Sex – David Bradley

The orgasmic heart beat

TL:DR – Sex can double or treble a person’s heart rate, but this is a normal physiological response provided the rate goes back to normal within a few minutes.

Love might make your heart skip a beat, but love-making definitely gets it pumping. Indeed, sexual activity will inevitably raise your bpm, beats per minute, especially as a person approaches orgasm. A friend with a fake FitBit was curious about the trajectory of heart rate during sex and wore his monitor (around his wrist) in the bedroom one night. As he and his missus slid between the sheets, he set it to “other” workout and then synced the output from the monitor to his phone…the morning after.

Photo via Pexels user https://www.pexels.com/@olly/

My friend was astonished to see that his heart ultimately raced up to 156 bpm. That is within what the fitness app refers to as the anaerobic region. He was relieved to see that it fell to a near-normal resting rate within a couple of minutes afterwards though. But, that peak had him worried, especially at his age. So rather sheepishly he asked me, as his go-to-science friend, to check out the numbers.

I assumed he knew that during sexual activity, the body undergoes various physiological changes, including an increase in heart rate. It is normal for the heart rate to increase during sexual arousal and activity, and this increase is generally not a cause for concern in healthy individuals.

Heart rate recorded by a fake fitbit during sex

But, it was the orgasm bpm he was worried out. During orgasm, the heart rate typically reaches its peak, and in some people, it can exceed 180 bpm. However, this increase in heart rate is usually brief and does not pose a significant risk to health. 156 bpm during orgasm is within the normal range for sexual activity. And, the fact that his heart rate quickly returned to around 80 bpm within a couple of minutes is a healthy response and indicates that his cardiovascular system is functioning properly.

Certainly, there would be something to worry about if it had gone very high and stayed at that level for a prolonged period. Moreover, chest tightness and pain, stabbing or shooting pains in the left arm or pain in the neck or jaw would indicate a need to seek medical attention either urgently or sooner, rather than later.

As an aside, my friend finds it amusing that he does a lot more “steps” when he is alone than when he’s with his missus…now…I know some readers are going to think “friend…? Yeah, right!” But, it’s true.

Sexual activity, including arousal and orgasm, causes the release of hormones such as adrenaline, noradrenaline, and dopamine, which can increase heart rate. Additionally, physical activity during sex, such as thrusting or movement, also contributes to the rise in heart rate. The body also experiences increased blood flow during sexual activity, which places an additional demand on the heart to pump blood. All of these factors work together to increase heart rate during sexual activity.

Increased blood flow is necessary during sexual activity to deliver oxygen and nutrients to the muscles and tissues involved in the sexual response. This includes the genitalia, which require increased blood flow to become engorged and maintain an erection in men and to lubricate and swell in women. The increased blood flow also contributes to the overall sensations of sexual arousal and pleasure. Increased blood flow to the genitals facilitates sexual function and satisfaction.

During orgasm, the male heartbeat can exhibit variations. While some individuals may experience a sensation akin to their heart skipping a beat, it’s not a universal occurrence. The physiological response during orgasm involves a complex interplay of various bodily systems, including the cardiovascular system.

Typically, during sexual arousal and orgasm, there’s an increase in heart rate and blood pressure as a result of heightened arousal and the release of adrenaline. This can lead to palpitations or a perceived skipping sensation in some individuals. Additionally, the release of neurotransmitters such as dopamine and oxytocin during orgasm can also impact heart rate and rhythm.

However, it’s important to note that variations in heartbeat during orgasm can differ greatly from person to person, and not everyone may perceive or experience it in the same way. If someone experiences significant irregularities in heartbeat or has concerns about their cardiovascular health during sexual activity, it’s advisable to consult with a healthcare professional for further evaluation and guidance.

Male moths and butterflies often fire blanks but nobody knows why

A few days ago I tweeted about a famous picture of a moth, the Death’s Head Hawk-moth used in the artwork surrounding the 1991 psychological thriller “The Silence of the Lambs”. At first glance, the moth looks genuine, but closer inspection reveals that what is thought of as markings resembling a skull on the moth’s thorax is, in the movie illustration, actually an imprint of a well-known 1951 creation of Salvador Dali and photographer Philippe Halsman.

In that image, In Voluptas Mors, a group of naked women were posed in such a way as to create the illusion of a skull. Of course, this morbid allusion fits perfectly with the theme of a murderer who skins his female victims in the movie. The women are lambs to the slaughter, their fleeces flayed from their bodies by the serial killer and a symbolic moth placed on their tongues to silence them forever.

