I have seen plenty of evidence to suggest this works. Couple that with a healthy diet and happy lifestyle and people could go on for a lot longer I am sure.
Just wondering how this works though... in times of low food, people eat less, live longer, maybe have offspring less frequently. In times of plenty maybe the young ones have kids younger, die off sooner, and the generation gap gets smaller, more food = more generations of people = faster evolution.
That was a bit of a ramble, not sure if I made sense or even if I understood what I was trying to say! But I just find it a peculiar mechanism that puzzles me, less food = longer life. Nature must have had a reason for doing that.