Von Economo neurons, exceptionally large neurons found in the posterior insula, are uniquely enriched in humans compared to chimpanzees and elephants.

“Well, in your posterior insula, you have a very interesting population of very large neurons, these are exceptionally large neurons called von Economo neurons. These are neurons that are, again, unbeknownst to most neuroscientists and they seem uniquely enriched in humans. Chimpanzees have them and some other large animals have them. So, they're found in whales, chimpanzees, elephants, and in humans. But even though we are much smaller than most whales and even though we are much smaller than most elephants, I mean, remember there are baby elephants. As far as I know, they haven't bred up like mini-elephants yet, they seem to have a teacup version of pretty much every dog breed. You can look that up, I certainly have mixed feelings about this notion of trying to downsize everything to the point where you could kind of like the pocket-sized bulldog I think of someday will arrive. I'm not a fan of that kind of downsizing of different breeds, but because there aren't teacup elephants and teacup gorillas, and teacup chimpanzees, and so forth, most all of those other species are larger than us. They have these von Economo neurons and we have these von Economo neurons, but we have in upwards of 80,000 of these things in our posterior insula. These other species tend to have somewhere in the range of 1,000 to maybe 10,000 or so.”