[ExI] Is Evolution more random mutation than adaptation?
pharos at gmail.com
Wed May 6 09:47:15 UTC 2015
A Surprise for Evolution in Giant Tree of Life
Researchers build the world's largest evolutionary tree and conclude
that species arise because of chance mutations -- not natural
By: Emily Singer May 5, 2015
Honeycreepers, small birds inhabiting the Hawaiian Islands, have a
rich assortment of beak shapes. Some species have long, thin beaks
suited to plucking insects from leaves. Others possess thick beaks
good for cracking open tough seeds. According to the classic view of
evolution, natural selection drove the development of these different
species. Each variant adapted to suit a different ecological niche.
But Blair Hedges, a biologist at Temple University in Philadelphia,
has proposed a provocative alternative: Adaptation had little to do
with it. It was simply a matter of chance and time.
Hedges contends that speciation and adaptation are two distinct
processes, each proceeding along its own path. (A team led by Mark
Pagel, an evolutionary biologist at the University of Reading in
England, has made a similar proposal, though for different reasons.)
According to Hedges' model, after about 2 million years the two groups
of birds accrued so many random genetic differences that they became
incompatible. It wasn't adaptive mutations that made it impossible for
the birds to intermingle, but rather the accumulation of enough
mutations overall, most of them neutral ones. Geographic isolation
provided the necessary spark for speciation, but simple time drove the
process to its conclusion.
Needless to say, this proposal has caused much controversy and discussion. ;)
But just looking at the design of the human body, it is very difficult
to believe that every function is the result of adaptation producing
the best of all possible worlds. More like random kludges that were
'good enough'. That's why transhumanists can see so many ways that the
human design can be improved.
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