Copyright © 2002 American Psychological Society

187

CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE

Abstract

Evolutionary approachesare on the rise in the social sci-ences and have the potential tobring an all-encompassing con-ceptual f ramework to thestudy of human behavior. To-gether with neuroscience,which is digging the grave ofmind-body dualism, evolu-tionary psychology is bound toundermine the still reigninghuman-animal dualism. If aDarwinian reshaping of the so-cial sciences seems inevitable,even desirable, this should notbe looked at as a hostile take-over. The underlying theme ofthis essay is that it is time forpsychologists to join the Dar-winian revolution, yet the es-say also critically reviewscurrent evolutionary psychol-ogy. It questions the loose ap-pl icat ion of adaptat ionistthinking and the fragmenta-tion of the genome, behavior,and the brain. From biologywe learn that not every spe-cies-typical trait is necessarilyadvantageous, and from neu-roscience we learn that not ev-ery psychological ability ortendency necessarily needs tohave its own specialized braincircuitry. But even if the con-cept of adaptation is hard toapply, psychologists would dowell to start looking at humanbehavior in the light of evolu-tion.

Keywords

evolution; adaptation; modu-larity; biology

Few topics are as hotly debatedwithin psychology today as evolu-tionary psychology. It is not thatthe issues are new—some go backto William James and the heydayof social Darwinism—but evolu-tionary ideas about human behav-ior are being forwarded with newforce, backed by innovative con-cepts derived from the study of an-imal behavior, at a time when theonce-popular environmental andcultural explanations are increas-ingly recognized as inadequate.

The stated goal of evolutionarypsychology is to provide an evolu-tionary account of human behav-ior. By hypothesizing about the se-lection pressures that have shapedbehavior in the past, evolutionarypsychologists expect to arrive attestable hypotheses about present

behavior. Because evolutionary psy-chology does not focus on geneticexplanations at the exclusion ofother explanations, it is not geneti-cally deterministic, even though itobviously emphasizes genetic evo-lution more than psychologistshave been used to. Whereas its ob-jectives are broad and laudableenough, evolutionary psychologyis unfortunately better known for afew narrow theories about whywomen fall for rich guys, why step-fathers are not to be trusted, andhow rape is only natural. More-over, in the promotion of theseideas, theoretical convictions haveoften been more conspicuous thandata. Nonetheless, there is no wayaround an evolutionary approachto human behavior. Although Itake a critical approach to evolu-tionary psychology in this essay,my arguments should not be taken

to mean that it has no future. Onthe contrary, I see evolutionarypsychology as an inevitable, evendesirable development plagued byserious growing pains that need tobe addressed for its own good.

Looking at the social sciences asa relative outsider, I see thousandsof ideas that are barely intercon-nected (Staats, 1991). One could ar-gue that they do not need to inter-connect, yet this amounts to anadmission that every area withinthe discipline is free to come upwith its own explanations. This ap-proach results in a serious lack ofmooring to the thinking in psychol-ogy, a lack of an overarchingscheme within which everythingmust make sense.

A younger generation of psy-chologists, anthropologists, andeven economists and political sci-entists is gaining enthusiasm for aDarwinian framework, which hasthe potential to tie together the for-est of hypotheses about human be-havior now out there. My hope isthat this generation will turn evo-lutionary psychology into a seriousand rigorous science by being criti-cal of its premises without aban-doning the core idea that impor-tant aspects of human behaviorhave been naturally selected. In the

end, evolutionary theory may serveas the umbrella idea so desperatelyneeded in the social sciences (Wil-son, 1998).

