University students now see nothing wrong with showing friendship to another man through a kiss on the lips.
Heterosexual male students are more comfortable kissing their friends than ever before, researchers say.
Researchers at the University of Bath found that 89 per cent of white undergraduate men at two UK universities and one sixth form college said they were happy to kiss another man on the lips through friendship.
They found that 36 per cent of respondents had also engaged in sustained kissing, initially for shock value, but now they occurred just for "a laugh".
Daniel Eagles, an undergraduate at University of Bath, said he did not have a problem with kissing his male friends.
He said: "I am comfortable to kiss my friends in situations such as their birthday or when someone scored a goal or just if we are having a laugh.
"Physical contact with your friends helps to bring you closer. I have been in a relationship with my girlfriend for more than a year and she doesn't think anything of it when I kiss my guy friends."
Dr Eric Anderson, from the university's department of education, said: "Heterosexual men kissing each other in friendship is an offshoot of what happens when homophobia is reduced.
"At these universities, overt homophobia has reduced to near extinction, permitting those men to engage in behaviour that was once taboo.
"Men are kissing each other in university clubs and pubs, in front of their peers, and for many it serves as an occasional, exuberant greeting or banter when partying.
"The kiss is a sign of affection in student social spaces, a sign of victory on the pitch, or celebration at a nightclub but it does not have a sexual connotation in any of these spaces.
"It seems generally younger people are becoming more and more open minded with each generation."
PhD sociology student Adi Adams, who helped Dr Anderson with the research, said: "We noticed that more and more men were kissing each other in clubs or after scoring a goal as a form of celebration, and many would put pictures of themselves kissing their friends on Facebook.
"We then began our research and realised that the way men tell each other that one has made it into their circle of close friends is to kiss.
"In this respect, men are catching up with women who regularly use a kiss as a sign of affection to a female friend."
Adi, who is heterosexual, added: "My first experience of kissing a man was at uni and I was a bit taken aback, but now it feels like a normal act of friendship.
"It doesn't feel that it threatens my masculinity or heterosexuality - instead it is becoming part of acceptable masculinity and heterosexuality."
Dr Anderson's research is published online in the journal, Archives of Sexual Behaviour.
He is now expanding his research to see how these attitudes are affected by race and social class.
