From: Damien Broderick (thespike@earthlink.net)
Date: Thu Jan 16 2003 - 13:46:22 MST
http://www.theage.com.au/articles/2003/01/16/1042520723454.html
Biologists say they have found what is quite likely to be the first
documented case of "re-evolution", suggesting that nature does indeed offer
second chances - a species can evolve a new characteristic, lose it and then
regain it.
That's a radical idea, because for most of modern times, scientists have
taught that evolution, at least in part, functions on the principle of "use
it or lose it". This is one reason seals no longer have paws, moles see
badly and humans lack heavy fur.
The biologists are challenging that assumption based on its analysis of DNA
from 37 species of the insect order Phasmatodea - commonly known as "walking
sticks" - which showed that they evolved from winged to wingless and back
again. In fact, walking sticks made the shift four times.
The discovery calls into question one of the tenets of evolutionary biology:
that if a species loses a complex characteristic, the gene or genes that
express it will subsequently mutate so much that the function can never be
recovered. [etc]
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