By 2050 the population of Nigeria will be 402 million

The two countries on track to make the biggest population gains are Nigeria and Ethiopia. Nigeria currently boasts 166 million people, but by 2050 its population is expected jump to 402 million. Ethiopia's population will likely triple from 91 million to 278 million, bringing the east African nation into the one of the top 10 most populous countries in the world for the first time. In fact, according to the United Nations Population Division, although only 18% of the world's population lives in so-called "high-fertility" countries (places where women have more than 1.5 daughters on average), most of those countries are in Africa; the continent is expected to experience significant population growth in the coming decades, which could compound the already-dire food supply issues in some African nations