About the Authors
Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
The authors have declared that no competing interests exist.
Conceived and designed the experiments: SS NP SP DR. Performed the experiments: SS NP HL . Analyzed the data: SS NP HL DR. Contributed reagents/materials/analysis tools: SS NP HL. Wrote the paper: SS SP DR.