Marc Breedlove

S. Marc Breedlove (born 1954 in Springfield, Missouri) is currently the Barnett Rosenberg professor of Neuroscience at Michigan State University in East Lansing, Michigan. He was formerly a professor of Psychology at the University of California, Berkeley from 1982-2002. He earned a Ph.D. in Psychology at UCLA in 1982 after getting a bachelor's degree in Psychology at Yale in 1976. He was born and raised in the Ozarks of southwestern Missouri. He works in the fields of Biological Psychology and Neuroendocrinology. In numerous papers, he has demonstrated that steroid hormones and sexual behavior affect the developing and adult spinal cord and brain. He has also found that lesbians have a more masculine digit ratio than straight women, a finding that has been replicated by many other labs and which indicates that lesbians, on average, are exposed to more prenatal testosterone than straight women. This finding joins many others that biological influences, such as prenatal testosterone and fraternal birth order, act before birth to affect the later unfolding of human sexual orientation. Copies of these papers, and others, can be obtained at his lab home page listed below. He is a member of the Society for Behavioral Neuroendocrinology and the Society for Neuroscience.