The point isn't to eat what cavemen ate, it's to look at what their bodies were optimized for and eat things with similar components. Dairy is a very good source of saturated fat, especially for a vegetarian like me.
And the average life expectancy of a caveman was what, maybe 20 years? Cavemen perished too soon to have to worry about the diet-related health problems that we deal with today.
Ancient life expectancy numbers are misleading because of very high infant mortality. And even if that weren't the case, your reasoning is faulty. I have more or less the same gut as a caveman, so it makes sense to eat what they were optimized for. The fact that we have surgery and antibiotics and aren't at significant risk of being eaten by saber-toothed tigers isn't relevant to diet.
The human digestive system evolved over millions of years, and there is not much that is known with certainty about the human diet over that span of time - however, it is known that humans have a better ability to process starchy foods than other primates. So the assumption that a 'paleo' diet wouldn't include lots of starch is not based on science. Take a look at this article: http://news.bbc.co.uk/2/hi/6983330.stm
If you read my comment a little more carefully, you'd know I'm not anti-starch. I avoid anti-nutritious and harmful grains like wheat, but I eat potatoes with zeal.
