Human selection

Courtesy of Jonathan Pritchard / Public Library of Science

B.F. Voight et al., "A map of recent positive selection in the human genome," PLoS Biology, 4:446-58, 2006. (Cited in 138 papers)

In 2006, Jonathan Pritchard's team at the University of Chicago used the newly released HapMap data to look for groups of linked SNPs with elevated frequencies among three human populations from around the world. They found that hundreds of regions of the genome may have undergone positive selection.

A suite of biological functions was identified in the selected regions, ranging from food metabolism to reproduction. Except for rare cases, such as the lactase gene, the reasons why some haplotypes are selected for are unknown, says Carlos Bustamante of Cornell University, who was not involved in the study. "The tough challenge is going from a bird's-eye view of recent selection to knowing what the selective agents [acting on traits] really are," he says.

Together with the paper, Pritchard's team made its methods freely available in the form of a Web browser called Haplotter. In 2007, Bernard Crespi of Simon Fraser University in Burnaby, Canada, used Haplotter to show that genes associated with schizophrenia showed more evidence of recent positive selection than other neuronal genes.

The third phase of the HapMap Project, along with the Human Genome Diversity Project, and the 1000 Genomes Project should go beyond the limited number of original SNPs to reveal more selected genomic regions, as well as more geographic differences between human populations, says Lluis Quintana-Murci of the Pasteur Institute in Paris.