Received 26 April 2016; accepted 27 June 2016; published 30 June 2016
The question of “What makes us human?” has found several answers from evolutionary anthropologists (Calcagno & Fuentes, 2012) . The answers refer to anatomy (upright gait), to behavior patterns (child-rearing), and to mental attitudes (explorative curiosity). Yet, in relation to subjective experience, the answers remain vague. Recent research has demonstrated that non-human primates show much more complex emotions than previously considered. Some primatologists, such as Frans de Waal, conclude that between animal and human emotions and motivations, there is only a difference of degree (de Waal, 2011) . My thesis, however, is a different one: In emotional life there is a difference in kind, with regard to sexuality―that in humans has become eroticism.
Usually eroticism is considered to be a recent reflective concept of western cultures. As such, it is seen to be of no use in empirical research about sexual life. Consequently, most biologists have avoided this topic because the difference between sex and the erotic is difficult to determine and to demonstrate, since it touches upon psychology, which biologists regard with suspicion. To be sure, internal factors like hormones, internal stimuli, and neuronal systems determine what the psychologist calls motivation (Ledoux, 1996) . Nevertheless, human love- stories demonstrate that in sexual life erotic fancies run wild, transcending simple responses to sensory stimuli. Thus, eroticism, unlike mere sexual activity, is a psychological issue dependent on, and at the same time independent of, sexuality. This issue serves as a lens through which to understand related issues such as family, society, and human freedom. If the assumption of eroticism as the specific difference between animal and human emotionality is correct, new light will be shed on the evolutionary road to human self-consciousness comprising conscience and moral sense. The difference lies in the fact that in evolution the erotic has turned the sexual activity of humans away from the primary goal of reproduction and the welfare of the horde. A more detailed explanation of this phenomenon will help us to understand the evolutionary question of “why us?” and “why not them?”
The methodological fabric of this article is as follows. Deviating from the normal way of making statements and giving explanations, I have inserted possible objections that are usually made from the biological point of view. This method of reasoning is close to Aristotelian dialectics as a method of scientific research by exchanging questions and answers (Topics). The dialectical art of reasoning is subject to constraints enforcing plausibility rather than cogency. Plausibility seems to me to be a way of breaking the ice of first principles and stopping the endless discussion about a seemingly unanswerable question. The advantage of this procedure is not only strategic but also epistemological, making the presentation more comprehensive than the usual piece of empirical research. Confrontation and comparison of different points of access is the correct means of approaching the problem of what it is to be a human being living in a complex world.
2. The Meaning of Eroticism
“Eroticism” as a term constitutes a problem, linguistically as well as semantically. As with the adjective “erotic,” one associates the erotic with prostitution, obscenity, and pornography. In normal language lust, sex, and the erotic are interrelated terms (Ellis, 1936: p. 132) . Subsequently, a scientific definition of eroticism is very difficult to formulate. In order to find a core meaning of “eroticism” I will therefore give an overview of the use of this term in biology, sociology, and psychology.
Biologists rarely use the term. If I have read him correctly, in The Mating Mind Geoffrey Miller speaks of sexuality, sexual relation etc., but often in the sense of erotic feelings transcending mere sexual excitement (Miller, 2001) . The same applies to The Evolutionary Biology of Human Female Sexuality by Thornhill and Gangestad (2008) . When describing the display of women’s extended sexuality, the authors speak of “sexual interest,” but the term “eroticism” (p. 14) only appears once. As a result, there seems to be no sharp demarcating line between eroticism and sexuality.
In his classic The Evolution of Human Sexuality, Symons (1979: p. 172) discusses the issues of “psychology of sexual arousal,” including erotic pictures as stimuli. For him, erotic material that is close to pornography reveals little about sexuality that exists in ordinary life. On the other hand, Symons refers to sexuality as emotionally volatile and seeking the exceptional. Jim Pfaus in his research on human sexual function focuses on subjective and objective measures of sexual desire and pleasure, and has shown how such measures are altered by different types of erotic stimulation (Pfaus, 2013) .
