Estimates from some 700 mostly national studies of survival in the past are assembled to create a broad picture of regional and global life expectancy gains across space and time and to examine implications of that picture. At the initiation of their health transitions, most countries had a life expectancy between 25 and 35 years. Countries that began later made gains at a faster pace. Those faster gains are usually associated with the dissemination of Western medicine. But rapid gains occurred in the period 1920–50, largely before the availability of antibiotics or modern vaccines. Especially rapid gains came in the years immediately after World War II in countries where the leading causes of death were communicable diseases that could be managed with antibiotics but also in countries where the leading causes of death were degenerative organ diseases. Both periods of rapid gain await satisfactory explanation. The bibliography of more than 700 sources is published separately on the web at «http://www.lifetable.de.RileyBib.htm».