Actually, it's recently been researched by behavioral scientist trying to understand social issues with homosexuality in modern culture and the connection to the social stigma with the concept of femininity. Socially, once boys hit a certain age, it is no longer acceptable for them to find physical comfort in each others' presence without it being sneered upon as 'weak', 'girly', or, most commonly, 'gay'.
The same behavior - Hugs, hand holding, close physical contact - is considered perfectly acceptable and is seen as normal for females.
Therefore, to anchor their masculinity while compensating for the physical interacting their natural instincts crave, males turn it into a joke, a game, or a challenge, therefore muting the 'affection' of the interaction.
Basically, with the birth of tough heroes such as the John Wayne Cowboy and other brawny lonewolf idols, the fear of being feminine made guys stop physically interacting in affectionate ways and that has, over the decades, translated into a fear of being seen as 'gay', leading to many of the 'games' guys currently play.
If the concept interests you, I would suggest C.J. Pascoe's Book 'Dude, You're a Fag Masculinity and Sexuality in High School'.