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Bringing in Darwin: Evolutionary Theory, Realism, and International PoliticsAuthor(s): Bradley A. ThayerSource: International Security, Vol. 25, No. 2 (Autumn, 2000), pp. 124-151Published by: The MIT PressStable URL: http://www.jstor.org/stable/2626755 .Accessed: 28/06/2011 01:28

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Bringing n Darwin Bradley . Thayer

Evolutionary Theory, Realism, andInternational olitics

Efforts to develop afoundation or cientific nowledge that would unite the natural nd social sci-ences date to the classical Greeks. Given recent dvances in genetics nd evolu-tionary heory, his goal may be closer than ever.' The human genome projecthas generated much media attention s scientists eveal genetic causes of dis-eases and some aspects of human behavior. And although advances in evolu-tionary heory may have received less attention, hey are no less significant.Edward 0. Wilson, Roger Masters, nd Albert Somit, mong others, have ledthe way in using evolutionary heory nd social science to produce a synthesisfor understanding human behavior and social phenomena.2 This synthesisposits that human behavior s simultaneously nd inextricably result of evo-lutionary nd environmental auses. The social sciences, ncluding hestudy ofinternational olitics, may build upon this scholarship.3

In this rticle argue that volutionary heory an improve the realist heoryof nternational olitics. Traditional ealist rguments est principally n one oftwo discrete ultimate auses, or intellectual oundations. The first s ReinholdNiebuhr's argument hat humans are evil. The second is grounded n the work

Bradley . Thayer san Assistant rofessor fPolitical cience t theUniversity fMinnesota-Duluth.

I am grateful o Mlada Bukovansky, tephen Chilton, Christopher ayne, Michael Mastanduno,Roger Masters, Paul Sharp, Alexander Wendt, Mike Winnerstig, nd Howard Wriggins or theirhelpful comments. thank Nathaniel Fick, David Hawkins, Jeremy oseph, Christopher Kwak,Craig Nerenberg, nd Jordana hillips for heir ble research ssistance. Finally, wish to acknowl-edge the generous support of the Earhart oundation, nd Ingrid Merikoski nd Antony ullivanin particular, nd the University f Minnesota, which allowed me to complete my research.

1. See Edward 0. Wilson, Consilience: he Unity f KnozwledgeNew York: Knopf, 1998).2. Wilson has pursued this goal since 1975, most recently n ibid., pp. 8-14,197-228; Roger D. Mas-ters, The Biological Nature of the State," World olitics, ol. 35, No. 2 (January 983), pp. 189-190;and Albert Somit, "Human Nature as the Central ssue in Political Philosophy," n Elliott White,ed., Sociobiologynd Human Politics Lexington, Mass.: D.C. Heath, 1981), pp. 167-180.3. Ethology-the study of animal behavior-is significant s well, particularly heconcept of evo-lutionary table strategies, which was introduced by J. Maynard Smith nd G.R. Price, The Logicof Animal Conflict," ature, ovember 2,1973, pp. 15-18. This has informed uch important chol-arship as Robert Axelrod and William D. Hamilton's finding f the mportance f reciprocation rtit-for-tat trategies or ooperation. ee Axelrod and Hamilton, "The Evolution of Cooperation,"Science,March 27, 1981,pp. 1390-1396;Robert Axelrod, TheEvolution fCooperationNew York:Ba-

sic Books, 1984), chap. 3; and John Maynard Smith, Evolution nd the Theory f Games New York:Cambridge University ress, 1982).

Internatioinal ecurity, ol. 25, No. 2 (Fall 2000), pp. 124-151? 2000 by the President nd Fellows of Harvard College and the Massachusetts nstitute f Technology.

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Bringing n Darwin 125

of Thomas Hobbes and Hans Morgenthau: Humans possess an innate animusdominandi, r drive to dominate. Both ntellectual oundations re widely con-sidered to be weak, however, because they rely either n a theological force ra metaphysical recept o explain state behavior. After he publication of Ken-neth Waltz's Theory f nternational olitics, which anchored realism on themore scientific oundation f structuralism nd the anarchic nternational ys-

tem, few scholars found classical realism hereafter ealism) relevant for theirscholarship.4

Evolutionary heory rovides a stronger oundation or realism because it sbased on science, not on theology or metaphysics. use the theory o explaintwo human traits: goism and domination. submit hat he egoistic nd domi-nating behavior of ndividuals, which s commonly described as "realist," s aproduct of the evolutionary rocess.5 focus on these two traits ecause theyare critical components of any realist argument n explaining internationalpolitics.6

I also argue that volutionary heory may be applied not only to realism, utalso to some of the central ssues in international olitics ncluding he originsof war and ethnic conflict. n evolutionary erspective llows scholars of in-ternational politics to understand that war is not unique to humans, but ischaracteristic f other pecies in the animal kingdom as well. It also helps ex-plain the role that war has played in human evolution, nd why xenophobiaand ethnocentrism re contributing auses of ethnic conflict.

