Re: Speciation - how do you know?
Paul Crowley (Paul@crowleyp.demon.co.uk)
Thu, 17 Oct 96 22:26:16 GMT
In article <543i23$gm0@news.utrecht.NL.net>
ghanenbu@inter.nl.net "Gerrit Hanenburg" writes:
> Paul@crowleyp.demon.co.uk (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?
Paul.
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