Evolutionary psychology

Simone de Beauvoir captures the complexity of romantic love when she writes that its “supreme goal” is “identification with the loved one. . . . [I]t is not enough to serve him. The woman in love tries to see with his eyes; she reads the books he reads, prefers the pictures and the music he prefers; she is interested only in . . . ideas that come from him” (The Second Sex, 613‑14). There seems little possibility of science's explaining such a baffling emotion. Yet from other philosophical perspectives, the attempt to ground a comprehensive understanding of human sexuality in evolutionary biology would be cheered. Consider Donald Symons's aspirations:

If selection has always been potent at the level of the individual, individuals must have 'innate' mechanisms, probably best conceived as emotional/motivational mechanisms, to recognize and look after their own reproductive 'interests.' . . . [T]he complexity of sexual opportunity and constraint in natural human environments . . . made adaptive a human psyche uniquely informed by sexuality. That individual reproductive 'interests' must in some degree conflict with one another may account for the intensity of human sexual emotions, the pervasive interest in other people’s sex lives, the frequency with which sex is a subject of gossip, the universal seeking of privacy for sexual intercourse, [and] the secrecy and deception that surround sexual activities.” (308)

If so, Beauvoir's woman who sees everything through her beloved's eyes is ultimately, although not proximately, simply managing her reproductive interests.

This is why the evolutionary project is often accused of reducing the psychological complexities of love to a mating ritual of sexually charged agents. It is also charged with genetic determinism, of neglecting developmental and environmental influences on a trait’s expression in favor of its genotypic basis (see Rose, “Escaping Evolutionary Psychology”). But despite the fact that its initial rejection by the social sciences arguably endures, E. O. Wilson's sociobiology has been the source of many vibrant research studies. And though evolutionary accounts of human behavior and cultural phenomena are controversial, the development of the application of evolution to human behavior has become a growth industry, attracting the attention of scholars in many fields. Whether the accusations of reductionism and determinism, which had been powerfully leveled by Philip Kitcher against “pop sociobiology,” continue to be legitimate is unclear. Evolutionary theory is now interdisciplinary, drawing from, among other areas, cognitive psychology and ethology. From this convergence, approaches more subtle than Wilson’s have emerged, producing surprising new findings about cognition and behavior. According to Kevin Laland and Gillian Brown, whose survey includes human behavioral ecology, memetics, and gene-culture evolution, evolutionary psychology has proven to be an “enormously creative” example of such an approach. (Sense and Nonsense, 195).

Evolutionary psychology's guiding assumption is that many behaviors are adaptations to the ecological settings of an organism’s lineage or exist in virtue of broader psychological mechanisms and anatomical features that are themselves adaptive. It attempts to explain the adaptive function of observed traits: jealousy might be an adaptive solution to the problem of avoiding cuckoldry (Daly, Wilson, and Weghorst). Or it attempts to predict psychological traits from known evolutionary forces: humans today possess information-processing algorithms for recognizing degrees of kinship or detecting “cheaters” in swapping benefits for payments (Cosmides and Tooby, 1992). The explanatory project generally gets a more favorable assessment than the predictive (Davies; Grantham and Nichols). Evolutionary psychology's findings range over many areas. For example, logical reasoning improves dramatically when problems are stated in terms of social norms rather than in terms of truth or falsity. Evolutionary psychology explains this by positing a preference, an adaptation in our cognitive architecture, that emerged in response to repeated pressure to reason about social dominance hierarchies (Cosmides and Tooby, 1992). Politically sensitive topics often raise eyebrows, if not criticism: the hypothesis that rape is an adaptation to sexual exclusion (Thornhill and Palmer; Thornhill and Thornhill), or that the universality of Cinderella stories involving an evil step parent results from the decreased rewards felt, and hence decreased investment made, by substitute parents in caring for the young (Daly and Wilson, 83ff).

There are weak and strong versions of evolutionary psychology's guiding assumption. In the weak version, human behavioral traits are rooted in general cognitive mechanisms and learning rules that are adaptations explainable in evolutionary terms. The strong version claims that the specific forms our behaviors take are explainable by natural selection. The weak thesis, in postulating general cognitive mechanisms, extrapolates from the existence of one such mechanism, the culturally complex skill of language (Plotkin, chap. 4). Each human is genotypically programmed with a universal grammar, which manifests itself phenotypically in the ability to speak a language. The mind comprises other general mechanisms designed to solve problems that arose in our evolutionary past.

