Re: Speciation - how do you know?

Paul Crowley (
Thu, 17 Oct 96 22:26:16 GMT

In article <543i23$> "Gerrit Hanenburg" writes:

> (Paul Crowley) wrote:
> >In general, we should be able to assume that both late and early
> >hominids exploited shellfish.
> >If they were doing it 100kya, why not 5 mya?
> It's not that they *couldn't* have done it but we simply have no
> indication *that* they did it. There is no australopithecine
> equivalent of Grotta dei Moscerini.

Apologies for another go, but I didn't get it right last time.

Suppose we have a "chrono-species" of crocodile, or bovid or
bird or whatever, which shows striking and unique morphological
adaptations maintained over 5 Myr or so, and also shows a
distinct dentition indicating an adaptation to a specialised
diet. Now let's suppose that the fossil record tells us little
about the reasons for the speciation of the clade or about its
niche or diet; but the record demonstrates that later forms
consumed food Resource X.

Surely it's perverse to say that _there_is_no_evidence_ that the
earlier forms of the chrono-species consumed food Resource X ?

Surely we must conclude, in the absence of evidence to the
contrary, (1) that the whole clade probably consumed Resource X
and (2) that an adaptation to a niche involving the consumption
of Resource X was a probable cause of the original speciation?