Thursday, 6 August 2015

Group selection and WD Hamilton

WD Hamilton, one of the deepest thinkers on evolutionary theory, himself believed in group selection - this comes up repeatedly throughout his Narrow Roads of Gene Land. And this is a fact which people need to recognize and take seriously.

I was trained-up in the 'group selection does not exist'/ selfish gene school of Dawkins - and the Selfish Gene was a clear explanation of some insights from GC Williams and WD Hamilton. I arrogantly regarded all group selection explanations as naive and superficial - I saw the task of modern evolutionary theory as being to find the true selfish gene mechanisms to explain all apparent instances of group selection.

It was only when I read Hamilton's Narrow Roads, that I began gradually to realize that Dawkins, and mainstream evolutionary theory, has been highly selective and indeed deceptive in its advocacy of Hamilton's work - simply taking what it liked, and rejecting what it didn't.

(This ignoring applies especially to Hamilton's lifelong deep concerns over dysgenic change under modern selective, and not-selective, conditions.)

So belatedly, and much influenced by Michael A Woodley, I came around to acknowledging the validity of group selection - even when we are unsure of its mechanism.

After all, there is a mass of prima facie evidence of group selection! For more than a century, group selection was accepted by everybody (including people much smarter than ourselves) as the obvious explanation for many phenomena.

Why should we always assume that group selection can be, must be, an illusion that should be explained-away by selfish gene mechanisms? There is no good reason.

If we accept the validity of some of Hamilton's selfish gene work, then it is reasonable to accept the validity of his other work in which he used group selection explanations.

Group selection should not be regarded as an explanation of last resort, used only when all possible selfish gene selection explanations have been eliminated - but as a mechanism which is relevant in some situations, and not in others. the proper question to ask is what is the most plausible selective explanation for a given situation under consideration - sometimes this will be a group mechanism, other times not

The task is not to deny group selection, but to discover the mechanisms by which it works - by which adaptive genetic change can result from selection of the group. This is, in microcosm, a version of one of the main problems of evolutionary theory - which is how high level cooperation is maintained in the face of lower level selection mechanisms which tend to dismantle it.

(see The major Transitions of Life by Smith and Szathmary - 1995 - for an account of the multi-level problem - ):

One example is that natural selection within the body tends to produce neoplasms, such as cancers; thereby undoing the adaptations which enable the existence of multicellular organisms with specialized and cooperative cells. It is a problem to understand how multi-cellularity evolved when neoplasms were continually being produced.

That is what is lacking at present - one or more simple, comprehensible physiological and molecular mechanisms that enable group selection. There seem to be inklings of this in the literature, but the whole thing has not yet crystallized.

My hunch is that there is some kind of active/ purposive mechanism or process involved, or more than one such mechanism/ process - which is aimed-at higher organization and cooperation, and which under some circumstances can overcome the well-understood tendency to dis-integration.

This post is adapted from a comment at: