Science of Sex

Science of Sex is a monthly feature on Of Sex and Love in which I discuss the science of sexuality in an easy-to-digest format that’s accessible to the casual reader.

I end with some extended reading material for people who want to know more about the subject of each post.

Previous topics include the dual-control model of sexual arousal, pheromones, the women of sexology, and habituation of sexual arousal. Find the entire archive below.

Check back every second Saturday for a new sexy science post.

Science of Sex: The Complexities of Herpes

December 21st, 2019

Herpes

The last Science of Sex is about herpes and, more specifically the two viruses and why it’s been so difficult for us to find a vaccine for an STI that’s become increasingly common, perhaps because people do not realize that it can be spread even when there’s no outbreak. Herpes is spread through skin contact, which makes it easy to pass or contract, similar to HPV. And while there are medications to prevent and suppress breakouts, which come in the form of sores, a vaccine would go a long way to prevent that need in the first place.

Most people know about herpes but may not fully understand it. First, there are two viruses: Herpes Simplex Virus 1 and Herpes Simplex Virus 2. 6 million years ago, both viruses diverged from an ancestor.

While you may you may have been taught that HSV1 is “oral” herpes, that oversimplifies the subject. While HSV1 causes most cases of oral herpes, which 1 in 2 people have in the United States, those that give you cold sores, it can be transmitted to genitals through oral sex.

It’s possible for one person to have both viruses.

Furthermore, the two viruses like to mingle. It’s not uncommon for these viruses to mix, or recombine, and they’ve been doing this for some time. Most viruses of “genital” herpes contain DNA from oral herpes.

However, it’s possible for the two viruses to mix in new and unusual ways. A more recent study found a strain of HSV1 that contained ten times as much HSV2 DNA. The chunk was ten times larger than typically occurs. This particular mixture belonged to one patient who had genital infections of both HSV1 and HSV2 (known as co-infection) and the DNA mixed in that person specifically.

Interestingly, it always appears that genital herpes picks up chunks of data from oral herpes and not the other way around.

Aside from interesting, this could potentially be frustrating to researchers who want to create a vaccine for herpes. If they target HSV2 but the strain contains large chunks of HSV1 data or is able to swap out that DNA, the vaccine may not be effective.

Currently, we only have three antiviral medications available to treat existing herpes infections and no vaccine to prevent new infections. These medications enable people with herpes to live normal lives. However, there are times when herpes has led to recurrent keratitis, which can cause blindness, encephalitis, and other diseases, especially in people with compromised immune systems.

We may be closer to a vaccine than not, however. The company Excell Biotech is currently testing a herpes vaccine on animals with hopes to go into clinical trials next year. Another company, X-Vax, is looking into creating a herpes vaccine by altering the virus in an attempt to prompt the body to create a different type of antibody.

While one or both of these vaccines might prove dependable and come to market, it’s really too soon to tell. At least two previous attempts to make a herpes vaccine have failed. Last year, Genocea Biosciences abandoned their attempt at a herpes vaccine after a positive Phase II before heading to the next phase. Also in 2018, Vical gave up its attempt at a herpes vaccine after a failed trial.

Prior to that, a company attempting to create a vaccine against HSV2 actually found that the vaccine only protected against HSV1 in some cases. The way the two viruses mix could potentially explain that strange failure.

But that doesn’t mean we shouldn’t try, especially when teens might be at greater risk of contracting herpes than prior generations.

Further Reading

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Science of Sex: Sex Chromosomes Aren’t Binary

December 1st, 2019

Sex Chromosomes Aren't Binary

More than once, people have suggested that I cover biological sex in the Science of Sex feature. I have shied away from it because it seemed controversial. However, the more I know, the more I understand that some science isn’t at all controversial. In fact, understanding it can lend to our understanding of sex and gender and why it’s never been black-and-white.

One of the transphobic arguments often made is that two pairs of chromosomes determine if a person has the biological sex of a male or female: XY and XX, respectively.  Each cell contains each of these chromosomes, which each come from one of our parents. Most of us learned this in a science class, and many of us haven’t learned anything more since then.

However, there are actually more than two chromosomal possibilities, including

  • XX
  • XY
  • X
  • XXY and XXXY
  • XXX, XXXX, XXXXX
  • XYY
  • XX with translocation (XX male)
  • XY with deletion (Swyer syndrome)

With this in mind, sex seems much more of a spectrum than a binary.

