Re: Ping Rumple

On Sat, 19 Sep 2009 12:47:11 -0700, Rita <Rita@xxxxxxxxxxx> wrote:

In a post in reply to Emily about eugenics -- improving the
gene pool -- I cited Darwin and natural selection:

Another argument against is that
eugenic policies could also lead to loss of genetic diversity, in
which case a culturally accepted improvement of the gene pool could
very likely, as evidenced in numerous instances in isolated island
populations (e.g. the Dodo, Raphus cucullatus, of Mauritius) result in
extinction due to increased vulnerability to disease, reduced ability
to adapt to environmental change and other factors both known and
unknown. A long-term species-wide eugenics plan might lead to a
scenario similar to this because the elimination of traits deemed
undesirable would reduce genetic diversity by definition.


The cheetah is in danger because there's so little
diversity in its DNA. There's a lot of concern about
the lack of genetic diversity in, for example,
commercial wheat, since a plague organism could
rapidly devastate all the grain since all would be
equally affected, and there would be no varieties
that might have greater resistance and thereby
provide a basis for a grain more resistant to that
plague.

A "Eugenics plan" sounds very dangerous to me,
though life is dangerous anyway, for individuals and
for whole species. We humans don't know what
we're doing. As is well known, trying to protect
children against everything produces adults who
are not hardened to weather subsequent viral and
bacterial attacks in adulthood. As to mankind's
wisdom and expertise, Voltaire noted that "The course
of rivers to the sea is not so swift as the course of
man into error", and Burns of course wrote:

Now mousie, thou are no thy lane
In finding forethought might be vain.
The best-laid plans o' mice and men
Gang aft agley,
And leave us nought but grief and pain
For promised joy.

Humans had a bottleneck, it's now thought -
about 150,000 years ago. Homo sapiens is about
200,000 years old. The modern theory (opposed to
Darwin's gradualism) is that Homo sapiens arose as
a result of rapid speciation ("punctuated equilibrium")
and hasn't changed much since. According to the
site below, humanity might have been down to just
2000 people at that time. If we'd gone extinct, we
wouldn't have evolved again. Perhaps something
from another hominid line would have mutated into
a large-brained species like ourselves, or perhaps
something else would, or perhaps it wouldn't
happen at all for the foreseeable future.

Dawkins once, expressing (to my satisfaction)
his belief in the fundamentally chaotic nature of
evolution which I share, wrote approximately "If I
could go back in time to the age of the dinosaurs
and tell the second dinosaur on the left to take
three steps to the side, the human race would
never have evolved." The chaotic view of
nature is poetically expressed as a butterfly that
flits across a garden in Japan, and as a result of
that, a great storm ravages England a hundred
years later. The opposing view is that most
things average out, so England would be
exactly the same in a hundred years whether
that butterfly made its flight or not. (I don't know
how people who hold that view justify it,
because it seems insupportable to me.)

Here's a National Geographic article on the
human bottleneck:
http://tinyurl.com/6yagb4





And it is genetic diversity that natural selection makes use of. To
understand this argument you have to understand the current
version of Darwinian theory. Too complex to state it simply
here.

Could you expound on this -- I know you can do a far better job than
I can.

.

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