Even though psychology is atthe forefront in moving closer tothe life sciences, it has not yet freeditself from certain aspects of West-ern philosophy, which ultimatelycame out of the Christian tradition.Psychology is still burdened withancient dualisms, such as those be-tween body and mind, human andanimal, and nature and culture. Itwill have to rid itself of these dual-isms before it can fully integratewith the life sciences and their non-Christian, Aristotelian foundation.Whereas we can safely leave it tocognitive neuroscience to do away

Evolutionary Psychology: The Wheat and the Chaff

Frans B.M. de Waal

1

Yerkes Primate Research Center, Emory University, Atlanta, Georgia

188 VOLUME 11, NUMBER 6, DECEMBER 2002

Published by Blackwell Publishing Inc.

with any lingering mind-body du-alism, and to students of animalculture to bridge the nature-culturegap, psychology will also need toget over its pervasive human-ani-mal dualism.

DARWINISM 101

But before evolutionary psychol-ogy can be successful, social scien-tists will need training in evolution-ary theory. Many of the problemssurrounding evolutionary psychol-ogy have nothing to do withwhether human behavior has beensubject to evolution by natural se-lection—which to me is a given—but rather concern how broad ornarrow a view of evolution one em-braces. Many followers of evolu-tionary psychology overlook someof the simplest truths coming out ofevolutionary theory.

Dobzhansky (1973) wrote an ar-ticle with the now-famous title“Nothing in Biology Makes SenseExcept in the Light of Evolution.”This obviously means that leavingevolution out of basic science edu-cation constitutes a fatal deficiency.Because of continuing resistance toevolutionary theory, however, thisdeficiency unfortunately character-izes large parts of the U.S. publicschool system. After such an edu-

cation, the young social scientist goesto the university, where the curric-ulum, with few exceptions, also ne-glects evolutionary theory. As a re-sult, the way evolutionary theory isapplied to human behavior is oftenriddled with curious errors. Themost basic one is taking the exist-ence of a trait to mean that it mustbe good for something, thus ignor-ing the warning of Williams (1966),a contemporary evolutionary biol-ogist, that “adaptation is a specialand onerous concept that shouldbe used only when it is really nec-essary” (pp. 4–5).

An example straight out of theevolutionary psychology literature—and I could offer hundreds more—is found right in the opening sen-tence of a recent article. It states:“Both male facial hair and malepattern baldness are geneticallybased, suggesting that they con-tributed to fitness” (Muscarella &Cunningham, 1996, p. 99). Later inthe same article, we learn that malepattern baldness may signal socialmaturity, described as a friendlykind of dominance based on wis-dom. Is this supposed to explainwhy we have an entire industry that

removes hair from men’s heads? Ob-viously, every man wants to lookmature and wise!

The first common mistake inevolutionary explanations, then, isto think that if something is geneti-cally influenced it must serve apurpose. Alzheimer’s disease andcystic fibrosis have a genetic basis,as do many other diseases, but noone would argue that they contrib-ute to fitness. In addition, manycharacteristics are by-products ofothers, and all that matters from anevolutionary perspective is that theentire set of traits serves survivaland reproduction. Many individ-ual traits are imperfectly designedor positively costly. A human ex-ample is our back: Our species isnot fully suited for an upright pos-ture, hence many of us suffer backproblems, such as hernias, slippeddisks, and neck pain. Walking up-right must have had great benefitsfor these costs to be tolerable, eventhough there exists no universallyaccepted theory of why we walkupright.

It is no wonder that biologists of-ten refer to the evolutionary processas “tinkering.” Ballast often remainsvisible in the end-product. Ironi-cally, then, the natural world isrampant with flawed designs thatreflect the trouble evolution has hadturning one form into another, suchas a quadruped into a biped.

RAPE AS ADAPTATION

The lesson from the foregoing isthat one cannot atomize the organ-ism. One cannot single out a trait foran adaptive story, as is often donein evolutionary psychology. Rather,one needs to (a) consider the entireset of traits and (b) trace the organ-ism’s phylogeny, that is, the ances-tral forms that produced it.