Some of these variations have their own names. For example, a single X chromosome is Turner Syndrome, which is accompanied by several abnormal growth patterns. On the other hand, having three or more X chromosomes is labeled Triple-X syndrome or trisomy X, and these people have the nickname “super-female”. A “super-male,” on the other hand,  has an extra Y chromosome and will tend to be quite tall with extra testosterone. A person with Triple-X syndrome may be slightly taller and thinner than the typical XX woman, but may not be noticeably different. An assumed male who inherits an extra X chromosome or two has Klinefelter syndrome and may have stereotypically female traits and be unable to reproduce.

The latter two examples represent instances in which person’s sexual organs do not align with their karyotype. For example, a person may have the “male” sex chromosomes with female reproductive organs, which are typically not functional. This is known as Swyer syndrome/XY gonadal dysgenesis. These people are usually raised and treated as women while the counterpart is an XX “male,” who is viewed by the world as a boy. Those with this syndrome may not have a detectable SRY gene, which is responsible for an embryo turning male.

Discrepancies between chromosomes and genitals is sometimes known as being “intersex.” This term can also refer more broadly to anyone whose sexual anatomy doesn’t align with the binary (male or female) or whose internal and external genitals do not match. In the past, this has been confused hermaphroditism; however, many prefer the term “intersex” as a less offensive alternative. The World Health Organization explains how true hermaphroditism occurs when a person has mature testicle and ovary tissues. The term “intersex” is not accepted by everyone, however, because of the implication that something is wrong with someone who has these chromosomal differences.

Surgical interventions can be used on young children to “correct” these things, and those children may never realize that they do not conform to the binary. However, these surgeries. which are intended to allow a person to live normally and prevent or reduce psychosocial outcomes may not work as intended. Many surgeries were performed to feminize an intersex person, but this can affect adult sexual function. Furthermore, people may continue to develop with more typical male patterns.

And sometimes that discrepancy can exist but a person with XX chromosomes can have functional sperm while a person with XY chromosomes may have functional ovaries. So it’s possible for a person not to realize that there is a discrepancy if their sex organs are functional — to be “invisibly” intersex. While current estimates vary — some put the intersex population at about 1 out of 100 people in the US and others at 1 in 2000 — the real number could be higher because of these people.

The final nail in the coffin about chromosomes defining sex and, by association, gender, as binary might be the fact that it doesn’t take into consideration at all the role of hormones, which may not respond as expected, either. A person with XY chromosomes who has androgen sensitivity syndrome will develop female-typical sex organs because their body doesn’t respond to androgens, for instance.

There are cases of female-typical bodies and chromosomes responding in male-typical ways in limited situations. And people with similar chromosomes or bodies can still respond uniquely to different hormones and systems. Understanding these very specific differences has revealed the myriad ways that the sex binary fails us and the important things we must note to provide adequate medical care.

This messiness indicates why viewing male and female as the only two sex options is limiting and confusing. While simplifying these ideas has been helpful in some instances, it has been harmful in others. It’s not scientifically sound and can lead to social stigma for those people who do not fit within the binary.

This is all pretty basic stuff that has been researched, even if the general public hasn’t learned about it. When contrasted with gender identities, which have been conflated with sex and similarly viewed as binary, we see that there should be a lot more room for expression. It may very well be that there is overlap with people whose biology falls more toward the middle and those who identify as nonbinary or transgender (at least one study finds that the brains of trans kids match their gender identity). But these things aren’t mutually inclusive.

Further Reading

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Science of Sex: Vaginal Bacterial Transplants

October 1st, 2019

vaginal microbiota transplantation

According to recent estimates, our bodies consist of as much — or even more — bacteria than they do our own cells. While the exact numbers can vary, and researchers may occasionally disagree, bacteria help us function. Without the bacteria in our bodies, our bodies don’t work correctly. However, a bacterial imbalance or introduction of the wrong type of bacteria can lead to problems, namely, infections.

When it comes to sexual health, many people think of sexually transmitted infections. However, these are typically caused by viruses. Bacterial infections include bacterial vaginosis (BV) and infections of the cervix. These infections have traditionally been treated by antibiotics; however, this can lead to antibiotic resistance, which is an increasing concern especially given how frequently these infections reoccur. Furthermore, antibiotics can contribute to yeast infections.

Researchers are considering a new treatment option: vaginal bacterial transfers or vaginal microbiota transplantation. This would transfer the bacteria from a healthy vagina to a vaginal that has a bacterial imbalance. This procedure is not yet in practice and may never come to be. However, researchers are studying what would need to happen to make it a reality.

First, the ideal donor would have just a few bacteria. Specifically, there would not be a lot of Lactobacillus, which is what causes BV. People would need to be screened to see if they are a good match first via questionnaire. Then, swabs would take vaginal bacterial samples. Samples were tested for HPV and HIV before researchers moved on to bacterial analysis. It’s proposed that donors abstain from sex for 30 days before providing a donation, which can be self-collected.

