The Specialization of Scientists

Affiliations: Harvard Kennedy School, Harvard University, Cambridge, MA 02138, USA. National Bureau of Economic Research, Cambridge, MA 02138, USA. Department of Economics, University of Notre Dame, Notre Dame, IN 46556, USA. †These authors contributed equally to this work. *To whom correspondence should be addressed. Email: [email protected] Abstract: We use about 2 million papers published by 221,843 individual scientists over eight decades to document that scientists have become more specialized over time. Scientists who began their careers in 1975 contributed to 40% fewer areas of knowledge in the first thirty years of their career than did scientists who began in 1945. We demonstrate two factors that affect scientists' range of contribution. First, scientists narrow their range where their peer groups are large. Second, scientists may expand their range through coauthorship.