Life expectancy around the world has increased steadily for nearly 200 years.

During the nineteenth and early twentieth centuries, an increase in life expectancy was driven mainly by improvements in sanitation, housing, and education, causing a steady decline in early and mid-life mortality, which was chiefly due to infections. This trend continued with the development of vaccines and then antibiotics. By the latter half of the twentieth century, there was little room for further reduction in early and mid-life mortality. The continuing increase is due almost entirely to a new phenomenon: the decline in late-life mortality.