Data from: Darwinian sex roles confirmed across the animal kingdom

Since Darwin’s conception of sexual selection theory, scientists have
struggled to identify the evolutionary forces underlying the pervasive
differences between male and female behavior, morphology, and physiology.
The Darwin-Bateman paradigm predicts that anisogamy imposes stronger
sexual selection on males, which, in turn, drives the evolution of
conventional sex roles in terms of female-biased parental care and
male-biased sexual dimorphism. Although this paradigm forms the
cornerstone of modern sexual selection theory, it still remains untested
across the animal tree of life. This lack of evidence has promoted the
rise of alternative hypotheses arguing that sex differences are entirely
driven by environmental factors or chance. We demonstrate that, across the
animal kingdom, sexual selection, as captured by standard Bateman metrics,
is indeed stronger in males than in females and that it is evolutionarily
tied to sex biases in parental care and sexual dimorphism. Our findings
provide the first comprehensive evidence that Darwin’s concept of
conventional sex roles is accurate and refute recent criticism of sexual
selection theory.