Sizing Up the Brain

Mutations that produce small brains may reveal how human intelligence evolved

In the 1960s, Pakistan built a mammoth dam on the river Jhelum to generate electric power and store water for irrigation. Known as Mangla, the dam created an upstream lake that displaced about 20,000 families from the district of Mirpur. Around the same time, England’s textile industry was facing a major shortage of skilled laborers, especially in the county of Yorkshire.