Video: See some animals with a head for numbers

Gallery: Eight animals that can count

CLEVER HANS’s gift was just too good to be true. The Arabian stallion wowed the crowds in early 20th-century Europe with his apparent ability to stomp out the answers to simple mathematical problems, such as 12 – 3 = 9. He could even add fractions and factorise small numbers (see image). Then in 1907, a German psychologist, Oskar Pfungst, proved that Hans was no animal savant.

In a scientific trial of sorts, Pfungst demonstrated that Hans could do arithmetic only when his owner, a maths teacher, or another questioner provided unconscious body cues hinting that Hans had reached the correct answer. With blinkers on or with the questioner hidden, Hans’s abilities vanished. So, too, did the notion that animals could count.

Much has changed, however, in the century since Clever Hans’s ignominious exposure. Few now doubt that primates have a sense of number, and even distantly related animals, including salamanders, honeybees and newly hatched chicks, seem to have the knack, with some able to perform basic arithmetic. What’s more, the skills of this growing mathematical menagerie resemble our own innate abilities. Could basic mathematics have evolved hundreds of millions of years ago?

“The ability to represent time and space and number is a precondition for having any experience whatsoever,” says Randy Gallistel, a psychologist at Rutgers University in Piscataway, New Jersey.

Of course, without language or a precise symbolic system to represent numbers, animal numerical abilities will never reach human levels. No chimpanzee will ever learn long division, but with enough practice almost any human can …