These arguments re significant or two reasons. First, volutionary heoryoffers firm ntellectual oundation or the realist rgument hat egoistic and

dominating ehavior s the result f human evolution. Realist scholars can useevolutionary heory o construct erifiable cientific xplanations nd thus ex-pand realism's explanatory range,7 which may help to reinvigorate ealist

4. Kenneth N. Waltz, Theory f nternational olitics Reading, Mass.: Addison-Wesley, 979).5. For the sake of simplicity, discuss the "evolutionary rocess" even though four processes areactually at work: random genetic drift, migration, mutation, nd natural election. For discussionof these processes, ee Theodosius Dobzhansky, Genetics f he volutionary rocess New York: Co-lumbia University ress, 1970); John Maynard Smith, The Theory f Evolution Harmondsworth,United Kingdom: Penguin, 1958);Ernst Mayr, TheGrowth f Biological hought: iversity, volution,and nheritance Cambridge, Mass.: Harvard University ress, 1982); and Elliott ober, Philosophy f

Biology Boulder, Colo.: Westview, 993). Sexual selection s sometimes considered a fifth mecha-nism of evolution. See Charles Darwin, The Descent f Man, and Selection n Relation o Sex, Vol. 1(Princeton, N.J. Princeton University ress, 1981[1871]),pp. 256-279.6. I stress hat hey re critical omponents but not the totality f the realist rgument. n addition,evolutionary heory an be used to explain other types of human behavior.7. Both will improve the theory. n the desirability f constructing erifiable cientific xplana-tions, ee Gary King, RobertO. Keohane, and Sidney Verba, Designing ocial nquiry: cientific nfer-ence n Qualitative esearch Princeton, N.J.: Princeton University ress, 1994), p. 15. Stephen Van



International ecurity 5:2 | 126

scholarship.8 cholars who are attracted o realism but are not persuaded toground their arguments based on animus dominandi r anarchy will find asound scientific ubstructure n evolutionary heory.

Second, as the scholarship of Masters, renaus Eibl-Eibesfeldt, Wilson, andothers demonstrates, volutionary heory rovides an anchor for he study ofmuch of human behavior.9 or example, Masters uses evolutionary heory o

explain the origins of the state.10 omit and Steven Peterson rgue that t pro-vides a basis for specific forms of government.11 his article s intended tobuild on their work by "bringing n Darwin," that s, applying evolutionarytheory o realism and international olitics.

In the first ection, explain the ultimate auses of realism as presented byNiebuhr and Morgenthau.12 In the second, discuss evolutionary heory's on-tribution o realism. Finally, analyze the mplications f evolutionary heoryfor understanding he origins of war and ethnic conflict.

The Traditional ltimate auses of Realism

Like many theories n the natural nd social sciences, realism acks a commontheoretical oundation. n cosmology, or xample, scholars continue odebatethe cause of the continued expansion of the universe 12-15 billion years afterthe Big Bang created t argely because they disagree about the extent o whichphysical forces ther han gravity re at play. Paleontologists dispute whetherdinosaurs were warm-blooded and whether heir behavior s more closely re-

lated to that of modern reptiles r mammals. To understand why disciplines ortheories hat ack a common foundation an still be useful, cholars must dis-

Evera argues that better heories have broad explanatory ange.See Van Evera, Guide oMethods orStudents f Political cience Ithaca, N.Y.: Cornell University ress, 1997), p. 18.8. Gideon Rose also does this by combining lements f realism nd neorealism. Rose, "Neoclassi-cal Realism and Theories of Foreign Policy," World olitics, ol.51, No. 1 (October 1998), pp. 144-172.9. Roger D. Masters, The Nature of Politics New Haven, Conn.: Yale University Press, 1989);Irenaus Eibl-Eibesfeldt, Human Ethology New York: Aldine de Gruyter, 989); and Wilson,Consilience, p. 8-14, 197-228. See also Richard D. Alexander, TheBiology f Moral Systems NewYork:Aldine de Gruyter, 987); and Francis Fukuyama, TheGreatDisruption: uman Nature nd theReconstitution f Social Order New York: Free Press, 1999).10. Masters, "The Biological Nature of the State," pp. 185-189.11. Albert omit nd Steven A. Peterson, arwinism, ominance, nd Democracy: he Biological asesofAuthoritarianismGreenwich, Conn.: Praeger, 997). See also Laura L. Betzig, Despotism nd Dif-ferential eproduction: Darwinian ViewofHistory New York: Aldine de Gruyter, 986).12. I do not critique these arguments here. Both theorists have been widely criticized, erhapsmost perceptively y Kenneth N. Waltz, Man, the tate, nd War: A Theoretical nalysis New York:Columbia University ress, 1959), pp. 26-39.




tinguish between ultimate nd proximate ausation. Ultimate causes are uni-versal statements that explain proximate causes.13 Proximate causes aredeductively derivable from ultimate causes and focus on explanations of im-mediate occurrences. n general, theory s better f ts ultimate nd proximatecauses are testable.

