Evolutionary explanations of human behavior have produced many new insights, but also much resistance. This essay examines 2 books on sex differences written with very different approaches. Rosemary Hopcroft's Evolution and Gender argues that men and women can be both equal and different and that average biological differences between the sexes, which are often small, do not threaten the ideal of political equality. In Hopcroft's view, understanding these differences with the help of evolutionary theory is a condition for the realization of equality, not an obstacle. Saini's Inferior depicts an opposition between an ‘old science’, portraying sex differences as immense, and a ‘new science’, with most sex differences being so small that they cannot possibly account for social trends. While Evolution and Gender gives a concise and representative view of current evolutionary research on sex differences, Inferior claims that obsessions pervade entire research areas. Evolution and Gender has a careful tone, while Inferior often emphasizes the allegedly ‘controversial’ nature of studies. The essay ends with reflections on how to best communicate the results of evolutionary psychology to the public.