In moving this observation tohuman behavior, it is impossible toignore the evolutionary psychol-ogy book that has raised most eye-brows. In

A Natural History of Rape

,Thornhill and Palmer (2000) postu-lated that rape is an adaptation;that is, rape may have been fa-vored by natural selection becauseit furthered male reproduction.The authors extrapolated straightfrom Thornhill’s insect studies,which showed that there are in-deed species with male anatomicalfeatures that seem designed toforce females into sexual contact.But these are flies, and in humansrape is part of a far larger picture.Rape occurs at the interface of sexand power, two rich and complexareas of human behavior that areobviously interconnected. It is hardto see how any serious treatment ofrape can rip it from this larger con-text, explaining it as an isolated be-havior, as Thornhill and Palmer triedto do.

To be called an adaptation, rapewould need to have its own geneticbasis separate from the geneticbases of other sexual tendencies, aswell as personality characteristics,such as impulsivity or aggressivity.Rape would also need to offer spe-cial reproductive advantages, andhave been favored by selection forthis very reason. These are heavyrequirements that raise a numberof pressing questions. Do we knowif rapists are genetically unique?What are the advantages of rape, ifany, in terms of reproduction? Are

Copyright © 2002 American Psychological Society

CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 189

there costs associated with rape? Inrelation to the latter question,imagine a small ancestral commu-nity in which a man raped thewives and daughters of other men.I do not think this man would havehad good survival chances. Andwhy do men sometimes rape part-ners who are perfectly willing toengage in consensual sex? Declar-ing rape an adaptation raises amultitude of questions, questionsthat Thornhill and Palmer havefailed to answer.

A major problem with the strat-egy of singling out rape for evolu-tionary explanation is that the be-havior is shown by only a smallminority. The same criticism ap-plies to Daly and Wilson’s (1988)well-known work on infanticide bystepparents. They explained thiscategory of infanticide as arisingfrom a lack of shared genes withadoptive offspring. I would arguethat in seeking to understand rarebehavior we should never ignorethe norm. If child abuse by step-fathers is evolutionarily explained,why do so many

more

stepfatherslovingly care for their childrenthan abuse them? And if rape issuch an advantageous reproduc-tive strategy, why are there somany

more

men who do not rapethan who do? I have called this thedilemma of the rarely exercised op-tion: A Darwinian account of anatypical behavioral choice is in-complete without at least anequally good account of the typicalchoice (de Waal, 2000).

THE MODULE EXPLOSION

Followers of evolutionary psy-chology often talk about a gene forthis or a brain module for that,seeking to dissect the whole to ex-plain each part separately. If thiscannot be done with the compo-nents of a watch spread out on the

table, it most certainly cannot bedone with the genome, the organ-ism, and its behavior. As for thebrain, the current trend to divide

brain function into modules remindsme of early ethology, when therewas no limit to the number of in-stincts one could propose: from self-

preservation to aggression, andfrom sex to motherhood. In the1950s, each species-typical tendencyhad its own instinct, and Konrad

Lorenz’s

Instinktlehre

(German for“instinct doctrine”) even included a“parliament” of instincts to indicatehow all components together influ-ence decisions. These ideas appliedmainly to nonhuman species, buthuman instincts have been pro-posed many times as well, most en-ergetically by self-declared evolu-tionary psychologist McDougall(1908). Similarly, proponents of evo-

lutionary psychology have comparedthe brain to a Swiss army knife towhich evolution has one by oneadded modules for everythingfrom face recognition, to tool use,preference for kin over nonkin,child care, friendship, detection of

cheaters, and theory of mind

2

(Tooby & Cosmides, 1992).One problem with this ap-

proach—apart from the fact thatbrain modules at any specific task

level have yet to be demonstrated—is that this would make for an in-credibly unwieldy brain, much likea computer to which a new chipwould need to be added each timewe install another program: onechip for word processing, one forgames, one for spreadsheets, andso on. Instead, a computer is a mul-tipurpose device that allows eachapplication to draw on its full po-tential.

