Why do humans have such enormous brains for our size? One popular explanation is that we needed the added cognitive capacity to deal with large, complex social groups. And now, a fascinating new computer simulation suggests that cooperation really did make us smarter.
The basic concept of counting is beyond most animals, but not hyenas. They are able to count almost as well as primates, another indicator that these carnivores are unusually intelligent. It all goes back to their sophisticated, hierarchical societies.