Adult humans possess some mathematical abilities that are unmatched by any other member of the animal kingdom but there is increasing evidence that the ability to count sets of objects nonverbally is a capacity that humans share with other animal species.

In PLoS Biology, Elizabeth Brannon and Jessica Cantlon discuss how humans and nonhuman animals share a capacity for nonverbal arithmetic. The researchers tested monkeys and college students on a nonverbal arithmetic task in which they had to add the numerical values of two sets of dots together and choose a stimulus from two options that reflected the arithmetic sum of the two sets.

Monkeys perform addition like humans. Monkeys and humans exhibited ratio-dependent accuracy and response time when solving addition problems. For accuracy (left panel), solid lines
show the predicted data from Equation 1 for humans (red) and monkeys (gray) at the best fitting w. The R2 values for accuracy show the strength of the fit. Response times (right panel) are fit with a linear function, and the corresponding R2 values are reported. Error bars reflect the standard error among subjects.


The results indicate that monkeys perform approximate mental addition in a manner that is remarkably similar to the performance of the college students.

These findings support the argument that humans and nonhuman primates share a cognitive system for nonverbal arithmetic, which likely reflects an evolutionary link in their cognitive abilities.

Citation: Cantlon JF, Brannon EM (2007) Basic math in monkeys and college students. PLoS Biol 5(12): e328. doi:10.1371/journal.pbio.0050328