Men dating women 20 years younger
In August 2010, Michael Dunn of the University of Wales Institute, Cardiff completed and released the results of a study on age disparity in dating.
Dunn concluded that "Not once across all ages and countries ...
As well as asking participants a number of questions on mate selection criteria, they also had to provide the oldest and youngest partner they would accept.
It was found that for all ages males were willing to accept females that are slightly older than they are (on average 4.5 years older), but they accept females considerably younger than their own age (on average 10 years younger).
The rational choice model suggests that people look for partners who can provide for them in their life (bread-winners); as men traditionally earn more as they get older, women will therefore prefer older men.
One of the concerns of relationships with age disparities in some cultures is a perceived difference between people of different age ranges.
This is somewhat different to our close evolutionary relatives: chimpanzees.
The study found very few instances of older women pursuing much younger men and vice versa.
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).
These two theories explain why natural and sexual selection acts slightly differently on the two sexes so that they display different preferences.
For example, different age preferences may be a result of sex differences in mate values assigned to the opposite sex at those ages.
The theory predicts that preferred mate choices have evolved to focus on reproductive potential and reproductive investment of members of the opposite sex.