Re: An alternative to ST and AAT
Gerrit Hanenburg (G.Hanenburg@inter.nl.net)
Mon, 18 Nov 1996 09:24:06 GMT
pnich@digiworldinc.com (Phil Nicholls) wrote:
>>Lucy did have long arms. The A. afarensis humerus was about the
>>same length as in both H.s.s. and chimps. But the humero-femoral
>>index is misleading as the difference in arm length comes from the
>>ulna; and the male A.afarensis ulna is almost the length of the
>>male chimp's -- much longer than in H.s.s.
>Well now that is very interesting. I would like to know where you
>got your information. Everything I have read about postcranial
>morphology of A. afarensis indicates that there is only one good ulna
>from the plio-pleistocene -- one from the Omo basin associated with
>Paranthropus boisei. Everything else is too fragmentary.
There is a complete A.afarensis ulna from Hadar (AL 438-1a),presumed
male,and there are two fairly complete humeri,AL 137-50 from Hadar and
MAK-VP-1/3 from Maka.
The ulna is 268 mm and the AL 137-50 humerus is estimated to be 295
mm. This gives an ulna/humerus index of ~91% which is closer to the
chimpanzee mean of 95% (range 88-101%) than to the human mean of 80%
(range 74-88%). The same index for AL 288-1 is ~92.5%.
If it is true that relative humerus length in A.afarensis was similar
to modern humans then this means the forearm was relatively long. By
implication this means that total arm length was longer than in modern
humans.
See White,T.D.et al.(1994). The first skull and other new discoveries
of Australopithecus afarensis at Hadar, Ethiopia. Nature 368:449-451.
Gerrit
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