Early Primates Early primates were lemur-like in body form, and their brains were shaped like those of present-day lemurs, although smaller.
Somatosensory Cortex VP S1 S2 Ancestral State Derived State V3 DM MT V1 Visual System
Most of the large number of specializations that likely evolved in early primates or their immediate ancestors
Evolution of Hominin Brains Human brains are not symmetrical in shape, so that the planum temporale, the sheet of cortex on the lower surface of the lateral sulci, is usually larger in the left cereberal hemisphere than on the right.
Interestingly, however, great apes exhibit the same asymmetry of the temporal lobe as humans, despite their lack of language.
The issues of a Big Brain Inverse Ninja Law: The more ninjas there are, the weaker each individual ninja is Selection has to be based on a few developmental mechanisms Higher metabolic cost may require better diet .
Large brains generally devote much more of their mass to connections. Small morphological adjustments dramatically change the area affected.
Primates brains simply have many more neurons than rodent brains of the same size