How Sexual Desire Works- The Enigmatic Urge

by Frederick Toates

  Evolutionary mismatch

  The notion of evolutionary mismatch helps us to understand contemporary sexual desire. It refers to the disparity between the current environment and that in which our evolution occurred. For example, humans fear snakes and spiders, whereas these days guns and cars present a vastly increased risk in industrial societies. Fear of guns and cars has not evolved since they have not been around for long enough. That is to say, there is mismatch between what is feared and what presents the most danger to humans living today. Another example is the mismatch between the availability of food in rich countries and the evolutionary design underlying control of feeding.

  As a slight but relevant digression, consider again the similarities between feeding and sex. The term ‘addiction’ is increasingly applied to excess in either area. Supermarkets offer an abundance of foods of high fat and sugar content. These might be termed ‘supernormal stimuli’ to our appetites. Through endless permutations of ingredients, cookery programmes and advertising, such stimuli excite our gastronomic desires excessively.

  Rather as with sex, the outcome of this food-related stimulation is mixed. The gastronomic experience is hedonically potent, which might sooth a stressed brain in the short term, but the ills of superabundance include diabetes, obesity, heart disease and tooth decay. In the environment of our early evolution there were no refined foods. Whereas foods were obtained only after extensive foraging, hunting and exertion of effort, they now require little more than depressing the pedals of a car and steering to the nearest supermarket, take-away or burger bar. Yet, rather as with perceived excessive sexual behaviour, being obese carries something of a social stigma.

  The design of sexual desire similarly arose in an environment very different from that in which most people live today. Even in two or three decades, amounting to not even the blink of an eye in evolutionary time, major changes in the ‘sexual environment’ have appeared. Yet, it is a brain designed so long ago that finds itself in this current environment. Humans evolved in a social environment in which they relatively rarely met a stranger or non-kin individual (except possibly in conflict), whereas these days we might well pass thousands every day (Feierman and Feierman, 2000). Opportunities for at least attraction, if not contact, are now incalculably more frequent. For many people these days, there is also more time available to pursue sexual desires and more free conscious capacity to be engaged with sexual fantasy (C. Wilson, 1988). The key to understanding so much of the contemporary manifestation of sexual desire is to consider how such a brain works in the current environment, which is so different from that of early evolution.

  Once cultures acquired increasingly refined technology to change the body’s appearance, people used their ingenuity to find ways of increasing their desire value – in effect, to present supernormal stimuli. For example, on going to a social event, it is said that Venetian women dropped belladonna into their eyes to increase their pupil size. Thereby, a woman exaggerated her apparent level of interest in her male interlocutor and correspondingly increased her attraction value.

  In the contemporary sexual landscape, particularly in affluent countries, there is an abundance of supernormal stimuli. The triggers to sexual desire are ubiquitous and are enhanced artificially, such that their exaggerated presence becomes the norm. Many women dress provocatively and use hair dyes, padded shoulders, high-heeled shoes, artificial nails, elaborate hair-styles and make-up applied to lips, eyelashes and fingernails and toenails, as well as carefully crafted perfume, in an attempt to magnify their attraction value. Female dress is often chosen to make women look taller and thinner (Buss, 2003). In the countries where most readers will be living, female dress reveals more of the body than probably at any time in recorded history, something to be witnessed on weekend nights in British town centres even in the depths of winter. For those who prefer to stay indoors and watch television, Saturday night game shows offer comparable amounts of bodily exposure. Males are catching up fast with special fragrance products, amongst many other things.

  For those with money, perceived desire value can be increased by plastic surgery, so as to alter cheek bone structure or breast size, to straighten a nose, to increase lip size with the help of collagen, to make a face more symmetrical or a body curvier.

  Through billboards, magazines, television and the Internet, advertisers bombard us with triggers to sexual desire. Scantily clad models displaying erotically tailored clothing are shown in even long-established and traditional clothing stores. I just witnessed this even in the window of the charity shop Age UK in Milton Keynes! Specialist shops dedicated to the purchase of supernormal stimuli, in the form of erotically designed dresses, shoes, boots and stockings, are now a regular feature in many town centres. So-called ‘top-shelf magazines’ cater almost exclusively to the triggering of sexual desire, often with suggestions of how it might be linked to sexual opportunity. Explicit heterosexual, homosexual and bisexual pornography is available in what are often termed ‘adult’ bookshops as well as via the Internet. The uncertainty and novelty value of both moving and stationary erotic images available through the Internet would seem sufficient to satisfy the curiosity of even the most demanding sexual connoisseur for several life-times. The search for the best-ever image is almost bound to be endless.

  The triggers to desire and the means to translate this into novel sexual behaviour are probably more accessible to most people than at any time. I suggest that the knowledge of this availability contributes to triggering desire, and a paradoxical combination of ready availability and inherent transgression in gaining access is probably particularly potent. Locks on doors, rented rooms, employment away from home and fast transport offer the possibility of sexual liaisons undetected by snooping eyes.

