How & Why Did Humans Start Having Oral Sex? The Answer, According To Science Is Weird AF

Sure, it feels good to receive it and even feels good to give it, but have you ever thought about why did humans start having oral sex to begin with? From an evolutionary point of view, it’s not doing anything for keeping the species alive, so it sort of feels like it really doesn’t have a purpose except to feel good. But, according to science, giving and getting head is a bit more complicated than that.

  1. Swallowing semen is good for us. I realize that sounds like something you’d read in a men’s magazine, one that would urge all women to be guzzling as much ejaculate as possible. However, when semen is swallowed, it gets your body familiar with the DNA of the person with whom you’re having oral sex. While they may not be necessary in a lot of cases, should you go on to have kids with this person, having swallowed all that semen will keep your immune system in check.
  2. Giving a blowjob fights morning sickness. I know, I know; you’re like what the effing eff, and I’m right there with you, but apparently it’s true, according to Slate! If you’re suffering from morning sickness, giving your male partner oral sex can help with that nausea. However, the kicker here is that the semen you’re ingesting has to be the semen of the person who got you pregnant. If it isn’t, then all bets are off.
  3. Oral sex can make pregnancies easier. In addition to abolishing the dreaded morning sickness, another reason that oral sex exists is that consuming all that semen can help prevent pregnancy issues if your body has already had (and continues to have) a healthy dose of it. Yum!
  4. It keeps us from cheating. Another theory for oral sex is that it’s supposed to keep us from cheating. Ha! No; seriously. While there’s no proof that lapping up a woman’s vaginal secretions during oral sex is medically beneficial to men, the thinking is that because women tend to orgasm more frequently from oral sex than vaginal intercourse, a woman whose life is inundated with orgasms from cunnilingus, is less likely to go someplace else for sexual activity. If you’ve got the whole package at home, why go elsewhere? This theory makes me wonder if our male ancestors were better at locating the clitoris than the men of today, but I digress.
  5. It helps us to stay focused on our partners. Not only is oral sex meant to keep us from cheating, women especially, but proper oral sex given regularly is supposed to keep us focused on what we already have at home. So the fear of someone cheating isn’t just subtracted from the equation, but the fear of them even looking in the other direction, eye-fucking someone, else isn’t a concern either. Isn’t evolution kind of naïve?
  6. It detects unfaithfulness. In a theory that made me laugh so hard that I blew tea out my nose, evolutionists believe that men going down on women could also stem from them making sure that their female companion wasn’t getting P-in-V action from anyone else. Apparently, and this was more of a concern for men with really attractive female partners, a man would go down on his female partner to see if you could detect whether or not she’d been faithful. The longer he stayed down there, the higher the chance that he would taste or smell something that would make him figure out the truth of her afternoon activities. Who knew cavemen were such sleuths?

More surprising facts about oral sex

  1. It can make a woman get pregnant easier. Okay, before you freak out, count your birth control pills to make sure you didn’t forget one or decide to start using two condoms instead of just one during sex going forward, hear this theory out. This explanation comes from the way the female body responds during an orgasm, as in the fact that the uterus contracts. Because 75 to 80 percent of women need clitoral stimulation to climax, making oral sex a better option if a man would want to make his female partner come, evolutionists think that a man would go down, make his partner come, then immediately have intercourse with her so her contracting uterus (from the other orgasm) would do its thing in getting the sperm to where it needed to go in order to conceive a fetus. According to Psychology Today, this is “much more speculative” than other theories, but it’s still a possible explanation.
  2. It will make a man last longer. A 2009 study of short-nosed fruit bats found that the females would give head to the males so they would maintain their erection longer. Researchers have since theorized that the reason women go down on men is for the same reason. There’s something about the increased lubrication of a woman’s spit prior to intercourse that will keep a man’s erection going and going and going, like some sort of out-of-control Energizer Bunny.
  3. It eliminates sperm competition. If a woman is kept happy by ample amounts of oral sex so she doesn’t go looking for some other penis action, that means when a man has sex with her, it’s only his sperm inside her body. When there’s only one brand of sperm swimming to the money spot, sperm competition is eliminated and, in turn, it helps the man pass on his genes. And, if there’s anything we know about men, from then and now, is that they just have to “sow their wild oats.”
  4. It’s foreplay. For many, oral sex is foreplay. Although it can stand on its own as a main course, it’s more often than not a step to intercourse and that, in itself, has an evolutionary reason behind it. While it takes a matter of a few minutes for a man to become aroused, on average, it takes a woman at least 20 minutes. If a woman isn’t properly aroused, her vagina isn’t properly lubricated, meaning it can make sex unenjoyable or even painful. So getting to the oral action first, just makes sense from a biological standpoint.
  5. Basically, it’s just fun. If we delve into the animal kingdom one more time, one more reason why we might practice oral sex is that it’s fun. According to primatologists, we share 98 percent of our DNA with a type of chimpanzee known as bonobos. Although bonobos don’t give a ton of oral as they get older, when they’re young, they indulge in it quite a bit. The reason? Because it’s just how they play and have a good time. So there you go.
Amanda Chatel is a sexual health, mental health, and wellness journalist with more than a decade of experience. Her work has been featured in Shape, Glamour, SELF, Harper's Bazaar, The Atlantic, Forbes, Elle, Mic, Men's Health and Bustle, where she was a lifestyle writer for seven years. In 2019, The League included Amanda in their "15 Inspirational Feminists Every Single Person Should Follow on Twitter" list.

Amanda has a bachelor's degree in English and master's degree in Creative Writing from the University of New Hampshire. She divides her time between NYC, Paris, and Barcelona.

You can follow her on Instagram @la_chatel or on Twitter @angrychatel.