Human evolution is happening faster than we thought, according to a new study led by John Hawks, an anthropologist at the University of Wisconsin-Madison. The recent genetic changes were driven by the huge population growth of the last several thousand years, the researchers say, which created greater opportunity for beneficial mutations and required people to spread to new environments where they had to adapt. Africans, for example, have new genes that provide resistance to malaria, while Europeans have a gene that helps them digest milk as adults. According to the study, there hasn't been much gene flow between Africa, Europe, and Asia, where genes are evolving quickly and local environmental and cultural factors are affecting them differently, and as a result, people worldwide are becoming less genetically similar to each other. The research team includes two of the University of Utah scientists who proposed in 2005 that natural selection may be responsible for enhanced intelligence, but also genetic diseases, among Jews of central or northern European origin. —Heather Wax