How Sexual Desire Works- The Enigmatic Urge

by Frederick Toates

  Even where desire takes an unusual form, as in coercive and violent sexual behaviour, its roots can still be understood better in terms of the intermeshing of biological and social factors, rather than either factor alone. Researchers can identify the properties of particular brain regions and how they appear to deviate from normal in the case of sexual offenders (Raine, 2013). Of course, such brains exist in an environment of the individual’s upbringing, which all too often contains identifiable aspects of abuse, and this environment might be assumed to lock into interaction with the brain to affect brain development and to contribute to later deviance.

  Emerging sexual desire at adolescence is triggered in part by increasing levels of sex hormones. It tends to be restrained in its expression by social controls, for example parental (Udry, 1990). To ignore either source of influence would lead to erroneous conclusions.

  The bigger picture

  Accounts of sexual desire do not exist in a social vacuum (Tolman and Diamond, 2001). Rather, societal attitudes, prohibitions and morals to some extent reflect the contemporary understanding of desire and contribute to theories on its nature. Suggested advice and therapeutic interventions build upon such understanding. Popular articles, books and magazines explain how to boost desire by the correct choice of diet and life-style, or what to do in terms of dress, gestures, language and body image to trigger irresistible desire in others. Apart from religious texts, few instruct us on how to live with frustrated desire or how to resist temptation. As will be described later, insights into how desire can be increased or reduced illuminate its bases.

  Whether men and women are treated as equals surely relates to an understanding of the bases of sexual desire. Traditionally, male sexuality has been described as something ubiquitous, ever-ready and relatively straightforward. By stark contrast, over the centuries women have variously been portrayed as, on the one hand, essentially devoid of any intrinsic sexual desire and simply the passive targets of men’s desires, but on the other hand, as beings with insatiable drive (Sherfey, 1973), who present devious lures for men’s downfall (discussed by Hrdy, 1999; Laqueur, 1990; Tolman and Diamond, 2001). In the latter terms, men are said to have conspired to suppress female drive. The present book will argue that neither extreme position is strictly true, and will attempt to give balance to this debate.

  Scientific explanations and lay accounts often appeal to metaphors and analogies and these say much about the interpretation of sexual desire within different cultures. For example, reflecting on his upbringing, the British art historian and journalist Brian Sewell wrote (Sewell, 2011, 169):

  I had too to contend with the increasing pressure of sex and its conflict with piety. I could no longer persuade myself that masturbation was no more an assisted bodily function, a purging as natural and necessary as the emptying of bowel and bladder –‘Think no more of it’, my parish priest once said, ‘just as you think nothing of going to the lavatory’.

  Evolutionary psychology

  Evolutionary psychology spawns passionate disciples and opponents in roughly equal measure. It follows in the tradition of sociobiology but starts from psychological considerations. Features of desire often fit its predictions on what has proved successful in reproduction during the evolutionary history of humans (Buss, 2003). For example, this perspective makes sense of the observation that men tend to find younger women more attractive than older, since the younger usually have a higher reproductive potential. Similarly, sexual jealousy and mate-guarding make sense since they help to protect against infidelity. Gender differences in sexual behaviour feature at centre-stage in evolutionary psychology, and the underlying assumptions will be examined later.

  The brains that emerged in evolution now find themselves in a twenty-first-century society, very different from that in which they evolved. Therefore, in the spirit of evolutionary psychology, it will be argued that consideration of the intermeshing of evolved brains and contemporary culture is again the only way to gain insight.

  The framework

  Understanding sexual desire and behaviour requires a new organizing framework, one that does justice to the influences of both biology and culture and which can mesh with evolutionary psychology. This will go some way towards showing how desire works, encompassing its constant features as well as its richness and diversity. The framework needs to account for the fact that social and biological factors are not in competition in terms of their relative weight in the control of desire. Rather, it needs to show how biological and social contributions interweave. It must be able to accommodate the fact that different influences arising from cultures can be assimilated by the brain and contribute to differences in sexual desire. Some individuals, because of a combination of biology and life-time experience, either feel no sexual desire or are able to suppress such feelings with little discomfort or harm.

  Byrne (1986) argued that sex research has been bedevilled by a tendency to look at the bits rather than the whole. He sees the problem as rather similar to that of one individual describing a trunk, another legs and a third portraying tusks and so on but missing the notion of a whole elephant. This book will try to sketch the whole elephant.

