Ugh… old window… that was for Kal. 
Nature has no purpose.
Evolution, then. If the survival of our species once benefitted from middle aged heart attacks, that would explain the success of fatty foods in our diet. Early humans who ate lots of greens and found themselves with extra aging relatives in their caves may not have been able to find enough food, so those mutations got nixed.
That’s much more in line with current thinking about evolution. It’s still a much more complex hypothesis than what’s currently believed, so unless it offers something extra-special, Occam’s razor says to go with the current one.
It’s still a much more complex hypothesis than what’s currently believed
What’s currently believed?
Pretty much what’s been put forth in this thread, that at one point our cravings for high-calorie foods were beneficial, but the environment has changed faster than our instincts.
at one point our cravings for high-calorie foods were beneficial, but the environment has changed faster than our instincts.
I see. I think that jibes with my theory: A system requiring high calorie foods may have succeeded in an evolutionary balance. We (well Native Americans at least) killed buffallo, keeping their population down to a sustainable level, and at the same time slowly killed our predator-less selves, keeping our population down to a sustainable level.
That’s all encapsulated in that ‘high-calorie foods were beneficial’ part.