The Scientific Reasoning Behind Our Strange Sex Practices

Let's face it, the very act of sex is weird. And gross. And the reason you exist. And the driving force behind the world's technology. Human beings have developed some very strange habits, and it's easy to look at something like, say, nasolingusts (nose lickers) and wonder, simply: why? But the science behind bedroom practices is actually fascinating.

The oft-repeated "Rule 34" states that for every action there is an equal and opposite adult version of that somewhere on the internet. If that's so, then Rule 35 states that for every quirk and preference, there is also a team of scientists studying that exact quirk in a lab.

We've come a long way since the days of Alfred Kinsey and this article looks at all the best guesses about what's happening down there from top biologists, psychologists, sociologists, and...ahem..."professionals." After examining the science of getting it on, it turns out our practices may not be so strange after all. There's generally a very reasonable scientific rationale behind why you like what you like. 

Photo: Gabriel S. Delgado C. / Flickr / CC BY 2.0

  • We Kiss To Ensure Our Mates Are Capable Of Raising Children

    According to Smithsonian philematologists (scientists who study kissing), when people kiss, we exchange nine milliliters of water, 0.7 milligrams of protein, 0.71 mg of fats... and somewhere between 10 million to one billion bacteria. So why do it? Why expose yourself to the risks of orifice-to-orifice contact, which may include disease, infection, or bad breath?

    Well... science is still working on finding out. The most likely explanation seems to be that kissing is a strategy for testing a potential mate's genetic code.

    The idea is that if a partner tastes bad to you, you care less about what they had for lunch and more about detecting major histocompatibility complex (MCH) genes. Humans are capable of tasting and even smelling MHC genes, which can indicate just the right amount of biodiversity in order to optimize your chances at having a healthy baby. 

    So maybe Betty Everett was more right than she knew when she sang "it's in his kiss."

  • A Fixation On Breasts Is Indicative Of A Desire To Find A Reproductively Viable Mate

    To say that humans have historically displayed an interest in breasts is perhaps a bit of an understatement. The question, however, is "Why?" Why do these seemingly innocuous deposits of fat above the pectoral muscles hold such sway?

    The prevailing theory is that breasts are a good indicator of fertility and reproductive health. They draw attention to the fact that the bearer of said mammary presence is of a child-bearing age, that she is nutritionally advantaged, and perhaps even suggests elements of her reproductive cycle. 

    Another theory is that breast fetish is just another case of partialism (a fetish that applies only to a specific body part). People associate breastfeeding with pleasure at an early age, and that flood of feel-good chemicals becomes associated with this part of the body. 

  • Member Size Is Only Important in Relation to Physical Compatibility

    Okay, the results are in and we can conclusively say that in the case of the "size of the boat" versus the "motion of the ocean," the truth is: size matters. To some people. Sometimes. Okay, so the real truth is that it is a highly individual preference. Some folks prefer men with large members; others, not so much. It also depends on length versus girth in terms of size.

    Turns out, dongs are just as different as va-jay-jays and it's all about the right combination. Trial-and-error can be pain or pleasure - depending on the person. Until you figure it all out, here are some helpful stats about male members: the average length is about 5.56 inches, the average girth is 4.59 inches. From there, it's all about figuring out what each person likes best. 

  • Big Butts Show a Woman's Ability to Handle Pregnancy

    What is it about junk-in-the-trunk that gets people excited? Similar to breasts, a big booty can be an indicator of genetic health and sexual maturity. Studies have also shown that people with a little more bass tend to be more resistant to chronic illness.

    Current research indicates that it's not even so much the butt itself that we are interested in, but the alignment of the spine and hips. Women, specifically, shift their center of mass backwards during pregnancy to compensate for the extra baggage up front, and a lot of butt indicates the body's capacity to handle that shift. 

  • Moaning During The Act Fosters Communication

    Moans, groans, and dirty talk are not merely the overwrought provenance of raunchy films; they actually serve multiple purposes within the mating ritual. The first purpose is perhaps the most obvious: it's about communicating with your partner. Moans of pleasure are positive affirmations, and dirty talk often conveys specific messages about rate, position, and orientation.

    Moans also are a form of method acting, helping you get in the mood by acting like you're already there. Vocalizations can help with the arousal process and can even contribute to the ability to climax. 

  • Women's Pleasure Centers Exist Solely For The Good Feelings

    The clitoris is a wonderful oddity on the human body: it is the only piece of anatomy, male or female, that exists purely for the purpose of pleasure. Far from the tiny button it's traditionally described as, the clitoris is actually a deep network of more than 8,000 nerve endings that stretches well into the pelvis and connects to another 15,000 nerves.

    This organ engorges during arousal and becomes highly sensitive - sometimes too much so. The clitoris can retreat into its hood as it swells, preventing direct contact which, given how sensitive it is, is not always a helpful thing for achieving climax. We are still trying to catch up with clitorises scientifically - it wasn't until 2009 that we had a full sonograph of an aroused clitoris, and myths about clitorises and this form of climax still abound in modern society.