In Why We Love, the renowned anthropologist Fisher (2004: p. 95) gives a list of types of love: “The most celebrated is eros, or passionate, sexual, erotic, joyful, high-energy love for a very special partner. I think eros is a combination of lust and romantic love.” In chapter 8 of her Anatomy of Love, entitled “Eros: Emergence of the Sexual Emotions,” Fisher states that sexual emotions are millions of years old and evolved along with the brain (p. 162ff.).
Cross-cultural research shows a great variety in the relation between sex and society (Wilson, 1975) . Sexual life in natural societies has been studied by ethnologists such as Bronislaw Malinowski. For Malinowski “eroticism” comprises “sexual approaches” as well as “erotic approaches.” In The Sexual Life of Savages, he writes: “Sex, in the widest meaning is rather a sociological and cultural force than a mere bodily relation of two individuals. But the scientific treatment of this subject obviously involves also a keen interest in the biological nucleus” (p. xlv). In this statement Malinowski reminds sociologists that man is not a blank slate. Cultural configurations are always based on a ground. The ground is nature, inner and outer, which provides the structure or style of awareness, the way of seeing, as Malinowski called it. Nature is preformed: “materia signata,” in medieval ontology. This means, in regard to eroticism, that sexuality is not merely receptive but transforms intimate relations into meaningful gestures of social consent.
In describing late twentieth-century processes of social change, the renowned sociologist Anthony Giddens postulates a transformation of intimacy in the direction of “confluent love” and “plastic sexuality.” The model of plastic sexuality provides for the possibility of sexual interaction as a means of emotional communication separate from procreation. In this context Giddens defines eroticism not as a particular skill of stimulating sexual desire but as “the cultivation of feeling, expressed through bodily sensation, in a communicative context” (Giddens, 1992: p. 202) . Eroticism thus is sexuality within a wider range of emotional intentions leading to personal ties between man and woman as equals. This optimistic view of eroticism appears utopic since empirical research shows that sexual intimacy―modern egalitarian views notwithstanding―continues to be structured by inequalities (Jamieson, 2005) . This state of affairs is certainly due to sociological accounts, but a more basic anthropological view points to the biological roots of the male-female polarity in the realm of erotic love. Far from holding out a promise of boundless social progress, eroticism stands for sexual relationships with their inherent contradictions that mark the complexity of human social life.
More explicitly, psychologists such as Richard Wollheim emphasize the ambivalence of love as “prospective satisfaction” coupled with “prospective frustration” (Wollheim, 1999: p. 83). Psychoanalytic thinkers speak of erotic love as superior to mere sexual arousal shown by animals. Erich Fromm, for example, reproaches Freud for making no distinction between sexual and erotic love, thus missing human uniqueness (Fromm, 1971: p. 54) . Fromm’s famous The Art of Loving reminds us of the Latin poet Ovid, who in The Art of Love considers love as a mental disease to be cured. Fromm suggests that problems among couples reflect the fragility of modern eroticism which often requires the therapeutic discourse to recreate the psychological stability of the partners.
On the other hand, Freud states that Eros assenting to life is not alien to death. It is the ambiguity, and hence the self-transcendence, of Eros which we are insisting on. The sexual nature of Eros does not cease wholly to exist but is thoroughly transmuted and blended in the higher character of mental life. The connection between sexual excitement and death, experienced in the ambivalent feeling of mutual orgasm, constitutes the paradox of the human mind as a part of nature and at the same time as distant from nature. Following Freud, the French thinker and writer Georges Bataille, in his late work Eroticism, affirms that the domain of sexuality is a domain of violence (Bataille, 2001) . Sexual violence is not merely physical but mostly psychical, breaking down the social order with fearful excesses of erotic fantasy. Erotic transgressions involve the idea of death, leading to “sacred eroticism,” as Bataille calls the outbursts of passion inherent in religious sacrifice. In eroticism mental energy is expended for the sake of establishing contact with the backside of modern utilitarian society.