  The formal and legal rules on what is available have probably seldom, if ever, been so relaxed. In Britain and other countries, so-called massage and escort services are advertised even in the local press. Cheap flights mean that sexual tourism is brought within the reach of many more people. In terms of finding novelty outside the marital bond, there are Internet sites for those seeking adulterous liaisons, whereas other Internet sites and retreats/clubs are available for those who prefer to seek novelty together as couples. Sexual minorities have not been left out of this erotic charging by supernormal stimuli. Specialist magazines, clubs and Internet sites cater for a wide range of legal and other tastes. This change in the landscape needs to be understood before we can make sense of such things as sexual addiction.

  The brains of animals are equipped with a process of cost–benefit analysis (Assadi et al., 2009). The decision-making takes both the estimated benefits and costs of any activity into account in choosing a course of action. Researchers are now able to attribute responsibility for this calculation to particular brain regions.5 It seems logical to suppose that in our present environment the estimated cost–benefit of sexually motivated decision-making is skewed towards the benefit.

  It is not just modern, sexually charged environments where evolutionary considerations give insights into behaviour. For example, people in the Ituri region of Zaire show high levels of promiscuity and sexually transmitted disease leading to infertility (Bailey and Aunger, 1995). From evolutionary considerations, why do some groups show behaviour that is likely to be counterproductive to genetic perpetuation? Why has evolution not provided a design that, metaphorically speaking, takes the danger into account and restrains promiscuity? Evolutionary mismatch is a possible answer: today’s diseases were not around during most of human evolution and therefore no psychological defence mechanisms have evolved. It would be difficult for evolutionary processes to have provided a psychological defence. Presumably, if the diseases were manifest externally by, say, sores, this would act as a signal and deterrent to sexual activity, but they often remain hidden.

  Bailey and Aunger (1995) found that the Ituri people were fully aware of the link between promiscuity and sexually transmitted diseases. It seems then th
at the cultural transmission of information by word of mouth on the risks of promiscuity can be inadequate in providing inhibition. A sexual encounter poses a theoretical risk, not a certain one that can be assessed there and then. Any negative consequences in the form of disease follow later. Under conditions of high desire, such theoretical risks can often be ineffective as deterrents.

  Development

  Desire might be non-existent, straight, gay or bisexual, or with an abnormally strong attraction to certain body shapes or hair colours. There might be a fetishist element to desire, where it requires leather or shoes for its triggering. Fetishes reveal much about desire (Chapter 19). Sadly, desire might be directed to a target of a kind where any sexual action would be illegal, as in paedophilia or rape. How does the individual adult brain acquire these particular features that characterize its desire?

  We start life as a single fertilized egg cell in the womb. This cell splits into two, and these two cells in turn divide. This process continues until there are the billions of cells that make up the adult. In the womb, there is the physical environment of the mother’s body. Following birth, there is an environment having both physical and social dimensions. To understand the emergence of human sexuality, a study of development is essential.

  Investigators are increasingly coming to recognize the tight interlocking of genes and environment as determinants of development. Consider that men tend typically to find casual sex more attractive than women do. According to evolutionary psychologists, this is to be understood in terms of evolutionary strategies for maximizing reproductive chances. Thereby, genetic differences between men and women bear the weight of responsibility. However, according to Sarah Blaffer Hrdy, the social controls that men apply to women’s sexuality, such as severe punishment for infringement of the moral code, mean that girls assimilate the cultural rule that they are not supposed to feel, let alone express, sexual desire (Hrdy, 1999). Either way, there are problems in trying to understand what is going on. Evolutionary psychologists point out that the gender difference is found across all cultures, which suggests a genetic explanation. A feminist counter-argument is in terms of male domination. A possible resolution will be described later.

  The next chapter looks at some of the history of attempts to explain desire, which then leads into a modern view of how sex works.

  In summary

  Sexual desire is manifest in conscious experience and in corresponding activity in particular regions of the brain.

  Automatic and controlled processing underlie behaviour.

  Some brain processes operate outside conscious awareness and others are associated with full conscious awareness.

  Classical and instrumental conditioning are involved in sexuality.

  Communication of information involved in sexual desire and behaviour is by means of neurons and hormones.

  The role of particular regions of brain (e.g. the nucleus accumbens) and particular neurochemicals (e.g. dopamine) can be identified.

  Similarities between sexual behaviour and other activities provide insights into how desire works.

  A functional explanation is in terms of how behaviour contributes to genetic perpetuation.

  Evolutionary psychology, the account of how the features of human sexuality were designed in our early evolution, has given powerful insights, as in the notion of evolutionary mismatch.

  Three Sexual desire in a broad context

  The greatest enterprise of the mind has always been and always will be the attempted linkage of the sciences and the humanities.

  (Wilson, 1998, p. 6)1

  What is to be explained?

  Sexual desire arises within an historical, cultural and religious context, which powerfully influences how it is interpreted (Hawkes, 2004). Assumptions on how desire works are made and assimilated into cultures. Discussion of this issue is much more than armchair philosophy; what is believed about desire tends both to reflect and inform laws, social and religious attitudes, and policy. This chapter cannot give an even remotely comprehensive view of this vast subject. All it can do is give some examples of the various assumptions that surround the nature of desire, show their implications and relate them to a modern interpretation. Throughout history, eminent thinkers have suggested how sexual desire arises and what the consequences are for well-being of either following its call or voluntarily resisting it. The effects of thwarted and frustrated desire have also attracted speculation.

