Tomorrow, as you are almost certainly aware, is Valentine's Day. For some of us, this a particularly blissful time of year. For others it's one that calls for intense cynicism. But regardless of your stance on Valentine's Day, there's no way to avoid being bombarded with romantic imagery. So you might as well take this as an opportunity to learn something new.
With that in mind, here are ten things you probably didn't know about sex, love and lust. Who knows? Maybe you can use one of these to impress your valentine — in fact, some of these could probably even be crafted into clever pickup lines.
10) You can break a penis
There are no bones in the penis, but it can, in fact, become "broken." Doctors refer to the injury as a "penile fracture," and it's every bit as harrowing as you'd imagine. (All right, so if you're going with the whole pickup line angle, you might not want to start with this one.)
"[Penile fracture] is a severe form of bending injury to the erect penis that occurs when a membrane called the tunica albuginea tears," explains Hunter Wessells — chair of the urology department at the University of Washington School of Medicine. He continues:
The tunica albuginea surrounds the corpora cavernosa, specialized spongy tissue in the core of the penis that fills up with blood during an erection. When the tunica albuginea tears, the blood that is normally confined to this space leaks out into other tissues. You get bruising and swelling.
So how does a penis actually, you know, break? According to Wessels, any form of vigorous intercourse when the penis is rammed into a solid structure... "during sexual acrobatics," for instance.
"We had this patient who suffered penile fracture after running across the room and trying to penetrate his wife with a flying leap," he says.
9) Ovulating strippers make more money
In 2007, researchers at the University of New Mexico recorded a surprising correlation between strippers' ovulatory cycles and their tip earnings. Strippers who were ovulating (and thus most likely to conceive) averaged $70 per hour in tips. Those who were menstruating, and those who were neither menstruating nor ovulating, pulled in $35 and $50, respectively. One hypothesis for this strange observation is that men are, subconsciously, more inclined to tip a woman who they believe they have a better chance of producing a child with.
8) Women can smell genetic incompatibility
How a strip club attendee could possibly differentiate between a woman who is ovulating and another who isn't is not entirely clear. While this distinction is almost certainly made subconsciously, studies suggest that one of the most likely explanations is the effect of scent-signaling chemicals called pheromones.
Pheromones are hypothesized to do more than inspire liberal tipping habits; they're also believed to alert both sexes of potential genetic compatibility. The genes that comprise your major histocompatibility complex (MHC) play an important role in regulating your body's immune response — most notably in determining compatibility of donors for organ transplant. Some data have shown that the more dissimilar a man and woman's MHC are, the more likely they are to bring a child to term — but even more interesting is that women are thought to be capable of actually smelling this genetic differences.
In a study led by Claus Wedekind at the University of Bern in Switzerland, women were asked to smell T-shirts that had been worn by anonymous men for two nights and choose ones which appealed to them. According to the researchers, the women consistently preferred the odors of shirts worn by men with dissimilar MHCs.
7) Birth control could mess with a woman's ability to assess a mate
In the study conducted by Wedekind and his colleagues, the womens' preference for men of dissimilar MHCs was actually reversed when the women rating the odors were taking oral contraceptives.
6) Fat men last longer in bed
The relationship between obesity and sexual health is sort of a mixed bag. On one hand, obesity is associated with erectile dysfunction; on the other, studies like this one — published in 2010 in the International Journal of Impotence Research: The Journal of Sexual Medicine — suggest that the fatter a man is, the less likely he is to suffer from premature ejaculation. In fact, men with a higher body mass index (BMI), were able to make love for an average of 7.3 minutes, while slimmer test subjects averaged 1.8 minutes.
So what's the secret behind those extra five and a half minutes? Men with excess fat also pack higher levels of the female sex hormone estradiol. One hypothesis is that this substance interferes with the the body's ability to achieve orgasm... at least for a few minutes.
5) The seven year itch may not be a myth
Originally made famous in the 1955 film by the same name, the phrase "seven-year-itch" is used to describe the tendency for someone to become unsatisfied with their partner or marriage after a period of seven years, at which point they may feel an urge to move on.
If you're measuring by way of divorce, the myth of the seven year itch may not be a myth after all; according to the 2009 U.S. Census Bureau, the median duration of first marriages that end in divorce is 7.9 years.
4) We will actively avoid temptation
Even if the seven year itch is real, evidence also suggests that men and women will actually avert their attention from tempting alternatives to their partners — even if this aversion is subconscious.
In a study published in 2008, psychologist Jon K. Maner showed male and female test subjects pictures of faces on a computer screen for half a second, followed immediately by a circle or square on some other region of the computer screen, which they were asked to identify by pressing a corresponding keyboard key as quickly and accurately as possible.
The results show that the gazes of single, heterosexual men and women were liable to linger on photographs of attractive members of the opposite sex, in what the researchers refer to as a high level of "attentional adhesion." But the test subjects who were already in relationships reacted differently, and actually looked away from attractive faces more quickly; in fact, some test participants in relationships turned their attention away from "attractive" members of the opposite sex more quickly than they did from "average" looking faces.
3) Masturbation starts in utero
Those of you flying solo on Valentines day should know that masturbation is nothing to be ashamed of — in fact, there's a good chance you've been practicing it since you were in the womb. What you see here is a sonographic image from a paper titled "Sonographic observation of in utero fetal 'masturbation.'" In the image on the left, the baby's hand can be seen hovering above the penis. In the image on the right, the yellow arrow shows the hand engaged in what researcher Israel Meizner describes as "the hand grasping the penis in a fashion resembling masturbation movement."
"Bear in mind," explains Mary Roach — author of Bonk: The Curious Coupling of Science and Sex — at her TED talk on things you didn't know about orgasms, "this was an ultrasound, so [Meizner would have observed] moving images." [figure by Meizner et al via TED]
2) There's more to the clitoris than you probably realize
If you picture a clitoris in your mind, there's a good chance that what you're imagining is actually the tip of a bigger, internal clitoral iceberg — a sexual organ that is much larger than the sensitive bundle of nerve endings on the outside of the body (the tiny part of this diagram which is labeled as "Glans") would lead you to believe.
We covered the enigmatic clitoris in greater detail here but the upshot is that prior to the late 90s, researchers had never studied the internal structure of an excited clitoris. In fact, it wasn't until 2009 that scientists produced the first 3D sonography of a stimulated clitoris. The sexual organ is depicted here in its excited state in an illustration by the Museum of Sex Blog's Ms. M, which she drew for this fascinating post on the internal clitoris. Do yourself a favor and go educate yourself.