Hamilton O. Smith, MD, FAACR, a microbiologist who shared the Nobel Prize for Medicine or Physiology in 1978 for the discovery of enzymes that serve as “scissors” for reliably cutting DNA, died October 25, 2025. He was 94 years old.
Smith shared the Nobel with Werner Arber and Daniel Nathans, who had already studied restriction enzymes that cut DNA molecules at random locations. Smith and his colleagues discovered enzymes that cleaved molecules at specific sites, making them valuable tools in DNA technology.
Born in New York City in 1931, Smith attended University High School in Urbana, Illinois, where his father was on the faculty of the University of Illinois. Smith started at that university but transferred to the University of California at Berkeley, graduating with a bachelor’s degree in mathematics.
He obtained a medical degree from the Johns Hopkins University Medical School in 1956, followed by internship at Barnes Hospital in St. Louis. After fulfilling a two-year service obligation in the U.S. Navy, he had medical residency training at the Henry Ford Hospital in Detroit. In 1962, he began a fellowship in genetics at the University of Michigan in Ann Arbor.
He joined Johns Hopkins University as an assistant professor of microbiology in 1967, became a professor in 1973, and served for a time as director of the Department of Molecular Biology and Genetics.
In 1998, Smith Joined Celera Genomics. He became scientific director at the Institute for Biological Energy Alternatives (IBEA) in Maryland in 2002. In 2006, IBEA merged with other groups to form the J. Craig Venter Institute, where he became leader of the synthetic biology and bioenergy research group.
He was elected as a Fellow of the AACR Academy in 2022.