however a elephant is also a lot bigger. It's like musels actually a larger animal needs a larger brain. Some whales for example have brains 6 times the size of a human brain. While the difference between sepperate humans can be up to 10%, depending on your body weight note that those with 10% less brain aren't anymore stupid then the other people. http://www.livescience.com/history/050310_neanderthal_reconstruction.html neanderthals on the other hand had like 15% more brains. So it would be difficult to say that they had less potential then modern day humans.