Critics of Paleo often proclaim: “Why should we emulate the diet of our ancestors when they all died before they were 30?” While it’s true that the lifespans of our Paleolithic forebears were shorter on average than our lifespans today, those averages don’t consider significant challenges those ancestors faced that are largely absent from our modern lives. These include high rates of infant mortality, tribal warfare and violence, exposure to the elements, and lack of emergency medical care.
Studies show that when these challenges are taken into account, our ancestors (as well as contemporary hunter-gatherers) lived lifespans roughly equivalent to our own. But more important, they reached these ages without developing any of the chronic, inflammatory diseases like obesity, diabetes, heart disease or autoimmune disease that plague us today.
I think most people are in agreement that genetics play a large role in the development of some diseases. Let's not forget that our genetics have been shaped by our ancestors. Who's to say that the very diet our ancestors lived off of altered our genetics in such a way to make us more susceptible to certain diseases? It's a little "out on a limb", but the point I'm trying to make is that there is too much unknown to really draw any solid conclusions.