There’s a reason why not all species can do calculus. A new model species offers insight into why. It’s not easy being smart. Oscar Wilde once lamented: “I am so clever that sometimes I don’t ...

It has long been thought that the brain size of anthropoid primates—a diverse group of modern and extinct monkeys, humans, and their nearest kin—progressively increased over time. New research on one ...

This illustration compares the brain sizes of a variety of primates, including humans (top left) and the fossil Chilecebus (bottom middle), based on a new method (phylogenetic encephalization quotient ...

a See refs. (McHenry, 1992 and 1994). b Endocranial volume is transformed into brain volume by formula 4 in ref (Aiello and Dunbar, 1993). c EQ is the ratio of brain volume and expected volume.