Re: Dissecting the Aquatic Ape: Bipedalism

HARRY R. ERWIN (herwin@mason2.gmu.edu)
2 Aug 1996 13:08:52 GMT

Paul Crowley (Paul@crowleyp.demon.co.uk) wrote:
: In article <4tnl7l$521@portal.gmu.edu>
: herwin@mason2.gmu.edu "HARRY R. ERWIN" writes:

: > Paul Crowley (Paul@crowleyp.demon.co.uk) wrote:

: > : > : > The niche is large-bodied suspensory feeding in open-canopy forest.
: > : > : > [..] you have to climb down out of the tree to move to another tree.

: > : I was querying: "The niche is . . . . ". It is not one currently
: > : occupied by any animal. It is an imaginary niche -- and therefore
: > : highly suspect.
: >
: > But one apparently occupied in the past.

: I suggest that a serious re-examination of this "niche" would reduce
: or eliminate its plausibility. There would definitely have been
: niches for a larger bodied terrestrial apes or cercopithecoids (the
: current chimp/baboon) able to climb, feed, hunt and sleep in the
: trees; there would have been niches for smaller almost entirely
: arboreal primates. But one in between . . . ?

Dryopithecus laietanus, Sivapithecus indicus, Pongo (and ancestors, which
were widely distributed in eastern Asia).

: Maps or aerial photographs might could the extent of suitable
: habitats - open, but not too open canopy. I'd suggest it's not
: common enough and is too dispersed and impermanent for a viable
: species.

Working from memory, I seem to recall that this biome extends across much
of East Africa today. It was more important prior to the emergence of the
open savannah about 3 MYr ago. Note also that the ancestors of the
advanced hominoids were broadly distributed during the late Miocene from
Spain to Turkey to East Africa to India and to China. Most of this region
was open forest.

---trimmed---

: >
: > : Leopards are mostly nocturnal. They're why chimps sleep in trees.
: >
: > Point?

: I was saying that reduced vision caused by lack of height has never
: been reported or indicated as a possible handicap to chimps, baboons
: or other species in field observations. And since big cats, including
: leopards, are mostly nocturnal a hominoid victim won't see them at
: night - no matter how tall s/he is.

Er? Big cats hunt when there's prey available--their camouflage patterns
are adapted to daylight hunting. African apes are diurnal and move on the
ground when the light is good enough that they can see risks and rewards.
Although you can use tree-climbing to substitute for height when the group
has stopped moving, eye height over ground can still provide an advantage
in fitness if it enables predator or food resource identification at a
longer distance. This is particularly the case if a significant proportion
of your preferred food resources are close to the ground, as the thick
enamel of early hominids suggests.

The dentition of early hominids is consistent with a more ground-based
diet than that of modern African apes, including a significant proportion
of rougher food items and less leaves. 

--

Harry Erwin, Internet: herwin@gmu.edu, Web Page: http://osf1.gmu.edu/~herwin 

49 year old PhD student in computational neuroscience ("how bats do it" 8)

and lecturer for CS 211 (data structures and advanced C++)