Life Expectancy 1000-1999
The chart above (click to enlarge) shows life expectancy at birth from 1000-1999, taken from "The World Economy," by Angus Maddison, published by the OECD.
Group A includes Western Europe, U.S., Canada, Australia, New Zealand, and Japan. Group B includes Africa, Asia, Eastern Europe and Latin America.
Note that a) life expectancy more than doubled during the 20th century, b) life expectancy remained basically the same from 1000 to 1800, and c) more gains were made in the last 100 century than all previous centuries combined.