51动漫

A couple of weeks ago we ran a review of 鈥榮 latest book, Bonk: The curious coupling of science and sex, in which Roach explains how scientists have tackled human sexuality using strange and often hilarious experiments. We invited readers to send in their sex questions for Mary Roach, and you can read a selection of the Q&As below.

Does the female orgasm serve a biological purpose?

A few years back, a biologist at Indiana University, , devoted an entire book to this question called The Case of the Female Orgasm. She evaluated ten theories purporting to explain the evolutionary function of female orgasm, and found all of them lacking. Her conclusion: female orgasm belongs in the same file with male nipples. Male and female embryos start out with the same equipment, and then part ways. Men are left with nonfunctioning breasts; women are left with nonfunctioning penises. Not everyone agrees with her, however. You鈥檙e welcome to refer to a .

I am a happily married woman. However, I like to masturbate once in a while because I am able to give myself multiple orgasms. After having the 鈥渞eal鈥� orgasm, I can have 10-15 鈥渟mall鈥� ones. To have these, I do not really need to entertain sexual fantasies 鈥� even thinking about eating chocolate can give me one. As a scientist, this situation makes me extremely curious. Is this a rare condition? How can I have orgasms by just thinking 鈥渘ice, happy鈥� things?

Orgasm is a reflex of the that is triggered by a delightful variety and/or combination of stimuli. once interviewed a woman who could be brought to orgasm by stroking her eyebrows. In my research I found a case study of a woman who had an orgasm each time she brushed her teeth (followed by a mild epileptic seizure). and , researchers at Rutgers University, have studied a dozen or so women who can 鈥渢hink鈥� themselves to orgasm. Some use imagery, some use breathing techniques. The woman I met who could do it (she demonstrated her skill for me on a bench outside a sushi bar in Oakland, California) had taught herself using imagery and breathing skills learned in a weekend workshop given by sex educator Annie Sprinkle. It took her two years to master the technique.

It is fairly common for women, once they鈥檝e had an orgasm, to be able to bring themselves quite easily and quickly to a succession of smaller 鈥渁ftershocks鈥� (especially with the help of a vibrator.) This is true not only for orgasms obtained through masturbation but also through intercourse. To be able to do this just by thinking about chocolate, however, is, as far as I know, a rare and delightful talent!

When and why did humans switch from the standard mammalian estrous cycle to being continuously sexually minded? Does this relate to the fact that women鈥檚 breasts are permanently enlarged, rather than only during lactation as with other mammals?

Humans, unlike many other mammals, have 鈥渃oncealed ovulation鈥� 鈥� that is, males cannot tell at a glance whether females are ovulating or not. Human female reproductive and sexual organs don鈥檛 swell, as they do in other primates, advertising their fertility 鈥� so yes, the breasts are related. One school of thought holds that this permanent swelling adapted to help increase the likelihood of pair bonding. In order to be sure he鈥檚 spreading his seed, the male needs to stick around for at least 30 days. The hope, from an evolutionary perspective, is that he鈥檒l bond with the female during that time.

Is there an evolutionary advantage to the female hymen and do any other animals exhibit a tissue with similar function?

theorized that since breaking the hymen is painful, the membrane is nature鈥檚 way of making sure young women don鈥檛 enter into a sexual relationship lightly, thus squandering their genetic material upon a union with some cad who isn鈥檛 likely to stick around to help raise the child. There are, however, two problems with this notion.

First, it鈥檚 not all that painful. Studies suggest that as few as 30% of women report bleeding, suggesting that the hymen is often not torn at all, but simply stretched. Second, we would then have to assume that the hymen served the same purpose in horses, whales, moles, hyenas and the many other mammals that have them. This seems unlikely. Short answer: no-one knows what they鈥檙e for.

At what age does the average human stop having sex?

According to researcher at the University of Texas, Austin鈥檚 , there鈥檚 very little data on people over the age of 60. Older people are less likely to have partners, and thus it鈥檚 hard to discern whether it鈥檚 a lack of desire/interest or simply the fact that they don鈥檛 have a partner.

Are there any 鈥渁naphrodisiacs鈥� 鈥� substances which might be the opposite of aphrodisiacs? I鈥檝e heard that saltpetre might work, but that sounds like an old wives tale.

Anything that lowers testosterone (so anything that has a negative impact on serotonin or dopamine) will lower one鈥檚 libido.

Has anal sex always been a popular pursuit as it is today, or has its popularity been artificially boosted by the porn industry? Is anal sex physiologically pleasurable or is the pleasure all social/psychological?

I believe that men have always enjoyed being on the giving end of anal sex simply because it鈥檚 a tighter squeeze. As for being on the receiving end, men obtain pleasure from it because it stimulates their prostate gland. Women have only a vestigial prostate gland, thus it鈥檚 not the same sort of pleasure for them.

Does circumcision make it harder for a man to have an orgasm?

Some argue that, yes, removing part of the foreskin removes a bunch of nerve endings and lowers sensitivity but others say no. This is a hotly and endlessly debated topic.

After a male has ejaculated, how long does it take for the scrotum to refill with semen?

The time is hugely variable. Like the , this amount of time gets longer with age.