This is not to imply that thebrain is a

tabula rasa

. It seems pre-pared to acquire certain skills moreeasily than others, and to be wait-ing for certain kinds of informa-tion. The studies by Tooby andCosmides (1992) do indeed suggest

such preparation, as do many ani-mal studies, going back to the earlywork on imprinting, according towhich ducks and geese are prepro-grammed to pick up informationabout their species in the first daysof life. What makes this happen isunclear, however, and the variouslabels now in use to indicate ge-netic influences on behavior—frombiogrammar, to biological algorithm,brain module, epigenetic rule, andlearning predisposition—are re-ally not much better at solving themystery than the good-old instinctconcept. The term module, in par-ticular, carries the connotation of abrain part that is self-contained, en-capsulated, and localized, render-ing the idea unpalatable to neuro-scientists (Panksepp & Panksepp,2000). Quite possibly, our pre-paredness for particular sets ofstimuli or problems (e.g., the facil-ity with which we recognize faces;Gauthier & Tarr, 1997) boils downto learned stimulus relevancerather than specialized brain cir-cuitry.

Williams (1966) was right towarn that adaptation is an onerousconcept that should be applied par-simoniously. What evolutionary psy-chology needs to develop is a tastefor multilevel thinking in which at-tention freely shifts between imme-diate (proximate) explanations ofbehavior, which are the traditionaldomain of psychology, and evolu-tionary (ultimate) explanations. Inother words, it needs to addressboth the “how” questions of howthings work and the “why” ques-tions of why evolution favored aparticular behavior—to put a littleless evolution and a little morepsychology into its explanations.

CONCLUSION

Current problems with evolu-tionary psychology may be serious,

190 VOLUME 11, NUMBER 6, DECEMBER 2002

Published by Blackwell Publishing Inc.

but they are not insurmountable.Evolutionary psychology is boundto overcome them. I dare predictthat 50 years from now every psy-chology department will have Dar-win’s bearded portrait on the wall.Evolutionary approaches have thepotential to introduce a conceptualframework that will accommodateor replace the current proliferationof disconnected theories in thestudy of human behavior.

Even though evolutionary psy-chology, like the rest of psychol-ogy, oftentimes acts as if the hu-man species is a world apart, itcannot help but undermine its ownanthropocentrism given the sourceof the theories that it is so eagerly

adopting. They derive from scien-tists, such as Darwin, who first ofall were naturalists. If evolutionarypsychology embraces Edward Wil-son it cannot help but get coveredin ants, and if it embraces WilliamHamilton it cannot overlook thebeetles and parasites that fasci-nated this brilliant biologist. Withregard to animals closer to us, theparallels are even more striking.Chimpanzees, for example, en-gage in political alliances whenjockeying for power, show empa-thy toward others in distress, es-tablish an economy of services andfavors, and reconcile with oppo-nents after a fight by means of akiss and embrace (Fig. 1; de Waal,

1982/1998, 1996). Because evolu-tionary explanations require closeattention to phylogeny, and giventhat primatologists are used to be-havioral complexity not unlike thatof our own species, evolutionarypsychology and primatology makenatural partners.

The questions asked by evolu-tionary psychology may strikesome readers as simplistic, yet theyare here to stay. Questions aboutwhy we choose particular mates,avoid incest, and favor kin, andwhat modes of cooperation we en-gage in, for example, are not thetraditional questions of psychol-ogy, yet they emerge naturallyfrom an evolutionary perspective.

Fig. 1. Example of chimpanzees’ use of eye contact and hand gestures to invite a reconciliation. This photograph shows the situa-tion 10 min after a protracted, noisy conflict between two adult males at the Arnhem Zoo in the Netherlands. The challenged male(left) fled into the tree, but 10 min later his opponent stretched out a hand. Within seconds, the two males had a physical reunionand climbed down together to groom each other on the ground. Photograph by the author.

Copyright © 2002 American Psychological Society

CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 191

These basic questions are central toany evolutionary approach. Psy-chologists who do not like the sim-plicity of the answers currentlycoming out of evolutionary psy-chology should make an effort toimprove them, to broaden its intel-lectual horizon, because all of psy-chology would stand to gain froma more enlightened evolutionarypsychology.

Recommended Reading

de Waal, F.B.M. (1999). The end of

nature versus nurture.

ScientificAmerican

,

281

, 94–99.de Waal, F.B.M. (2001).