Evolutionary heory eeks to understand he ultimate auses of behavior. n

evolutionary heory, ltimate ausal analysis explains why proximate mecha-nisms occur and why animals respond to them s they do. It does not describebehavior, but rather frames the parameters of a proximate causal explana-tion.14 Proximate causal analysis seeks to explain, for example, why or howhormonal or stimulus-specific actors perate within an animal.15 To under-stand why birds fly outh for he winter, n ultimate ausal explanation of birdmigration would consider factors hat contribute o fitness uch as the avail-ability f food, ccess to mates, nd the presence of predators t both the ndig-enous and wintering reas. A proximate xplanation would consider high sex

hormone evels that are correlated with spring migrations, r changing envi-ronmental onditions o which birds are sensitive, uch as fluctuations n tem-perature, ainfall, nd barometric ressure.

Realists have traditionally rgued that there re two ultimate auses of hu-man behavior. The first, rounded in theology, s expressed by Niebuhr: Hu-mans are evil. Human evil is the primary ause of human behavior, speciallyof the desire to dominate others. Humans possess "unlimited nd demonic po-tencies of which animal life s innocent."16 vil manifests tself n sin, or the re-

13. The distinction etween ultimate nd proximate ausation is commonly made in biology. eeErnst Mayr, Toward New Philosophy f Biology: bservations f n Evolutionist Cambridge, Mass.:Harvard University ress, 1988),pp. 24-37. I base the distinction etween universal nd proximatecausation on Mayr and Wesley Salmon's distinction etween fundamental nd derivative heories.A universal cause is a fundamental, awlike sentence. t is general and adequately supported byempirical vidence. A proximate ause is derivable from undamental heories. Wesley C. Salmon,Four DecadesofScientific xplanation Minneapolis: University f Minnesota Press, 1989),pp. 18-20.Salmon's argument s based on Carl Hempel and Paul Oppenheim's distinction etween funda-mental aws and derivative aws. Hempel and Oppenheim, "Studies in the Logic of Explanation,"Philosophy f Science,Vol. 15 (1948), pp. 135-148, reprinted n Carl G. Hempel, Aspects f ScientificExplanation New York: Free Press, 1965), pp. 245-290, 267.

14. Most explanations f behavior or events often mplicitly ely n ultimate nd proximate ausalanalysis, although n most everyday explanations, proximate nes are sufficient.15. As Wilson explains: "Proximate xplanations nswer the question of how biological phenom-ena work, usually at the cellular nd molecular evels," whereas ultimate auses explain "why heywork .. the advantages the organism njoys as a result f evolution that reated the mechanismsin the first lace." Wilson, Consilience, p. 85-86 (emphasis in original).16. Reinhold Niebuhr, TheNature nd Destiny f Man: A Christian nterpretation, vols. (New York:Charles Scribner's Sons, 1941, 1943), Vol. 1, p. 179.




fusal of humans to accept inherent imitations."7 urthermore, ll humanactivity s tainted with narcissistic elf-love hat, or Niebuhr, s the essence ofevil.18Self-love r pride causes humans to seek power because "the ego doesnot feel secure and therefore rasps for more power in order to make itself e-cure. t does not regard tself s sufficiently ignificant r respected or fearedand therefore eeks to enhance its position n nature and society."19

The recognition hat humans are finite reatures auses them to seek power:"Man is the only finite reature who knows that he is finite nd he is thereforetempted o protest gainst his fate. One form which this protest akes s his im-perialistic mbition, his effort o overcome his insignificance y subordinatingother ife to his individual or collective will."20

The recognition f human sinfulness manifests tself n Niebuhr's consider-ation of international olitics. Pride and a desire for power exist not onlyamong individuals, but also among states. And because national pride s capa-ble of causing greater vil, t s especially dangerous.21 Niebuhr argues that he

traditional ealist mechanism f stability, hebalance of power, s the only forcecapable of bringing ustice to the world. The balance of power is necessary be-cause the "natural weakness of democracy as a form of government whendealing with foreign policy is aggravated by liberalism s the culture whichhas informed he life of democratic nations."22As Niebuhr explains, "In thisliberalism here s little understanding f the depth to which human malevo-lence may sink and the heights o which malignant power may rise."23

