The last chapter looked at how the bases of sexual desire are established in the child. The present chapter revisits this topic in the context of how processes established in the child are revealed in:

• the emergence of adult sexual behaviour;

• changes and stability in adult behaviour.

It first looks at how brain development is manifest in sexual risk-taking (by also drawing on earlier chapters that described levels of the control of behaviour) and it then considers the direction taken by adult sexual desire and expression.

Transitions between adolescence and young adulthood: brain bases

Adolescence and young adulthood represent a stage during which there is a strong tendency to engage in risky activities, including dangerous driving, drug-taking and unsafe sexual behaviour (Steinberg, 2008). For many, it is the time of first sexual intercourse (Hawes et al., 2010). Educational programmes designed to warn of risky activities by appealing to rational cognition appear to have a very limited effect. Do young people fail to appreciate the risks, as a result of using wrong and irrational calculations? Do they trust in their own invulnerability? It is not a failure of knowledge; the beliefs and calculations of 16-year-olds are much like those of adults.

1. But she hath lost a dearer thing than life,

2. And he had won what he would lose again;

3. This forced league doth force a further strife;

4. This momentary joy breeds months of pain;

5. This hot desire converts to cold disdain.

6. (Shakespeare, The Rape of Lucrece, lines 687–91)

Rapists come in different varieties with different underlying motivational dynamics (Hickey, 2010). Therefore, it is possible to present here a description in only very broad brushstrokes, highlighting certain features that might usually be present. Some rapes are planned well in advance and target a stranger, whereas others can be the sudden impulsive reaction to thwarting of the male’s goals towards a familiar woman, as in date rape. Some appear to be second best to consensual sex, where force is only instrumental to achieve the goal. For others, the element of coercion is an integral part of the desire. So, it appears that rape can serve goals in addition to sexual fulfilment (Marshall and Barbaree, 1990) and interactions of sexual desire with other motivations are evident. A desire for power and dominance can contribute to the motivation (Calhoun and Wilson, 2000). Some rapists use violence only to gain access to a woman, whereas for others the violence continues beyond this point suggesting fusion of sexual and aggressive motivations (Zillmann, 1984). Sadly, rape is evident across cultures, including even the sexually permissive land of Polynesian Mangaia (Marshall, 1971). Novelty, excitement and transgression doubtless often play a role. As the ex-wife of the British rapist known as the ‘monster of the M5’ expressed it (quoted by Apter, 2007, p. 152): ‘We always had a perfectly healthy sex life – but he always seemed to need that little bit of extra excitement, like a racing driver.’

What goes on in the brain of a rapist?

Hare (1993) estimates that one half of all repeat/serial rapists meet the criteria for being psychopaths. The non-psychopathic rapists would feel some guilt and remorse.

This chapter looks at several types of explanation that can be applied to sexual desire and the links between them. It starts by considering desire in the here-and-now; that is, events in the mind and brain as individuals experience sexual desire. Some basic psychology and biology will then be introduced. The book suggests that we can gain insight by exploring similarities between sex and a number of other activities, for example feeding, gambling and drug-taking. The chapter then asks how the processes underlying sexual desire came into being. Two very different time scales will be considered: the evolutionary history of humans and the development of the individual.

The ‘here-and-now’: broad principles

The study of desire in the here-and-now is in terms of brains and minds, as well as such things as heart rate and blood flow to the genitals. Of course, desire is often triggered by the perception of an attractive person. This much would be obvious simply from talking to the one feeling the desire, quite apart from monitoring events in the body and observing behaviour. In the physical absence of an attractive other, representations of such an individual in the form of pictures or simply memories in the mind can trigger desire. Sensations arising in the genitals also contribute to desire and lock into interaction with the factors just described.

What exactly is it?

Sexual homicide consists of (Burgess et al., 1986, p. 252): ‘one person killing another in the context of power, control, sexuality, and aggressive brutality’. A defining feature is: ‘the infliction of physical or psychological suffering on another person in order to achieve sexual excitement’.

The motivational basis

Not all serial killings arise from sexual motivation, though many do (Hickey, 2010). As a broad generalization, Buss (2005, p. 219): ‘serial killers murder because they seek vengeance for status denied’. Non-sexually linked serial killings are motivated by the desire for such things as attention, financial gain, political action (e.g. ‘mission killings’ to rid the world of undesirables) or ‘pure anger’ associated with retribution (Holmes and DeBurger, 1998).

The central argument of the present study is that biology and environment are inextricably mixed in the determination of all forms of desire, whether normal or at the fringe. The following examples are based upon this.