The strong version of evolutionary psychology involves the application of sociobiology to psychology. The idea is that humans are “inclusive fitness maximizers” in the sense that “the major goals toward which humans direct action” are resolutions of “problems that historically had to be solved to enable reproductive success” (Buss 1991, 484). The weak version, by contrast, limits itself to providing evolutionary explanations of cognitive mechanisms, learning rules, or so-called “Darwinian algorithms,” as opposed to explaining specific behaviors (like rape). Leda Cosmides and John Tooby have sociobiology in mind when they write, “In the rush to apply evolutionary insights to a science of human behavior, many researchers have made a conceptual ‘wrong turn’. . . . This wrong turn [is] . . . attempting to apply evolutionary theory directly to . . . manifest behavior, rather than using it as a heuristic guide for the discovery of innate psychological mechanisms” (1987, 278ff). Observed behaviors are better understood as enhancing fitness, not necessarily maximizing it (as sociobiology has it), and perhaps only in the particular settings within which human brains evolved. For weak evolutionary psychology (I omit “weak” henceforth, considering the strong version equivalent to sociobiology), homosexuality, homicide, and violence might enhance fitness in less direct ways than permitted by Wilsonian sociobiology. Nonethess, evolutionary psychology and sociobiology share commitments to five principles: (1) the ancient provenance of current traits, (2) some degree of adaptationism (natural selection is the only important factor in a trait’s evolution), (3) a close fit between an organism’s design and the environmental problems pressuring that design, (4) the plausibility of speculations about the Pleistocene environment, and (5) the existence of universals across diverse contemporary cultural settings. (The best illustration of a universal cognitive capacity is language. Theorists such as Pinker [1994] point to Noam Chomsky’s universal grammar [1968] as a paradigmatic finding of evolutionary psychology.)

If there is, as David Buss (1992) claims, an innate device, “a mate preference mechanism,” that governs human sexual strategy, it developed over long periods of history. Since the approximately 500 generations that have lived since the end of the Paleolithic age (and the agricultural revolution) represent less than half of one percent of all generations of Homo sapiens, principle (1) says that we are essentially now what we were long ago. (Rose and Rose dispute this [2000, 2].) Principle (2) claims that Buss’s sexual selection mechanism is, like other complex psychological traits, the result of an inherited modification of our ancestral gene pool, is therefore built by genes, and is not an accident of random evolutionary forces such as genetic drift. Adaptationism is a much debated view (see Ferguson's typology), and to avoid “Panglossian” extremism (i.e., every trait is perfectly suited to its environment), evolutionary psychology must supply criteria for a property to be considered an actual trait. It argues, for example, that the mechanisms involved in mate selection are adaptive traits because strong selection pressures operate on choice, and choosing a mate is psychologically complex. Principle (3) claims that we are able to individuate adaptations and traits because there is a close fit between design problems (e.g., to have humans “hook up” for a reasonably long portion of their mature lives) and the observed design solutions (in this case, romantic love). The existence of dating rituals and other strategies males and females adopt (coyness, chastity) illustrate this principle.

It is perhaps the Pleistocenic cast of these psychological speculations (see principle [4]) that draws most of the informed criticism of evolutionary psychology. Its modus operandi is a sort of bootstrapping operation, in which anthropological theorizing about human origins helps identify problems humans faced then, and psychological studies done now are meant to show the ways humans have solved them. This procedure is fraught with difficulty. The very idea of an “environment of evolutionary adaptedness” has changed from a historical time and place (the Pleistocene’s African savannah) to a “statistical composite” of ancient niches faced (and of course partly constructed!) by our ancestors (see Laland and Brown, 179). Of course, the mere existence of culture and industrial civilization present obstacles to drawing analogies between ancient and contemporary behaviors. For instance, Randy Thornhill and Craig Palmer’s ascription of a reproductive function to rape involves not only massive speculations about the psychology of Pleistocene man but also problematic “zoomorphic” comparisons of animal and human sexual acts (Tobach and Reed, 112).

