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Where did the Australopithecines come from?
Ludvig Mrtberg (lugmog95@student.umu.se)
Mon, 05 Aug 1996 13:50:16 GMT
The accepted answer to that question is that Australopithecines shared a common
ancestor with the Chimpanzee 5-8 MYA. The real answer is that we don't know. But
we can guess. What is the best guess with the information available? I came
across a passage in a book on physical anthropology that I think gives part of
the answer. Or at least an opening to learn more:
PALEOECOLOGY OF SIVAPITHECUS Of course, what everyone
would like to know about Sivapithecus is: To whom is it related? We
have just taken our best shot at that difficult question. Another
fascinating research effort involves recontructing the way of life
of this early hominoid and speculating upon factors that influenced
its evolution.
For example, what were these ramapiths eating? By referring to
certain structural/functional analogs seen in modern primates,
investigators have postulated a diet that correlates with ramapith
dental structure. This diet is thougt to chiefly include tough hard
morsels, such as seeds, which some belive were exploited primarily
on the ground (Jolly, 1970).
A more comprehensive comparison of a wide variety of living
primates, however, reveals ramapith dental parallells (especially
larger, flat-wearing, more thickly enameled molars) among several
arboreal species eating nuts, seeds, and hard fruit found in the
trees (Kay, 1981). Thus, ramapith dental features quite possibly
could have originated in an arboreal setting. Most researchers
attempting to reconstruct the paleoecology of the ramapiths,
however, assume that, eventually, ramapiths did take greater
advantage of terrestrial environments than their dryopith cousins.
Evidence from Eurasian sites (Potwar Plateau, Lufeng, Rudabnya)
suggest that ramapiths lived in evironments exhibiting greater
seasonality than the tropics (where most dryopiths lived).
Consequently, fruits would not have been available all year long,
and ramapiths could not have been primarily frugivorous (i.e.,
fruit-eaters) (Andrews 1983).
Moreover, within these environments, there was less continous
forest vegatation, with more woodland/bushland mosaic niches. These
changes were further stimulated by a general cooling of the earth's
climarte, after about 16 m.y.a. (see p. 247). Such a niche, being
ecologically poor is no place to find a primate. It is
hypothesized, therefore, that ramapiths may have been environmental
"opportunists", analogous to bears and pigs, exploiting
below-ground resources, such as roots and tubers.
Utilization of nonarboreal resources would, of course, require
some ground-living. Ramapiths are generally larger-bodied than
dryopiths, a fact which could argue for greater terrestriality. Of
course, body size varied greatly (some individuals may have
exceeded 150 pounds) largely as a result of marked sexual dimophism
(Andrews, 1983).
[from Understanding Physical Anthropology and Archeology by Robert Jurman, Harry
Nelson and William A. Turnbaugh, pages 255-257]
They were definately on the road to Australopithecus. "ground-living",
"environmental "opportunists"", "take greater advantage of terrestrial
environments" and so on. The feeding on seeds is in line with "Zinj".
This is where we stand today. How can we move on? More fossils? What if we don't
find anything more? Is this as good as it is going to get?
One thing that could and should be done is to go through all the miocene
ramapith/sivapith fossils from Greece to Pakistan to China and see if the
picture can be enhanced. But who will dare to do this when every
paleoanthropologist belives that we diverged from chimps 5 MYA?
Perhaps we will never find the missing link. Maybee it will always be an
abstract reconstruction in the mind of scientists. Or is there a fossil out
there somewhere - the missing link? Something between Sivapithecus and
Australopithecus?
Ludvig Mrtberg
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