Re: chimps on the savanna? Nooooo.....

Harry Erwin (herwin@gmu.edu)
Sat, 28 Oct 1995 19:42:51 -0400

In article <Pine.OSF.3.91.951027082317.27838B-100000@curly.cc.utexas.edu>,
David Froehlich <eohippus@curly.cc.utexas.edu> wrote:

> On 26 Oct 1995, H. M. Hubey wrote:
>
> > >authoritative statement that chimps don't go onto the savanna. Hubey
> >
> > Look guy, here it is, from CEHE, page 192.
> >
> > Number of simian primates plotted against degree of plant cover.
> > Plant cover ranges from Equatorial Forest (EF) to grassland (G). There's
> > no "savannah" because it means "grassland" or "steppe"
> > as I already posted. The number is 8 at EF and zero at G.
> > You want to argue; write to CEHE. Peter Andrews wrote this section.
>
> Why can't youunderstand that savannah indicates an environment
> intermediate between EF and G. If you continue to use savannah as an
> equivalent statement for grassland, it is not my problem it is yours.
> Let me put this in terms you might actually understand
>

Etc...

Let me lay it out explicitly. Although 'savannah' may _mean_ grassland, it
is commonly used as a non-technical term equivalent to the woodland biome,
which is defined by its lack of a closed canopy, not by its lack of trees.
The lack of a closed canopy means that primates of any size had to be
prepared to move at multiple levels, including the ground. (Monkeys
apparently represent an early lineage of primates that moved out of the
forest biome into the woodland biome in the Oligocene or thereabouts. The
evidence is seen in their dietary adaptations.) During the Miocene,
woodland biomes spread in East Africa, ranging from near-forest to
scrub-land in nature. Since most animals are _narrowly_ adapted to a
specific niche, this created an opportunity for a major adaptive
radiation, and we see evidence for at least the following:
1. Arboreal brachiators approaching the gibbons in their specialization,
2. A second lineage of gibbon-like arboreal brachiators apparently associated
with flooded areas,
3. Arboreal brachiators similar to the orang,
4. Lots of unspecialized arboreal quadrupeds,
5. Big terrestrially adapted apes (not well enough known to determine if they
were specialized knuckle-walkers, but likely to have been fist-walkers).
6. Monkeys of various types, eventually some with fully terrestrial adaptations,
7. A number of pre-hominids.
A few of these became adapted to fairly open conditions, but there was
little true grassland at that time. If what we see just before the
emergence of H. erectus is representative of the hominid component of the
radiation, there might have been 5-6 species of early hominids, each with
its specific niche in this area. I think it is only with H. erectus that
we see a hominid actually adapted to grassland. H. erectus seems to have
put paid to the hominid complexity (probably by burning), but the outcome
of that burning was an opportunity for the development of the extremely
rich modern grassland ecosystem that is still to be found in the
Serengeti.

-- 

Harry Erwin

Internet: herwin@gmu.edu

Home Page: http://osf1.gmu.edu/~herwin (try a couple of times)

PhD student in comp neurosci: "Glitches happen" & "Meaning is emotional"