These similarities between evolutionary psychology and sociobiology led Kim Sterelny and Paul Griffiths to call evolutionary psychology the “second-wave sociobiology of the 1990s” (14). The charge of reductionism attendant with this association do not, however, obviously stick to evolutionary psychology. Its unique problems and advantages are best seen regarding culturally complex and psychologically anomalous phenomena. Consider how Steven Pinker, following Robert Frank, explains the behavior of “fools for love” (1997, 417ff). He wants to explain “why . . . romantic love leave[s] us bewitched, bothered, and bewildered” (a version of Beauvoir's woman in love). He proceeds to “reverse engineer” this “mad love” by connecting it to the choice and promise to “spend your life and raise children with someone.” Given that this promise is most credible when the “promiser” cannot back out, our brains have evolved an emotion that is involuntarily “triggered” not by you and your loved one’s respective “mate-values,” but by “a glance, a laugh, a manner that steals the heart.” As far back as Plato’s [428-348bce] Phaedrus, the folk-psychological account of love’s madness has turned on the strength of its appetitive desire; love’s passion overcomes reason’s restraint (492, ln. 245c). Pinker’s account is consistent with this but goes farther. Evolutionary psychology trades in “ultimate explanations” and in turn explains the adaptive function of this cognitive-affective phenomenon. The emotions, being nonvoluntary, serve as subpersonal, noncognitive, motivational states, executing Darwinian algorithms within us unbeknownst to us. In addition, being so closely tied to physiology, emotions are harder to fake than the result of a hedonic or pragmatic calculation.

Evolutionary psychology's response, then, to the accusation of reductionism is that it is merely bridging the gap between emergent features of human cognition and their biological substrates. Evolutionary psychology does recognize, indeed emphasizes, the importance of individual development and historical contingencies in the behavioral expression of innate mechanisms. If evolutionary psychology reduces anything, it reduces a range of behavior to a (narrower) range of mental modules, thus leaving open their eventual reduction to biology. But evolutionary psychology does not necessarily diminish the cultural or historical vectors in language, love, and other psychological phenomena (see the rejection of the biology-is-destiny model by Cosmides and Tooby [1992]). A case can be made that Sigmund Freud’s [1856-1939] theory of the instincts (1933) is no more or less reductionistic than Pinker’s theory of the language instinct. (See Glymour for parallels between Freud and cognitive psychology.)

In his “fools for love” example, Pinker can be seen as starting either with a behavioral observation--the apparent irrationality involved in choosing a mate on romantic grounds--or, alternatively, with a design problem of Mother Nature: how can humans be designed to mate for as long as it takes to raise a child? The first strategy is “reverse engineering,” the second “adaptive thinking.” Both make strong assumptions about the selective history and current function of the trait in question.

Evolutionary psychology must assume that the current utility of a trait in a modern setting is at least a useful guide to its selective history in a Pleistocene environment. But, given the differences between these and modern environments and the fact that traits are a function of genetic expression within specific ecological and social settings, the assumption is dubious. Further, the interaction of genetic and environmental factors in a trait’s expression and fitness might make it impossible to decide whether a particular behavior is an inherited adaptation or learned. The research programs of memetics (see Aunger), human behavioral ecology (see Hrdy), and developmental systems theory (see Oyama et al.) are predicated in large part on this problem. Outside the biological sciences, in Marxist and feminist theory in particular, much is made of the influence of culture and the inextricable interaction of the social and the biological (see Lewontin, Rose, and Kamin).

Pinker’s account of romantic love also emphasizes one dimension of the phenomenon to the exclusion of others. Romantic love is more than falling head-over-heels over someone (e.g., crazily seeing everything through their eyes), even if this was its adaptive function. He recognizes that the irrationalities of romantic love have to be tempered by “the other component of courtship, smart shopping,” and claims that “the contradiction of courtship--flaunt your desire while playing hard to get--comes from the two parts of romantic love: setting a minimal standard for candidates in the mate market and capriciously committing body and soul to one of them” (419). This yields a situation full of tension. One Darwinian algorithm tells me I should not accept a partner who wants me for rational reasons, while another instructs me to employ those same rational reasons. Should I mate with somone who has nonvoluntarily fallen for me or with one who has calculated that I am the best thing going?

