This week we report on the continuing debate about female ejaculation: is it real, and if so why does it happen?
Ejaculation is just one of the aspects of female sexuality that are being demystified by research. In particular, the female orgasm, the subject of so many myths and folk beliefs, is gradually being understood.
Following some intense field research, here are some of the key facts about the female orgasm, as revealed by modern science.
The G spot is real
The G spot is a small region in the vagina that, if stimulated, can produce wildly intense orgasms – or so the popular claim goes. However, for decades, strong evidence for the region's existence was harder to find than the spot itself.
However, in 2008, an Italian research team found anatomical differences between women who could have G-spot orgasms and women who couldn't; apparently solving the mystery. The researchers have since begun teaching women with G spots how to put them to use.
The brain switches off
It's folk wisdom that people can't think straight when they have sex on their minds, but when women have an orgasm most of their brains switch off.
A brain scanning study showed that many areas of women's brains were deactivated during orgasm, including those involved in emotion. The effect was less striking in men, but that may be because male orgasms are so short they are hard to detect in a brain scan.
Many women can't have orgasms
According to a 1999 survey, around 43 per cent of women in the US have some sort of problem with their sex lives (Journal of the American Medical Association, vol 281, page 537).
Female sexual dysfunction (FSD) is so common that the very idea that it is a medical disorder has come under attack. If nearly half the female population has a problem, say critics, does that mean it is our society that is dysfunctional?
Even so, efforts to develop drugs to treat it are underway. The impotence drug Viagra has had mixed results in women, but there are many other avenues being explored.
See: What women want
Genes affect orgasm frequency
According to the first genetic study of the female orgasm, up to 45 per cent of the variation in women's ability to have them could be down to genes.
Many women never have orgasms during intercourse, and some also cannot have them through masturbation. Some of this may be down to external factors like upbringing, but the study showed the genetic factor is significant.
Technology can help
Perhaps the most extreme solution is the so-called "orgasmatron"; an implant inserted into the spinal cord, which stimulates the user when switched on via a remote control.
Despite an initial struggle to find subjects for clinical testing, the device is now in development.
See: Push my button
Some mystery remains
The female orgasm is a puzzle for evolutionary biologists. It is unclear why women should have orgasms at all, and it is particularly baffling that so many women should be unable to have orgasms during penetrative sex, but able to have them by masturbation.
According to researcher Elisabeth Lloyd, that implies that female orgasms are an evolutionary accident. Like male nipples, they persist simply because there is no good reason to get rid of them.