Voyeurism

Starting from childhood, the Victorian writer Walter was an insatiable and creative voyeur, an activity which he accompanied by masturbation, but this did not prevent him from developing an active ‘conventional’ sex life in parallel. Having found a hiding place in a basement and looking up to the street above through a hole, Walter would sometimes wait for hours before catching a glimpse of the legs of an unsuspecting woman. On visits to the Continent, Walter spent hours peering through keyholes watching women or couples. Kronhausen and Kronhausen (1967) observe (p. 318):

Sexual desire could at times appear to bring pleasure and misery in somewhat equal proportions. It is my firm conviction that a better understanding of it can help to tilt the weight away from misery, the present book being based upon the belief that knowledge is empowering. For example, rightly or wrongly, people sometimes think that their tastes are socially and morally unacceptable and better knowledge could prove valuable in seeing how the taste might have arisen and coming to terms with it. Similarly, couples frequently find that discord arises from divergent tastes or intensities of desire. Insights into how desire works might yield greater tolerance of differences and thereby harmony. To give a full account of the range of desires, Chapters 20–1 describe the nightmare world of sexual violence, for which, of course, there can be no degrees of tolerance. I believe that a greater insight into the causes of sexual violence could help to combat it. However, the reader seeking only insight into harmonious and consensual sex might wish to skip these two chapters.

I have a wide range of different readers in mind, such as neuroscientists, psychologists, psychiatrists, philosophers, counsellors, teachers, social workers, police and probation officers, as well as the general public. I have tried very hard to write it in a style that is accessible to such a spectrum of different readers and I can only hope that I have succeeded. To respect such a spectrum, some information on, for example, details of brain processes is put in footnotes, which can be ignored without losing the story-line.

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.

Looking back in time, what led to an adult’s brain/mind, with its ‘regular’ as well as idiosyncratic features of sexual desire? Considered in this way, the individual has a history in terms of two related aspects:

• human evolution, starting millions of years ago;

• development of the individual from conception to adulthood.

To understand how desire got here, it can be insightful to look at events happening over these two very different time scales, which is done in this chapter and the next. Such questions arise as:

• What are the roles of nature and nurture in determining human sexual desire?

• What evolutionary factors contributed to contemporary sexual culture and how did they do so?

• How does the early experience of the child lead to the later emergence of sexual desire?

• What is the role of interactions between the child and its parents in leading to a brain/mind that finds other humans attractive?

• What sort of individual becomes the object of desire and how does this occur?

• How can an unusual development lead to unusual sexual behaviour?

The development of sexual behaviour can be best understood in terms of general principles of development, described next.

A broad framework: some general processes underlying development

From conception and starting ‘simply’ as a single fertilized egg cell, the newly formed individual develops and grows, by means of cells dividing and thereby their number multiplying astronomically. The growing foetus interacts with its physical environment, by absorbing nutrients, making limb movements and bodily adjustments. This is believed to facilitate the wiring of the motor controls of the body, in forming coordination between brain and muscles.

Evidence suggests that general arousal triggered by a range of non-sexual events can sometimes spill over into sexual arousal. The chapter will address the issue of the relationship between sexual arousal and sexual desire. The chapter will consider first ‘general arousal’ and then more specifically ‘sexual arousal’.

Basic principles

Some environments are said to be arousing, even some colours are given this description, while other colours are described as relaxing (Apter, 2007). When humans seek to increase arousal, to find excitement, they might go to a busy part of town or engage in a challenging and even dangerous activity. By contrast, to decrease arousal, they might lie on a tranquil beach. Such observations lead to the notion of an optimal level of arousal and humans can try to bring their actual level towards this optimum. People differ in their optimal levels; one person will commonly seek sources of high arousal, while another will try to avoid them.

The nature of inhibition

The means by which desire is inhibited (‘restrained’) represent an important feature of ‘how desire works’ and will be explored here. St Paul describes one form of conflict: that between the will and desire. Throughout the ages, prohibitions and disapproval of ‘inappropriate desire’ and its expression seem as evident as desire itself.

Social harmony requires that all societies have curbs on sexual behaviour, whether of an aesthetic, legal, cultural, religious or moral nature. Some potential inhibitors of sexual desire, such as public censure, have eased with more relaxed attitudes. However, jealousy, anger and disgust over what are judged to be unacceptable desires in others are still universal. For some, the existence of desire and its inhibition represent proverbial conflict.

Evidence suggests that they might not be quite the sovereign masters that Bentham supposed, though pleasure and pain feature large in any explanation of human sexuality.

Basics

Engaging in sexual behaviour has immediate consequences and these are generally assumed to influence future sexuality in terms of desire and the chances of sexual behaviour being repeated (Bancroft, 2009). Consequences of behaviour that encourage us to repeat the behaviour are known as ‘reinforcers’ (Chapter 2). Conversely, the consequences can be such as to reduce the future tendency to repeat the behaviour, in which case they would be described as ‘punishing’. Viewed in evolutionary terms, reinforcement encourages people to repeat behaviour that has served reproduction, whereas punishment persuades them to resist, stop, take stock of the situation and change behaviour. This chapter looks into the details of these immediate consequences of sexual behaviour and their link to desire.