This screening is important because samples could contain bacteria that would do more harm than good. For example, you might have read about two cases earlier this year where patients who underwent experimental fecal transplants, which has been undergoing experimentation as a possible treatment for rectal issues such as C. difficile infections, died. They received material from a donor that was tainted with E Coli. The specific train was antibiotic-resistant. Furthermore, the patients both had weakened immune systems.

With proper screening, this could be avoided. Since bacterial transplants of any form are still in their infancy — the fecal transplant hasn’t received FDA approval yet — now’s the time to eliminate the risk for when these procedures eventually become approved and used on patients.

A similar procedure known as vaginal seeding occurred when doctors would take samples of a birth parent’s vaginal bacteria and apply it to a newborn infant who was born through cesarian section. This practice started because it was believed that vaginal delivery transfers bacteria that can boost an infant’s immune system. While one study initially found limited success from the practice, a more recent study suggests that there is little evidence that vaginal seeding provides microbial benefits to infants and that health difference between vaginal and cesarian-born babies may be due to the antibiotics administered to the parent during birth.

Thus far, results from fecal transplants have been more promising, and vaginal microbiota transplantation may prove the same. However, it’s incredibly early in the game to make that assessment.

Further Reading

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Science of Sex: What’s New In Sex Research (Summer 2019 Edition)

August 31st, 2019

What’s New In Sex Research (Summer 2019 Edition)

While I prefer for each entry in the Science of Sex archive to be a deeper dive into a specific topic, I’ll be taking a break from that this month. There’s simply so many articles that have recently come across my dashboard that I want to write about them. We’re always expanding our knowledge about sexuality, gender, and related topics, but this summer ushered in a flurry of news that really exemplifies this. It’s so exciting!

Let’s jump in. Note that relevant links are included in each section and not at the end of this post per usual.

The most recent of those articles is one about how genetics can explain same-sex behavior. Researchers concluded that there is no one “gay gene” but that several genes do connect with homosexual behavior. Furthermore, gay men and women (presumably cisgender) are affected by different genes. The survey has a few week spots including focusing on behavior versus attraction, but it’s fascinating nonetheless.

Another discovery that’s gotten a lot of media attention is how scientists isolated a gene that, when activated, would create sperm that resulted in male offspring. They successfully applied this to the sperm of mice to produce a higher ratio of male offspring than usual. They believe this applies to all mammals.

In a positive turn for preventing HIV transmission, one studies found that repeated exposure to semen can change vaginal tissues and actually make a ciswoman less susceptible to contracting the virus.

And in other STI news, there could be a chlamydia vaccine on the way! A study of the effect of the drugs on people has been found to be safe. This is good news for the 100+ million people who contract the STI globally each year.

A team looked into why men send dick pics, finding that men who do tend to be more narcissistic.  However, they determined that “he unsolicited dick pic phenomenon cannot be viewed solely as a sexist campaign, nor as a positive outlet for sexuality; instead, cases must be considered on an individual basis.”

After surveying over 2,000 polyamorous people, researchers discovered they were less likely to be religious and more likely to support political third parties. While poly folks were more likely to be nonbinary or bisexual and pansexual, they were not more likely to be gay or lesbian than monogamous people. Poly people were also more likely to make less than $40,000 annually. Research Justin Lehmiller states that,

While our results do not come from representative samples, they suggest that the stereotype of polyamorists as young, White, wealthy liberals doesn’t necessarily match up with reality. Indeed, compared to monogamists, polyamorists were not any younger, Whiter, wealthier, or more likely to identify with the Democratic party.

Surprisingly, women who were married multiple times have more surviving offspring than men who do found researchers after analyzing data about the community of Pimbwe in Tanzania.  This seemingly contradicts the idea that men achieve greater reproductive success by having a variety of partners.

According to his recently released book, ADHD After Darker, Dr. Ari Tuckman has found that a woman who has ADHD have sex 25% more often than when the man in a couple has ADHD due to ADHD’s correlation with sexual eagerness. This can lead to greater sexual satisfaction than when the man has ADHD and this leads to a great discrepancy in sex drive.

Finally, one last study finds that women who take hormone replacement therapy for menopause relief have an increased risk of breast cancer, even more than a decade after they cease the medication. The longer a woman is on HRT, the greater her risk for breast cancer. This is potentially concerning as estrogen and other hormones have been prescribed to help women cope with the symptoms of menopause and to enable them to continue enjoying sex. There was not a similar risk for women who were obese, however.

