Francisco José Ayala Pereda (1934-2023) was a Spanish-American biologist and philosopher at the University of California, Irvine. He is known for his research on population and evolutionary genetics.

Ayala was a former Dominican priest, ordained in 1960, but left the priesthood that same year. After graduating from the University of Salamanca, he moved to the US in 1961 to study for a PhD at Columbia University. There, he studied for his doctorate under Theodosius Dobzhansky, graduating in 1964. He became a US citizen in 1971.

He had been President and Chairman of the Board of the American Association for the Advancement of Science. At University of California, Irvine, his academic appointments included University Professor and Donald Bren Professor of Biological Sciences, Ecology & Evolutionary Biology (School of Biological Sciences), Professor of Philosophy, (School of Humanities), and Professor of Logic and the Philosophy of Science (School of Social Sciences).

His discoveries have opened up new approaches to the prevention and treatment of malaria and diseases that affect hundreds of millions of individuals worldwide, including demonstrating that the reproduction of parasitic protozoa, such as Trypanosoma cruzi, the agent of Chagas disease, is mostly the product of cloning, and that only a few clones of T. cruzi account for most of this widespread, mostly untreatable South American disease that affects 16 million to 18 million people.

Ayala is the winner of the following awards: 2017 Dean’s Award for Distinguished Achievement, Graduate School of Arts and Sciences, Columbia University, 2017 Blaise Pascal Medal for Life Sciences, European Academy of Sciences, and a Fellow at The European Academy of Sciences.

He wrote often about philosophical questions related to biology, about ethics, and about the perceived conflict between science and religion.