For government, I believe next to nothing at the Federal level, and some in States.

The Social Security Administration has a history: http://www.ssa.gov/history/briefhistory3.html

And a Chronology: http://www.ssa.gov/history/chrono.html

Some libertarian guy wrote a book on the mutual aid, charity aspect of it in the early 20th century (his name rhymes with Hansky?, but I can't dredge it out of my neurons). Maybe someone else will recall.