The second ultimate ause of egoistic and dominating behavior s given byMorgenthau: Humans behave as they do because they possess an animus

dominandi.24hey seek power because human nature s fundamentally goistic

17. Ibid., pp. 178-179.18. Reinhold Niebuhr, aith nd History: Comparison fChristian nd ModernViews fHistory Lon-don: Nisbet, 1938),p. 9. See also Reinhold Niebuhr, TheChildren fLight nd the Children fDarkness:A Vindication f Democracy nd a Critique f ts Traditional efence New York: Charles Scribner'sSons, 1944), p. 55.19. Niebuhr, Nature nd Destiny f Man, Vol. 1, p. 189.20. Reinhold Niebuhr, Christianity nd Pozwer olitics New York: Charles Scribner's Sons, 1940),pp. 156-157.As Niebuhr observes, All of his ntellectual nd cultural pursuits .. become infectedwith the sin of pride. Man's pride and will-to-power isturb he harmony f creation." Niebuhr,

Natutre nd Destiny f Man, Vol. 1, p. 179.21. This is true even for liberal democracy uch as the United States. See Niebuhr, Children fLight nd theChildren f Darkness, p. 20-21, 183-186. Waltz also makes this point n Man, the tate,and War, p. 18ff.22. Niebuhr, Christianity nd Power Politics, . 26.23. Ibid., p. 47.24. Hans Morgenthau, Scientific an vs. Power Politics Chicago: University f Chicago Press,1946), p. 192. Classical realism contains many assumptions that are not addressed here, uch as:




and malignant. Thus conflict nd war occur because human nature s bad.25Thomas Hobbes provided the foundation or his econd, secular, pillar of real-ist thought: Humans are ruled by an insatiable desire for power.26 his lust forpower has created a state of war in which humans live in reciprocal nd per-manent fear of violent death, and in which peace is always precarious.

According o Morgenthau, he "desire for power ... concerns tself not with

the ndividual's survival but with his position among his fellows once his sur-vival has been secured.... His lust for power would be satisfied nly f the astbecame an object of his domination, here being nobody above or beside him,that s, if he became like God."27 So encompassing s this desire for power thatthe tendency o dominate "is an element of all human associations, from hefamily hrough raternal nd professional ssociations and local political orga-nizations, o the state."28

Two types of behavior are the proximate auses of the realist rgument: go-ism and domination.29 goism will cause an individual to place his interests

before those of others, he interests f himself nd his family before hose ofmore distant elatives, nd the nterests f relatives efore hose of his commu-nity, tate, nd so on.30 he desire to dominate, realists believe, s inherent ndoften eads to physical ggression gainst those who oppose one's objectives.

State eaders are expected to mirror his ordering y putting he nterests ftheir tate before hose of others r of the world community, nd by striving odominate other tates. Realists argue that only by possessing power can indi-viduals attack nd conquer others s well as deter nd defend themselves rom

States desire survival; states are the key actors n international olitics; nd the nature of nterna-tional politics s inherently onflictive.25. Demonstrating he brutality nd prevalence of war in prehistoric imes s Lawrence H. Keeley,War before ivilization: he Myth f the Peaceful avage New York: Oxford University ress, 1996).See also Carol R. Ember, Myths bout Hunter-Gatherers," thnology, ol. 17, No. 4 (October 1978),pp. 439-448; and Harry H. Turney-High, rimitive War: ts Practice nd ConceptsColumbia: Univer-sity of South Carolina Press, 1949).26. Thomas Hobbes, Leviathan, d. C.B. Macpherson Harmondsworth, nited Kingdom: Penguin,1985), chap. 11, p. 161.27. Morgenthau, cientific an vs. Power Politics, . 193.28. Hans J. Morgenthau, olitics mong Nations:The Struggle or ower nd Peace, 5th rev. d. (NewYork: Knopf, 1978), p. 37.

29. Here I am concerned nly with the minimal ssential traits f people necessary o make the re-alist argument. do not claim that ther raits re not used by realists, or am I making ny claimsabout what individual realists do or should do. It is only mportant o my argument hat realistsconsider these traits ignificant.30. Richard D. Alexander makes precisely his point in Alexander, Darwinism nd Human Affairs(Seattle: University f Washington Press, 1979), Figure 4, p. 44. For a discussion of egoism, seeElliott ober and David Sloan Wilson, UntoOthers: he Evolution nd PsychologyfUnselfish ehavior(Cambridge, Mass.: Harvard University ress, 1998), p. 224.




attack. The principal result of this process is that balances of power will formand reform yclically, roducing both periods of stability nd intense ecuritycompetition n international olitics.