To sum up, eroticism, in all its contexts, does not refer specifically to sexual techniques, but rather gives an interpretation of sexual desire. This interpretation is manifold: it is pragmatic, fantastic, and ethical. It is, strictly speaking, not a definition, but a formula that gives the meaning of eroticism in different aspects of behavior. To arrive at a better definition it would be necessary to check up on how eroticism interfaces with the manifold areas of emotional research (Lewis, Haviland-Jones, & Feldman Barrett, 2008) . Anyhow, the more humans are able to transform the sexual impulse into spiritual experience, the more they participate in subtle aspects of social life such as aesthetic taste, empathy, and mind reading. This shows that anthropology would do well to investigate notions of erotic culture to pave the way to establishing evolutionary criteria of human mental uniqueness.
3. The Evolution of Eroticism
From the point of the biologist, eroticism seems to apply to present-day societies, whereas humans evolved under much different conditions. Mating and hence sexuality was highly constrained by limited numbers of choices in small local bands, by the need to form lineage alliances by mating, and other such factors. Sexual feelings were there, probably more or less as today, but sex was not a very private matter in the way it is now. Our hormonal nature evolved under those kinds of conditions until very recently, and by then populations were larger so that selection was a much slower process, even in the evolution of mating patterns. Hence, the evolutionary inference that erotic manifestations are uniquely human attributes (other than, of course, the known human- specific cultural manifestations) is called into question.
To be sure, this consideration of a biologist who is interested in the genetic aspects of behavior is difficult to disprove. There is continuity in mating strategies adapted to social life, and I do not wish to minimize the power of social organization in influencing human mating behavior. Even so, evolutionary psychology transcends the typical situations of finding a partner. I fully agree with Donald Symons: “Sexual experience is largely adapted to the exceptional” (Symons, 1979: p. 167) . In this regard, it is crucial to distinguish between animal and human sexuality. Jared Diamond has described the difference by calling the human the animal with the weirdest sex life (Diamond, 1998) . Regarding behavioral differences, there is the human’s continuous readiness to have sex. Consequently, sex is, subjectively, the source of the most intense pleasure and at the same time the cause of the deepest sorrow. Evolutionary psychology has registered the built-in conflicts of human mating strategies (Buss, 2003) . However, the evolution of desire cannot be sufficiently explained on the functional level. The ambivalence of sexual emotions emerges parallel to mating strategies and refers to a mental state close to the dissolution of personal identity. It is here that the transition takes place from sexuality to eroticism, involving imagining and fantasizing about the desired as well as dreaded states of sexual arousal (Fellmann & Walsh, 2016) .
My aim is to define the erotic as a qualitative difference in sexual arousal. Only when this almost imperceptible but crucial distinction is made eroticism is applicable to the sexuality of primordial humans. In my view, this difference results from the upright gait, permitting the partners to look in each other’s face during the act of copulation. The expression of sexual emotion, of course, does not yet constitute intimacy, if it occurs in public, but it is the beginning of recognizing the partner as an individual. Perceiving and bestowing personal identity constitutes a higher-order awareness of what the other feels, intends, and thinks. In grooming, an ape is surely aware that the loused other feels good, but in this case feeling good is bound entirely to the present situation, whereas humans are thinking and caring of each other also in absence.
My suggestion that humans in their erotic complexity pay more attention to, or have more awareness of, individual partners is held by biologists to be very unlikely. For them all social animals, or at least many of them, seem to clearly recognize and respond to individual appearance. Recent studies on nonhuman primates have shown that intense female face coloration attracts male attention, and behavioral experiments found that chemical processes are involved in mate choice, regardless of environment or position (Pflüger & Wallner, 2014) . Consequently, it is not certain that face-to-face copulation makes things that different in humans, since other forms of attraction and mating seem to work fine.
My reply is: seeing eye to eye does make things different because the facial expression of the other in sexual arousal remains imprinted in the brain. Internalized impressions lead to facial-appearance-based judgments that are usually accurate (Slepian, 2016) . To be sure, signals of love can be false, but in intimate relations one is not very likely to deceive the partner about one’s emotional state. Here lies the polarity of making believe and sincerity, of pretention and truth, characteristic of eroticism as a configuration of conflicting attitudes. To feign “true love” in the long run would require a perfect actor or actress. In this faculty, humans are superior to animals. An ape cannot play the hypocrite, but he cannot be sincere either: the state of mind of an animal is beyond appearance and reality.
