study," Murphy
adds.

Overall, the chimpanzee male chromosome contains "only two-thirds as
many distinct genes or gene families as the human," says the study.
While the human and chimp gene maps differ in their entirety by less
than 1%, implying they shared a common ancestor around 6 million years
ago, the difference in human and chimp male chromosome genes "is more
comparable to the difference in autosomal gene content in chicken and
human, at 310 million years of separation," concludes the study.

By Dan Vergano

--
Bob.

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