There are also alternative social theories for age differences in relationships as well as suggested reasons for 'alternative' age-hypogamous relationships.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. Relationships with age disparity of all kinds have been observed with both men and women as the older or younger partner.Although the "cougar" theme, in which older women date much younger men, is often portrayed in the media as a widespread and established facet of modern Western culture, at least one academic study has found the concept to be a "myth".A British psychological study published in Evolution and Human Behavior in 2010 concluded that men and women, in general, continued to follow traditional gender roles when searching for mates.Parental Investment Theory refers to the value that is placed on a potential mate based on reproductive potential and reproductive investment.The theory predicts that preferred mate choices have evolved to focus on reproductive potential and reproductive investment of members of the opposite sex.As the graph on the right shows, there is a lower limit and an upper limit.As age increases, they age range of potential non-creepy partners widens.
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).
An overarching evolutionary theory which can provide an explanation for the above mechanisms and strategies adopted by individuals which leads to age disparity in relationships is called Life History theory Life History theory posits that individuals have to divide energy and resources between activities (as energy and resources devoted to one task cannot be used for another task) and this is shaped by natural selection.
Another study also showed a higher divorce rate as the age difference rose for when either the woman was older or the man was older.
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.