The French philosopher Jean-Paul Sartre, who was also a fine psychologist, has given a detailed description of the other’s gaze and how being looked at constitutes our self-image (Sartre, 1993) . This, of course, is a modern, existentialist explanation, but it can be helpful to understand the emergence of primordial subjectivity that is identical with the sense of personal life experienced as individual pleasure and pain. Darwin, in his discussion of how attention is affected, the most effective of all the powers of the mind refers to the face as the chief object of interest: “The eyes are generally averted or are restless, for to look at the man who causes us to feel shame or shyness, immediately brings home in an intolerable manner the consciousness that his gaze is directed on us” (Darwin, 1965: p. 346) . For lovers, however, the awareness of being looked deeply into the eyes turns sexual desire into erotic attraction. The salient point which distinguishes human love from animal mating is the dominance of the person over the situation.
In this regard, a human display of eroticism is different from the male animal’s demonstration. The peacock exhibition, for instance, is public and addressed to all hens present, and the patterns of display are rigid and fixed. Human face-to-face sexual display, to the contrary, is very particular and full of fantasy. Our descendants are considered children of love and not mere parts of the germ-line. Without doubt, this is a result of our cultural history. But my question is: Where does human culture begin? Why us and not the bonobos? To answer to this question requires locating the gap in subjective experience. Emotions are more basic, older, and universal than cognition is, and sexual emotions by their flexibility have at least provided a transition into social learning transcending animal intelligence which is simply pragmatic, problem-solving. Emotional intelligence of humans has become more free and imaginative. Humans do not only solve problems, they also create some which are sometimes unsolvable. At the bottom of this extravagance lies eroticism as a specific form of existential curiosity and ambiguity unknown to animals.
4. Eroticism and Ethics
The moral problems of human behavior can be resolved by a study of the extension of the sex impulse into erotic sentiments that combine feeling and cognition. I consider the emergence of erotic sentiments in mating behavior as the dawn of the moral sense. For an explanation of this seemingly unlikely position it is helpful to go back to Darwin, who approached the question of morality exclusively from the perspective of natural history (Darwin, 2004: p. 126) . He arrived at the conclusion that the moral sense results from a combination of social instincts and mental powers. Darwin stresses that the social instincts in animals do not contribute to individual happiness but to the general good or the welfare of the community. Compared with welfare as the primary impulse, happiness of the individual has to be considered a merely “secondary guide” in moral behavior (Darwin, 2004: p. 145) . In the animal kingdom, welfare and happiness coincide. The human, on the other hand, is the only animal for whom this congruence is broken. From these conflicting feelings there results the moral sense, which is qualitatively different from the act of helping a fellow-creature, as shown by Darwin’s heroic baboon blindly following its instincts.
The acclaimed anthropologist Frans de Waal follows Darwin on this track in his popular writings. However, whereas Darwin makes a difference between sympathy and love (Darwin, 2004: p. 129) , de Waal combines both in the ambiguous term of “empathy.” As welcome as the overcoming of the traditional anthropocentric view may be, anthropomorphysing animals, and zoomorphysing humans does not further the understanding of the different worlds we live in. The so-called “natural normativity” demonstrated by non-human primates is mainly a social technique for survival in their particular environment (de Waal, 2014) . Modern psychologists have studied the emotional and moral aspects of the helping attitude (Tscharaktschiew & Rudolph, 2015) . This leads to the conclusion that pro-social behavior in help giving does not yet reach the standard of human ethics. Different from cooperative behavior the moral sense is self-reflexive resulting from higher-order emotions. At this point morality is connected with eroticism. The connection is formal in the sense that erotic love and moral responsibility both require the faculty to take distance from the present situation and to consider the other as a means for pleasure and at the same time as an end in itself. Readers familiar with ethics will recognize in this idea the second formulation of Immanuel Kant’s moral imperative. This formula dictates that every rational being, whether yourself or another, “must be treated never as a mere means but as the supreme limiting condition in the use of all means, i.e., as an end at the same time” (Kant, 1989: p. 436) .