 

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Science of Sex: Paps Vs HPV Testing for Cervical Cancer Screening

August 1st, 2019

Pap Smears Vs HPV Testing for Cervical Cancer Screening

This month’s Science of Sex was inspired by research I was doing myself based on my own health, so this post will be a bit more anecdotal/personal than usual.

I’ve been getting Pap smears since I was 18. If I had to get, I’ve had about a dozen or so — one every year until a positive HPV result when the exams became twice yearly. After things returned to normal, I went back to annual paps. Seven years ago, the American Cancer Society changed recommendations official to three years, so my visits became less frequent. As an American, I went according to the suggested schedule because I thought it was helpful; although, I realize other countries have different recommendations. I imagine that many women, trans men, and nonbinary folks have followed a similar schedule.

I don’t know if the HPV test has always accompanied my paps, but it has a good portion of them. Combination testing is recommended for anyone over 30 as it’s believed that people in their 20s may have transitory strains of HPV that will be suppressed by the younger person’s immune system. The HPV test can now detect the very strain of HPV (13 of the highest-risk strains), which is helpful to prevent cervical cancer and benefits treating HPV itself.

Read more about HPV and the vaccine.

Imagine my surprise several months ago when my pap came back clear, but I was positive for HPV 16. For those who may not be familiar, the pap smear is a collection of cells using a swab. The swab can miss areas of the cervix where cells may be abnormal, so false negatives are possible. On top of that, false positives are also possible. Because samples are sent away to a lab where a person must identify if cells are abnormal are not, there’s a pretty high margin of error.

According to one 1996 article,

Pap smears, which can detect cancer of the cervix, are now said to have a false negative rate of 20 to 40 percent.

Things may be looking up; however. Modern paps experience false negatives been 10% and 20% of the time.

A false negative could allow abnormal cells to spread and potentially turn pre-cancerous or cancerous. However, a false positive can result in unnecessary, invasive procedures. My HPV results have led to biopsies colposcopies, which enabled doctors to examins the cells of my cervix to locate and sample abnormal cells. After finding moderately abnormal cells this time around, I was referred for a procedure known as a LEEP that involves cauterization of the cervix.

Considering that abnormal cervical cells are not uncommon and not always caused by HPV and can clear up by themselves, which could make any followup procedure unnecessary.

This leads me to the crux of this post: HPV tests alone are more accurate and better predictors of cervical cancer than paps. In fact, people have questioned how useful paps are as a tool for over two decades. Clearly, co-testing (combining both HPV testing and pap smears) is effective, but it may be effective enough to simply perform HPV testing.

However, for those people who may not routinely undergo STI screenings, the recommendation that paps should be performed less frequently may mean less frequent HPV testing as well. Because HPV testing can indicate when a person’s immune system is no longer suppressing the virus in addition to new viruses, it might be helpful to increase the recommendation for HPV testing even as paps become less frequent especially considering that the CDC now states virtually everyone who is sexually active will have HPV, and it may have gone unnoticed because of a faulty pap, or may reappear during times of a weakened immune system.

Further Reading

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Science of Sex: Using Drugs to Raise Women’s Libido

June 29th, 2019

Raising Women's Sex Drive with Medication

This month’s Science of Sex post comes on the heels of an announcement that the FDA has approved the second drug that intended’s to treat women with low libido, also known as hypoactive sexual desire disorder and which you might remember is one of several types of female sexual dysfunction.  The new medication, called Vyleesi, works differently than the previously-released Addyi. In both cases, however, the efficacy and methods of the drugs leave us with more questions than answers.

Vyleesi binds to melanocortin receptors in the brain. Although researchers aren’t sure why that would lead to increased libido because those receptors deal with pain and food intake among other functions. The current theory is that this helps to increase dopamine. Dopamine is a chemical that functions as a hormone in the body and a neurotransmitter in the brain, sending signals to other cells. Of the dopamine pathways in the brain, one is associated with the reward center. The association with pleasure is why dopamine plays a role in addition. It also helps to regular attention, emotional response, movement, and learning.

This drug may force the brain to process erotic stimulation as rewarding, which boosts libido. Because this happens immediately, Vyleesi only needs to be taken before sexual activity and not every day like Addyi, which has been around for several years but hasn’t performed well commercially.

Furthermore, Addyi works on another brain receptor to block serotonin, a neurotransmitter that contributes to feelings of happiness among many other functions. Serotonin plays a role in reward systems and too much can dampen libido as well as curb dopamine. Taken daily, Addyi can reduce serotonin

Both drugs have their risks. Because low serotonin levels are associated with depression, Addyi may be a poor fit with women who struggle from depression. It may be negated by SSRIs, which mitigate depression by boosting serotonin levels in the body but often reduce sex drive. The drug also comes with side effects such as dizziness and “sedation.” It shouldn’t be used with alcohol.

