First it's chatty dolphins, now it's mathematical monkeys. They can add, subtract and make decisions on the basis of their calculations, new research shows.
A team at Germany's University of Tubingen trained monkeys to look at a number of dots on a screen and compare them with a different set shown later.
They were able to work out which image contained more dots, and make decisions based on the answer. When there were apples to be had as a reward, they got it right as much as 90 percent of the time.
"The findings suggest that basic mathematics is hard-wired into evolution," lead author Professor Andreas Nieder told the Daily Telegraph.
"It is a primitive version of maths which we think has a survival advantage. If you are foraging, then it is an advantage to choose a tree with more berries on it."
Similarly, he points out, it's useful to know whether there's more of you or of them before you get into a fight with a rival group.
The full report appears in the Proceedings of the National Academy of Sciences.
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