The biological key point of how to interpret each species’ particular ways of living together is to acknowledge various emotional adjustments under various environmental conditions. Regarding ideas about human moral uniqueness, the differences alone don’t make the difference, as Gregory Bateson would have said. In terms of mere quantitative differences, all is relative; hence relativism is not a good method of validation, it would just be surrendering to the facts. Sexuality connects species in their genes, physiology, and behavior. Erotic pursuits, on the other hand, deal with concrete processes in the life history of the individual. Only subjective experiences enable our species to review and tax the differences in a moral sense. Humans assume personal responsibility for their actions and are bound to justify them. This faculty, of course, is highly cultural, but since Margaret Mead wrote in the 1962 introduction to Male and Female that she would lay more emphasis on man’s biological inheritance from earlier human forms of life (Mead, 2001) , I feel justified to look for the earliest small emotional deviation between animal and human sexuality―and I find it in the reading of erotic face-to-face expression.
To be sure, nobody really can “feel” the feelings of another being. There is no argument about explanations of the state of feeling per se; in other words: feeling cannot be translated into thought without transformation in accordance with the attributional model of emotions elaborated by modern psychology. On the other hand, however, there are states of mind that the other may feel in a manner similar to my own feelings. This “evidence of you” is characteristic for common subjective experiences in intimate relations, especially in erotic love. In animals most behavior patterns are performed without an associated emotion, in fact without any empathy and participation, as is shown by the well known case of birds pairing and caring for their young ones. If a young one falls out of the nest and dies, the parent birds fly over its corpse without recognizing it as their dead nestling. Their sense of identification is restricted to a definite area of time and space. Similarly, a dog recognizing his former master after a passage of many years has the usual impression of the man’s appearance, but of the time that has since elapsed he surely has no memory such as humans would have. And elephants may indeed recognize their dead descendants and be sad, but only for a relatively short time. Human parents, on the contrary, never forget their deceased children.
The biologist would maintain that domesticated mammals feel in the same way as humans (Weiss, 2016) . Take the example of the dog awaiting with impatience the return of his master. He is anticipating the master’s return and is clearly happy when the master arrives. The dog’s whole attention is concentrated on the door where his master will enter. In a similar way, a husband awaits the return of his wife when she is late. He is listening for the door like the dog. Even so, there is an important difference: He is concerned about her, afraid that she may have been in an accident. This mental attitude presupposes detachment from present restlessness as well as making inferences about it. Concern is more than merely feeling someone’s absence, and it is very unlikely that a dog is concerned about his master’s fate in a similar way. There exists, in fact, a vast discussion regarding the question of whether a dog can hope or not (Wittgenstein, 2001; Baker, 2012) . Hope is a specific attitude, a higher- order mixture of feeling and thinking, transcending mere expectations and implying sensitivity to the pain of deception. As an ambivalent emotion, combining joy and fear, hope is intrinsic to love, and this turns eroticism into the comprehensive medium of human social existence.
5. Remarks on Methodology
Having thus made my position clear as to why eroticism still matters (in spite of modern trends in sex education), I would add a word of discussion of the dialectics concerning the relation between biology and psychology. Biologists consider interpreting anything evolutionary, or discussing the “why” of the origin of things like the concept of eroticism, very problematic because our entire way of life is so very different from that in which and from which we evolved. Yes, it is problematic, but it is the only way to attain to human uniqueness. As John Maynard Smith puts it in his article “Why Sex?”: “To watch animal behavior without human analogies would be to rob oneself of a major source of insight. Of course, any insight gained must be tested …. Only people who have no intention for studying animal behavior are likely to reject the human analogy” (Smith, 1993: p. 178f) .
Arguing in the other direction, from animals to man, as evolutionary biology does, shows that humans are not as unique in their mating systems as humanists think they are. Alan F. Dixson (Dixson, 2009: p. 184f) gives examples of idealistic views regarding sexuality that lack a fundamental knowledge of the physiology of reproduction. Such questionable reports alert us to examine the terrain of eroticism with care and to look for the slightest deviation, the “clinamen,” as Democritus has called it. The difference appears to be hidden beneath an unbroken chain of sexual and reproductive events, extending way back through time.
Consequently we have to go in both directions. The reason is that we cannot find an absolute beginning for the human mind, that we lack an Archimedian point, as it were. Idealistic philosophers consider God the creator of our soul, and for them evolution is only a substitute for God. However, in this case the substitute is better than the original, remaining on the earth with a concept of time that exceeds our brief historical moment. The biologist posits a solid frame of reference for explaining human subjective experience as a whole―thus taking the “naturalistic turn” (Callebaut, 1993) .
