Can older males deliver the good genes?

Females of many species choose to mate with old rather than young males, po ssibly because older males pass superior genes on to their offspring. Recen t theoretical and empirical investigations have rejuvenated interest in the evolution of mating preferences based on age, and in the relationship betw een longevity and fitness. If the cost of signalling is a reduction in futu re survival and reproduction, mate choice based on age is one possible outc ome when males signal their genetic quality. These recent investigations hi ghlight the importance of understanding sexual selection from a life-histor y perspective.