It’s probably not something you want to discuss with your grandma on a Sunday afternoon, but evidence suggests that the powerful rhythmic contractions of the vagina during orgasm, help to retain sperm (link is external) and up-suck it into the cervix. This ultimately increases the likelihood of conception. The idea behind this is that female orgasm is another mechanism by which women can choose who they genetically combine with. An American study (link is external) suggests cunnilingus-assisted orgasms may actually be another way to help with sperm retention. Apparently, female orgasms that occur within 45 minutes of ejaculation help with retaining sperm.
#2. Symmetry is sexy
A physically symmetrical man is more likely than a non-symmetrical man to give a woman an orgasm (link is external). This follows on from the previous point. Although women can conceive without having an orgasm, it definitely helps (link is external). Symmetry indicates good genes. Men (and women) whose physical appearance is symmetrical (arms equal length, identical eyes etc.) have proven that they are able to withstand insults from the environment. The environment influences our development, and often in harmful ways. How much depends, to an extent, on our genetics. Think of the environment as an attacking army, and of your genetics as the shield you use to defend yourself. Symmetrical individuals are basically saying "My shield is so big and strong that you can’t hurt me." Physically asymmetrical individuals don’t have such a big "shield." A child whose father had a big "shield" is probably going to have a bigger ‘shield’ than someone whose father had a small "shield." Additionally, a study conducted in China found that female orgasm frequency increases when the male partner earns more (link is external).
#3. Women sometimes fake orgasms to win the devotion of their partners.
Everyone knows that women sometimes fake orgasms. Most of the time men don’t even know it (this might have something to do with the fact they are so caught up in their own experience). A recent American study (link is external) suggests that the female orgasm-fake may be a mate retention strategy. The study found that women who thought their partners might be playing around were more likely to report faking an orgasm. So in order to hang on to their man they pandered to his ego ("Honey, you’re so good in bed…").
#4. Major physiological changes take place during the female orgasm.
Don’t worry, all of these are temporary. During orgasm, the female hormonal profile changes quite markedly. The key change is the release of the hormone prolactin (also released during male orgasm.) Prolactin is secreted by the pituitary gland and has the primary function of helping with the production of milk (link is external). Additionally, the hormone oxytocin ("the love drug") is released when orgasms are achieved through clitoral stimulation. This hormone serves to regulate hormone level impairments caused by stress and/or menstruation. It also helps with child birth (link is external). A deficiency may lead to stress, obesity, and cognitive malfunctioning. In short, oxytocin is really good.
#5. Orgasms relieve pain
This might seem really obvious. There’s a reason that many doctors give out jelly beans to kids after they give them needles — in fact there are several, but one of them is as basic as "something good cancels out something bad." Positive stimuli also help to misdirect the person’s attention, helping them to forget about the bad thing that just happened. The benefits of orgasm are also physiological. Oxytocin also helps with bonding, relaxation and other emotional states. So if you have a headache, you may actually be better off having an orgasm than not having sex.
#6. Women can achieve orgasm WITHOUT ANY DIRECT STIMULATION!
This is not a myth. I guess most of us are familiar with the old cliché that "the most powerful sexual organ in the body is the brain." A lot of people undoubtedly subscribe to this idea. There is certainly a lot of truth in the statement that a big part of sex is psychological. For many of us (male or female), if you’re not in the mood it’s just not going to happen. Physical activity though, would seem to play a crucial role in the achievement of any kind of orgasm. Often vigorous physical activity is necessary for at least one partner. However, many women say they can ‘think themselves to orgasm’ (link is external). Such claims have received scientific validation from researchers looking at the sexual responses of spinal-cord injury patients (link is external).
#7. Time is of the essence
In keeping with the idea that women don’t always (or often?) achieve orgasm through sex, recent research conducted in Canada found that sex (excluding foreplay) on average lasts between three and seven minutes ("Canadian and American Sex Therapists' Perceptions of Normal and Abnormal Ejaculatory Latencies: How Long Should Intercourse Last?"), but both men and women report that they want it to be longer (link is external). Well-known sex therapist Barry McCarthy (link is external) suggests that it's pretty rare for continuous penetrative intercourse to go for longer than about 12 minutes. This is unfortunate since some estimates say it takes between 10 and 20 minutes for women to climax. Many women report that when it does occur it can last for more than 20 seconds!
#8. Orgasms get better with age
There are many reasons to want to maintain your youth. Medically, a number of things start to decline and/or decay as we get older. Orgasm frequency, however, is not one of them, at least for women. A study done in the United States found that among women, although older age was associated with lubrication problems, the likelihood of orgasm actually increased! This may or may not be due to the fact that the size of the clitoris increases as women age (link is external). Mixing things up in the bedroom also helps. Unfortunately, guys are more likely to suffer from pain, erectile dysfunction, and decreased orgasm frequency as they age (link is external).
#9. Orgasms aren’t the be all and end all, and that’s ok
Women don’t always orgasm (see above). Intimacy and closeness are an important part of sex. Although on average women don't orgasm as frequently as men, women can achieve them in a number of ways. In addition to #6 above, women have reported experiencing an orgasm from stimulation of the breasts or mouth (and obviously the clitoris), and even during sleep (link is external). Evidence for the existence of the (strictly) vaginal orgasm however, is questionable (link is external).
#10. No one knows why women orgasm
This statement might seem like privileged male propaganda, but the fact is that there is no well agreed upon explanation for the female orgasm. Accounting for the male orgasm is fairly straightforward — ejaculation is necessary for reproduction — but conception can occur in the absence of the female orgasm. In addition to some of the explanations that have been discussed previously in this article, scientists have speculated that it might just be a by-product of the male and female anatomy being similar (men have nipples). Evidence from twin studies is inconsistent with this theory however (link is external).