The study of human sexuality has been greatly influenced by trends in sociology, psychology and biology. Newer hybrid disciplines (such as sociobiology and evolutionary psychology) sharply highlight questions of human sexuality. In the early years of psychological inquiry, scholars and lay people depended heavily on the idea of sexual perversion. Any sexual behavior that did not fit into a narrow scope of socially acceptable activity was deemed a sickness. In many cases, the idea of perversion is no longer credible. One obsolete theory is that of female hysteria. Female hysteria was a 19th century medical diagnoses. Doctors treating female patients for what we now identify as depression and anxiety thought that their symptoms were due to sexual deprivation or perversion. They used sexual stimulation to “cure” their patients. We now know that women suffering from these conditions are better served through the same kinds of clinical treatments as benefit men. Scientists and researchers have also left behind the perversion model when explaining homosexuality, transgendered identity and a host of other sexual acts and expressions.