Ahmed Wahidi is an Afghani goatherd with three wives, Aafifa, Latifa and Fatima. They live high in the Hindu Kush.

David Burton is a computer programmer who works for HP on the West Coast of the USA. He recently married Linda, a coworker with a joint degree in economics and computer science.

Which family is likely to multiply faster?

1. The Wahidis

2. The Burtons