after weaning and survive bad harvests. These two key developments paved the way for communities of farmers and herders to rapidly displace the hunter-gatherers who once prevailed across Europe. Today, lactase persistence can be found in 90% or more of the populations in Northwestern and Northern Central Europe, and in pockets of Western and Southeastern Africa, Saudi Arabia, and South Asia. It is not as common in Southern Europe (40%) because Neolithic farmers had already settled there before the mutation existed. On the other hand, it is rather rare in inland Southeast Asia and Southern Africa. While all Europeans with lactase persistence share a common ancestor for this ability, pockets of lactase persistence outside Europe are likely due to separate mutations. The European mutation, called the LP allele, is traced to modern-day Hungary, 7,500 years ago. In the twenty-first century, about 35% of the human population is capable of digesting lactose after the age of seven or eight. Milk-drinking humans could produce offspring up to 19% more fertile than those without the ability, putting the mutation among those under the strongest selection known. As an example of gene-culture co-evolution, communities with lactase persistence and dairy farming took over Europe in several hundred generations, or thousands of years. Prior this mutation, dairy farming was already widespread in Europe. A Finnish research team reported that the European mutation that allows for lactase persistence is not found among the milk-drinking and dairy-farming Africans, however. Sarah Tishkoff and her students confirmed this by analyzing DNA samples from Tanzania, Kenya, and Sudan, where lactase persistence evolved independently. The uniformity of the mutations surrounding the lactase gene suggests that lactase persistence spread rapidly throughout this part of Africa. According to Tishkoff's data, this mutation first appeared between 3,000 and 7,000 years ago, and has been strongly favored by natural selection, more strongly than even resistance to malaria, in fact. In this part of the world, it provides some protection against drought and enables people to drink milk without diarrhea, which causes dehydration. Lactase persistence is a rare ability among mammals. It is also a clear and simple example of convergent evolution in humans because it involves a single gene. Other examples of convergent evolution, such as the light skin of Europeans and East Asians or the various means of resistance to malaria, are much more complicated. The shift towards settled communities based on farming was a