Small investments in nutrition could make the world brainier

Kebita Naima was a month pregnant when men with guns burned her home and stole everything she had. Terrified, she fled her village in eastern Congo. With a dozen relatives she walked for a week, hoping to reach Uganda, the calmer country next door. “We had nothing, no food at all,” she recalls—only water from streams and wild fruit. When she crossed the border she was “so weak and so hungry”.