Samuel Jackson Holmes (March 7, 1868 – March 5, 1964) was an American zoologist and eugenicist. He was a professor at the University of California, Berkeley (UC-Berkeley) for 27 years. Noted as a genetics pioneer, and for his studies of animal behavior, heredity, and evolution. Over the course of his career he migrated from studying animals to humans, taking the behaviors and traits learned in the former and looking for them in the later.
After attending Chaffey College in Ontario, California, he obtained his Bachelor of Science (1893) and Master of Science (1895) from the UC-Berkeley. His biological research at Berkeley earned him a fellowship to the University of Chicago in 1895, where he received his Ph.D in 1897.
After teaching at San Diego High School for the academic year 1897–1898, between 1898 and 1906 he was an instructor of zoology at the University of Michigan. From there he moved to the Stevens Point Normal School (University of Wisconsin–Stevens Point), 1906 to 1912. In 1912 he returned to UC-Berkeley as an associate professor, and then in 1916 was promoted to full professor. He was named faculty research lecturer in 1929. He retired in 1939 but continued on as professor emeritus until his death in 1964.
Holmes was a vocal proponent of eugenics, particularly in reference to immigration to the United States from Mexico and parts of Asia. In 1925, at a major conference on race relations along the Pacific Coast at Stanford University, Holmes told an audience of social scientists and public officials that, “the Mexican problem is by far the greatest race problem which confronts the people of California at the present time. .. We are in a considerable amount of trouble before we see the amicable adjustment of the whole Mexican situation. The Mexican problem urgently needs to be studied very thoroughly.” His later work advocated for the sterilization of citizens and immigrants who might diminish the genetic quality of America. He was one of the original incorporators of the Human Betterment Foundation,