One, two, three, many

The results [from studies of primates, salamanders and other animals] suggest that the two abilities - to precisely identify small numbers and to estimate the relative size of large numbers - have deep roots in our evolutionary history. "There's a good chance that this thing goes way back," says Marc Hauser.

-- from Animals that count



P.S. 8 July: Primates 'can intuitively recognise some rules of grammar', according to a study of cotton-topped tamarin monkeys