bluegenes writes:
Incidentally, can you think of any characteristics which are at fixation in the phenotype of our own species that could have become so and remained so without the help of selection at some point? Surely, with all this neutral evolution going on, as P.Z. informs us, in small population groups like ours, there must be a long list?
No need to be snide. I've said a few times that non-selective processes aren't mutually exclusive of selection in evolution. The problem comes in when we automatically start speculating about an adaptive history for a trait, and in the process focus so closely on selective scenarios that we lose sight of the context of the organism and population as a whole.
In
Message 46 I described the way Evolutionary Medicine's exclusively adaptationist thinking creates problems in clinical practice: the speculative adaptive history of a condition becomes more important than the treatment of the patient. In a more general sense, adaptationist thinking becomes a method through which to define well-being and normalcy in ways that aren't strictly scientific but can have consequences for the way we view racial and gender differences; the sociocultural context of things like health and diversity gets de-emphasized in favor of more "objective" bases.
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