How Sexual Desire Works- The Enigmatic Urge

by Frederick Toates

  All who subscribe to a Darwinian world agree that brains are ‘designed’ by evolutionary processes to solve problems that have been confronted in evolution. The solution to some of these can be specified in a modular structure, such as to trigger fear to a large menacing animal quickly and automatically, or disgust in the case of rotting food. These solutions can be hard-wired as modules into the brain. However, there is also ‘spare capacity’ in the human brain left for flexible solutions to problems and this creates a need to perform juggling between these flexible solutions and the more automatic reactions to events. Sometimes people will override the tendencies of the modules in the interests of serving a conflicting goal. Humans probably more than any other species have to juggle what are often conflicting goals competing for expression in behaviour and have to find creative new solutions to problems.

  For example, although most of us are terrified by snakes, reflecting the action of a fixed module, some appear not to be. Some people even show affection towards them as household pets. Were they born lacking the appropriate fear module, or was it, as seems more likely, that an idiosyncratic goal, to overcome fear and gain mastery, has dominated the control of behaviour?

  Models have attempted to reconcile the existence of modules with the obvious flexibility of behaviour (MacDonald, 2008; Toates, 2005). Modules are sensitive to the regularities of the environment (e.g. avoid snakes at all times), whereas flexible control is needed in dealing with the irregularities (e.g. approach snakes if you are making a nature film).

  The book will follow the logic of Stanovich (2004), who coined the term ‘the robots’ rebellion’. In such terms, humans are the robots who, metaphorically speaking, staged a rebellion against the hard-wired dictates of genetic destiny. This was possible because of spare capacity that can be exploited in pursuit of goals that are not specified by the brain’s collection of modules. Affect is our guide in goal pursuit.

  Concerning sexual desire, perhaps the most important shot fired in the robots’ revolt was when the first human realized that there is a connection between sexual desire and producing children. This was a necessary step to the invention of contraception in its various forms, which weakened the link between desire and the consequence of having babies. From then on, humans could to varying degrees ‘have their affective cake and eat it’.

  Sexual jealousy as an example to illustrate the argument

  Sexual jealousy can be a particularly powerful emotion, as illustrated by Trachtenberg, (1989, p. 81): ‘Suddenly she’s an unknown quantity, someone whose failure to call or answer the phone shocks me into spasms of jealousy. I twitch like someone strapped into the electric chair.’ The fear of the consequences of jealousy probably represents the strongest single factor inhibiting the expression of sexual desire outside the established bond. Evolutionary psychologists see jealousy as a ‘module’. It seems to be universal, triggered automatically and is not open to rational conscious reasoning.

  Consider, for example, David and Clara Harris. They appeared to be living the American dream, having achieved prosperity through a chain of orthodontist clinics in Texas.5 However, after doubting her husband’s fidelity, Clara hired a private detective to track his moves. On hearing that David was staying at a hotel with his mistress, Clara drove there with their daughter in the passenger seat and, when the husband and mistress appeared, she drove her car into David three times, killing him at the scene (Buss, 2005).

  Jealousy can even be retrospective. A classic account was given by Count Tolstoy’s wife, after he had presented his diaries to her as an engagement gift (!), wherein she read of brothels, venereal diseases and so on (A. N. Wilson, 1988, p. 197):

  I don’t think I ever recovered from the shock of reading the diaries when I was engaged to him. I can still remember the agonizing pangs of jealousy, the horror of that first appalling experience of male depravity.

  On meeting one of her husband’s former mistresses and the child that he had fathered, she wrote ‘I think I shall kill myself with jealousy’ (A. N. Wilson, 1988, p. 205).

  There is some difference between men and women in the triggers to this emotion. Men tend to find sexual infidelity the most upsetting, whereas women are most disturbed by emotional infidelity. This corresponds to the bedroom versus the candlelit restaurant

  Within the social sciences, jealousy has traditionally been interpreted as a product mainly of culture and can correspondingly vary widely across cultures. Indeed, from this perspective, it is often seen as (Meston and Buss, 2009, p. 100) ‘an immature emotion, a character defect, and a sign of low self-esteem’. By contrast, evolutionary psychologists suggest that jealousy is a universal adaptive trait that cuts across all cultures and has served a useful role in evolution (Meston and Buss, 2009). Indeed, one might suppose that an ever-responsive jealousy module would form an indispensable part of any viable individual, as omnipresent as an organ for cleaning the blood. For the male, the fitness cost of his partner’s infidelity is so high that evolutionary psychologists emphasize the particular premium on men’s sexual jealousy (Pinker, 1997, p. 488): ‘A woman having sex with another man is always a threat to the man’s genetic interests’ and ‘Men should squirm at the thought of their wives or girlfriends having sex with another man.’

