I just saw this video over at Mads Jacobsen’s blog which does a great job of explaining the Paleo diet approach:
Personally I mostly follow the Paleo diet where possible (in Zone Diet proportions), but I do add milk and dairy. The reason is, we did evolve to drink milk, your mum’s milk. Now I realise that cows milk isn’t quite breast milk, but unless you want to be drinking other women’s breast milk (although that’s apparently available on some choice American websites!) it’s the best you can do. I do generally insist on whole Organic milk though, and when I can get it, unpasteurised raw (real) milk.