Re: Why Large Gap Between Species...?

Paul Crowley (
Fri, 06 Dec 96 23:11:53 GMT

In article <> "Gerrit Hanenburg" writes:

> Goodall (1986 p.505) reports that after the Kahama community at Gombe
> was annihilated by the Kasakela males their community range was
> annexated by the latter.

In 1974, before the split, the Kasakela/Kahama were one group
with 14 full adult males. By 1978 at the end of the "civil war"
there were only 4 full adult males left - all Kasakela. But
the commmunity was so reduced, and with such a small territory,
that Goodall thought it might be wiped out by its northern and
southern neighbours. Without the discouraging presence of
human beings it might well have been.

It's likely that this is a normal chimpanzee cycle. When a band
is successful, it expands. It then becomes too big with too many
adult males. So it splits. There is then a "civil war" and it
wipes itself out -- or nearly. Fourteen adult males is probably
too much for a band of promiscuous males.

However, this cycle puts chimpanzees into an evolutionary rut.
Success is penalised. The breaking of this cycle by hominids
must have been *the* major step. Learning how to manage stable
groups of more than 14 males must have been exceedingly difficult
and required great ability in diplomacy and made language and
other social skills a high priority. Monogamy would probably
have replaced promiscuity at an early stage. The ability to
control static sites of varying sizes with good food and water
supply would have been the incentive to those tribes that could
manage it.

To come back to Nat's perceptive and penetrating questions.
They present serious problems to inland theories of hominid
evolution. The australo's, etc., could easily have found
habitats, somewhere between those of pygmies and orangs, where
subsequent hominids would have left them alone.

> And how was this competition played out anyway? Erectus kills
> off the piths, habilis kills off erectus, H. sapiens kill off
> habilis? Which begs the question, "Why didn't the piths kill
> off apes and chimps?"

The only reasonable answer is that all hominids occupied the
same niche, or closely similar niches - well away from those
of the apes. It was, of course, the littoral one, where
competition forbade more than one species after 1 mya.