I don't understand, Ken, because yesterday you were
indicating you wanted a human in the Oval Office.
Which is it?
--- Kenny H [EMAIL PROTECTED] wrote:
Chimps More Evolved Than Humans
http://tinyurl.com/2m6qaa
Jeanna Bryner
LiveScience Staff Writer
LiveScience.com Tue Apr 17, 11:10 AM ET
Since the human-chimp split about 6 million years
ago, chimpanzee
genes can be said to have evolved more than human
genes, a new study
suggests.
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The results, detailed online this week in the
Proceedings of the large
brains, cognitive abilities and bi-pedalism.
Jianzhi Zhang of the University of Michigan and his
colleagues
analyzed strings of DNA from nearly 14,000
protein-coding genes shared
by chimps and humans. They looked for differences
gene by gene and
whether they caused changes in the generated
proteins.
Genes act as instructions that organisms use to make
proteins and thus
are integral to carrying out biological functions,
such as
transporting oxygen to the body's cells. Different
versions of the
same gene are called alleles.
Changes in DNA that affect the making of proteins
are considered
functional changes, while silent changes do not
affect the proteins.
If we see an excess of functional changes (compared
to silent
changes) the inference is these functional changes
occurred because
they were positively selected, because they were
useful in some way to
the organism, said study team member Margaret
Bakewell, also of UM.
Bakewell, Zhang and a colleague found that
substantially more genes in
chimps evolved in ways that were beneficial than was
the case with
human genes.
The results could be due to the fact that over the
long term humans
have had a smaller effective population size
compared with chimps.
Although there are now many more humans than
chimps, in the past,
human populations were much smaller, and may have
been fragmented into
even smaller groups, Bakewell told LiveScience. So
random events
would play a more dominant role than natural
selection in humans.
Here is why: Under the process of natural selection,
gene variants
that are beneficial get selected for and become more
common in a
population over time. But genetic drift, a random
process in which
chance decides which alleles survive, also occurs.
In smaller
populations, a fortuitous break for one or two
alleles can have a
disproportionately greater impact on the overall
genes of that
population compared with a larger one.
Chance events could also explain why the scientists
found more gene
variants that were either neutral and had no
functional impact or
negative changes that are involved in diseases.
There is still much to learn, the scientists say,
about human and
chimp evolution. There are possibly a lot of
differences between
human and chimps that we don't know about, [perhaps]
because there are
differences in chimps that nobody has studied; a lot
of studies tend
to focus on humans, Bakewell said.
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