Evolutionary heory s the Ultimate ause ofRealism

Contemporary volutionary heorists ffer xcellent rguments or xplainingsome of the human behavior expected by realism. Particularly nteresting rethose in the subdiscipline of evolutionary heory known as sociobiology, hestudy of human behavior from he perspective f evolutionary heory.31 husfar, however, realists have not used evolutionary heory o place realism on astronger oundation.32 fter riefly eviewing he evolutionary rocess, dis-cuss how it can explain the origins of egoism and domination nd why it s abetter ltimate ause of realist behavior than those put forth y Niebuhr andMorgenthau.33

THE PROCESS OF EVOLUTION

In evolutionary heory, omo apiens, r the anatomically modern human, s ananimal, nd like all animals behaves as he does as a result f evolution by natu-ral selection.34 he essence of evolution by natural election s that most behav-ioral characteristics f a species evolve because they help the species surviveand reproduce.35 ccording to philosopher of biology Elliott Sober, there re

31. Formally, ociobiology s a subdiscipline of evolutionary heory hat pplies the theory o thesocial behavior of animals, ncluding Homo apiens, n order o study how social behavior s shapedby natural selection. The locus classicus s Edward 0. Wilson, Sociobiology: New Synthesis Cam-bridge, Mass.: Harvard University ress, 1975). Wilson defines t as "the systematic tudy of the bi-ological basis of all social behavior." Ibid., p. 4. Sober offers broader definition: a researchprogram hat eeks to use evolutionary heory o account for ignificant ocial, psychological, ndbehavioral characteristics n various species." Sober, Philosophy f Biology, . 184.32. In a broader context, he ntellectual ntercourse etween social sciences and biology hould beincreased. Notable for heir work at the nexus of biology and social science, n addition to the au-thors noted elsewhere, re Luigi Luca Cavalli-Sforza nd Francesco Cavalli-Sforza, The Great Hu-man Diasporas:TheHistory f Diversity nd Evolution Reading, Mass.: Addison-Wesley, 995); PeterA. Corning, The Biological Bases of Behavior and Some Implications orPolitical Science," WorldPolitics, ol.23,No. 3 (April 1971), pp. 321-370; Jared Diamond, Guns,Germs, nd Steel:TheFatesofHuman Societies New York:W.W. Norton, 1997); and Thomas C. Wiegele, d., Biology nd the ocialSciences:An Emerging evolution Boulder, Colo.: Westview, 982).33. While evolutionary heory an explain this behavior, he egoism or drive to dominate of anyindividual may result from ther causes as well.34. More precisely, uman behavior s the result of the environment nd genotype. The perspec-tive begins with Charles Darwin's description f natural election, he mechanism of evolution nDarwin, On the Origin f SpeciesbyMeansofNatural election Cambridge, Mass.: Harvard Univer-sity Press, 1964[1859]).35. "Those whose genes promote characteristics hat re advantageous in the struggle o survive




three onstituents f this process.36 irst, here must be genetic variation n thespecies. If all individuals are the same, then there s no basis for hange. Genefrequencies, however, alter regularly hrough genetic drift, migration, muta-tion, nd natural selection.37 hus for exually reproducing pecies, only den-tical twins or other monozygotic multiple births) re truly dentical; ll otherspossess differences. econd, genetic variation must improve what biologists

term fitness": A member of a species is fit f t s better ble to survive and re-produce-hence the term survival of the fittest."38 hese individuals will bebetter epresented n the next generation han those ess fit. inally, heremustbe heritable ariation n fitness: he characteristic ust be passed from arentto offspring.39

According to evolutionary theory, human behavioral traits the geneticcauses of human behavior) evolve and genes that increase fitness spreadthough the population. By displaying hese traits, n individual stands a betterchance of surviving ong enough to reproduce nd of having her genes repre-

sented n the next generation. This is the essence of the basic model of evolu-tionary heory upon which realism may build.40

THE ORIGINS OF EGOISM

Evolutionary heory ffers wo sufficient xplanations for the trait f egoism.The first s a classic Darwinian argument: n a hostile environment where re-sources are scarce and thus survival precarious, organisms typically atisfytheir wn physiological needs for food, shelter, nd so on before ssisting oth-

and reproduce are rewarded through the transmission f their genes to the next generation."Phillip Kitcher, aulting mbition: ociobiology nd the Questfor Human Nature Cambridge, Mass.:MIT Press, 1985), p. 42.36. Sober, Philosophy f Biology, . 9.37. Cavalli-Sforza and Cavalli-Sforza, GreatHuman Diasporas, pp. 92-104; Richard Dawkins, TheExtended henotype: heGene s the Unit of SelectionOxford: W.H. Freeman, 1982),pp. 38-54; andSober, Philosophy f Biology, p. 18-19.38. In addition, what is ultimately mportant s relative, ot absolute, fitness. hat s, t s not onlythe number of offspring ne produces, but that one produces more than others. ober and Wilson,Unto Others, . 23. For excellent discussions of the complexities ssociated with fitness, ee JohnBeatty, Fitness: TheoreticalContexts," n Evelyn Fox Kellerand Elisabeth A. Lloyd, eds., Keywordsin Evolutionary iologyCambridge, Mass.:Harvard University ress, 1992),pp. 115-119; nd SusanK. Mills and John Beatty, The Propensity nterpretation f Fitness," n Elliott ober, d., Conceptual

