Modern medicine, and "germ theory", as well as "better sanitation" is what has allowed people to live so much longer. Antibiotics, and amazing surgical methods have helped a huge amount as well. A century and a half ago, a compound fracture, or even a severe cut or burn could EASILY turn into a death sentence. "Blood poisoning" (ie. sepsis), so,so easily avoided today, killed millions of people. There used to be a joke: "My grandfather is soooo old, he remembers when mercurichrome was considered a miracle drug." [For the younger set, mercurichrome was a VERY common topical antiseptic drug that was in probably every medicine chest in the world by the 1930's...).
What's a real trip is to wander around old cemeteries and look at the number of people who died from influenza in the World War I era..."Spanish flu" killed MILLIONS of people, world-wide, in a roughly three-year span in the late nineteen-teens!