The one social factor that researchers agree is consistently linked to longer lives in every country where it has been studied is education. It is more important than race; it obliterates any effects of income.
Year after year, in study after study, says Richard Hodes, director of the National Institute on Aging, education “keeps coming up.”
The study is partly based on empirical studies of Adriana Lleras-Muney. It is not clear how it works (correlation vs causation) but some suspect that education may somehow teach people to delay gratification. Lleras-Muney's papers can be found here and one of the papers relevant to the above article may be mortalityrevision1.pdf. There are other papers on this issue by Angus Deaton, some of them available at the electronic journaledited by Padma Prakash. This site has also an article by Kaushik Basu on teacher truancy in India
Kuffir in his blog and comments in various Indian blogs has been frequently emphasizing the merits of education for all.