The Extended Phenotype
I know, I know--many of you probably breezed through the work. But I'm largely self-taught from having read Gould, and this stuff is new to me. In addition, the question of the definition of "adaptation" is a complex one, and until recently I was still unclear about the difference between genetic drift and natural selection. There is a lot that I never learned at all.
Gould was my guide while I was young, the only atheist I knew (until a niece "came out;" several others since have) in a Christian, and largely creationist, environment. I owe much to Gould's and Sagan's writing, but it is Dawkins who requires patience of me. Compared to my journey through The Extended Phenotype I practically inhaled The Selfish Gene, and that book required re-readings as well.
So far, here is what I have absorbed (Dr. Dawkins, if you're reading this, jump in at any time and correct me!):
-There is survival value in the "packaging of life into discrete units" called "vehicles" or organisms.
-We can speak of "adaptations as being 'for the benefit of' something, but that something is best not seen as the individual organism" but the "active, germ-line replicator" which are not selected directly, but by proxy.
-A behavior pattern "can be treated like an anatomical organ."
-A species or "group" is not the unit of selection, and gene selectionism is not genetic determinism.
Regarding the defining of what constitutes an adaptation, Dawkins first takes on the concept of extreme adapationism and identifies three proposed constrants on "perfection" (or optimal function) that he finds less persuasive:
-Neutral mutations, which are changes in polypeptide structure having no effect on enzymatic activity of the protein, and thus having no phenotypic effect at all.
(Biochemical controversy: Do all gene substitutions have phenotypic effects?)
(Adaptationist controversy: Is this phenothypic effect the result of natural selection?)
Though it is possible to a phenotypic effect to be selectively neutral, beware human subjectivity in these judgements. Genetic drift plus natural selection may result in more optimal function than just the effects of natural selection alone.
-Allometry, which is the disproportionate growth of a characteristic (such as a large head in small humans and in large ants).
-Pleiotropy, which is the possession by one gene of more than one phenotypic effect.
Damn, but this is fun. I used to read about quantum mechanics for fun; this stuff is even better. The only thing that spoils it is the fact that I have so many books to get through before September, because I buy books the way most women buy clothes, and because grad school! is practically barking! down! my snorkel! and I won't have time for pleasurable reading, hanging around archaeological sites, or the writing of the continuing adventures of my anti-creationist female android.
TO BE CONTINUED...