A study of people with language difficulties suggests that mathematical skill evolved independently.

A team led by Rosemary Varley at the University of Sheffield, UK, studied three people with extensive damage to the brain's left hemisphere, including language areas. Two could not speak at all, and the third only in fragmentary sentences. All were competent calculators, though, able to solve simple subtraction, division and multiplication problems.

Most experts believe that understanding syntax is essential for processing mathematical statements. "We've blown that one to pieces, I think," says Varley.