The phenomena

This chapter examines variations in the form of behaviour, where it is idiosyncratic. Some of these forms are perfectly harmless exaggerations of ‘normal’ desire, as in the above, or where some individuals are sexually excited by particular items of clothing, most usually shoes. However, at the other extreme, some are ‘all-engaging’ and extremely dangerous. One person’s desires are fuelled by coercion and violence, whereas most of us are horrified by this. To most, a reciprocating and empathetic human is essential to sexual desire, but a few seek sex with terrified victims or even corpses. Another’s fantasies are mainly masochistic. Others are drawn to peeping through their neighbours’ windows to glimpse a naked body, whereas some want their own exposed genitals to be displayed. Some of the best known such ‘paraphilias’ these days, such as voyeurism, fetishism and exhibitionism, are apparently little if at all evident in traditional societies (Gebhard (1971). They might arise in societies where people are able to remain anonymous.

How can we understand these outliers of desire? Chapters 18–21 look at various forms of desire ‘at the fringes’ and the kind of underlying processes that appear to give rise to them. I cannot provide definitive answers to why someone exhibits a particular ‘fringe desire’, but there are now some strong pointers. The incentive-based model developed in Chapter 4 can serve as a framework for understanding.

Basics

The use of representations of aspects of life is part of what it is to be human (Byrne and Osland, 2000). Representations exist outside the brain on film and paper and in its inner workings of fantasy. Our early ancestors left us cave paintings depicting hunting scenes and wild animals. In the period up to 600 bc, Etruscan art was already explicit in its depiction of heterosexual and homosexual activity (Byrne and Osland, 2000). These days we have films, the Internet, television, photographs, novels and paintings to convey other worlds to our imaginations, including those of sexuality and its possibilities.

Representations of sexuality can trigger arousal in the present as well as plans for the future and reflections upon the past. In the absence of a partner, as in masturbation, or even in their presence during sexual activity, people commonly employ ‘virtual’ means of boosting sexual excitation: erotic visual images, stories and the use of pure fantasy in the imagination (Byrne and Osland, 2000).

Attractiveness is, of course, not the same as sexual desire. For example, a heterosexual man might judge another man to be attractive without feeling any sexual desire towards him. In one experiment, heterosexual women did not show a change in pupil size (an index of desire) on viewing an image of a woman whom they described as attractive (Laeng and Falkenberg, 2007). However, an effect seen across cultures is that normally a necessary, though not sufficient, condition for someone to elicit strong sexual wanting is that they would be judged as ‘attractive’ (Ford and Beach, 1951). Physical appearance (‘attractiveness’) is valued highly by both men and women in terms of what triggers desire (Regan and Berscheid, 1999). There is a sex difference in that men tend to find women more attractive than women find men attractive (Istvan et al., 1983).

Features and qualities

The quality of attractiveness is not simply a product of Hollywood and the advertising industry, though doubtless this has a role in promoting certain stereotypes. In experiments, even human infants as young as 2–3 months of age spend more timing looking at those women’s faces which were judged by adults as attractive (Langlois et al., 1990). By 12 months of age, they spend more time interacting with strangers wearing attractive masks as compared to unattractive masks.

Swelling detected at the genitals appears to add to desire arising from the stimulus of a potential partner (Georgiadis et al., 2012) and might even provide the principal stimulus to desire (Laan and Both, 2008). Positive feedback seems to be involved (Mouras et al., 2008); in response to a visual stimulus, desire would contribute to genital arousal and, by means of signals from the genitals to the brain, there would be an amplification of desire.

The bits that make up the whole

Knowledge of the brain bases of desire comes from several sources (Chapter 2):

1. research on non-humans and cautiously extrapolating to humans;

2. looking at changes in the sexual desire of people following brain damage or disease;

3. using neuroimaging to examine activity in the brains of people exposed to erotic images.

Neuroimaging reveals a network of interacting brain regions, parts of which are excited and others of which are inhibited by erotic visual stimuli (Georgiadis et al. 2010; Redouté et al. 2005). Researchers distinguish regions serving some closely related but nonetheless somewhat conceptually distinct roles:

1. to make an initial assessment of the sexual value of the content of the image;

2. to produce a signal that is sent to the genitals to trigger swelling;

3. to receive feedback from the genitals on their arousal – this signal is thought to contribute to the conscious awareness of the state of the body, particularly the dimension of eroticism;

4. to create a motivational signal, having unconscious and conscious aspects, which tends to direct behaviour towards the sexual stimulus – a feature of this is conscious desire.

It would be informative to discover how Damasio’s readers (and indeed mine too) have reacted to this invitation to reflection. If they are like the population sampled by sex researchers, some would find it hard to recall any such lust-filled moments, whereas others would be inundated with recent memories jockeying for occupation of the conscious mind. Some would doubtless find their desire triggered instantly by such parts of the whole as an ankle or leg, whereas a number might find it fuelled by the shoes worn. Others would only be excited slowly by a whole speaking and socially interacting personality.

The enormous variation in the reactivity of human sexual desire is why I use the term ‘enigma’ and is a feature that must be accommodated by any attempt to explain desire’s foundations. What are the implications of this wide spectrum of responses? Is there a healthy norm, while deviations to either side indicate that something is wrong? Accounts by individuals, both famous and not, on their experience of desire are invaluable in understanding how it works and they will be used widely throughout the following pages.