News: Natural Selection May Not Produce The Best Organisms.

Natural Selection May Not Produce The Best Organisms

http://www.sciencedaily.com/releases/2008/07/080717201837.htm

ScienceDaily (July 17, 2008) ? "Survival of the fittest" is the catch
phrase of evolution by natural selection. While natural selection
favors the most fit organisms around, evolutionary biologists have
long wondered whether this leads to the best possible organisms in the
long run.

A team of researchers at The University of Texas at Austin, led by
Drs. Matthew Cowperthwaite and Lauren Ancel Meyers, has developed a
new theory, which suggests that life may not always be optimal.

Genetic mutations create the raw material that natural selection acts
upon. The short-term fate of a mutation is often quite clear.
Mutations that make organisms more fit tend to persist through
generations, while harmful mutations tend to die off with the
organisms that possess them. The long-term consequences of mutations,
however, are not well understood by evolutionary biologists. The
researchers have shown that what may be good in the short run, may
hinder evolution in the long run.

The team developed computer models of RNA molecules evolving by
mutation and natural selection. RNA molecules, which are very similar
to DNA, play key roles in essential life processes and serve as the
genetic material for some of our deadliest viruses, including
influenza and HIV.

Their computer models show that the evolution of optimal organisms
often requires a long sequence of interacting mutations, each arising
by chance and surviving natural selection. As Cowperthwaite explains,
"Some traits are easy to evolve -- formed by many different
combinations of mutations. Others are hard to evolve -- made from an
unlikely genetic recipe. Evolution gives us the easy ones, even when
they are not the best."

The group's analysis of RNA molecules from a wide variety of species
suggests that life is indeed dominated by the "easy" traits, perhaps
at the expense of the best ones.

--
Bob.

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