Last May, with considerable trepidation, I wrote an article about what seemed to be extraordinarily high rates of rape in Africa. The original data came from a study by South Africa's Medical Research Council in 2009 which found that more than a quarter of South African men - 27.6 per cent - admitted that they had committed rape. Almost half of those men had raped two or three women or girls. One in 13 had raped at least 10 victims.
Over the next couple of years, I ran across a couple of other less detailed studies suggesting that the problem was not just South African.
A report from the eastern Congo last year said more than a third of the men interviewed - 34 per cent - had committed rape, and an older report from Tanzania found that 20 per cent of the women interviewed said they had been raped (although only one 10th as many rapes were reported to the police).
So I wrote a piece called "An African Iceberg" in which I said this was a phenomenon that needed urgent investigation continent-wide - but it did occur to me to wonder if there were similar icebergs in other developing countries.
The only figures that were available for developing countries elsewhere were official ones, and those normally only record the number of women who tell the police they have been raped. Most don't.
Women are reluctant to report rape in any society, and in traditional societies much more so. The South African study was the only one that had adopted the strategy of asking men directly. Maybe if the same sort of study were done in other continents, I thought, it would return equally horrifying figures. And somebody else had the same thought, and the resources to do something about it.
The new report, conducted under the auspices of four United Nations agencies co-operating as "Partners for Prevention", was published last week in the online version of The Lancet Global Health, a respected British medical journal. The study was undertaken to learn if the South African figures were duplicated in developing countries outside Africa.
The researchers chose six countries in the Asia-Pacific region: China, Cambodia, Bangladesh, Sri Lanka, Indonesia and Papua New Guinea. As in the South African study, the word "rape" was not used in the questionnaire. The 10,178 men interviewed were asked if they had ever "forced a woman who was not your wife or girlfriend at the time to have sex" or "had sex with a woman who was too drunk or drugged to indicate whether she wanted it".
There were further questions about forcing a wife or girlfriend to have sex (which is also rape), about gang rape, and about raping males, but let us stick with the questions about what the researchers called "single perpetrator rape" of a woman who was neither wife nor girlfriend. The answers varied, but the overall picture was clear. Africa (or at least South Africa) is all alone out there.
In most of the Asian countries involved in the study, between 2 and 4 per cent of the men interviewed said they had raped a "non-partner" woman. That falls into the same range that prevails, one suspects, in most developed countries (although their reported cases of rape are much lower).
There were some local peculiarities, like the fact that in rural Bangladesh men are more likely to get raped than women. China came in high, with 6 per cent of the men interviewed admitting to rape, but that may be related to the growing surplus of males in a society where the gender ratio has become very skewed: there are 99 large Chinese cities where more than 125 boys are born for every 100 girls.
But Papua New Guinea was right up there with South Africa: 26.6 per cent of the men interviewed had committed "single perpetrator rape" of a non-partner woman. The other numbers were as startling: 14 per cent of PNG men had participated in a gang rape, and 7.7 per cent had raped a man or boy. So Asia as a whole is different from Africa on this count - but PNG is practically identical.
What is so special about PNG? It is a country with an extravagantly large number of different tribes and languages. It is an extremely violent country, where most people live in extreme poverty. It is a place where the law is enforced only sporadically, and often corruptly. And it is a place where traditional tribal values, patriarchal to the core, reign virtually unchallenged among a large part of the population. Remind you of anywhere?
Well, you already suspected that this was at the root of it, didn't you? You just didn't want to say so, for fear of being accused of being racist, anti-African or something of that sort.
But it does need to be said, loudly and repeatedly. Women and girls are more likely to be the victims of sexual violence in Africa than almost anywhere else, and the only way to change that is to change the behaviour of African men. By persuasion if possible, but also by enforcing the law.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries.