|
|
Re: Lumper or Splitter?
debra mckay (debra.mckay@utoronto.ca)
Tue, 17 Dec 1996 03:43:29 GMT
dbarnes@liv.ac.uk (Dan Barnes) wrote:
>In article <01bbe490$426d3f20$LocalHost@dan-pc>,
>rohinton@collins.prestel.co.uk says...
>>
>>In an attempt to inject some *scientific* discussion into this group lets
>>have some opinions on the following:
>>
>For the sake of time I will answer question 3 now and the others later:
>
>>3. Following on from 1 and 2, do you think that the specimens classified as
>>H. habilis are representative of a single species?
>>
>As luck would have it I have Bernard Wood's paper from Forli 'Homo habilis:
>Variability and its significance'. Within this he states:
>
>'When variation within the regions and timebands is considered the most
>parsimonious conclusion is that while there is apprently only one early Homo
>taxon at Olduvai, there are multiple taxa in the Koobi Fora sample' [p. 42]
>
>'...the hypodigm from Koobi Fora most probably samples more than one, and
>probably two, species of early Homo not counting H. ergaster. The same data
>suggest that these two taxa are marginally more likely to be synchronic than
>time succesive' [p. 42]
>
>He then goes on to conclude that:
>
>'The identity of the second early Homo taxon at Koobi Fora is a more complex
>problem' After discounting the possibility of it being placed with ergaster he
>says 'The cranium KNM-ER 1470 has already been proposed as the type
>specimen of a new species, H. rudolfensis, by Aleveev (1986). If H. rudolfensis
>is a 'good' species, and it seems to be in that it was promulgated correctly with
>respect to the ICZN, then the second early Homo taxon at Koobi Fora is H.
>rudolfensis Alexeev, 1986.' [p. 43]
>
>He also sees nothing within the postcrania to contradict this conclusion.
>
>Although early hominids are not my field I would tend to agree with Wood up to
>this point. However, I am unsure about the concluding statement:
>
>'Taken overall, these results suggest that species which are shown to be closely
>related in cladistic studies are not always functionally eqivalent. This, in turn,
>implies that if the clades are an accurate reflection of phylogenetic history, then
>there is as much variation in functional adaptation within clades as there is
>between them. It also calls into question the wisdom of continuing to include
>either Homo habilis or Homo rudolfensis within the genus Homo' [p. 45]
>
>I hope this has given everyone something to chew on.
>
> Dan
>
As far as I know, the only people who *don't* think _H. habilis senso lato_ is more
than one species are Tobias and Johanson. Beyond them, the main disagreement
seems to be just which fossils go into which taxa: Rightmire, for instance,
assigns them rather differently than Wood does. The hypodigm outside of ER 1470
and 1813 is fragmentary and confusing, and it's easy to disagree on what the
informative features are.
I'm a little confused by the last paragraph, myself. Is he somehow suggesting
that there shouldn't be "variation in functional adaptation" within clades?
I didn't know that was a criterion, but then I'm still on the learning curve
wrt this cladistics stuff....
Deb
|