Re: longevity
Sun, 21 Nov 1999 16:16:12 EST

In a message dated 11/20/99 8:06:51 PM Pacific Standard Time, writes:

> Yes, I can see that. I still wonder if evolution can select for shorter life

> spans in a particular population (not necessarily an entire species) via
> speeding up the process of adaptation: shorter generations equals more
> experiments to run, and hence greater probability of solving problems
> by a changing environment. If so, this would yield an advantage to a
> population over a long-lived one.

It can, it's just that any individual advantages will overwhelm the group advantage.
Roughly, a group allele benefits only with the frequency of groups going extinct. An individual allele benefits with the frequency of individuals dying. Obviously the latter is far more common, so the selection to improve individual fitness is typically orders of magnitude larger than group fitness.

There's an experimental problem in that the power of group selection is generally lower than the lowest effects on individual selection we can detect. So we can't say that individual selection on any particular real trait or allele is low enough for group selection to go.