Age-disparate relationships have been documented for most of recorded history and have been regarded with a wide range of attitudes dependent on sociocultural norms and legal systems.A study released in 2003 by the UK's Office for National Statistics concluded that the proportion of women in England and Wales marrying younger men rose from 15% to 26% between 1963 and 1998.[17][18] 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.[19] A 2011 study suggested that marriage of younger men by women is positively correlated with decreased longevity, particularly for the woman, though married individuals generally still have longer lifespans than singles.[24] Although the "cougar" trend, 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.[42] In contrast to above, in short-term mating, females will tend to favour males that demonstrate physical attractiveness, as this displays cues of "good genes".In some countries in Europe such as France, Netherlands, United Kingdom, Norway, Estonia, Finland and Denmark, 20–30% of women aged 20–34 are cohabiting as opposed to legally marrying.[56] In regions such as the Caribbean and Latin America there is a lower SMAM difference than expected; however, there are also a large proportion of partners living in consensual unions; 24% in Brazil, 20% in Nicaragua and 18% in Dominican Republic.[57] A 2011 study suggested that age disparity in marriage is positively correlated with decreased longevity, particularly for women, though married people still have longer lifespans than singles.[20] Social structural origin theory argues that the underlying cause of sex-differentiated behaviour is the concentration of men and women in differing roles in society.[58] In a Brown University study, it has been noted that the social structure of a country determines the age difference between spouses more than any other factor, challenging evolutionary explanations.[59] In regard to mate selection, social structural theory supports the idea that individuals aim to maximise what they can provide in the relationship in an environment that is limiting their utilities through expected gender roles in society and marriage.[64][66][67][68][69] Slang terms such as "cougar" have been used in films, TV shows and the media to depict older females with younger male mates.The picture often displays a stereotypical pairing of a divorced, middle-aged, white, affluent female dating a younger male with the relationship taking the form of a non-commitment arrangement between the partners.[74] However, more recent evidence has found that women belonging to racial categories besides African American or White were more likely to sleep with younger men,[64] showing that it is still unclear which, if any, ethnic groups are more likely to have age-hypogamous relationships.[76][77] Similarly, a 2023 study found that women with younger male partners scored higher in emotional intelligence, sexual self-efficacy, and subjective happiness.[86] In many early sources, the rule was primarily presented as a formula to calculate the ideal age of a female partner at the beginning of a relationship."[88] A similar interpretation is also present in the 1951 play The Moon Is Blue by F. Hugh Herbert: "Haven't you ever heard that the girl is supposed to be half the man's age, plus seven?For example, in John Fox Jr.'s aforementioned 1903 novel The Little Shepherd of Kingdom Come, the rule is cited immediately before a woman is described as being "too young [for her potential partner], and she can wait.[97][98] An attractive younger woman pursued by a wealthy man who is perceived as wanting her only for her appearance or as a status symbol may be called a trophy wife.[101] In the latter case, the term trophy is broadened to include any substantial difference in power originating from physical appearance, wealth, or status.[citation needed] Where the primary perceived reason for a relationship with a significant age difference is sexual, many gender-specific terms have become popular in English-speaking cultures.If the woman is extremely young, the man may be labelled a cradle-snatcher (UK)[109] or cradle robber (US)[110][111] In gay slang, the term chickenhawk may be used.[112] If the much-younger target of affections is not of the legal age of consent or appears as such, the term jailbait may be applied to them, cautioning older partners against involvement.