Monkeys’ mental maths almost matches humans’

A MENTAL arithmetic challenge between two monkeys and 14 university students almost ended in an embarrassing draw, it was revealed yesterday.

The pair of female rhesus macaques, Feinstein and Boxer, were as quick at working out sums as the students and nearly as accurate, scientists in the US found.

Both “teams” found certain problems more difficult than others in very similar ways.

The ability to perform simple mental arithmetic may be part of the shared evolutionary past of humans and other primates, pre-dating the emergence of language by millions of years, researchers believe.

It was already known that some animals can discriminate between larger and smaller groups of objects. The study showed for the first time that, like humans, monkeys can add numbers in their heads.

In the tests at Duke University in North Carolina, Feinstein and Boxer were shown a variable number of dots. These were removed, and after 500 milliseconds replaced by a different dot array. A third display had two boxes, one containing a number of dots equal to the first two sets added together, and the other an incorrect number of dots. Touching the correct box earned the monkeys fruit juice.

In hundreds of trials involving 40 addition problems the monkeys had an average accuracy of 76%. Fourteen students were correct 94% of the time. Response times for monkeys and students were similar — 1,099 milliseconds and 940 milliseconds respectively.

Feinstein and Boxer’s ability to pick the right answer was much better than that expected by chance.

They were not simply choosing the box containing the most dots, said the scientists in online journal PLoS Biology.

Nor were they just reacting to the amount of space taken up by the dots.

Varying the dot surface area did not lead the monkeys to choose wrong answers.

The way humans dealt with mathematical concepts had been strongly influenced by language and writing, said the scientists. But basic mental arithmetic ability appeared to date to the ancestors of monkeys and humans.

Being able to juggle numbers may have helped assess enemy strength or work out how much food should be gathered, said the researchers.