memo: Thickness of the cerebral cortex is a good proxy for intelligence.
Several years ago, another group had discovered that this gene had arisen after an ancestral gene made an incomplete copy of itself. Because humans had the additional version whereas chimps did not, they concluded that the duplication occurred after the human and chimp lineages split off. Neither mice nor chimps have ARHGAP11B, but modern humans and their ancient relatives, the Denisovans and Neandertals, do. “That it was a human-specific gene duplication made it very exciting,” Huttner says.
You WANT wrinkles on your brain.