"Robert Karl Stonjek"  wrote 

> But
> Haile-Selassie and his collaborators suggest that the teeth of these
> specimens indicate that they are very similar to A. kadabba. On the
> basis of the available evidence, they contend, all three may belong to
> the same genus or even species.
> 
> A contrary view comes from David R. Begun of the University of Toronto,
> who counters that the A. kadabba, Sahelanthropus and Orrorin dentitions
> differ in important ways. "Rather than a single lineage, the late
> Miocene [hominid] fossil record may sample an adaptive radiation, from a
> source either in Eurasia or yet undiscovered in Africa, the first of
> several radiations during the course of human evolution," 

The base of the cladistics tree of human evolution is 
always going to be/appear bushy.  This is a direct 
consequence of the fact that human evolution began when 
our chimpanzee-like ancestors began to settle down into 
relatively separate and geographically isolated 
communities which itself was a direct result of the 
onset of the dry season of the monsoon habitat, which 
began about 8 mya.  This geographic isolation dictated 
reduction in gene flow which shows up in the fossil 
record as higher degrees of morphological variation 
between members of the same species, similar to what we 
see with respect to different breeds of dogs.  And just 
as we don't consider the morpholgical differences between 
a great dane and a miniature terrier to be indicative of 
them being members of different species we should not 
consider the differences between different early hominid 
fossils to be indicative of different species.

Jim
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