From: Robin Hanson (hanson@econ.berkeley.edu)
Date: Thu Sep 24 1998 - 10:31:43 MDT
Curt Adams writes:
>> The bottom line is that this paper *assumes* punctuated equilibrium,
>> and so is not evidence in favor of it.
>
>Not exactly. The paper provides a theoretical model for adaptation, which
>predicts punctuated equilibrium when adaptive changes to new situations
>is involved. The evidence is not from the paper, but from previous results
>on quantitative genetic traits which indicate the effects of genes causing
>differences between species follow an exponential distribution. ...
Agreed. But just as with other observations of self-scaling phenomena,
it is important to note how many order of magnitude it has been observed
over. There was a recent critique of this in Science, I think, saying
the vast majority of such observations had hardly even looked at one
order of magnitude.
Granting that there is some variation in the rate at which environments
change, the question is: how much variation is that? If it is just one
order of magnitude on average, then yes the puntuated equilibrium hypothesis
is correct in some some sense, but the "small changes dominate" evolution
view is also correct. It's just that "small" varies by an order of magnitude,
sometimes tiny and sometimes very tiny. If environment rate changes vary
by ten orders of magnitude, on the other hand, then maybe it's a new world.
I'd have to go look up those QTL data papers to see how many orders of
magnitude their data varies over. But I'm not optimistic - Orr brags that
one of the data sets covers 82 traits, which isn't even enough to see a
half an order of magnitude.
Robin Hanson
hanson@econ.berkeley.edu http://hanson.berkeley.edu/
RWJF Health Policy Scholar, Sch. of Public Health 510-643-1884
140 Warren Hall, UC Berkeley, CA 94720-7360 FAX: 510-643-8614
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