Re: Why Large Gap Between Species...?

Gerrit Hanenburg (
Sat, 07 Dec 1996 12:54:54 GMT (Paul Crowley) wrote:

>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.

Body size dimorphism in A.afarensis expressed as the ratio male/female
bodyweight is estimated to be 1.52 (human formulae) or 1.78 (ape
formulae) (McHenry 1991). Both figures are well above that of Pan
troglodytes (1.37) and make a monogamous mating system unlikely.

McHenry,H.M.(1991), Sexual dimorphism in Australopithecus afarensis.