What role do cresting and postorbital constriction have in d

What role do cresting and post-orbital constriction have in determining brain size?

Solution

Cresting is the provision of crests in the brain whose main function is attachment of muscles. In small-skulled species, the brain size is small, therefore there is not much space for holding muscles. But cresting helps in accommodation of muscles in small skulls. These muscles are required for chewing if hard food and supporting heavy face. Thus, more cresting corresponds to a smaller brain size.

Post-orbital constriction is referred to the narrowing of the skull, just behind the eyes and it plays a role in determining the cranial capacity. It has been observed in different species that a narrower post-orbital constriction results in a smaller size of brain, especially the frontal lobe. This constriction is said to be associated with abstract thoughts and reasoning. Also a lesser post-orbital constriction results in a larger frontal lobe, or a larger brain size.