Monkeys Can Be Calculating Creatures, Researchers Find

Monkeys can count, at least up to nine, researchers reported Thursday.

They said their study shows monkeys and other primates are more intelligent than they are usually given credit for.

“This finding is important because it shows that monkeys know things about numbers that we haven’t taught them,” said Elizabeth Brannon, a graduate student at New York’s Columbia University who worked on the study.

Brannon and psychology professor Herbert Terrace worked with two rhesus monkeys and a computer screen. They found the monkeys could count to nine and learned to count better with time.

“Though monkeys do not recognize the word ‘two’ or the symbol ‘2,’ they share with humans the ability to master simple arithmetic on at least the level of a 2-year-old child,” Brannon said.

“We don’t have direct evidence yet, but it seems likely that these monkeys, and other nonhuman primates, can count.”

The monkeys were shown a series of 35 different images on a touch-sensitive video screen. Pictures of grouped objects such as bananas, hearts and triangles popped up randomly, the researchers reported in the journal Science.

Color, size and position also varied, but the monkeys got a food reward if they touched the pictures in the right order according to number: For example, if they touched the picture of one banana first, then two trees, then three flowers and so on.

“It’s like using your password to get money from a cash machine, but it’s actually much harder for the monkeys,” Terrace said.

Other animals also have been shown to count. Some birds, for instance, seem to be able to count their eggs.