In the "Descent of Man", Darwin wrote that by choosing tools and weapons over the years, "man has ultimately become superior to woman", but Blackwell's argument for women's equality went largely ignored until the 1970s when feminist scientists and historians began to explore Darwin. As recently as 2004, Griet Vandermassen, aligned with other Darwinian feminists of the 1990s and early 2000s (decade), wrote that a unifying theory of human nature should include sexual selection. But then the "opposite ongoing integration" was promoted by another faction as an alternative in 2007. Nonetheless, Darwin's explanation of sexual selection continues to receive support from both social and biological scientists as "the best explanation to date".