On Tue, 2 Jul 2002, Chuck Grimes wrote:
>
> This isn't true, Chuck. It is very easy for non-adaptive or even
> anti-adaptive traits to survive, because it isn't this trait or that
> trait that survives, but whole complex bundles of traits. Gould's
> hypothetical example is a brain trait that had adaptive use for a
> paleozoic fish, has survived ever since in various lineages through
> periods in which it had _no_ effect, adaptive or non-adaptive, and
> _now_, under modern condtions, has suddenly become destructive.
>
> Carrol
>
Here's a good example of this from Lewontin: the human chin. Why does it exist? Feeble-minded sociobiologists jump to the idea that it must have some adaptive uses; otherwise, why would we have chins? However, the chin is more or less an accident of the adaptive shortening and lengthening of various facial bones at varying rates. The upshot, as Carrol stresses: characteristics of organisms are not necessary "adaptive" in any practical sense, even if natural selection does occur.
Interesting how this links up with the levels of abstraction thread...
Miles