  Feminists have also been critical of tendencies to view nature in terms of sexualized dichotomies. This is evidenced in Anne Fausto-Sterling's research on sexuality and intersexed individuals (2000). She shows that biology and medicine, literally, surgically construct intersexed individuals to fit more closely into either one gender or the other. Feminist philosophers of biology have been particularly vigilant in pointing out the problems with the association of sexual dichotomies with male activity and female passivity. This is supported by analyses, discussed above, of how the narrative of the sleeping egg being awakened by the sperm distorted our understanding of fertilization. There has also been work along these lines in analyses of developmental biology in which it is assumed that embryos develop along a female path by default unless a gene of the Y chromosome switches on the male pattern of development (Gilbert and Rader 2001, Richardson 2008). Finally, there is significant non-feminist work on pluralism in the philosophy of biology (for example Dupré 1993, Kellert et al 2006, Fehr 2006).