The problem is not that Pinker’s account cannot make some sense of the stuff of soaps and sonnets. Rather, problems internal to evolutionary theory and cognitive psychology weaken the inference to the best explanation that his conclusions rest on. There is, first, the problem of identifying adaptive traits. Without cross-species comparisons--close relatives of Homo sapiens are extinct--evolutionary psychology might not be able to separate genuine adaptationist explanations from “just so stories” (Sterelny and Griffiths, 214). Theorists do have, however, other means to isolate adaptive problems and the complex mechanisms that are their solutions. For instance, Pinker establishes the “language module” in part through its capacity to be selectively damaged. That is, one can lose the ability to perform certain linguistic tasks without losing general cognitive function, and modularity is indicative of an adaptation. Yet, as Stephen Jay Gould emphasizes, natural selection is given too much explanatory work to do; it is best thought of as the first-among-equal forces at work in evolution. “Fundamentalists” such as Daniel Dennett distort the pluralist approach of most working biologists and of Charles Darwin [1809-1882] himself, by claiming exclusive explanatory efficacy for natural selection (see Darwin’s Dangerous Idea, 229ff). As Gould reminds us, not every contingent property or cluster is an adaptation: “Reading and writing are now highly adaptive for humans, but the mental machinery for these . . . capacities must have originated as” by-products. They were “coopted later, for the brain reached its current size and conformation tens of thousands of years before any human invented reading or writing” (113-14).

Thus, that romantic love has the function for which Frank and Pinker claim it has been adapted is questionable; who may have sex with whom and who may have children is regulated by the social group to such a degree that romantic attachment might not be, and might never have been, linked that closely with marriage and sexuality and their resulting parentage. (See Gorer on the nonuniversality of romantic love.) Melvin Konner speculates that the function of romantic love may have been to get people out of arranged relationships (315-16), and others in the field (Buss, 1992, 261) put more emphasis on male competition for females, and hence on jealousy, in their understanding of the ties that bind. Similarly, consider speculation about the function of concealed ovulation in human females: it fosters cooperation among (male-led) groups by keeping their minds off the fertile females; it fosters a long-term parental pair bond by minimizing a female's attractiveness to other males based on her procreative power; it conceals paternity, which is adaptive among (primate) species that regularly kill the offspring of others; and because ovulation is concealed from the females themselves, it increases the likelihood of their engaging in the costly affair of motherhood. Still other functions have been proposed (Diamond, 79 ff.). Now, if it is hard to find expert consensus on this physiological trait, which is as closely linked to procreation as any, then why expect more than well-grounded hunches about the function of romantic love?

Further, there is the conundrum of individuating traits. Is romantic love one trait or many? If our descriptions are too coarse-grained, if love is taken to be whatever draws us towards an object, we will not be able to trace a selective history for what might be in fact multifaceted. But if we analyze love too narrowly, as the emotion responsible for procreative mating-for-life, we will not see that it is part of a larger emotional/cognitive nexus, that pair bonds might have variable utility in different environments, or that nonprocreative (e.g., homosexual) relationships based on love are perhaps equally adaptive. (Michael Ruse has tried to explain homosexuality on the basis of inclusive fitness theory or kin selection: benefits to extended kin can outweigh the individual’s costs of not breeding. But see Rice and Barbone, who in part complain that Ruse homogenizes homosexality.) Sterelny and Griffiths’s criticism of Wilson's sociobiology has some purchase here: “Our behavior is produced by mental mechanisms that play a role in many different behaviors. Some of the mental mechanisms used in hunting are also used in storytelling. So speculations about the adaptive significance of rape, xenophobia, child abuse, or homosexuality seem to be at the wrong grain of analysis” (321). In part this is a problem of the constraints and constants we propose about early humans. Are we essentially social, bonding, even (which is rare) parenting mammals, or do these represent problems the solutions to which are still operative within our unconscious minds?