  To modern scientifically informed minds, early attempts at explanation can sound comical, but modesty here would not be out of place. In past centuries people were, of course, without any knowledge of evolution, modern anatomical description, neuroimaging and chemical analysis. However, concerning their own desires and behaviour and the behaviour of others, they were probably no less astute observers than we are. Early explanations say much about ubiquitous aspects of the experience and expression of sexual desire.

  So, which features of sexuality might be equally as evident to pre-scientific as to present-day people and would prompt a search for understanding? Consider the following.

  Desire has much to do with (an) attractive other(s), as well as events within the body, often with a focus on its lower parts.

  Denial of a sexual outlet can be distressing, while engaging in sexual activity can at least temporarily lower desire.

  Some factors act in the opposite direction to desire, either to lower it as such or to leave it unchanged but lower its chances of expression in sexual behaviour.

  Intense desire can cause people to act against their better judgement, leading some to argue for a lack of ‘free will’.

  Desire can sometimes be a mixed blessing, when it brings social problems in its wake, and moral advice, if not social/legal sanctions, might be needed to curb its excesses.

  Over the centuries, the assumption has commonly been made that sexual behaviour serves as a ‘regulator’ of particular events within the body; something needs to be maintained within an alignment and healthy limits.2 People are ‘driven’ into sexual activity by a misalignment. Successful sexual activity then reduces the strength of this ‘push’. Implicitly or explicitly, two related assumptions have frequently been made about this push:

  It is aversive, harmful or at least undesirable in quality, so that its reduction brings some relief.

  It can arise within the body but outside the brain.

  Doubtless such arguments arose partly from analogy, e.g. a full bladder triggers the desire for urination, which, when acted upon, lowers the strength of the trigger. Sometimes the role of an attractive individual in triggering or enhancing the push is described and attempts made to link such external and internal triggers.

  Closely related to the issue of what gives rise to sexual desire has been that of the consequences of either expressing it in sexual activity, resisting its pull or being denied the chance of an outlet. Opinions have ranged from, on the one hand those describing sexual desire as an imperative, the command of which must be respected in order to attain bodily health, to on the other seeing it as an unfortunate distraction that is best suppressed or ignored in the interests of moral virtue and sanity.

  By not engaging in sexual behaviour, a particular bodily disturbance might increase over time, with possibly harmful effects on body and mind. How early writers envisaged such a disturbance and its link to desire gives insight into attitudes towards sexuality prevalent at the time. So, the present chapter will look at prominent ideas that were based upon disturbance to the body: what is the nature of the disturbance, how does it link to desire and what are the consequences of thwarting its expression?

  Some have argued that a disturbance from equilibrium could arise with sexual under-activity; that is, sexual behaviour is regulatory. For example, as a possible index of a belief in sex as a regulator, the early church condemned prostitution but nonetheless showed some tolerance towards it ‘as a kind of sewer’ (Bullough, 1987). In this way, it was seen as providing a relatively ha
rmless outlet for male sexual needs. Similarly, the virtues of masturbation as a safety valve have sometimes been championed. It is perhaps no coincidence that the only form of sexual release outside marriage that has not attracted universal moral censure is that of nocturnal orgasm (Kinsey et al., 1948). Presumably, this has been seen as totally involuntary and serving some kind of regulatory function, provided it is not induced by prior lascivious thoughts.

  By contrast, others have taught mainly of the perils of sexual over-activity (Money, 1990). To them, excessive sexual activity or even inappropriate sexual activity was considered to be seriously debilitating and in the extreme even lethal, depleting the body of vital resources and causing madness. This is a non-regulatory view. Various ‘experts’ described the horrific consequences of misuse of the sexual function, as in masturbation. Therefore, any regulation of a bodily condition would be far from perfect, otherwise behaviour would switch off when the optimum was achieved and serious disturbances accompanying excessive masturbation could not arise.

  Historically, in terms of regulation, the male has sometimes featured at centre-stage. Correspondingly, women have been viewed rather ambivalently, some writers claiming that, unlike the male, they lack any intrinsic sexuality. Still others advanced egalitarian unisex theories (see Tolman and Diamond, 2001). In the medieval period, long-term virginity was seen as something of a health hazard associated with a closed body, a condition that could be treated by marriage. Where marriage was not yet appropriate, girls were sometimes given instructions in masturbation by midwifes (Meston and Buss, 2009). Up until the eighteenth century, doctors were worried about the dangers to health of protracted virginity, believing that ailments would find a natural home in the closed body. In earlier times, it was generally assumed that it was necessary for women to have orgasms in order to conceive (Everaerd et al., 2000a), based upon the belief that orgasm triggered the fusion of male and female seed. Midwifery manuals of the sixteenth century described this (Wagstaff et al., 2000). The Victorian period was one during which women’s intrinsic sexuality was largely denied (Crepault et al., 1977).