Peter Grant is the Class of 1877 Professor of Zoology Emeritus in the ecology and evolutionary biology department at Princeton. Together with his wife, Rosemary Grant, also emerita, he has spent his career seeking to understand the origin of new species, their ecological interactions, their persistence in different communities and their ultimate extinction. His current research focuses on hybridization, especially in understanding how an exchange of genes between species affects fitness-related traits, and how hybridization may have contributed to the origin and proliferation of species. He has written several books with his wife on the evolution of Darwin’s finches on the Galápagos islands.