Better nutrition. That has more to do with longevity than anything else. I'm not going to bother providing citations, but look in articles in the last 3 years of Scientific American- the evidance is obvious. Interestingly, in addition to high quality nutrition, reducing your overall caloric intake has a major effect too. But most people are not willing to examine or alter their diet in order to live better and longer. People treat food like sex- as though it's mainly for entertainment. Don't get me wrong, I love the social customs of eating together, and traditional cuisines are great. But there are several other meals of the day, and if you want to live long and avoid disease, you should make sure you get at least two meals with really high nutritional density (like dark green vegetables).

romulus brings up some good point.

it is surprising that you got to know this fact only now..

Surprisingly, I didn't know about this fact. What I know is, the past generations lived a lot longer than now and its probably due to the food they eat, water they drink and air they breath. Precisely, food in the early times are less if not totally zero, of chemical substances and preservatives. Water and Air are not contaminated/polluted as well. Medicines are of natural formula, etc. generally, people may live longer today than before probably because of the technology that plays a very crucial role in sustaining one's life - i.e. improved medicines/medical equipments. ~tnx.

There's a few reasons why our lifespan continues to increase over time. The first reason is the access to better medical care. Time has allowed scientists to discover and develop better medicines and other treatments for illnesses. Our average level of education have been increasing as well, and a higher level of education is linked to better health. We also have cleaner and safer living conditions than we did in the past - we don't have to go out and hunt for our own food and we have dry, stable shelter.