It is inaccurate to assume that 5,000 years ago a third of the population in Spain wasn't already lactose tolerant based on the dna of eight individuals from the northern region. All of Spain, except for these poor eight individuals could have been dairy drinkers 5,000 years ago. Either assumption is equally inaccurate. It does however help pose a question, a hypothesis, but answering that question accurately would require a sample of the whole population, not just one small region. -----Original Message----- From: Matthew Simonds [mailto:[email protected]] Sent: Thursday, January 30, 2014 2:32 PM To: [email protected] Subject: Re: [yDNAhgI] Another Ancient DNA Study: A Milk Mystery... For thousands and thousands of years, adults couldn't digest dairy products without an upset stomach and a trip to the bathroom. And then one day, poof! A few changes in our DNA gave about a third of the world's population - mostly Europeans - the ability to knock back cheese, pizza and chocolate ice cream without a care in the world. But why? Why did this ability to digest lactose suddenly crop up in our European ancestors about 10,000 years ago? That's been a big mystery for scientists. To start filling in those blanks, Sverrisdóttir and her team analyzed the DNA of bones from 5,000-year-old farmers found in northern Spain. None of the eight individuals had the genetic mutation giving them the ability to digest milk as adults. In contrast, a third of the population in Spain today is lactose tolerant. So in the span of just a few thousand years, that ability spread rapidly throughout the country. http://www.npr.org/blogs/thesalt/2014/01/23/265224739/a-milk-mystery-did-gloomy-weather-make-us-love-the-stuff