Researchers at 91社区 have found that the gap in life expectancy between white and black people in America has narrowed substantially, largely because of a decrease in deaths of young African American males from homicide and AIDS. The study, conducted by Sam Harper, a postdoctoral fellow in 91社区's department of epidemiology, biostatistics and occupational health, and John Lynch, Canada research chair in population health, is published in the March 21 issue of the Journal of the American Medical Association.