Male chimpanzees tend to prefer older females than younger and it is suggested that specific cues of female mate value are very different to humans.
Buss attributed the young age preference for females to the cues that youth has.
A study conducted by David Buss investigated sex differences in mate preferences in 37 cultures with 10,047 participants.
In all 37 cultures it was found that males preferred females younger than themselves and females preferred males older than themselves.
Age-disparity relationships have been documented for most of recorded history and have been regarded with a wide range of attitudes dependant on sociocultural norms and legal systems.
Within sexual selection Darwin identified a further two mechanisms which are important factors in the evolution of sex differences (sexual dimorphism): intrasexual selection (involve competition with those of the same sex over access to mates) and intersexual choice (discriminative choice of mating partners).
This theory is directly relevant and compatible with the two already mentioned theories Life History and Parental Investment.