Although a representation of the Death’s Head Hawk-moth (Acherontia atropos) features in the promotional materials for the film. Fellow science writer Rowan Hooper reminded me that in the movie itself, it is the pupae of a different moth, the Carolina Sphinx Moth (also known as the Tobacco Hawk-moth (Manduca sexta) that feature in the plot. In our chat, I mentioned that I wasn’t particularly interested in moths when that movie was first on release, but he said he was very much interested in Lepidoptera (moths and butterflies) at the time, Indeed, Hooper was specifically working in research trying to figure out something rather odd about Lepidoptera.

It turns out that the males of all Lepidoptera, all 180,000 species of moths and butterflies produce two types of sperm. They make sperm that carry their genetic material, their DNA, in the sperm’s nucleus, so-called eupyrene sperm, but they also make sperm that lack that DNA, apyrene sperm, or parasperm. Indeed, at least half of the sperm are blanks. In one type of swallowtail butterfly, 90 percent of the male’s sperm lack DNA. That percentage is 96 in Manduca sexta. Even more bizarrely, Lepidoptera are the only creatures that do this.

Obviously, the fusion of sperm with egg is fundamentally all about fusing the genetic material from the male with that of the female to fertilise the egg and create offspring from both parents. So, why would males make sperm that contain no genes to pass on and more to the point would be incapable of fertilising the female’s eggs. To cut to the money shot: nobody knows, for sure.

There are hypotheses, of course. It might be that the blank sperm act as some kind of useful filler, inactive biological padding. The blanks perhaps take up the female’s resources somehow while the active sperm do their job. Maybe this precluded further matings with other males ensuring that the first male’s active sperm are the ones that fertilise her eggs. Alternatively, perhaps Lepidoptera females have defences within their reproductive tract to ensure that only the fittest sperm reach their eggs and so the males produce these blanks as decoys (after all blanks would require fewer material resources and energy to produce, if many are going to be wasted). An alternative theory might be that the blank sperm are some kind of nuptial gift for the female, not so much inactive filler as nutrients.

There is evidence that a gene known as Sex-lethal (Sxl) is involved in the production of apyrene sperm in Lepidoptera. A paper in PNAS looked at the activity of this gene in the Silk Moth, Bombyx mori, and found that it was partially responsible for the generation of apyrene sperm. Moreover, the team showed that apyrene sperm have to be present in the male moth’s ejaculate to allow the active eupyrne sperm to travel from the female’s genital opening, the bursa copulatrix, to her spermatheca (where she stores sperm prior to egg fertilisation).

So, while no definitive answer is known for all Lepidoptera that produce eupyrene and apyrene sperm, for the Silk Moth at least it seems that firing blanks is the best way for the active sperm to hit the target.

Thirty years of the barrier method and other science stories

Thirty years ago this month I wrote my first professional article. It was a short feature about the biggest organism having the biggest orgasm and was entitled ‘The Barrier Method’. It explained some of the chemistry, biology, and geography of the sex life of Australia’s Great Barrier Reef and appeared in the April 1990 issue of the Royal Society of Chemistry’s young chemists’ newsletter Gas Jar.

Incidentally, I later renamed the magazine and helped relaunch it in full colour as New Elements with Editor Dr Mandy Mackenzie, which carried my Elemental Discoveries news round-up for several years from 1995 onwards.

I also used to publish Elemental Discoveries online on what was perhaps the first chemistry news website. It was to become a model for several news site launches over the following years that I instigated or was involved with for various organisations, including Reactive Reports for ACD/Labs, PSIGate Spotlight, which became Intute, Spectral Lines (for Wiley, now SpectroscopyNOW.com), Distillates for the RSC magazine Education in Chemistry, and a couple of others. Elemental Discoveries itself was hosted by ChemDraw creators Cambridge Soft for a couple of years before I relaunched it as Sciencebase.com in July 1999.

The article ‘The Barrier Method’ was chosen as runner-up in the 1990 Young Science Writer Awards hosted by The Daily Telegraph and the British Association for the Advancement of Science. A later article entitled “Not every sperm is sacred” won in 1991 and led to my writing about science for The Telegraph for several years after that. I got a merit award after the sperm and eggs with an article about xenon and anaesthesia, but sex science has remained a focus of much of my writing over the years, hah!

You can see a hopefully complete list of all my clients from the last thirty years as a freelance science writer here.

