Savannahs and models

J. Moore (
Thu, 21 Sep 95 18:06:00 -0500

Ad> The savanna theory basically suggested that at some point in our past, a
Ad> chimp-like animal decided to begin living on the savanna, and >>WHAM<<
Ad> became bipedal. The idea has been abandoned for two reasons: 1)
Ad> evidence that the earliest bipeds lived in mosaic habitats, and had
Ad> adaptations that would have allowed them to use all aspects of those
Ad> habitats, and 2) a greater recognition of the limits of anthropological
Ad> science.

I would suggest that another, perhaps major, reason was that the
field of paleoanthropology reached an important point during the
mid to late 60s and after; large numbers of new students and
cross-discipline research became the norm. This allowed for the
possibility of really getting into the minutia which tells you a
lot about a site. For instance, you find out more about a
specific area's micro-climate by identifying micro-fauna -- small
rodents, for example -- than you would by knowing that, for
instance, antelope were found there. The antelopes, though
partial indicators of general conditions, travel through several
types of habitat as a matter of course, while small rodents tend
to be stuck in certain specific types of areas.

This helped lead to the realization that the word "savannah" covers
much more than just the narrow idea of arid plains (even then it's
seasonally arid, and also contains rivers, lakes, and waterholes).

Ad> Chimps may not be the best model for the earliest hominids, however.

A point that's often not understood is that an animal may be a
good model in some ways but not others, although it's best to have
as well-rounded a model as possible, to help avoid the pitfall of
using a pick and choose model like you see done in bad
sociobiology (and some other endeavors in the field of human
evolution ;-). Chimpanzees are probably the best model for ideas
of social organisation, problem-solving, dealing with predators,
tool-using, and indeed much behavior (similar birth-rates, etc.).

But in terms of locomotion, they seem likely to have become, if
anything, more specialised than humans rather than keeping an
ancestral form. Therefore, they aren't a particularly likely
locomotor model for the ancestral population, and their importance
in terms of locomotor skills and physique is that since both
chimps and humans (and possibly gorillas at the same time but
possibly earlier) were derived from a common ancestor, that
ancestor must obviously have had a form which could be modified
into either derived form. This is why it is generally thought
that the common ancestor will turn out to be a more generalised
form, compared to chimps and humans (although it's *possible* the
CA could've been either a knuckle-walker or bipedal).

Jim Moore (

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