I've heard that...but really hard to compare when the life expectancy of our Neo-lithic ancestors was 30 years.
Of course, living in a state of nature will cut down on life expectancy - a small cut could become infected, animals and other humans followed the rule of the club, "nature blood red in tooth and claw," all the many natural hazards.
Still, we ARE what we were - what our human ancestors did for 100 millenia, what our pre-human ancestors did for a few million years.
It was feast or famine - mostly the latter. It's why nature puts weight on you when you get older - in the raw state the elders (save the chiefs, soothsayers, medicine men and women) did not get fed much. The provisions went first to the hunters and warrior, then the child bearing women and children, So Nature changed the metabolism of the seniors, to allow them to survive the inevitable lean times.
It's only in recent centuries that we've eaten our fill every day, the proverbial three squares a day. It's simply too much. (I suspect my not so remote ancestors - a few hundred years ago - did not get "enough" to eat, enough by our generous standards)
It's why women have more body fat than men - in times of severe famine they, the future, can survive longer with little food.
Again, all laborratory experiments, starting with mice, progessing to dogs and simians, have irrefutably proven that restricting calories is the ONLY way to both extend life and to banish many ailments.
In times of nature famine short of actual starvation the life expenctancy rises dramatically. (Ditto for when doctors go on strike!)
We are not created to consume three squares a day. Not even, on a regular basis, one square a day.
That said, I'll confess that I'm not on the CR diet, tho I do fast once or twice a year, for 7 to 21 days. (Organic juice fast). The CRD requires a change of life, of the way you live. I travel too much now to do it, eat on the run, sometimes junk food. But if I ever settle I may make the leap.