Valentine’s Day is here and everyone is talking about love! But for many people in our modern society, a fulfilling love life also involves an active and healthy sex life. Although we have come a long way in the liberation of our minds and bodies from cultural taboos and socially imposed restrictions on our sexual attitudes and activities, we still carry with us many remnants from the past, from times when natural aspects of sexuality were frowned upon, discouraged or even demonized. Despite our recent sexual revolution, for many of us, the topics of sex and its idiosyncrasies are still difficult ones to discuss openly because of personal embarrassment or ignorance. It turns out that if we look at our sexual activity through a scientific lens that we may be able to better understand and even embrace our sexual enigmas.
The topic of masturbation, for example, is one of the most difficult ones for many to discuss… but it may actually play an important role in our sexual behaviour and have dramatic effects on male fertility.
The classic sociological explanation for why males (in particular) of most mammal species engage so readily and frequently in acts of masturbation is that it is just another form of playing or practice. Playing is a common feature of juvenile mammalian life that may act as a safe means to practice the skills that will become necessary upon becoming an adult.
In this sense, masturbation may be seen as a means to hone our skills in preparation for sex, should the opportunity arise later. Additionally, masturbation may also be a by-product of the pleasure associated with the act, which itself is an evolved feature to promote engaging in sex as an essential component of propagating the species.
Whereas these preceding explanations may certainly apply, studies of a biological nature point out that masturbation also plays an important role in maintaining male fertility by ensuring that each sperm ejected during sex has the highest potential for fertilizing the available egg.
To set the scene for understanding the journey and fate of each individual sperm cell, a little note about testicular anatomy may be in order. Human testes are divided up into several small compartments, within which are up to 800 tightly coiled seminiferous tubules that house the sperm cells as they are produced. Each tubule is so tightly packed that if they were all laid out end to end, every man would have over one and a half kilometers of sperm ducts in their scrotal sac. That’s a lot!
As the sperm are produced within the base of the tubules, they are pushed outward towards the ejaculatory duct, where they sit and wait in the epididymis for 2 weeks or so, while they fully mature to become fertile. This process is continuous, producing hundreds of millions of sperm per day and leading to ejaculates that may contain upwards of 400 million sperm. That’s an impressive assembly line, and it must make the epididymis a crowded place, as anyone who has seen Woody Allen’s film Everything You Wanted to Know About Sex can testify!
Once sperm are mature, however, their lifespan is quite limited, on the order of a few days to a week or so. Given that the production of sperm originates in the testes and pushes the older sperm to the outside, after about a week those sperm waiting to be part of the next ejaculate load may actually be infertile and useless to the reproductive aspects of sexual intercourse.
It is obvious then that males that do engage in semi-regular bouts of masturbation, may actually be cleaning out the epididymis of older, less-fertile sperm and ensuring that each ejaculate contains only the most viable and fertile ones. This would be an important evolutionary adaptation that favours successful reproduction, rather than shooting blanks, as would be the case in those males who allow a build-up and long-term storage of sperm. Interestingly, even among males who do not regularly masturbate, their bodies have a back-up plan that helps to maintain sperm viability by spontaneously expelling old loads during sleep, in a process commonly known as nocturnal emissions.
It seems, therefore, that our bodies and minds may have been primed over evolutionary time to include masturbation into our regular sexual repertoire because of the many fertility-related advantages that it may bring to our species.
Another sexual enigma that has fueled much intrigue and speculation surrounding human sexuality relates to the role of the female orgasm. Although it is clearly associated with female sensual pleasure and may act to increase their willingness to engage in sex, thereby promoting the propagation of our species, there is strong evidence that it may also play a role in enhancing female fertility.
Scientific studies that have been capable of visualizing the internal muscular contractions during female orgasm have noted that it may actually act as a uterine-pump, actively drawing up sperm deposited into the vagina and directing it towards the uterine or Fallopian tubes, where fertilization takes place. As such, although orgasms in women are not required to ensure fertilization during sex, they certainly act to make it more likely. In this way, the female orgasm can be seen as another evolutionary trait in our complex range of sexual behaviours that promotes successful reproduction in our species and even has an effect on who’s fathering whom, because those men that can induce orgasms will be more successful at fertilizing eggs in the process.
Once again, evolution has primed our species to be able to make the most of our sexual encounters in such a way that a viable and successful reproduction is the most likely outcome. Wow, being sexy is smart!
So, on this day of Love and all of its parameters, let’s not forget that the behaviours that we associate with our sexuality, mating and reproduction are all important features of being human and that these are all good reasons to celebrate with your partner (or alone) on this Valentines Day, as well as every other day of the year!
Dr. Adam Brown PhD