During the nineteenth-century, numerous scientific studies had been conducted to search for scientific evidence about racism. From the late nineteenth century to early twentieth century, even though most of the cultural norms as well as standards for social hierarchies were still mainly constructed on patriarchal bias, the sexual inversion gradually changed into the model of homosexuality. Meanwhile, African American and white people had become more harshly segregated than ever (Somerville, 16). Along with those two major changes in sexuality and race, more and more discourses raised by sexologists, psychiatrists and medical scientists begun to focus on how racial segregation and sexual inversion reinforced and shaped each other. In “Scientific Racism an Invention of Homosexual Body,” Siobhan B. Somerville systematically discusses the intertwining relationship between race and various sexual orientations. This document also shows a variety of historical evidence that how medical knowledge was used to strengthen the purity of white women as well as the theory of eugenics by belittling biological differences of different races, and pathologizing the sexual inversion. Theory about deviant sexual inversion was first originated from the fear of the possible damages it would cause to the concept of “separate spheres” (Lecture, September 22). Early sexologists transferred the concept of sexual inversion from “sexual abnormality” to a medical disease. Even though Sigmund Freud once mentioned that “homosexuals” aren’t a separate group from psychoanalytic perspective, it still didn’t substitute the model of early sexologists (Somerville, 21). Aside from the report of sexologists, medical scientists also supported this theory by showing the differences heterosexual female and inverted women had in their shape of genitalia (Somerville, 28). However, this way of comparing heterosexual women and inverted women neglected individua