The U.N. estimates that the world's population will pass the 7
billion mark on Monday. Much of that growth has happened in Asia
— in India and China. Those two countries have been among the
world's most populous for centuries. But a demographic shift is
taking place as the countries have modernized and lowered their
fertility rates. Now, the biggest growth is taking place in sub-
Saharan Africa. Due in part to that region's extreme poverty,
infant mortality rates are high and access to family planning is
low. The result is high birth rates and a booming population of
900 million — a number that could triple by the end of the
century. Population expert Joel Cohen points out that, in 1950,
there were nearly three times as many Europeans as sub-Saharan
Africans. If U.N. estimates are correct, there will be nearly
five sub-Saharan Africans for every European by 2100. As NPR's
Adam Cole reports, it was just over two centuries ago that the
global population was 1 billion — in 1804. But better medicine
and improved a