If you were born in 1900, you had a pretty good chance of dying by your 50th birthday. Today, thanks to improved health and safety around the world, that would be — in many countries — a life cut short by at least a few decades.
"The dramatic increase in average life expectancy during the 20th century ranks as one of society’s greatest achievements," notes a report from the National Institute on Aging, a division of the National Institutes of Health.
These gains have not been universal; the average life expectancy in the world's least developed countries is still about 61.
But overall, people are living longer. A number of factors have contributed to this upswing in our longevity, including declining infant deaths, better management of infectious diseases, and more widespread access to clean water. In the decades leading up to the nineteenth century, much of the improvement in life expectancy was not because people were living into what we now consider old age — it's because fewer children were dying before they reached adulthood.