While Vyleesi isn’t taken daily and can be used with alcohol, which might mitigate some risks, users will face a tighter schedule. The drug can be used once daily, up to eight times a month. Boosting libido twice a week is better than the one additional sack session prompted by Addyi over placebo during clinical trials, but Vyleesi comes as an injection while Addyi is a pill. Furthermore, Vyleesi’s side effects include nausea, which affected 40% of women who took it, mostly after the first injection. A small number of participants experienced changes in skin color that remained even after they stopped the drug. Consider that 90% of participants remained in the trial, however.

Before Addyi was even approved, some sex educators were wary of the drug. I imagine Vyleesi will receive some of the same critiques. Vyleesi appears to be a better deal than Addyi in some ways, but neither drug increased the number of sexually satisfying events n a statistically significant way. The FDA no longer requires companies making these drugs to count sexual sessions, and critics point out that women may simply be having more sex that they don’t enjoy. 

And this leads us to one of the main complaints. Is it really beneficial to boost a woman’s sex drive just so it’ll be closer to her partner’s? Should we make women to feel bad for having less desire than men (apparently)? It is a win to force women to sit through more bad sex? Certainly there are women who would feel just fine having less sex if society allowed them to.

The CEO of the drug company has stated “It’s not just about low sexual desire, but about how it impacts patients’ relationships and quality of life. These women are really suffering.” However, this drug doesn’t examine why women are suffering. Dr. Adriane Fugh-Berman, a professor in the department of pharmacology and physiology at Georgetown University Medical Center who studies pharmaceutical marketing has.

I think it’s worth noting what’s an acceptable level of libido is socially influenced. Making women care less about the bad sex that they’re having is a dubious goal.

And for those women who want to want more sex? There are non-drug options that are more effective than both of these options and present fewer risks. Mindfulness can increase libido and sexual satisfaction. Sex education can ensure that women know and ask for what they want in bed, that their partners are better lovers, and that people understand that responsive desire does not necessarily mean low desire. On top of this, education explains concepts such as the dual-control model, which helps explain how external factors play into libido and enables people to ditch the shackles placed on them by society in the form of (useless) sexual scripts.

Can we even diagnose low libido before tackling those issues?

Reading a book or experimenting doesn’t require a prescription, abstinence from alcohol, or perfect health to produce results that are more statistically significant than Addyi and Vyleesi have shown.

Further Reading

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Science of Sex: Male Squirting

April 23rd, 2019

male squirting

As I browsed Reddit a week or so ago, I came across the story of a man who had accidentally urinated in his partner’s mouth when oral sex continued after initial orgasm/ejaculation. Many people in the thread were confused as to how OP didn’t know this was possible. Several commenters revealed that people with penises can experience an ejaculatory orgasm and then experience a pleasurable orgasm-like sensation afterward. However, they’re not ejaculating again.

What is happening then? It appears to be male squirting.

It’s not often that I come across a sexual activity that is new to me. Imagine my surprise to learn there’s an entire subreddit dedicated to it.

A study was able to replicate this transmission to produce “translucent misty fluids with a creatine level similar to that of urine.” The patient experienced muscle contractions as well. Researchers concluded that this was urine being expelled because of the contractions.

Personal stories show that people have been able to squirt this way by rubbing just the head of the penis or via anal stimulation. Although, some people are hesitant because of how sensitive they become after orgasm.

Many people have made the comparison to female squirting, which originates in the bladder but doesn’t appear identical to urine. Both can cause the sensation of needing to pee (this is common when the G-spot is stimulated). There can be similar muscle contractions and fluid is expelled. through the urethra. It’s very dilute, however.

We’ve long been taught that an erection makes it difficult to pee; although, morning wood proves that it’s not impossible. Male squirting seems to be another example.

This is a short recap because there’s only one study from October 2018 that focuses on a single subject. However, the Internet is full of videos stimulating their penises to squirt, and you can see the difference between that and ejaculation, which happens in spurts and not streams.

Knowing that anyone may be capable of achieving an involuntary bladder reflex in response to sexual stimulation might lend more credence to what many women experience when they squirt. At the very least, it can expand how people view sexuality.

Further Reading

Male squirting: Analysis of one case using color Doppler ultrasonography

New insights from one case of female ejaculation.

The Female Prostate Revisited: Perineal Ultrasound and Biochemical Studies of Female Ejaculate

Off Topic: Male Version of Female Ejaculation (Squirting)

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Image © MisterUnlucky; used with permission.