Re: newb question

saraband <darwin886@xxxxxxxx> wrote or quoted:

> I don't have a background in science so please go easy on me. I would
> like to know if there is a set of criteria that have been generally accepted
> as indicators that a given behavioral trait in humans is vestigial.

Vestigal traits should have had a function in the past - a relative
which has retained the function is probably the best evidence there.

Vestigal traits should not be much use to their owners. That's hard
to show - unless you can compare organisms with and without the trait
in their natural environment for long periods of time - perhaps
*very* long periods of time.

If a trait has been vestigal for very long, it can tend to be subject
to drift - and become quite variable.

Vestigal traits should not be side effects or consequences of other
adaptations or developmental processes. E.g. belly-buttons are
pretty useless - and quite variable - but even if they had once
had some functon, they would not really be vestigal.

I think that's about it. The several of these "indicators" can be
difficult to demonstrate - so determining whether an apparently-useless
trait really is vestigal can be tricky.
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