If men in our evolutionary past did not invest in offspring, they would not have evolved strict mate preferences and thus women would be as drab as peahens. The fact that women are not as drab as peahens suggests a long history of male mate choice, which in turn suggests a long history of pair bonding and high male parental investment.

(p. 149) - The Ape that Thought It Was a Peacock: Does Evolutionary Psychology Exaggerate Human Sex Differences? (2013)