1. Range of Homo neanderthalensis. Peoples of non-African descent have from one to five percent Neanderthal DNA in their genetic makeup.
2. Rates of interbreeding. From high degrees of consanguinity (light) to low degrees of consanguinity (dark).
Christian canon law followed Roman civil law, which forbade marriage within four degrees of consanguinity. This mandate has persisted among Christians of the Middle East.
3. Civilizational accomplishment. The shaded areas indicate the incidence of people whom Charles Murray terms "significant individuals," who discovered or invented 98% of the artifacts and processes of modern civilization. They were all men, by the way. However, the map also includes the Hajnal lines, which demarcate the area of lower nuptiality centered in Europe (lower total fertility rates and higher minorities of women who marry later or remain single).