Monkeys can add, and they're not half bad at it, researchers announced this week, saying two monkeys scored about as well as college students on the same basic-addition test.
Scientists have known that both humans and animals have the ability to mentally represent and compare numbers. For instance, animals, infants, and adults can discriminate between four objects and eight objects.
Until now, however, it was unclear whether animals could perform mental arithmetic.
The findings shed light on the evolutionary origins of arithmetic ability in humans and nonhumans, said researchers Elizabeth Brannon and Jessica Cantlon of the Duke Center for Cognitive Neuroscience.
Their study was published in the December 2007 issue of the journal PLoS Biology.
That monkeys—in this case two adult female rhesus macaques—and humans share the ability to add suggests that basic arithmetic may be part of a shared evolutionary past, the scientists said.
Earlier this month, Japanese researchers pitted young chimps against human adults in tests of short-term memory, and overall, the chimps won. (See story.)
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