Over on Chris Kresser's blog is an article, itself linking to another article over on PaleoNu, that raises an interesting point. There are a lot of people who spout off about "paleo" and "primal" diets, but they all seem to have slightly different takes. Some say beans are okay, others say they're not. Some say dairy is good, others say no. Same thing for cashew nuts. And so on.
Much as I'd like to just copy-and-paste the last 8 or 10 paragraphs here, that would be rude. So, I'll urge you to go read his article instead. Essentially, it's impossible to know *exactly* what a paleo diet consisted of, and it probably varied over time and by region anyway. But the fundamentals work - a diet that emphasizes nutrient-dense, whole food without a lot of refined starch and sugar is known to be good for us. So, find what works for you personally, and I'll find what works for me personally, and we'll both be happy. Unless you're one of those people who isn't happy unless everyone else is doing what you want, in which case you're never going to be happy anyway, sorry.