from their ancestors of 5,000 years ago than their ancestors from that era were to the Neanderthals who went extinct around 30,000 years ago. They tied this effect to new selection pressures arising from new diets, new modes of habitation, and immunological pressures related to the domestication of animals. For example, populations that cultivate rice, wheat, and other grains have gained the ability to digest starch thanks to an enzyme called amylase, found in saliva. In addition, having a larger population means having more mutations, the raw material on which natural selection acts. Hawks and colleagues scanned data from the International HapMap Project of Africans, Asians, and Europeans for SNPs and found evidence of evolution speeding up in 1800 genes, or 7% of the human genome. They also discovered that human populations in Africa, Asia, and Europe were evolving along divergent paths, becoming ever more different, and that there was very little gene flow among them. Most of the new traits are unique to their continent of origin. As Europeans and East Asians migrated out of Africa, those groups were maladapted and came under stronger selective pressures. John Hawks reported evidence of recent evolution in the human brain within the last 5,000 years or so. Measurements of the skull suggests that the human brain has shrunk by about 150 cubic centimeters, or roughly ten percent. This is likely due to the growing specialization in modern societies centered around agriculture rather than hunting and gathering. More broadly, human brain sizes have been diminishing since at least 100,000 years ago, though the change was most significant within the last 12,000 years. 100,000 years ago, the average brain size was about 1,500 cubic centimeters, compared to around 1,450 cubic centimeters 12,000 years ago and 1,350 today. Examples for adaptations related to agriculture and animal domestication include East Asian types of ADH1B associated with rice domestication, and lactase persistence. Around 11,000 years ago, as agriculture was replacing hunting and gathering in the Middle East, people invented ways to reduce the concentrations of lactose in milk by fermenting it to make yogurt and cheese. People lost the ability to digest lactose as they matured and as such lost the ability to consume milk. Thousands of years later, a genetic mutation enabled people living in Europe at the time to continue producing lactase, an enzyme that digests lactose, throughout their lives, allowing them to drink milk