Emily Sohn, NPR
Where can people expect to live the longest? The answer to that question is and often dependent on wealth: People generally live longer in richer countries like Japan and Switzerland, where average life expectancies exceed 83 years. In lower income countries, expected years of life are often far shorter — hovering below 55 in a number of sub-Saharan countries, including Chad, Mozambique and Sierra Leone. But a recent data-crunch turned up a few surprises with some particularly encouraging news coming out of Niger.