"Our results clearly show that uniquely human branches of mathematics interface with an evolutionarily primitive general magnitude system," says lead author Stella Lourenco, a psychologist at Emory University. "We were able to show how variations in both advanced arithmetic and geometry skills specifically correlated with variations in our intuitive sense of magnitude."
Babies as young as six months can roughly distinguish between less and more, whether it's for a number of objects, the size of objects, or the length of time they see the objects. This intuitive, non-verbal sense of magnitude, which may be innate, has also been demonstrated in non-human animals. When given a choice between a group of five bananas or two bananas, for example, monkeys will tend to take the bigger bunch.
"It's obviously of adaptive value for all animals to be able to discriminate between less and more," Lourenco says. "The ability is widespread across the animal kingdom -- fish, rodents and even insects show sensitivity to magnitude, such as the number of items in a set of objects."