[Evgeny]

What if they were just plain hugnry all the time, it was miserable and only the strong survived?

I think the point is that regardles of being miserable, hungry or happy, the bodies adapted to the circumstances. Now what happens if you take the body that is best adapted to being hungry for periods of time and place it in the limitless food environment? Chances are that you will get a very happy and a very overweight person, with a shortened lifespan.

That would certainly jive with the caveman hypothesis, but does it sound like fun? How miserable are we willing to make ourselves for a few extra years in a nursing home?

I think that's a good point and not quite a false dichotomy. There probably are not enough studies to confidently state that "reducing calories by X% lengthens lifespan by Y%" but if the choice is "eat everything that will make me happy" and "be alive from my 80th to 85th birthday", different people would make different choices.

[jamii]

We became optimized for the environment we were in. Thats not the same thing as saying that that environment is optimal for us. We adapted to being cold and wet but chucking out your clothes and umbrella wont make you healthier.

Always remember - poison ivy is natural, pants aren't.

[Evgeny]

Okay, I see the point. It is quite obvious with the pants - "pants keep me warm and protect from poison ivy, therefore they are good for me". With food, not so obvious. "Chips and pizza with coke are tasty and make me happy, therefore they are good for me". Doesn't work the same way. In fact, I can't easily think of any artificial food that is definitely good for humans.

[jamii]

Thats not what I was saying at all. My point is that just because we are adapted to a certain diet doesn't make that diet optimal. Much modern food is undeniably unhealthy but starving yourself because our ancestors were hungry too is scientifically questionable. Nutrition is complicated but there is no reason we can't do better than our ancestors.