South African rape survey shock
One in four South African men questioned in a survey said they had raped someone and nearly half admitted having attacked more than one victim.
The study, by the country's Medical Research Council, also found three out of four who admitted rape attacked for the first time while in their teens.
It said practices such as gang rape were common because they were considered a form of male bonding.
The MRC spoke to 1,738 men in KwaZulu-Natal and Eastern Cape provinces.
The research was conducted in both rural and urban areas and included all racial groups.
Using an electronic device to keep the results anonymous, the study found that 73% of respondents said they had carried out their first assault before the age of 20.
Almost half who said they had carried out a rape admitted they had done so more than once.
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One in 20 men surveyed said they had raped a woman or girl in the last year.
Professor Rachel Jewkes of the MRC, who carried out the research, told the BBC's World Today programme: "The absolute imperative is we have to change the underlying social attitudes that in a way have created a norm that coercing women into sex is on some level acceptable.
"We know that we have a higher prevalence of rape in South Africa than there is in other countries.
"And it's partly rooted in our incredibly disturbed past and the way that South African men over the centuries have been socialised into forms of masculinity that are predicated on the idea of being strong and tough and the use of force to assert dominance and control over women, as well as other men."
She added that all the victims in the main survey were said to be women, but participants were also interviewed about male rape.
'Sad state of affairs'
The study found that one in 10 men said they had been raped by other men.
I don't think it's cultural per se; I think it has to do with how a lot of us men worldwide were raised
South African Men's Forum
Some 3% of the men interviewed said they had coerced a man or a boy into sex.
The participants were also tested for HIV and the authors of the survey were surprised that men who had raped were not more likely to test positive for the virus.
Mbuyiselo Botha, from the South African Men's Forum, which campaigns for women's rights, told the BBC's Focus on Africa programme that any view of women as "fair game" had to be challenged.
Mr Botha, a father of two girls himself, said: "I think that yes, the figures are that high and for us, for me in particular, that is a very sad state of affairs.
"It means that we continue in South Africa to be one of the highest capitals of rape in the world.
"I don't think it's cultural per se; I think it has to do with how a lot of us men worldwide were raised. The issues of dominance against women, issues of inequality, are pervasive and you find them throughout the world."
South Africa's government has been repeatedly criticised for failing to address the country's rape epidemic.
A recent trade union report said a child was being raped in South Africa every three minutes with the vast majority of those cases going unreported.
un fuckin believable...sounds like a fun place to visit with the world cup coming and all