"brain shrinkage is correlated with agricultural development." - cwcaton.

I would be curious to know whether the pattern of shrinkage coincided with the development of agriculture as that may play into either or both of our hypotheses.

Here's my uneducated theory: our brains might be smaller now because the extra brains we were carrying around were devoted to our sense of smell as that sense would be highly valuable in locating food sources both animal and vegetable in our hunter/gathere past. As we learned how to domesticate animals and grow our own food, a highly developed sense of smell was less necessary and the attending brain matter lessened over the generations.

Hmnfefefefe (supressed laughter)...now I see you without pants, I know why you had me fix. You just jealous...hmnffefefefe.

Heheheh, You're right; I did just swallow a canary. How did you know ?

Off Topic: Is it just me, or does the man pictured above bear a striking resemblance to Franklin D. Roosevelt ?

use the link below and compare pictures.

http://history1900s.about.com/library/photos/blyfdr89.htm