Issues n Evolutionary iology Cambridge, Mass.: MIT Press, 1994), pp. 3-23.39. The ability f zebras to run fast s one example; on average, fast ebras tend to produce fasteroffspring. f course, there re genetic, phenotypic, nd environmental imits to the speed of ze-bras. Furthermore, s Sober notes, he environment may be especially mportant, articularly f off-spring receivebetter utrition. o there might e a purely nvironmental xplanation for imilaritybetween parental and offspring henotypes. ober, Philosophy f Biology, . 11.40. Evolutionary theory s concerned with ultimate causes of behavior rather than proximatecauses.




ers.41 n times of danger or great tress, n organism usually places its ife-itssurvival-before that of other members of ts group, be it pack, herd, or tribe.For these reasons, egoistic behavior contributes o fitness.

Evolutionary heorist Richard Dawkins's selfish gene theory provides thesecond sufficient xplanation for egoism. A conceptual shift s required herebecause Dawkins's level of analysis s the gene, not the organism. As Dawkins

explains, at one time there were no organisms, ust chemicals n a primordial"soup."42 At first, ifferent ypes of molecules started orming y accident, n-cluding some that ould reproduce by using the constituents f the soup-car-bon, nitrogen, hydrogen, and oxygen. Because these constituents were inlimited supply, molecules competed for them as they replicated. From thiscompetition, he most efficient opy makers emerged. The process, however,was never perfect. ometimes mistakes were made during replication, nd oc-casionally these accidents resulted n more efficient eplication r made someother ontribution o fitness. ne such mistake might have been the formation

of a thin membrane hat held the contents f the molecule together-a primi-tive cell. A second might have involved the division of the primitive ell intoever larger components, rgans, nd so on to create what Dawkins calls "sur-vival machines." He explains, "The first urvival machines probably consistedof nothing more than a protective oat. But making living got steadily harderas new rivals arose with better nd more effective urvival machines. Survivalmachines got bigger nd more elaborate, nd the process was cumulative ndprogressive."43 rom a genetic perspective, here s no intentionality n thisprocess, but it continued nonetheless because of evolution. Dawkins makes

clear, however, hat the nterests f the gene and the organism need not coin-cide at different tages in an organism's ife, particularly fter eproduction.44In general, however, he selfishness f the gene increases ts fitness, nd so thebehavior spreads.

THE ORIGINS OF DOMINATION

Evolutionary heory an also explain the trait f domination. n evolutionarytheory, omination usually means that particular ndividuals in social groupshave regular priority f access to resources n competitive ituations. or most

social mammals, form f social organization alled a "dominance hierarchy"

41. Although, s I discuss below, nclusive fitness may modify his argument.42. Richard Dawkins, The Selfish ene,new ed. (Oxford: Oxford University ress, 1989),p. 258.43. Ibid., p. 19.44. Ibid., chap. 6.




operates most of the time.45 he creation f a dominance hierarchy may be vio-lent nd is almost always competitive. A single eader, lmost always male (thealpha male), leads the group. The ubiquity of this ocial ordering trongly ug-gests that such a pattern f organization contributes o fitness.

Two principal types of behavior are evident among social mammals in adominance hierarchy: ominant and submissive. Dominant mammals have

enhanced access to mates, food, and territory, hus ncreasing heir hances ofreproductive uccess.46Acquiring dominant status usually requires aggres-sion. Dominance, however, s an unstable condition; o maintain t, dominantindividuals must be willing to defend their privileged access to available re-sources as long as they re able. Ethologists Richard Wrangham nd Dale Pe-terson explain why an individual animal vies for dominant status: "Themotivation f a male chimpanzee who challenges another's rank s not that heforesees more matings or better ood or a longer ife."47 ather those rewardsexplain why. . . selection has favored he desire for power, but the mmediate

reason he vies for tatus ... is simply to dominate his peers."48Dominant animals often ssume behavior reflecting heir tatus. For exam-ple, dominant wolves and rhesus monkeys hold their tails higher than doother members f their roup n an effort o communicate ominance. A domi-nant animal that engages in such displays is better ff f t can gain priority faccess to resources without having to fight or t continuously.49