Mention of the unconscious raises another possible confusion, this one concerning levels of description. It is responsible for some of the confusion over reductionism in evolutionary psychology, and can be best pursued through an example. According to Terry Burnham and Jay Phelan,

Men throughout the world show a preference for younger women and for traits associated with youth--full lips, big eyes, and radiant hair. There’s nothing specifically desirable about youth per se: it’s simply that fertility tends to decrease with age. (163)

That the sociological status, economic benefits, psychological appeal, and sensuous pleasures a young woman offers a man can be explained in terms of increased fertility strikes many as facile. Antireductionists argue that one-dimensionalizing motives by viewing humans as “fitness maximizers” is to commit what David Buller, citing David Buss, calls “socio-biological fallacy,” in which “a theory of the origins of mechanisms (inclusive-fitness theory) [is conflated] with a theory of the nature of those mechanisms” (Buller, 106). The standard view is that evolutionary psychology avoids this by considering the human not as a “fitness maximizer” but as an “adaptation executer,” so that while fertility doesn’t “motivate” male preference in women, men have evolved in a manner that leads them to prefer features historically linked to fertility. The difference is subtle but important in distinguishing the reductionist aspects of sociobiology from evolutionary psychology's naturalistic agenda.

Motives are not functions. But the neurochemistry underlying our emotions and feelings does have a functional, adaptive history. Instead of fearing for the loss of the self at the hands of evolutionary psychology, we (properly forewarned) can look forward to a deeper understanding of both the origins of our personal goals and of the subpersonal, neurobiological nature of our motivational states.

See also Evolution; Sociobiology

Aunger, Robert, ed., Darwinizing Culture: the Status of Memtics as a Science. Oxford: Oxford University Press, 2000.

Beauvoir, Simone de. (1953) The Second Sex. Translated by H. M. Parshley. New York: Bantam, 1961.

Burnham, Terry, and Jay Phelan. Mean Genes: From Sex to Money to Food, Taming our Primal Instincts. Cambridge, Mass.: Perseus, 2000.

Buss, David M. “Evolutionary Psychology: A New Paradigm for Psychological Science.” Psychological Inquiry 6: 1 (1995), 1-30.

-----. “Mate Preference Mechanisms: Consequences for Partner Choice and Intrasexual Competition.”In Jerome Barkow, Leda Cosmides, and John Tooby, eds., The Adapted Mind: Evolutionary Psychology and the Generation of Culture. New York: Oxford University Press, 1992, 250-66.

Chomsky, Noam. Language and Mind. New York: Harcourt Brace Jovanovich, 1968.

Cosmides, Leda, and John Tooby. “Cognitive Adaptations for Social Exchange.” In Jerome Barkow, Leda Cosmides, and John Tooby, eds., The Adapted Mind: Evolutionary Psychology and the Generation of Culture. New York: Oxford University Press, 1992, 163-228.

Cosmides, Leda, and John Tooby. “From Evolution to Behavior: Evolutionary Psychology as the Missing Link.” In Jared Dupre, ed., The Latest on the Best: Essays on Evolution and Optimality. Cambridge, Mass. The M.I.T. Press, 1987, 277-306.

Daly, Martin, and Margo Wilson. Homicide. New York: Aldine, 1988.

Daly, Martin, Margo Wilson, and Suzanne Weghorst. “Male Sexual Jealousy.” Ethology and Sociobiology 3: 1 (1982): 11-27.

Davies, Paul. “The Conflict of Evolutionary Psychology.” In V. Gray Hardcastle, ed., Where Biology Meets Psychology: Philosophical Essays. Cambridge, Mass.: The M.I.T. Press, 1999, 67-82.

Dennett, Daniel. Darwin’s Dangerous Idea. New York: Simon and Schuster, 1995.

Diamond, Jared. The Third Chimpanzee: The Evolution and Future of the Human Animal. New York: HarperCollins, 1992.

Ferguson, Sally. “Methodology in Evolutionary Psychology.” Biology and Philosophy 17: 5 (2002), 635-50.

Frank, Robert. Passion within Reason: The Strategic Role of the Emotions. New York: Norton, 1988.

Freud, Sigmund. New Introductory Lectures on Psycho-analysis (1933). In vol. 22 of James Strachey et al., ed., Standard Edition of the Complete Psychological Works of Sigmund Freud. London: Hogarth Press 1953-1974, 1-182.

Glymour, Clark. “Freud’s Androids.” In Jerome Neu, ed., The Cambridge Companion to Freud. Cambridge, Eng.: Cambridge University Press, 1991, 44-85.

Gorer, Geoffrey. The Danger of Equality. [I'll add the details.]

