I feel like the "paleo" aspect of the paleo diet was really just a starting point to test some hypotheses. Whether or not we actually know what our paleolithic ancestors ate or not is really irrelevant outside of the big picture. The big picture I refer to is whether it works or not. The bottom line is that it does work, whether it is truly what humans ate 700,000 years ago or not. Maybe paleo man did eat grains, as Lyle seems to believe. This absolutely in no way rules out the fact that most people do better eliminating grains and therefore elimintating toxins like gluten and lectins and reducing the insulin response to high carb foods. Maybe we shouldn't call it the paleo diet anymore and name it something else to clear up the confusion. What seems to bother most people about it is that we can't really know for sure what early man ate, we can only infer based on the evidence we can obtain, and that leads most people to call it pseudo-science.
Where the real science comes in though is in the studies done by people interested in the implications of cutting grain, dairy, legumes, and that seem to show that people's health improves as they cut these foods. While the science is far from being set in stone, it is hard to deny the fact that in certain populations the "paleo diet" has reversed type 2 diabetes, alleviated ms symptoms, improved blood lipids and blood chemistry in general, reduced inflammation and the associated problems, and generally improved people's health and well being. That for me seems to imply that this diet might be a good one to try if one's concern is health, longevity, and well-being, whether or not it is our "true" paleolithic diet.
Whether or not it is the "optimal diet" is really a pointless argument because there will always be people who do well on wacky diets, but for the majority of people, myself included, this one works better than any others I've tried or researched.