It is by its methods rather than its subject-matter that philosophical psychology is to be distinguished from biology and sociobiology. This is not to say that psychologists are not concerned with facts, but they are in the strange position that all the evidence which bears upon human self-validation has to be made compatible with hard facts. What is in dispute in psychology is not whether this or that event has happened, but rather how all that has happened in evolution is to be interpreted in the light of human development. What is required for understanding human uniqueness is not a golden mixture of methods, but a combination of complementary views, as is found in quantum theory with its wave-particle dualism.
In the light of individual self-understanding, the human mind changes its function as a mere information- gatherer in order to survive. The mating mind transforms information in isomorphic patterns that create libidinous body images through erotic contacts. In 1935, the psychiatrist Paul Schilder introduced the concept of “body image” underlining the erotogenic zones of man and woman (Schilder, 2000) . In his late work A Theory of Meaning (1940), the father of the world of animals, Jacob von Uexküll, suggests that environment and meaning should be considered to be complementary topics in social biology―thus initiating the “biosemiotic turn” (von Uexküll, 2011) . In this sense, evolutionary psychology speaks of reflexive awareness of the world. This is not the classical positivistic realism, but rather a “perspectivist realism.” Perspectives play a role both for our subjective and mind-dependent conceptualizations of reality and as mind-independent features of organic life, thus bringing together biology and psychology, which is fundamental to “robustness” in the life sciences (Sarto- Jackson, 2016) .
To reach this aim within the limited field of sexual life, I would like to remind modern biologists of Charles Darwin, whose works are no longer read with proper attention. The first part of The Descent of Man, and Selection in Relation to Sex deals with the evolution of the social and moral faculties under the head of “natural selection.” In the third part, the evolution of humans is considered in the light of sexual selection. This is not only supplementary, but actually provides a wholly new method of perception, presenting an emphasis regarding “the double or mutual process of sexual selection” that comes close to the erotic as a combination of lust and attachment.
As a Victorian thinker, Darwin was bound to monogamy, but his cultural frame of thought did not prevent him from having general insights into the unstable nature of sexual desire. The agendas of cultural anthropology in his day were very different from those of today, and he clearly did have agendas to advance. Nobody is a completely objective, detached observer. Nowadays our cultural frame is that of individualism and free love, which in the evolutionary view is not brutish, but merely a consequence of the human instinct reduction. As far as I know, no animal has sex randomly, except perhaps the bonobo―an “invention” of Frans de Waal (de Waal, 2013) . In my view, individualism requires more than engaging in sex according to my changing moods. It requires a sustained ability to love and be loved by my beloved partner.
Animal sexuality is a primary urge serving procreation. Humans, on the other hand, have an erotic life by socializing sexuality through their imagination, which makes the erotic a higher-order emotion full of emotional ambivalence. Human individuals feel good and bad at the same time, and their expressions combine love and hate and often show shame and guilt, moral attitudes that are known in every culture all over the world. The cultural drive determines the characteristic reactions to sexual stimulus in any and every situation in life.
Different from other motivational factors, erotic desires completely mould the whole emotional life of humans. This is due to the high amount of sexual energy, the “libido,” as psychoanalysts call it. The overflowing energy in biologically lost motion results in a strong spiritual make-up that makes human personal identity unique. Passion, or sensuality, tends to dominate over mere strategic Machiavellian intelligence. Thus, the psyche is in a continuous state of change, movement, and quest that make human life so eccentric and fascinating. This is precisely the reason why eroticism still matters.
In light of natural selection, the difference between animals and humans is regarded as gradual, whereas sexual selection disrupts the continuity. Emotions have become complex and ambivalent, and this announces the step from sexuality to eroticism. What has rightly been called the “Darwinian pivot” argues against the reduction of evolution to one single track. In order to avoid this phylogenetic fallacy, I consider eroticism the hallmark of behavioral and mental plasticity in human evolution.
The author would like to thank Horst Kruse and Ken Weiss for the comments and directions given in the revision of this paper.