Reflectorites
On Sun, 30 Jul 2000 18:31:18 -0700, Cliff Lundberg wrote:
[...]
>SJ>I have recently received my mark (92% = High Distinction) in my first unit
>>of my Biology degree: "Origins & the Evolution of Life".
CL>Congratulations, I hope you carry through with the program.
Thanks to Cliff. I must say I was surprised at the result!
CL>But
>I wonder about the 8%, the missing answers! That is, I wonder what
>the biological weak points are among those who have read a lot
>in evolution but lack biology degrees. (Like me).
[...]
Despite the `priestly' claims of Chris, et al., to the effect that there is some
mysterious `higher knowledge' of evolution to which only those like him,
who are possessed of the `inner light' (namely atheism/agnosticism), and
which therefore is inaccessible to lesser mortals (namely creationists), there
were no major surprises in evolution (except one-see below).
While there is plenty to learn about *biology* (especially cell and
molecular biology) the evolution is pretty much the same that we all
know. For origin of life we had the primordial soup and the Miller-Urey
experiment. For natural selection we had the peppered moth (but
interestingly the name "peppered moth" was gone, only the pictures
and the story was the same).
But what was *really* interesting was our last Lab. for the unit where we
simulated genetic drift and natural selection.
We divided into groups of four and each group used 60 green and yellow
beads in containers to represent alleles in individuals in a population. We
drew the breads out singly at random to simulate genetic drift while
reducing the population by 5 pairs each generation, i.e. 55, 50, 45 pairs,
and recorded the gene frequency and phenotypic effect.
As the population dropped, the random effect of drift got stronger and it
would be easy to see how some genes could be lost from the population
altogether and others predominate just by random chance.
Then we did the same again but this time we simulated natural selection by
drawing out yellow beads each time, to represent an unfavourable allele.
I intuitively expected that this strong natural selection would easily win
out, but what was *really* surprising was that as the population size
reduced, random drift started to assert itself more strongly than natural
selection. The other groups reported that too. I wrote this up as my answer
and the lecturer told us all that it was right.
So it seems taht Darwin, who by his own admission was mathematically
challenged [like me! :-)], was wrong in his intuition about the power of
natural selection.
Random genetic drift is a major factor to be reckoned with in populations
and it is problematic that natural selection could work consistently over a
long enough time to accomplish any major directional change. But random
drift is even more unlikely to lead to any directional change. This is
probably why the pervasive pattern of the fossil record is stasis and why
there are so few examples of natural selection accomplishing anything.
So if there is no evidence that natural selection could the designing, I
wonder what (or who) did do it? :-)
Steve
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"To the question, "What happens to species when environments change?",
the standard post-Darwinian answer became, "They evolve." Species
become transformed to meet the new conditions-provided, of course, they
are well stocked with the necessary genetic variation on which natural
selection may act to effect suitable evolutionary change. Failing that, the
fate is extinction. Here we have imagination colliding with common sense-
and, worse, with empirical reality. Given the benefit of some 130 years of
post-Darwinian scrutiny of the natural world, it has become abundantly
clear that by far the most common response of species to environmental
change is that they move -they change their locus of existence." (Eldredge
N., "Reinventing Darwin: The Great Evolutionary Debate," Phoenix:
London, 1996, p.64)
Stephen E. Jones | sejones@iinet.net.au | http://www.iinet.net.au/~sejones
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