Fast Milk

Here's a cool recent finding: new proof that the adaptation among Northern Europeans to be able to digest milk as adults happened very fast in evolutionary terms. 

Researchers at SUNY Stony Brook, working with others from Mainz, Germany, analyzed the genetic material of skeletons from a massive German battlefield from 1200 BC. They found that at that time — about 4,000 years after the introduction of agriculture and animal domestication — only an eighth of the soldiers had the gene for adult milk digestion.

Today, that percentage varies between 70 and 90 percent in populations from the same area. But it reached 60 percent well before the year 1000 AD, so the change happened in a couple of millennia, which indicates that

simply [by] possessing this one genetic change, past European individuals with the ability to digest lactose had a six percent greater chance of producing children than those who could not... With milk being a high-energy, relatively uncontaminated drink, its ingestion may have provided greater chances of survival during food shortages or when supplies of drinking water may have been contaminated.