In 1900 the life expectancy in the US was about 47 for men, as I recall (I could have checked, to get the exact number, but that is close enough). By the time I was born in 1936 it was up to near 65. The major reason for the dramatic increase was not medical improvement, but rather good water and improved transportation. The clean water stopped water borne disease, and the mostly rail tranportation got better food to people in urban areas during the winter. I have long thought that improved water supply is the thing that is most needed by people in Africa, Pakistan, India, and similar "third world" areas where people have to spend a lot of their time getting water. (Some DDT would also help those people.) Here is an interesting article that I got from Powerline on what Coke is doing to improve water supplies in third world countries.

From Powerline:

I adopted Coke products as my non-alcoholic beverages of choice in response to the 2005 Columbia University Business School commencement speech given by Pepsi CEO Indra Nooyi. (I wrote about Nooyi's speech in the Standard column "The straight story.") Yesterday's page-one Wall Street Journal story by Betsy McKay about Coke accordingly caught my eye: "Why Coke aims to slake global thirst for water." I was struck by the basic things we take for granted as well as the scope and ingenuity of Coke's efforts to help in Africa. McKay writes:
In Kenya, where more than half of the rural population has no access to clean water, the Atlanta beverage giant brought water-purification systems, storage urns, and hygiene lessons to 45 schools in a poor western province. Children learn how to use a chlorine-based solution to kill diseases that come from contaminated, muddy pools or remote wells -- and are taught to teach their parents.
In Mali, Coke is helping extend municipal water taps beyond the country's capital of Bamako. In India, where the company has been accused of draining water from poor communities for its own use, the company is building rainwater-harvesting structures to help alleviate chronic water shortages. Coke's bottlers are also implementing water-efficiency measures.
More than 1.2 billion people lack access to safe drinking water, and 2.6 billion -- about 40% of the world's population -- lack proper sanitation, resulting in waterborne diseases that infect and kill about two million people a year, according to the United Nations. And global population growth and rising industrial production are increasing competition for the world's freshwater supplies.
Coke has some 70 clean-water projects in 40 countries, a service it hopes will eventually boost local economies and broaden its consumer base. But the efforts are also part of a broader strategy under Chairman and Chief Executive E. Neville Isdell to build Coke's image as a local benefactor and global diplomat. "You have to be an integral and functioning part both in perception and reality in every community in which you operate," he said in an interview. Thanks to the Wall Street Journal's David Patton, who kindly responded to my request that the Journal make McKay's story available to our readers. Message: Drink Coke!