20 August 2008
NewScientist.com news service
Add elephants to the growing menagerie of animals that can count.
An Asian elephant named Ashya beat this reporter at a devilishly simple addition problem. When a trainer dropped three apples into one bucket and one apple into a second, then four more apples in the first and five more in the second, the pachyderm recognised that three plus four is greater than one plus five, and snacked on the seven apples. (In my defence, I watched the video in a noisy and crowded auditorium.)
"I even get confused when I'm dropping the bait," says Naoko Irie, a researcher at the University of Tokyo, Japan, who uncovered the elephant's inner genius. She presented her findings last week at the International Society for Behavioral Ecology's annual meeting in Ithaca, New York.
Moreover, Irie found that as well as summing small numbers with almost 90% accuracy, elephants can discriminate between small numbers.
That's not so surprising, considering that animals from salamanders to pigeons to chimpanzees can discern numerical values. But all animals, including humans when forced to make split-second decisions, are best at telling apart two quantities when the ratio between the large and small number is greatest.
Spot the difference
Not so for elephants, Irie says. The four that she tested distinguished between five and six apples as well as they did between five and one. They picked the bucket with the most fruit 74% of the time, on average, far above 50-50.
"It really is tough to figure out why [elephants] would need to count," says Mya Thompson, an ecologist at Cornell University who studies elephants and attended Irie's talk. Asian elephants live in close-knit groups of six to eight, and they may count one another to make sure the herd sticks to together. "You really don't want to lose your group members," she says.