The photo accompanying the article was by Mrs Sciencebase long before she was Mrs Sciencebase. I can’t find the original magazine, hence the monochrome copy.

The truth about penis enlargement

When it comes to penis size, there is probably not a man on the planet who has not worried about it at some point in his life. Moreover, there is probably not a single person on the planet who has not received at least one spam email announcing some way of increasing length, girth, or both.

So, what is the truth about penile enhancement? Is it possible? Is there even a grain of truth in any of those spams and even if there is does it really matter how big your p3n!s is? Are all those spam subject lines merely empty promises: “Reliable method of natural pen!s enlargement!”, “GretaSizeableMembr!”, “Special offer for your little willy!”, “All Natural Enlargement Add Inchees”, et ceteeeeera.

The simple fact of the matter is surgery is the only way to increase penis size, but surgeons will point out that it can be painful, involves a lot of heartache, can go seriously wrong and will not increase the size of your penis by more than a few millimetres even in a best-case scenario.

But, what about all those other techniques, pills, and remedies mentioned in billions of spam messages, surely some of them work? Well, clinical trials are limited, but there is absolutely no definitive evidence that suggests any of them work at all, there may be a marginal placebo effect that boosts a man’s confidence a little without actually boosting his dimensions, but that’s as far as it goes. Anecdotes, by the way, are not medical evidence.

Vacuum pumps – These devices are supposed to increase size by increasing blood flow, but in reality can cause damage to blood vessels, reduced sensitivity, and even cause impotence.
Pills and potions, and pills – There is no known medication that will increase penis size. Moreover, miracle pills could be contaminated with
toxic material, such as lead and even faecal matter.
Hanging weights – Stretching human tissue usually leads to stretch marks and there is no evidence that any lengthening will be permanent once the weights are removed. There is evidence of loss of sensitivity, tissue damage, and impotence in men using such an approach, however.
Exercises – The penis is not a muscle so cannot be made bigger through any form of exercise. Even Kegel exercises to strengthen the pelvic girdle, which allows you to seemingly “flex” your penis have potential drawbacks if overdone, such as potentially leading to retarded ejaculation (an inability to reach orgasm).
Jelqing – You may have heard this odd word, which refers to basically tugging and slapping your penis (without masturbating). There is no evidence that it works.
Surgery – Not generally recommended by surgeons and potentially dangerous.

So, there you have it. The truth about penile enlargement is that it cannot be done safely. More to the point though, unless you are suffering from the medical condition known as micropenis, you really shouldn’t worry about it, after all the human penis is proportionally much bigger on average than that of a gorilla!

Actually, now that I mention gorillas you may not wish to read on if you really are worried about your size. Gynaecologist Edwin Bowman explains in the journal Archives of Sexual Behavior that humans evolved a proportionally larger penis in parallel with the evolutionary widening of the birth canal as our brains got larger.

Males with a larger penis would have fared better in natural selection as they had more chance of ejaculating during sexual intercourse and so more chance of mating resulting in a pregnancy. “I have had many occasions to discuss penile size with women,” Bowman says, “In general and within reason, women prefer larger penises. The preference is ingrained in our culture and probably has been so since prehistoric times.”

It sounds like nonsense to me, given that the average aroused vagina is only about 4 inches long and the average aroused penis about 5 to 6 inches. More to the point, surely a widening birth canal would only select for a thicker penis rather than a longer one.

Bowman, E. (2007). Why the Human Penis is Larger than in the Great Apes Archives of Sexual Behavior, 37 (3), 361-361 DOI: 10.1007/s10508-007-9297-6

Sex pheromone for an Emperor

I made a rookie research error. Saturnia pavonia, the Emperor Moth, was previously known as Pavonia pavonia, and in my search for the chemical identity of its sex pheromone (which is in the moth lure I mentioned previously) I’d assumed these were its only names. But, apparently, it was also known as Eudia pavonia.

Once I’d realised this, a scientific literature search quickly found a paper discussing the moth’s sex pheromone: (Z)-6,(Z)-11-hexadecadien-1-yl acetate. This is closely related to another chemical gossyplure, a 1:1 mixture of the (Z,E) and (Z,Z) isomers of hexadeca-7,11-dien-1-yl-acetate. That chemical is used commercially to lure cotton-infesting moths to traps to reduce breeding of different species Pectinophora gossypiella.

