Increased availability and use of vaccines is the strongest reason for longer life expectancy in the modern world.
In the modern world where there is solution of each and every problems, it is hard for problems to stay here. In the past era life expectancy is a major problem for humans to solve as there were a lesser amount of things that were discovered later. Many humans had to face death because of the lesser or no availability of vaccines and medicines, as those diseases were deadly to take any life. Where in today's era there were solutions to each and every complex thing,availability of enough drugs and vaccines. We have also solutions of each and every hardcore problems starting from organ damage to loosing any body parts. As we are evolving day by day and making things easier for us which makes us easier to inhabit in this planet. so existence of life is increasing day by day.