I see a lot of articles saying something to the effect of “Nobody knows what paleolithic man ate, it was probably different by region and season, and therefore Paleo is make up.” I think that is a poorly thought out argument.
I completely agree with the first part. There are countless combination of foods that men would have ate at the time, many of which are sadly extinct. It could have been meat and veggies for some, it could have been bark and insects for others. Some ate plenty of fruit and honey, some ate little but blubber and meat. The fact that there was no one true paleo diet does not invalidate the philosophy.
We can say with certainty that before the last ice age they never had year round access to large quantities of grain and sugar. Many would not have had access to dairy until modern times unless they were in certain geographical areas where animal domestication began. Have we evolved since then? Yes. Have we evolved to eat those foods in the quantities they are currently available? That depends on the person and the food.
Paleo is not a historical reenactment, it is a philosophy of eating that suggests we examine from an evolutionary standpoint what may or may not be optimal for humans to eat, and then test those assumptions with things like science and elimination diets.