Math for Apes: Humans and Baboons Understand Numbers

Apes are known for their opposable thumbs, ability to use sign language and complex social patterns. What they're not known for, though, is their math skills. Yet new research seems to hint that our primate cousins have the ability to understand numbers--a trait that was once thought to be uniquely human.

"The human capacity for complex symbolic math is clearly unique to our species," said co-author Jessica Cantlon, assistant professor of brain and cognitive sciences at the University of Rochester, in a new release. "But where did this numeric prowess come from? In this study we've shown that non-human primates also possess basic quantitative abilities."

In order to find out if primates had the capability to understand simple math problems, the researchers tracked eight olive baboons between the ages of four and 14 in 54 separate trials. In order to assess the math skills of these primates, the researchers conducted a simple test; they gave the baboons a choice between two cups filled with varying amounts of peanuts--between one and eight. The baboons received all of the peanuts in the cup they chose, whether it was the one with the most or the least. It turned out that, like humans, the baboons could choose the larger amount; they guessed right roughly 75 percent of the time on easy pairs, while accuracy fell to 55 percent on harder ratios.

The researchers argue that the baboons' choices actually show that they rely on the ability to compare the approximate differences between counts--a "more than" or "less than" cognitive approach. The same response can be seen in children that have no yet learned to count; as long as the difference between two amounts is relatively large, they can point out which grouping has more.

"What's surprising is that without any prior training, these animals have the ability to solve numerical problems," said Cantlon in a news release. The results indicate that baboons not only use comparisons to understand numbers, but that these abilities aren't learned and instead occur naturally in the wild.

Although the findings do reveal that the creatures can understand the difference in amounts, it's unlikely that the baboons will be solving calculus equations any time soon. That said, the findings could allow researchers to better understand the evolutionary origins of human thought and points to the fact that we are closer to our primate relatives than we once thought.

The findings are published in the journal Frontiers in Psychology.