Clemens received his bachelor's degree from
College of the Holy Cross in 1961 and in 1966 his Ph.D. from the
University of California, Berkeley, under
Phillip Griffiths with thesis
Picard–Lefschetz Theorem for Families of Algebraic Varieties Acquiring Certain Singularities. In 1970 he became an assistant professor at
Columbia University and went on to become an associate professor before leaving in 1975 to become an associate professor at the
University of Utah where he became a full professor in 1976 and a Distinguished Professor in 2001. In 2002 he left Utah to become a professor of mathematics and mathematics education at the
Ohio State University. Clemens was a visiting scholar at the
Institute for Advanced Study from September 1968 to March 1970 and from September 2001 to June 2003. He was an
invited speaker at the International Congress of Mathematicians in 1976 at Vancouver and in 1986 at Berkeley and gave a talk
Curves on higher dimensional complex projective manifolds. For the academic year 1974–1975 he was a
Sloan Fellow. In 1972 Clemens and Griffiths proved that a cubic
three-fold is in general not a
rational variety, providing an example for three dimensions that unirationality does not imply rationality. In 1986 Clemens was an editor of the
Pacific Journal of Mathematics. He married in 1983 and has three children. ==Selected publications==