  The direction to be taken here

  I have spent my academic life researching motivation, including sexual desire. Advances in experimental psychology and neuroscience, particularly since around 1980–1990, now offer some important new insights. However, this information on the brain is not enough. We need all the help that we can get and I will call upon evidence from biology, evolutionary psychology, sociology, feminist studies, psychiatry and clinical psychology, as well as seeing what classical literature and philosophy have to offer. Crucial to understanding desire is the personal witness of the experience and this will also play a key role by being integrated with a scientific perspective.

  There are two principal and interacting strands of the research with which I have been closely associated and these will be brought together and set into a broader context of sex research. They are described now.

  The difference between wanting and liking

  In 1990, working as an academic at The Open University in England, I had a visit from a good friend, Kent Berridge, an experimental psychologist from the University of Michigan at Ann Arbor. I had spent some years studying the psychology of motivation – what moves us? How do desires arise? Based upon ideas advanced by the late Canadian psychologist Dalbir Bindra, I had developed a theoretical model that offered some new insights and could start to accommodate diversity of desire (Bindra, 1978; Toates, 1986). However, this research needed to be grounded better in how real flesh-and-blood brains work and how their chemical messengers underlie desire.

  Kent described some surprising results that he and his Michigan colleagues had obtained (Berridge and Valenstein, 1991). These findings appeared to overturn a cherished belief, shared initially by the researchers themselves, on the role of the brain’s chemical messenger, dopamine. Previously, it had been thought that dopamine is the brain chemical that confers pleasure on the events of life. That is to say, the pleasures of food, drugs, gambling or sex, or whatever, are a result of the activity of this chemical in the brain. For example, a cold drink to a dehydrated person would taste pleasant because the water on the tongue sends messages to the brain that cause it to release dopamine. To the same person when not dehydrated, the water on the tongue would trigger the release of little or no dopamine and there would not be such an intense hedonic feeling. When viewed in such terms, orgasm would represent an enormous burst of activity by dopamine.

  Contrary to established belief, the Michigan researchers’ evidence showed that changing dopamine levels did not alter the apparent pleasure that rats derive from tasting food. Therefore, this suggested that dopamine did not mediate the pleasures of life. Rather, dopamine appeared to mediate wanting of such things as food, sex, and so on. So, it would follow that some other substance in the brain (introduced later in the book) must serve the role allocated to
dopamine as the physical basis of liking, also expressed as pleasure and hedonics. To many investigators, this represented a radical shift in thinking. To be precise, the new results showed that dopamine is not involved in the pleasures of eating and drinking with a likely extension to sexual contact and orgasm. However, this substance might still have some role in other pleasures, such as the pleasure of contemplating, pursuing and achieving a goal (Klein, 1987), a theme that will be investigated later.

  Many scientists, myself included, do not necessarily welcome radical change, preferring to see confirmation of what we know already with a few new i’s dotted and t’s crossed. Surely, I protested, common sense dictates that we want what we like and like what we want and the two invariably go up and down in parallel. The thirsty person both wants and likes water. So, why should evolutionary processes have ‘invented’ two distinct mechanisms, each exploiting a different chemical, to solve this one problem? The researchers were as surprised by the results as I was but they had had more time to assimilate them.

  That evening over a drink in the local pub, Kent countered my scepticism by pointing out that one of the intellectual foundations for their new ideas on the role of dopamine in mediating wanting was my own theoretical research (Toates, 1986). Sharing the trait of vanity with most of the world, scientists are particularly susceptible to their own research being cited and I am no exception to this. I started to lower my resistance.

  Within two years of his visit, Kent Berridge sent me the first draft of a paper that he and Terry Robinson had written, in which they applied their distinction between wanting and liking to drug addiction. Dopamine was given a role in only the wanting aspect. There is a fracture line: the dopamine-mediated wanting of drugs can go up as addiction progresses, while liking them can even come down over the same time. This paper (Robinson and Berridge, 1993) has gone on to become one of the most (if not the most) cited articles of all time in biological psychology. Their perspective has now given a whole new meaning to the relationship between desire and pleasure. The paper dispelled any doubts, convincing me of the distinction and reinforcing my curiosity in tackling the issue. Of course, sex is not exactly like taking drugs but there are some common features and the book applies related ideas to sexual desire.

