Sure. We were the ones who originally domesticated farm animals, to include dairy animals like goats and cows. Before that occurred, all humans had something like a 1 in 100 chance (or less) to possess the gene that permits milk digesting beyond childhood. Once drinking milk or eating cheese became possible, it was an avenue by which those few had a survival advantage during periods of famine. Gradually, famine after famine (eliminating huge numbers of those who didn't have this survival advantage, and thus nearly eliminating the genetic characteristic among Europeans), the percentage of Europeans who had the gene increased over those who don't to the point that almost all Europeans have it.
