Re: An alternative to ST and AAT
Gerrit Hanenburg (G.Hanenburg@inter.nl.net)
Sun, 17 Nov 1996 12:42:58 GMT
"John Waters" <jdwaters@dircon.co.uk> wrote:
>The part of the Australopithicene anatomy which is most
>likely to make them less efficient is the heel.
That doesn't seem to be case. The calcaneus of A.afarensis had already
developed the primary adaptive alterations to bipedality that are also
seen in humans. These include:an inflated posterior corpus,a discrete
lateral plantar process,and a specialized geometry and orientation of
the posterior articular surface. (Latimer,B.and Lovejoy,C.O.(1989),The
calcaneus of Australopithecus afarensis and its implications for the
evolution of bipedality. American Journal of Physical Antropology
78:369-386)
>Modern humans gain their bipedal efficiency from the ligaments of
>the lower leg which attach to the ankle via the achilles
>tendon.
It is the muscle group composed of M.soleus and M.gastrocnemius that
inserts via the achilles tendon into the posterior calcaneus.
Contraction of these muscles causes plantar flexion of the foot in
which the calcaneal tuber functions as a lever arm and the talar body
as a fulcrum. The morphology of the australopithecine calcaneus does
not indicate that this was much different in A.afarensis.
Gerrit
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