Re: Punctuated Equilibrium Theory

Robin Hanson (
Mon, 28 Sep 1998 10:25:30 -0700

Curt Adams writes:
>>And even for genes which do "follow the exponential model", the
>>crucial question is "over how many orders of magnitude"?
>Wouldn't you say that if the exponential model fits for the important
>changes during speciation, it's not really relevant whether it fits
>minor changes? After all, had the minor changes not happened you'd
>still have two distinct species; but had the ones modeled by the expo-
>nential model not happened, the species would be indistinguishable.

I'll grant that this is plausible.

On reflection, it seems to me that even if most of the big change genes are fixed at speciation, and even if most of the fitness variance is explained by these, its still not clear that most of the biological innovation happens at speciation. Speciation may mostly allow previous potential to be realized by relaxing modularity constraints. Within the larger species, a variation must be ready to work with most of the genes out there. In the new small species, gene combinations can get rewarded for working together, even if they each work poorly with other possible genes. Between speciation, the big species collects lots of possible genes, and combinations of these are tried in new small groups to see if some combination is a winner.

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