  Jealousy is indeed represented very widely across cultures (Marshall and Suggs, 1971). However, the circumstances that trigger it can sometimes be quite subtle, as can those in which it is not triggered or at least not expressed. There are some important cross-cultural differences in how marital ‘infidelity’ is treated or even, one might suppose, how it is felt. The evolutionary psychologist David Buss acknowledges (Buss, 2003, p. 11): ‘Jealousy is not a rigid, invariant instinct that drives robotlike, mechanical action. It is highly sensitive to context and environment.’ The Toda ethnic group in India are widely tolerant of what would be called ‘adultery’ in Western cultures (Ford and Beach, 1951). Indeed, bad feelings are generated not so much by ‘adultery’ but by trying to thwart a married woman’s opportunity for it. Jealousy between brothers who share the same wife is apparently very rare. In some societies extramarital sex is permitted on certain specific occasions such as festivities and ceremonies (Ford and Beach, 1951; Gebhard, 1971). Amongst some Aboriginal Australians, group sex involving pair-bonded partners was incorporated as part of fertility rituals (Gregersen, 1986; Roy, 2005). Gebhard (1971, p. 212) speculates: ‘in most human societies the regulatory concern is not with the extramarital coital act itself but is rather with its social implications. Does it constitute a defiance of the spouse and society?’ A wife on the Polynesian island of Mangaia will occasionally show jealousy at a husband’s infidelity, specifically if he had not told her about it (Marshall, 1971). Amongst the Ammassalik Inuit, under certain conditions that were culturally sanctioned (the invitation of ‘turning out the lamp’), a man could offer his wife to a visitor for a period of sexual pleasure (Hupka, 1981). Of course, this could be seen as reflecting male power, but nonetheless does not suggest uncontrollable male jealousy. Such ‘sex hospitality’ was also found in certain Australian aboriginal cultures (Gregersen, 1986). However, outside this accepted framework of mutual agreement, intense jealousy could be triggered even leading to murder. At the start of the twentieth century, the Toda community of southern India practised a form of polyandry, within which sexual relations with the spouse of another individual were acceptable, provided all parties agreed to this (Hupka, 1981).

  Some in the Western world might doubt anthropological accounts from remote cultures, so let us look nearer to home. Consider the phenomenon variously known as ‘co-marital sex’ or ‘swinging’. It is hardly the case that the male is invariably suffering under duress or simply seeing this as quid pro quo for access to someone else’s wife.

  People in the group sex situation report little jealousy and much less than they would feel in the case of non-consensual adultery (Smith and Smith, 1970). When the situation is not evaluated as one of threat, some apparently
are even excited sexually by their intimate partner’s ‘infidelity’, as witnessed at swinging clubs. It could be that the aroused state deriving from infidelity detection has been recruited into the service of a goal not of anger and hostility but of sexual arousal and permissive tolerance with a bonus of earning sexual novelty in the bargain.

  So, even this basic and primitive emotion can only be understood in terms of any module being embedded within some sophisticated and peculiarly human brain processes. Jealousy is determined in large part by how the situation is interpreted and evaluated (e.g. as threatening to the bond) within the particular couple and broader culture (Hupka, 1981). A possible solution is that we are all equipped with a jealousy module but human ingenuity and discovery are such that the module’s potential role can sometimes be overridden (‘corrupted’) by other brain processes, according to context. Again this points to the plasticity of the human brain with the possibility of subtle nuances of emotional reactivity. Thus, a module is not exactly like an organ. The heart can serve only the one role of moving blood around the body and cannot temporarily be commanded to suspend its activity in the interests of another organ. The modules of evolutionary psychology appear to be more flexible in their operation.

  MacDonald (2008) discusses Buss’ argument that sexual jealousy is a powerful cue for aggression. Given the threat to genetic perpetuation posed by infidelity, it is easy to appreciate that such a jealousy module might emerge in evolution. However, as MacDonald argues, its effect can often be overridden by mental representations of longer-term gain (maintenance of family, stoical resignation), as well as anticipation of negative consequences of violating the law. Such assessment of costs and benefits is likely to be highly specific to the social context and culture. They could not represent evolutionary regularities and thereby genetically transmitted information.

  Given the wide variety of different reactions to infidelity, some have speculated about whether a dedicated jealousy module actually exists. The reaction to infidelity can variously trigger fear, anger, disgust or sadness, or some combination of these, according to cultural norms, individual experience, expectations and intentions (Hupka, 1981). Maybe the reaction is to be understood in terms not of a dedicated jealousy module but as a combination of these more general-purpose systems.6

  So, now let us turn to sexual attraction and see where these ideas can be applied.

  In summary

  Sexual desire, arousal and behaviour are based upon automatic and controlled processes.

  Acting in an automatic mode, the brain would seem to fit rather well the notion of ‘modules’, as advanced by evolutionary psychologists.

  The brain can multi-task and set idiosyncratic goals. Culture appears to exert a profound role in human sexuality. So, in addition to modules, the brain has a capacity for flexible control.

