" Women past and present face the adaptive problem of choosing men who not only have the necessary resources but also show a willingness to commit those resources specifically to them. This problem may be more difficult than it seems at first. Although resources can often be directly observed, commitment cannot. Instead, gauging commitment requires looking for probabilistic cues. Love is one of the most important cues to commitment. "

― David M. Buss , The Evolution Of Desire: Strategies of Human Mating