Re: complexity of cetacean and human brains

Ralph L Holloway (
Tue, 21 Nov 1995 17:16:34 -0500

On 20 Nov 1995, HARRY R. ERWIN wrote:

> I suspect the enormous expansion of the human frontal cortex is associated
> with three things:
> 1. Planning,
> 2. Working memory,
> 3. Reafference associated with cued search (as opposed to general
> attentiveness, which may be involved with the locus coeruleus).
> If those are important to your definition of 'being human,' you probably
> need to specifically associate human intelligence with frontal cortex
> expansion.

I think Harry's post does a great job on the questions regarding cetacean
brains and the expansion of the temporal lobe, related to adaptations
that are specifically "cetacean in intelligence". I do have a problem
with the above, however, in that I am unaware of any truly good
quantitative data that shows a tremendous expansion of human frontal
cortex beyond a purely allometrically related increase to overall brain size.
Everything I've seen suggests that there is just as much frontal cortex
(and also prefrontal cortex) as would be expected for a primate with a
human brain size. I mean, in absolute terms, yes, the frontal and
prefrontal cortex is expanded, say, compared to a chimpanzee or macaque,
but that expansion is not relatively greater.
Ralph Holloway