Re: Brain Temperature Control & A. Africanus

Gerrit Hanenburg (
Sat, 26 Oct 1996 11:39:34 GMT

Doug McKean <> wrote:

>As you may well already know, you are referring to
>"encephalisation in australopithecines" which has two things to consider:
>1. The development of an increased cooling system necessary
> for the sensitive intra-cranial nervous system was the driving
> factor for increased brain sizes.
> Commonly known as the "radiator theory".

I wouldn't say that it was the driving factor but only one of the
factors that made increased encephalization possible.
The system of emissary veins may have been necessary from the point of
view of thermoregulation,in my opinion it does not explain the
selective advantage of a big brain.

>2. Diet may well have been a serious factor in the development of
> of the cooling system for the brain.

Diet is anyway a constraint on encephalization because of the
metabolic demands of brain tissue. Apparently you can't have a big
brain (i.e. high EQ value) without a high quality diet. (see
Foley,R.A. and P.C.Lee (1991),Ecology and energetics of
encephalization in hominid evolution. Phil.Trans.of the Royal Soc.of
London series B 334:223-232)