In the last two centuries, a sizable portion of the world's people have become prosperous thanks to a historically anomalous period of sustained economic growth. According to a paper in the December 2010 issue of the Journal of Economic Growth, one important reason for the takeoff in productivity may be that older folks began to stick around longer.
San Francisco State University economist Michael Bar and University of Washington economist Oksana Leukhina argue that longer-lived adults were better able to transmit information to the younger generation. The educationally jump-started youngsters could then spend more time and effort innovating new technologies and institutions. Using data from England, the two economists conclude that the decline in adult mortality (as opposed to infant mortality, which declined later) accounts for 50 percent of the rise in per capita output between 1680 and 1880.