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(( Lab tricks show dogs can count ))

Exclusive from New Scientist Print Edition

Dogs can count, new work on mongrels reveals. Dogs are descended from wolves, which not only have a large neocortex - the brain's centre of reasoning - but live in large social groups. So their mathematical ability could, in evolutionary terms, have been useful for working out how many allies and enemies they had in a pack, the researchers think.

Animals such as birds and rodents can tell when one pile of objects is bigger than another. But to count, an animal has to recognise that each object in a set corresponds to a single number and that the last number in a sequence represents the total number of objects.

Many primates have this basic mathematical ability. But Robert Young, an animal behaviour expert at the Pontifical Catholic University of Minas Gerais in Belo Horizonte, Brazil, suspected that dogs do too.

To test the idea, Young and his colleague Rebecca West of De Montfort University in Lincoln, UK, borrowed a technique that has been used to show that five-month-old babies can count.


Sleight of hand


A number of toy dolls are placed in front of a baby and then a screen is raised to hide them. The infant then watches as some dolls are added or taken away before the screen is lowered to reveal the final result.

If the experimenter has played a trick and surreptitiously added or taken away a doll, the baby looks at the dolls for much longer, presumably because he or she had done the calculation and the number of dolls contradicts the baby's expectations.

Young and West repeated the experiment on 11 mongrels using doggie treats. Sure enough, the dogs stared at the bowls for much longer when the sums did not add up.

Dogs paid little attention when one plus one treat resulted in two treats, the researchers will report in an upcoming issue of Animal Cognition. But they were confused when the experiment was manipulated to show that one plus one treat appeared to equal three treats, for example.