The ape andthe sushi master: Cultural reflectionsby a primatologist

. New York: BasicBooks.

Mayr, E. (2001).

What evolution is

.New York: Basic Books.

Zimmer, C. (2001).

Evolution: The tri-umph of an idea

. New York: HarperCollins.

Acknowledgments—

I thank AllisonBerger and Virginia Holt for providing

the transcript of my 2001 Focus on Sci-ence Plenary Address, which was pre-sented at the annual meeting of theAmerican Psychological Association inSan Francisco and was on the topic of thisessay. I am also grateful to Mauricio Pap-ini and Scott Lilienfeld for comments onprevious versions of the manuscript.

Notes

1. Address correspondence to FransB.M. de Waal, Living Links, Yerkes Pri-mate Research Center, Emory Univer-sity, 954 N. Gatewood Rd., Atlanta, GA30322.

2. Theory of mind means that oneunderstands the mental states of others(a capacity that may be limited to hu-mans and apes).

References

Daly, M., & Wilson, M. (1988).

Homicide

. Haw-thorne, NY: Aldine de Gruyter.

de Waal, F.B.M. (1996).

Good natured: The origins ofright and wrong in humans and other animals

.Cambridge, MA: Harvard University Press.

de Waal, F.B.M. (1998).

Chimpanzee politics

. Balti-

more: Johns Hopkins University Press. (Origi-nal work published 1982)

de Waal, F.B.M. (2000, April 2). Survival of therapist [Review of the book

A natural history ofrape: Biological bases of sexual coercion

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New YorkTimes Book Review

, pp. 24–25.

Dobzhansky, T. (1973). Nothing in biology makessense except in the light of evolution.

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Gauthier, I., & Tarr, M.J. (1997). Becoming a “Gree-ble” expert: Exploring mechanisms for facerecognition.

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McDougall, W. (1908).

An introduction to social psy-chology

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Muscarella, F., & Cunningham, M.R. (1996). Theevolutionary significance and social percep-tion of male pattern baldness and facial hair.

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Panksepp, J., & Panksepp, J.B. (2000). The sevensins of evolutionary psychology.

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Staats, A.W. (1991). Unified positivism and unifi-cation psychology: Fad or new field?

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Thornhill, R., & Palmer, C.T. (2000).

A natural his-tory of rape: Biological bases of sexual coercion

.Cambridge, MA: MIT Press.

Tooby, J., & Cosmides, L. (1992). The psychologi-cal foundations of culture. In J. Barkow, L.Cosmides, & J. Tooby (Eds.),

The adapted mind:Evolutionary psychology and the generation of cul-ture

(pp. 19–136). New York: Oxford Univer-sity Press.

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Wilson, E.O. (1998).

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Mutually Responsive Orientation Between Mothers and Their Young Children: A Context for the Early Development of Conscience

Grazyna Kochanska

1

Department of Psychology, University of Iowa, Iowa City, Iowa

Abstract

Some parent-child dyads es-tablish a mutually responsiveorientation (MRO), a relation-ship that is close, mutuallybinding, cooperative, and af-

fectively positive. Such rela-t i o n s h i p s h a v e t w o m a i ncharacteristics—mutual re-sponsiveness and shared posi-tive affect—and they foster the

development of conscience inyoung children. Children grow-ing up with parents who are re-sponsive to their needs andwhose interactions are infusedwith happy emotions adopt awilling, responsive stance to-ward parental influence and be-come eager to embrace parentalvalues and standards for behav-ior. The concurrent and longitu-

dinal beneficial effects of MROfor early development of con-science have been replicatedacross studies, for a broad rangeof developmental periods frominfancy through early schoolage, and using a wide variety ofbehavioral, emotional, and cog-nitive measures of conscience inthe laboratory, at home, and inschool. These findings highlightthe importance of the early par-ent-child relationship for subse-quent moral development.

Keywords

relationships; mutuality; con-science

How do young children becomeaware of rules, values, and standardsof behavior accepted within their