45. Social mammals are usually defined as those mammals that ive in groups (such as packs,herds, and tribes) that cooperate to raise the young and defend the group from nemies, and in

which there s overlap in the group between at least two generations.46. Dorothy L. Cheney and Robert M. Seyfarth, ow Monkeys ee the World: nside he Mind of An-other pecies Chicago: University f Chicago Press, 1990), p. 35; Alexander H. Harcourt nd FransB.M. de Waal, eds., Coalitions nd Alliances n Humans nd Other Animals Oxford: Oxford Univer-sity Press, 1992); and de Waal, Chimpanzee olitics: ower nd Sex among Apes,rev. ed. (Baltimore,Md.: Johns Hopkins University ress, 1998).47. Richard Wrangham nd Dale Peterson, DemonicMales: Apes and the Origins f Human Violence(Boston: Houghton Mifflin, 996), p. 199.48. Ibid., p. 199.See also Konrad Lorenz, On Aggression, rans. Marjorie Kerr Wilson New York:Harcourt, Brace, and World, 1966). Sociobiology s closely allied with ethology Both disciplinespay close attention o the evolutionary history f species and the manner n which behavior in-stinct n particular) dapts organisms to their nvironment. t differs rom ociobiology because"ethology focuses on the details of ndividual behavior, ncluding he activity f the nervous sys-

tem and the effects f hormones; ociobiology concentrates n the most complex forms f socialbehavior and the organization f entire ocieties." Charles J. Lumsden and Edward 0. Wilson,Pro-methean ire: Reflectionsn the Origin f Mind Cambridge, Mass.: Harvard University ress, 1983),p. 23.49. David P. Barash, Sociobiologynd Behavior New York: Elsevier, 977), p. 237. n this respect, ni-mal behavior s like deterrence nd coercion n international olitics. Animals, ike states, ignaltheir ntentions n efforts o deter nd coerce. As Waltz notes, Force s least visible where power ismost fully nd most adequately present." Waltz, Theory f nternational olitics, . 185.




Submissive social mammals recognize what is permitted nd forbiddengiven their lace in the hierarchy. hey often ry o be as inconspicuous as pos-sible. This behavior signals that the subordinate ccepts its place in the domi-nance hierarchy nd at least temporarily will make no effort o challenge thedominant animal.

Ethologists nd sociobiologists rgue that dominance hierarchies volve be-

cause they id defense gainst predators, romote he harvesting f resources,and reduce intragroup conflict.50 species that lives communally has twochoices:either t accepts organization with some centralization f power, or itengages in perpetual conflict ver scarce resources, which may result n seri-ous injury nd thus deprive the group of the benefits f a communal exist-ence.51 thological studies have confirmed hat a hierarchical ominance sys-tem within primate band minimizes overt aggression; ggression ncreases,however, when the alpha male is challenged.

The dominance hierarchy as had a profound ffect n human evolution. As

cognitive psychologist Denise Dellarosa Cummins argues, "The fundamentalcomponents of our reasoning rchitecture volved in response to pressures toreason about dominance hierarchies, he social organization hat characterizesmost social mammals."52 Her study and others have found that dominance hi-erarchies ontribute o the evolution of the mind, which n turn contributes ofitness.

According to Cummins, submissive individuals have the ability to detect,exploit, nd circumvent he constraints f domination. f an animal can takewhat t wants by force, t s sure to dominate the available resources-unless its

subordinates are smart enough to outwit it. A subordinate must use other

50. See James L. Boone, "Competition, Conflict, nd the Development of Social Hierarchies," nEric Alden Smith and Bruce Winterhalder, ds., Evolutionary cology nd Human Behavior NewYork:Aldine de Gruyter, 992),pp. 301-337; Joseph Lopreato, Human Nature nd Biocultural volu-tion Boston: Allen and Unwin, 1984), pp. 161-176; Donald L. McEachron and Darius Beer, A Re-view of Selected Sociobiological Principles: Application to Hominid Evolution II. The Effects fIntergroup onflict," ournal f Social and Biological tructures, ol. 5, No. 2 (April 1982), pp. 121-139; K.E. Moyer, The Biological Basis of Dominance and Aggression," n Diane McGuinness, ed.,Dominance, ggression, nd War New York: Paragon House, 1987), pp. 1-34; Wilson, Sociobiology,p. 287; and Fred H. Willhoite, r., Primates nd Political Authority," merican olitical cience Re-view,Vol. 70, No. 4 (December 1976),pp. 1110-1126. tanley Milgram also notes the mportance f

what he terms dominance structures." e argues that he "potential or bedience s prerequisiteof . . . social organization." Milgram, Obedience oAuthority: n Experimental iew New York:Harper and Row, 1974), p. 124.51. In this respect, nternational olitics resembles animal behavior. As an alpha male providesstability o the group, so too a hegemon n international olitics may provide stability or esserstates both in the realm of international ecurity nd for nternational olitical economy.52. Denise Dellarosa Cummins, "Social Norms and Other Minds," in Cummins and Colin Allen,eds., TheEvolution fMind (New York: Oxford University ress, 1998), p. 30.




