Mutation allowing to digest milk

In the current issue of the magazine "Investigación y Ciencia" (the spanish version of Scientific American) there are very interesting articles about the evolution. I would like to highlight one I feel very glad to discover: There is a mutation which allows people to be able to digest milk. It is well known that the percentage of people intolerant to lactose is very high, especially in Asian countries. Sorry that the information is in spanish. At least I hope you can get the main message with the graph.