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Re: Speciation - how do you know?
J E Hawcroft (J.E.Hawcroft@shef.ac.uk)
Tue, 10 Sep 1996 16:02:18 +0100
Susan S. Chin wrote:
> : In paleoanthropology, how do researchers determine that one creature
> : is not the same species as another? Am I correct in my understanding
> : that the question is still open vis-a-vis modern humans and
> : Neanderthals? Is it pretty much accepted that Homo Erectus was a
> : separate species?
>
> : Tim Edwards - interested lay-person
Just to add my tuppence-worth, what normally happens in
palaeoanthropology is that the fossils that are found are so few and so
far between in terms of time that no-one really has a problem with new
finds being assigned as a new species, unless they are very close in
morphology, time and space to a known species. But to be technical about
it, recently people have used cladistics to demonstrate speciation. (This
is basically using a science-based program to underscore what is
actually obvious to the naked eye. Computer programs such as PAUP
(Phylogenetic Analysis Using Parsimony) are used. You enter the
morphological characteristics of a whole bunch of fossils and the
computer churns out a family tree based on who shares what characteristic
with whom.) In cladistics, a species is defined by having at least one
characteristic that is unique to itself. Therefore if you find one fossil
that has a feature no other fossil has, you've got a whole new species.
Of course this method doesn't take into account the possibility of
pathological deformities.
Not every palaeoanth person likes cladistics, it has a lot of problems
relating to the real world. But if you're asking about protocol for
talking about species in palaeoanthropology, cladistics is it. See
Bilsborough's "Human Evolution", 1992, first chapter, for a good
explanation.
Jennie
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