  Sexual jealousy illustrates rather well how any module is embedded within some rather rich and flexible brain processes.

  Six Sexual attraction

  Beauty may be in the eyes of the beholder, but those eyes and the minds behind the eyes have been shaped by millions of years of human evolution.

  (Buss, 2003, p. 53)1

  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).

  What is attractive?

  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.

  Although there are such universals, there are also idiosyncratic culture-dependent aspects of exactly which features are judged as attractive (Ford and Beach, 1951). People occasionally express surprise at whom they find attractive, feeling that one should be able to offer a rational analysis for taste. However, appraisal of stimuli in terms of their value occurs at a largely unconscious level (LeDoux, 1999), and so we should not expect to find all the answers by conscious introspection.

  Some place a premium upon eyes whereas others emphasize ears. For women, smell plays a very important role, as do height and symmetry of the face (Meston and Buss, 2009). As the opposite side of the same coin, there are some universals in what is found to be unattractive (Ford and Beach, 1951), for example a face scarred by acne and what are judged as bad breath and body odours.

  Levels of analysis are evident in the assessment of attractiveness. The attraction value of a female to a man is more clearly defined largely (though, of course, not wholly) in terms of physical features, whereas male attractiveness to a woman has more to do with features set into context, such as what they indicate about the man’s social status (Ford and Beach, 1951; Symons, 1995). That is to say, women tend to place less emphasis upon physical looks, this being a consistently reported sex difference across cultures (Buss, 2003). Exactly corresponding to the heterosexual difference, homosexual males place a high premium on youth and looks, whereas homosexual women attach relatively little importance to these factors.

  A preference for female thinness or plumpness as attractive features to a male seems to vary with culture. In cultures where food has been scarce, there is a tendency to favour plumpness over thinness (Buss, 2003). Buss suggests that there is not an evolved predisposition to favour a particular body size, but rather the evolved disposition is to favour status, and what signals such status varies according to culture.

  Of course, it is not just physical characteristics that define attractiveness. Rather, psychological and behavioural features can also play an important role. For example, people find creativity, kindness, altruism and a sense of humour attractive (Laham, 2012). Meston and Buss (2009, p. 22) write:

  The tendency to be attracted to those who make us laugh and elicit a positive mood can partly be explained in terms of conditioning. After pairing a particular mood with a particular person on multiple occasions, eventually the person alone will elicit that mood. Indeed, studies have found that when women view photographs of strangers while enjoyable music is playing, they are more attracted to them than when they listen to music they find unappealing.

  A woman of 29 years reported (Meston and Buss, 2009, p. 22): ‘I had a relationship with someone who was very, very ugly but who made me laugh. He was very self-confident, as funny people tend to be I guess, so that was what attracted me to him.’ Similarly, the pop singer Madonna reported (Madonna, 1992, p. 83): ‘If I see someone who’s not necessarily conventionally beautiful, I can still be attracted based on their intellect or whatever.’ A general principle is that ‘mere exposure’ to something increases its attraction value and this principle applies to people too. Mere repeated exposure to someone has a tendency to increase their attraction value (Meston and Buss, 2009).

  The brain and attractiveness

  A region at the front of the brain2 seems to be involved in allocating attraction value; for example, it is activated in men by presenting pictures of women whom they judge to be beautiful (Stoléru and Mouras, 2006).

  An evolutionary psychology perspective
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  Evolutionary psychology explains why weight is placed upon certain stimulus characteristics: their value in signalling fitness. Hence evolutionary processes have built in such automatic assessments since they have paid over generations in terms of passing on genes. As with explanations in terms of what causes desire in the here and now, when the explanation is in terms of function, incentive motivation can also yield insight. By a selective attraction to certain female characteristics, the male maximizes his chances of successful genetic perpetuation, since they are indicative of good health. In other words, as Symons (1995) expresses it (p. 87): ‘male sexual attraction was designed to vary in intensity directly with perceived cues of female mate value’. He argues (p. 80):

  I will use sexual attraction/attractiveness as an index of sexual pleasure. That is, I will assume that if X perceives A as more sexually attractive than B, then X typically would experience more pleasure (and would anticipate experiencing more pleasure) from copulating with A than with B.

  In these terms, the fact that A is more attractive than B reflects the higher reproductive viability of A.

  He suggests that (p. 81): ‘human males evolved psychological mechanisms that selectively detect and respond to certain specific characteristics (such as smooth skin and bilateral symmetry) of women’s bodies’. Some qualities that contribute to female attractiveness, for example good skin, teeth and hair, are rather obviously related to physical health (Buss, 2003), whereas others, for example particular facial features, are not. However, sense can be made of the latter from an evolutionary perspective. Symmetry of the face is also a quality of high attractiveness and is an index of healthy development of the body.