Charles Choi has a post on Live Science that takes on the recent debate as to whether or not early humans were hunters. Some archaeologists maintain that early humans relied more heavily upon scavenging and gathering rather than hunting, thus eating a diet less focused on meat consumption.
of particular interest:
These findings suggest that “human brain development could not have existed without a diet based on regular consumption of meat,” Domínguez-Rodrigo said. “Regular consumption of meat at that time implied that humans were hunters by then. Scavenging only rarely provides access to meat and is only feasible in African savannas on a seasonal basis.”
gocarnivore.wordpress.com 
I had read a book called Primal Body, Primal Mind by Gedgaudas. She suggests that the added Omega 3 Fatty acids caused our brains to develop faster with greater consumption of meat and fish. Excellent post, you have a new fan.