What does brain size have to do with intelligence?
Very little—even if it's very big.
By Rachel Feltman 33 minutes ago
animal brain sizes
Size isn't everything.
Researchers used to think brain-to-body-size ratio revealed intelligence because it showed how a species devoted energy to its cranium. They were utterly wrong. Other ratios better predict smarts, but there’s still no perfect metric. This ranking, by brain-to-body ratio, shows just how little we know about, well, knowing stuff.
https://www.popsci.com/what-does-brain-size-have-to-do-with-intelligence