[xiaoma]

That's an excellent point. In fact, the rate of human evolution is hundreds, possibly even a thousand times faster than it was in paleolithic times. Less than 15,000 years ago, nobody had lactose tolerance or blue eyes as an adult. Now, lactose tolerance is the norm and blue eyes are no longer uncommon.

http://www.dailytech.com/Life+in+the+Fastlane+Human+Evolutio...

[electromagnetic]

IIRC lactose tolerance is only believed to have become endemic since about 8000 years ago, incidentally right around when agriculture hit the big time.

I wonder if the control of pasture lands necessitated the higher calorific quantity an animal provides when it is milked. Less herd land means a farmer would need to extract more calories per animal to survive. Similarly less migration also means less danger and higher populations, which again require more calories per animal to sustain.