Researchers find that densely packed neurons play an outsize role in quantitative skill—calling into question old assumptions about evolution.
AT AN UPSTATE New York zoo in 2012, an olive baboon sat with her baby at a table opposite a mesh screen and a curious grad student who was holding some peanuts. In one hand, the student had three peanuts. In the other, eight. The mother baboon could see both hands through the mesh, and she chose the one with eight. The student noted the correct choice. But she also noticed the baby, who followed along and interfered by reaching to make choices itself.
“It was clear that the baby understood what the theme was,” says Jessica Cantlon, who studies the evolution of cognition at Carnegie Mellon and led that Seneca Park Zoo study. In a second version of the test, her team found that even tiny baboon infants, at less than a year old, chose the bigger quantity on their own. The team concluded that both adult baboons and their babies could, in a sense, count.