Richard Timothy Durrett (born 1951) is an American mathematician whose research concerns probability theory, stochastic processes, and their applications to mathematical biology, including population genetics, ecology, epidemiology, and cancer modeling. He is the James B. Duke Emeritus Professor of Mathematics at Duke University, having previously held faculty positions at the University of California, Los Angeles (UCLA) and Cornell University. Durrett was elected to the United States National Academy of Sciences in 2007 and to the American Academy of Arts and Sciences in 2002. He is also a fellow of the American Mathematical Society, the Institute of Mathematical Statistics, and the American Association for the Advancement of Science. His textbook Probability: Theory and Examples was described in a review for the Mathematical Association of America as one of the two most popular graduate-level texts on probability, alongside Billingsley's Probability and Measure.
Education Durrett received his Bachelor of Science (1972) and Master of Science (1973) degrees in mathematics from Emory University. He then entered the Operations Research program at Stanford University, where he completed his Ph.D. in 1976 under the supervision of Donald Iglehart. His doctoral dissertation, titled Conditioned Limit Theorems for Some Null Recurrent Markov Processes, appeared in the Annals of Probability in 1976. Durrett has said that he initially enrolled at Emory as a pre-medical student during the Vietnam War era but switched to mathematics after finding the laboratory component of pre-med unappealing, while still wanting to apply mathematics to real-world problems; this led him to operations research at Stanford.
Career Durrett began his academic career at the University of California, Los Angeles (UCLA) in 1976 as an E. R. Hedrick Assistant Professor and was promoted through the ranks to full professor, remaining at UCLA until 1985. In 1985 he joined the faculty of Cornell University, where he remained for 25 years. In 2010 Durrett moved to Duke University as the James B. Duke Professor of Mathematics, a position he held until his retirement in 2023, simultaneously serving as associate director of the Statistical and Applied Mathematical Sciences Institute (SAMSI) in the Research Triangle from 2010. He was drawn to Duke partly by the milder climate of North Carolina and partly by the opportunities for collaboration with biostatisticians, computational biologists, and applied mathematicians at Duke, the University of North Carolina at Chapel Hill, and North Carolina State University. Upon retirement he became the James B. Duke Emeritus Professor of Mathematics. Durrett has supervised more than fifty doctoral students, including Rodrigo Bañuelos (UCLA, 1984), Claudia Neuhauser (Cornell, 1990), Nathaniel Berestycki (Cornell, 2005), Daniel Remenik (Cornell, 2009), and Shirshendu Chatterjee (Duke, 2011). He has also mentored postdoctoral fellows including Vlada Limic, Lea Popovic, Soumik Pal, Jon Peterson, David Sivakoff, and Matt Junge. He served as an editor of the Annals of Applied Probability from 1997 to 1999 and has been involved in organizing numerous conferences, including the Southeastern Probability Conference, the Workshop for Women in Probability, and programs at the Mathematical Biosciences Institute and the Banff International Research Station (BIRS).
Research Durrett's research spans probability theory and its applications. His early work focused on interacting particle systems, percolation theory, and contact processes, building on the frameworks developed by Thomas M. Liggett and Frank Spitzer. His 1980 paper with T. M. Liggett determined the shape of the limit set in Richardson's model for the spread of an infection.
Stochastic spatial models in ecology In the late 1980s Durrett began a long-running collaboration with the ecologist Simon Levin of Princeton University on stochastic spatial models in ecology. Their 1994 paper The Importance of Being Discrete (and Spatial) argued that spatial structure can qualitatively change the dynamics of ecological interactions and is among the most cited papers in mathematical ecology. Their subsequent papers studied species–area curves, allelopathy, interspecific competition, and the spread of epidemics using interacting particle systems and stochastic spatial models.
Population genetics and cancer Beginning in the late 1990s Durrett turned to population genetics, working with C. F. Aquadro and others on the evolutionary dynamics of microsatellite repeat length distributions and, with Jason Schweinsberg, on approximating selective sweeps by random partitions. His 2008 paper with Deena Schmidt, Waiting for two mutations, studied the limits of Darwinian evolution in regulatory sequence evolution. Durrett's later research has applied branching processes and stochastic models to cancer biology, including models of tumor heterogeneity, the evolution of resistance to therapy, and the dynamics of clonal expansion.
Random graphs A third strand of Durrett's work concerns stochastic processes on random graphs. He showed, with Shirshendu Chatterjee, that contact processes on random graphs with power-law degree distributions have critical value zero—meaning infection can survive for any positive infection rate. His 2010 Inaugural Article as a member of the National Academy of Sciences, published in the Proceedings of the National Academy of Sciences, examined the spread of epidemics and opinions on random graphs. This work is collected in part in his monograph Random Graph Dynamics (Cambridge University Press, 2007; second edition Springer, 2025).
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