While it might not be as dramatic a superpower as being able to live four kilometres up a freezing mountain, the ability of many humans to drink milk in adulthood is certainly handy. As the story goes, the spread of this gene through populations in some parts of the world coincided with the rise in dairy farming. In turn, this enabled people to get more protein and fat in their diets, grow healthy and strong, and outcompete the non-milk drinking populations around them. But the latest research suggests that this neat evolutionary Just So story may not be true.