[Eli5] what’s the meaning of the ratio brain size/body mass? Why a bigger brain isn’t alone a sign of bigger intelligence? What has body mass to do with it?

Question

[Eli5] what’s the meaning of the ratio brain size/body mass? Why a bigger brain isn’t alone a sign of bigger intelligence? What has body mass to do with it?

In: Biology

Answer 1

Intelligence is a function of the size of a specific area of the brain particularly the cerebral cortex.   

So you can have an animal like an elephant whose brain size is three times the size of humans but the cerebral cortex is much smaller than humans.