Gould, Stephen Jay. “More Things in Heaven and Earth.” In Hillary Rose and Steven Rose, eds. Alas Poor Darwin: Arguments against Evolutionary Psychology. New York: Harmony Books, 2000, 101-125

Grantham, Todd, and Shaun Nichols. “Evolutionary Psychology: Ultimate Explanations and Panglossian Predictions.” In V. Gray Hardcastle, ed., Where Biology Meets Psychology: Philosophical Essays. Cambridge, Mass.: The M.I.T. Press, 1999, 47-66.

Hrdy, Sarah B. “The past, present and future of the human family.” In The Tanner Lectures on Human Values, vol. 23. Edited by Grethe Peterson., pp. 57-110. Salt Lake City: University of Utah Press, 2002.

Kitcher, Philip. Vaulting Ambition: Sociobiology and the Quest for Human Nature. Cambridge, Mass.: The M.I.T. Press, 1985.

Konner, Melvin. The Tangled Wing: Biological Constraints on the Human Spirit. New York: Harper and Row, 1983.

Laland, Kevin N., and Gillian R. Brown. Sense and Nonsense: Evolutionary Perspectives on Human Behavior. Oxford: Oxford University Press, 2002.

Lewontin, Richard C., Steven Rose, and Leo J. Kamin. Not in Our Genes. London: Penguin, 1984.

Oyama, Susan, Paul E. Griffiths, and Russell D. Gray, eds., Cycles of Contingency: Developmental Systems and Evolution. Harvard, MA: MIT Press, 2001.

Pinker, Steven. How the Mind Works. New York: Norton, 1997.

-----. The Language Instinct. New York: Norton, 1994.

Plato. Phaedrus. In Edith Hamilton and Huntington Cairns, eds., The Collected Dialogues of Plato, translated by R. Hackforth, New York: Pantheon, 1961, 475-525.

Plotkin, Henry. Evolution in Mind: An Introduction to Evolutionary Psychology. Cambridge, Mass.: Harvard University Press, 1998.

Rice, Lee, and Steven Barbone. “Hatching Your Genes before They're Counted.” In Alan Soble, ed., Sex, Love, and Friendship. Amsterdam, Hol.: Rodopi, 1997, 89-98.

Rose, Hillary, and Steven Rose, eds. Alas Poor Darwin: Arguments against Evolutionary Psychology. New York: Harmony Books, 2000.

Rose, Steven. “Escaping Evolutionary Psychology.” In Hillary Rose and Steven Rose, eds., Alas Poor Darwin: Arguments against Evolutionary Psychology. New York: Harmony Books, 2000, 299-320.

Ruse, Michael. “Are There Gay Genes? Sociobiology Looks at Homosexuality.” Journal of Homosexuality 6:4 (1981), 5-34.

Sterelny, Kim, and Paul Griffiths. Sex and Death: An Introduction to Philosophy of Biology. Chicago, Ill.: University of Chicago Press, 1999.

Symons, Donald. The Evolution of Human Sexuality. Oxford: Oxford University Press, 1979.

Thornhill, Randy, and Craig Palmer. A Natural History of Rape: Biological Bases of Sexual Coercion. Cambridge, Mass.: The M.I.T. Press, 2000.

Thornhill, Randy, and Nancy Thornhill. “The Evolutionary Psychology of Men’s Coercive Sexuality.” Brain and Behavioral Sciences 15:3 (1992), 363-421.

Tobach, Ethel, and Rachel Reed. “Understanding Rape.” In Cheryl Travis, ed., Evolution, Gender, and Rape. Cambridge, Mass.: The M.I.T. Press, 2003, 105-138.

Wilson, Edward O. Sociobiology: The New Synthesis. Cambridge, Mass: Harvard University Press, 1975.

Wilson, Edward O. On Human Nature. Cambridge, Mass: Harvard University Press, 1978.

Nicholas Power

also need (from supp. bib):

Symons, Donald. “A Critique of Darwinian Anthropology.” Ethology and Sociobiology 10: 1-3 (1989), 427-44.

New additions to supp. Bib:

Gould, Stephen. J. Ontogeny and Phylogeny. Cambridge, MA: Harvard University Press, 1977.

Ruse, Michael. Homosexuality: A Philosophical Inquiry. Oxford: Blackwell, 1988