Re: Punctuated Equilibrium Theory

Robin Hanson (
Thu, 24 Sep 1998 09:31:43 -0700

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 RWJF Health Policy Scholar, Sch. of Public Health 510-643-1884 140 Warren Hall, UC Berkeley, CA 94720-7360 FAX: 510-643-8614