What is the numerical competence of monkeys? This is a matter that we must all wonder about from time to time. As I miscount the change that I’m proffering when purchasing a non-fat latte with one raw sugar, and not forgetting the cinnamon sprinkle, I sometimes wish that I had a numerically competent one handy, when feeling embarrassed as I get the extra coins back. One would prove even more useful when there are several of us trying to work out shares of a lunch bill.
Some primates, such as Lowland Gorillas have been shown to perform well at low levels, as would be appropriate to the species. Along with cats, dogs, chicks and mosquitofish as it turns out. However, Schmitt and Fischer of U of Göttingen have given a bunch of baboons and macaques their final term papers and have published the results yesterday (1).
If offered a choice of plates with different numbers of peanuts, or in other experiments, raisins, there was a little ambivalence, and their eagerness to eat overcame their abstract reasoning abilities. The baboons soon tired of peanuts and had to be tempted just with raisins. The real tests came when black pebbles were substituted for raisins. One raisin per pebble was given on their choice.
The results? The two types of monkeys did very well in working out if there were more pebbles in one dish that the other. They did care if there was only one pebble difference but cared a lot more if there was two or more different. With scores of 84%, they received a B+ grade. They did not like to be short changed any more than the rest of us.
1 . Schmitt V., & Fischer J., Nat. Commun. 2:257 doi: 10.1038/ncomms1262 (2011).
