 Fausto-Sterling addresses each of these assumptions in turn. She argues that science does not provide an objective account of biological sex, since science is a social and historical human activity and many of the ways of thinking about sexuality and sexual identity were guided by pre-existing conceptions of gender (also see the discussion of objectivity in  section 4.2).  As an illustration, she examines the gendered understanding of female sexuality as passive and the way that understanding influenced the design of experiments meant to test the effect of sex hormones on the sexual behavior of rats (Fausto-Sterling 2000: 195–232). These hormones were themselves classified as male and female, in spite their having other functions besides those related to reproduction and in spite of their presence in both those identified as male and those identified as female. The results of these experiments were in turn used to make claims about behavior and sex in humans. This move is problematically circular and additionally depends on analogical reasoning to human sexual behavior from the behavior of rats.