  On reflection, should we have been surprised that dopamine is implicated in wanting? On the one hand, scientific articles, textbooks and the popular media told us that dopamine equals hedonism (see the account by Salamone et al., 2007). At the time of writing, a Google search putting in the words ‘dopamine’ and ‘hedonism’ yielded 3,230,000 hits. On the other hand, there were already suggestions that the link is with wanting. Jaak Panksepp, then at Bowling Green State University in Ohio, published a review paper in 1982 in the influential journal The Behavioral and Brain Sciences, in which he described an ‘expectancy system’ that pulls animals, human and other, towards such things as food, drugs and sex (Panksepp, 1982). He suggested that dopamine is the most likely candidate to serve as a chemical messenger in this system. Ironically, I had worked with Jaak Panksepp some years before this and had published a commentary on his paper. At times we are so inundated with information that we simply don’t make the right mental connections.

  Levels within the brain

  A second theme of the book will be that the brain is organized at different levels, as a kind of hierarchy. This is not a new idea since numerous scholars have suggested it over many years. However, understanding of how this organization is embedded in the brain and the wide implications of it for understanding sexual desire is new (Toates, 2009). Furthermore, the role of dopamine acting at different levels is now better understood.

  The human brain contains regions that are old in terms of evolution and have much in common with those in other species (‘old brain levels’). These regions co-exist with other regions that have evolved relatively recently, which offer peculiarly human possibilities for flexible and creative behaviour and which can assimilate rich and complex information from culture (‘new brain levels’). For example, humans can perform what is probably a unique task of mental time travel, reflecting on early experiences and anticipating future mental states such as sexual pleasure or guilt. The capacity for time travel would seem to be highly relevant to sexual desire, which can be expressed in a wide range of different forms.

  Such hybrid brain organization has been compared to a jet engine being added to a horse and cart, something likely to create more than the occasional problem. Only by seeing how this combination of brain regions works can we understand the idiosyncrasies of human desire.

  These two sources of understanding, the role of dopamine and the way that the brain is organized in levels, are brought together with other information in the present book. Its central theme is that sexual desire can be much better understood in terms of how several such processes interact. If the logic to be developed here is correct, sexual differences (e.g. in tendencies to addiction or use of fetishes) do not require the postulation of completely new factors; rather, they arise from differences in settings and inputs to what are universal processes.

  The next chapter turns to the basic principles underlying the explanation of sexual desire.

  In summary

  An explanation of sexual desire must tackle the immense variation between people with regard to its intensity.

  To understand sexual desire two sources of evidence need to be brought together: (a) subjective reports from individuals about their feeling of desire and its expression; and (b) objective scientific findings.

  Sexual desire is that associated with the intention of attaining sexual pleasure.

  Sexual behaviour is not always motivated by sexual desire. Various other (some ‘ulterior’) motives can exist.

  Culture and biology intertwine as determinants of sexual desire and behaviour.

  Wanting can be distinguished from liking and these two factors sometimes get out of alignment.

  The organization of the bases of desire is by means of levels in the brain.

  At one level, the brain processes underlying sexual desire and arousal show certain similarities when we compare species.

  In spite of similarities across species, there are some peculiar (‘highly evolved’) features of human brains and behaviour that exist alongside the more basic and general features. Flexibility and creativity are at their most refined in humans.

  By considering how the general features and the peculiarly human features co-exist and interact in their effects, we can understand the complexities of human sexuality.

  The vagaries and varieties of sexual desire can be better understood by examining how some component processes in the brain interact.

  Two Explaining desire: multiple perspectives

  The clashing point of two subjects, two disciplines, two cultures – of two galaxies, so far as that goes – ought to produce creative chances. In the history of mental activity that has been where some of the breakthroughs came.

  (C. P. Snow, 1965, p. 16)

  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.

  How are objective and subjective linked?

  How does sexual desire arise? What might inhibit putting desire into effect? We have two different and what are sometimes seen as competitive types of answer. Some rationalists, believing in free will and the inscrutability of another’s mind, might suggest that answers are beyond the realm of science. Only the one doing the desiring can give an answer. By contrast, scientists sometimes argue that subjective conscious insight into the causes of behaviour is fallible, unable to be tested and therefore of no help to understanding. Rather, only the objective techniques of science, such as looking at the activity of a person’s brain or their genetics and life-history, can provide testable answers. The present book rejects both of these extreme positions and uses subjective and objective evidence.

  The relationship between brains and conscious minds has proven conceptually difficult for scholars over at least two thousand years. Clearly, it is not going to be solved here! However, some words are needed on the approach adopted. It is assumed that, for events in the mind, there are corresponding parallel events in the brain. This is taken to be true of the mind’s conscious and unconscious aspects. For example, the conscious feeling of desire corresponds to activity in particular regions of the brain, whereas the pleasure of orgasm might correspond to activity in different regions. So, as a short-hand, the term ‘brain/mind’ will be used to indicate activity in particular brain regions and the associated mind events.