So, with the systematic name, I could get the InChI string from one converter and then generate a chemical structure, so here it is together with the male moth I photographed, which is attracted to this chemical:

Sex antenna

TL:DR – The males of many species of moth have feathery antennae to detect the sex attractant pheromones released by the females to allow the males to locate a potential mate, often from several miles away.

That feathery protuberance on this moth (Pale Brindled Beauty, Phigalia pilosaria) is one of a pair of antennae. What you cannot see clearly in my photo is that it’s fractal with each tiny hair on the main stem having its own array of tiny hairs and so on down to the molecular level.

Feathery antennae like this are found only on male moths and are basically its sex radar. They can catch a few molecules of female moth sex attractant pheromone on the breeze sometimes coming from miles away and guiding the male to where the female might be found. The female of this particular species has no wings and so the male must go to her to mate.

Sonic hedgehog could save sex after prostate op

The cavernous nerve is often damaged during surgery for prostate cancer leading to erectile dysfunction (ED). Researchers previously found that the protein that goes by the name of sonic hedgehog (SHH) is critical if this nerve is to be regenerated post-operatively. The same team has now investigated the issue from a different perspective: might sonic hedgehog actually protect the nerves after the crush injury they often experience during surgery?

They have found that, “There is a window of opportunity immediately after nerve insult in which manipulation of SHH signaling in the nerve microenvironment can affect long-term regeneration outcome.” This bodes well for better outcomes for the sex lives of post-op prostate cancer patients.

Angeloni, N., Bond, C.W., Harrington, D., Stupp, S. & Podlasek, C.A. (2012). Sonic Hedgehog Is Neuroprotective in the Cavernous Nerve with Crush Injury, The Journal of Sexual Medicine, no. DOI: 10.1111/j.1743-6109.2012.02930.x

Scientific research into female orgasm

This is scientific research, honestly, but should this blog post have an NSFW flag? Well, if your boss doesn’t expect you to be reading about sex while on the job, as it were, then perhaps, yes it should be classed as not safe for work. The scientific conclusions come from an online survey of 323 women and their sexual preferences regarding penis size and their self-reporting of vaginal versus clitoral orgasm. Is this post likely to get a lot of retweets or just unwanted traffic from those who prefer their Monday morning web surfing to most certainly be NSFW?

The fundamental conclusion is that: “Women who prefer deeper penile-vaginal stimulation are more likely to have vaginal orgasm, consistent with vaginal orgasm evolving as part of a female mate choice system favoring somewhat larger than average penises.”

The researchers do concede that more work needs to be done to overcome length and girth measurement limitations and other confounding factors. Moreover, there is much (sexual) politics in this kind of research, particularly in terms of whether or not there is a valid differentiation between types of female orgasm, the initial motivations for such studies, the implications, the benefits and how the findings apply to evolutionary theory. But, it is Monday morning, so I’m not going to get into any more details, you can read the paper yourself via the citation below.

Costa, R.M., Miller, G.F. & Brody, S. (2012). Women Who Prefer Longer Penises Are More Likely to Have Vaginal Orgasms (but Not Clitoral Orgasms): Implications for an Evolutionary Theory of Vaginal Orgasm, The Journal of Sexual Medicine, no. DOI: 10.1111/j.1743-6109.2012.02917.x

The science of orgasms video

It’s all about nerve signals, dopamine and oxytocin…well…not all about that! From the Wiki entry: Orgasm is the sudden release of accumulated sexual tension during the sexual response cycle involving an intense sensation of pleasure. It is experienced by males and females and is controlled by the autonomic nervous system. The period following orgasm (the refractory period) is often a relaxing experience, attributed to the release of the neurohormones oxytocin and prolactin.

Science is sexy…

Frisky firefly sex tape

Once the lights go out, female fireflies apparently prefer a little more substance and a little less flash. Infrared imaging and other techniques have been used to monitor firefly behaviour and to show that the females of the species tend to choose mates that they perceive as able to deliver a large “nuptial gift” a high protein sperm package that helps females produce more eggs.

The team used programmed LED lights to simulate male firefly flashes. The team exposed one group of females to a flash pattern that earlier research had shown was highly attractive to females; second group saw only “unattractive” flash patterns. They also divided the males into two groups: those who had a large spermatophore to present, the virgins, and the experienced old-timers who had a smaller package. They then used IR lamps to shed light on the antics of their frisky fireflies and DNA paternity testing to figure out which males were most successful after dark.

You can read more about the research in my 1st July infrared news story on SpectroscopyNOW.com