Harry Harlow, an American psychologist, conducted groundbreaking research on social isolation and maternal deprivation in primates. His work revolutionized our understanding of attachment and provided evidence for prioritizing psychological over biological parenthood. Harlow's experiments with rhesus monkeys and cloth and wire mothers were considered "classic" in behavioral science. He argued that love and comfort were non-physical needs and his attachment theory postulated the developmental risks of adoption. Despite criticisms for his experiments being cruel, Harlow's work greatly contributed to the field of psychology and he was recognized as a leading figure in the 20th century. He received his BA and PhD in psychology from Stanford University and joined the faculty at the University of Wisconsin in 1930.