strategies-deception, guile, appeasement, bartering, lliance formation, rfriendship-to survive. Thus intelligence s particularly mportant o the sur-vival of subordinates. The evolution of mind emerges," Cummins writes, asa strategic rms race in which the weaponry s ever-increasing mental capacityto represent nd manipulate nternal epresentations f the minds of others."53

From their tudies of chimpanzee societies, thologists ave learned that he

struggle or urvival s best characterized s a struggle etween those who aredominant and those seeking to outwit them i.e., between recognizing n op-ponent's intentions nd hiding one's own). The following xample illustrateshow a subordinate himpanzee, Belle, who knows the ocation of hidden food,attempts o deceive Rock, who is dominant.Belle accordingly topped uncovering he food if Rock was close. She sat on ituntil Rock left. Rock, however, soon learned this, and when she sat in oneplace for more than a few seconds, he came over, shoved her aside, searchedher sitting lace, and got the food. Belle next topped going all the way [to the

food]. Rock, however, countered by steadily expandingthe area of his search

through he grass near where Belle had sat. Eventually, elle sat farther ndfarther way, waiting until Rock looked in the opposite direction before shemoved toward the food at all, and Rock in turn seemed to look away untilBelle started o move somewhere. On some occasions Rock started o wanderoff, nly to wheel around suddenly precisely s Belle was about to uncoversome food.... On a few trials, he actually started off trail by leading thegroup in the opposite direction rom he food, and then, while Rock was en-gaged in his search, she doubled back rapidly and got some food.54

Despite the "arms race" described by Cummins to outwit a dominant ndi-

vidual, the subordinate members of the group continue to participate n thedominance hierarchy ecause doing so increases their hances of survival. Associobiologist David Barash explains, f subordinates are more fit by accept-ing ... [subordinate] anking han by refusing o participate, hen some formof social dominance hierarchy will result."55

Humans and other primates evolve a mental architecture o address thedifficulties hey encounter when in dominance hierarchies. As result of this,Wilson submits: "Human beings are absurdly easy to indoctrinate-they eekit. 56 Three factors ontribute o the ease of ndoctrination. irst, urvival n a

53. Ibid., p. 37 (emphasis deleted). See also Alexander, TheBiology f MoralSystems, p. 114-117.54. E.W. Menzel, "A Group of Chimpanzees in a One-Acre Field," in A.M Schrier nd F. Stollnitz,eds., Behavior f Nonhuman rimates New York: Academic Press, 1974), pp. 83-153. Quoted inCummins, "Social Norms and Other Minds," p. 37.55. Barash, Sociobiology nd Behavior, p. 239-240.56. Wilson, Sociobiology, . 562 (emphasis in original). See also Lopreato, Human Nature and




hostile world dictates membership n a group and produces a fear of ostracismfrom t. Second, acceptance of, or conformity o, a particular tatus quo lowersthe risk of conflict n a dominance hierarchy. hird, conformity elps keepgroups together.57 f group conformity ecomes too weak, the group couldfall apart and become extinct ecause of predation from ne's own or anotherspecies.58

The consequences for the study of politics are great. Eibl-Eibesfeldt, omitand Peterson, Wilson, nd psychologist onald Campbell, among others, ug-gest that humans readily give allegiance to the state, or embrace religion orideologies such as liberalism r communism, ecause evolution has produceda need to belong to a dominance hierarchy.59 n overview of human historyprovides context. Much of t s a record of threats f force r wars to gain terri-tory nd resources.60 olitical nstitutions, hether monarchies r aristocracies,and leaders such as Julius Caesar, Louis XIV,and Somali warlord MohamedFarah Aidid typify ominance hierarchies-as do the modern state and its

many institutions, ncluding government ureaucracies and the military.61These political examples are readily vident, but dominance hierarchies lso

have more subtle ffects, or xample, mong the young and between the sexes.They help explain why people obey authority nd intensify he significance fbirth rder. Research on children's ocial interactions as shown that childrenas young as three years organize themselves nto dominance hierarchies. tan-ley Milgram's famous psychological experiments how that ordinary itizenswill obey those recognized s dominant ven when they re using their ower

Biocultural volution, p. 177-186; and Somit and Peterson, Darwinism, ominance, nd Democracy,pp. 77-84.57. Donald T. Campbell, "On the Genetics of Altruism nd the Counter-Hedonic Components nHuman Culture," Journal f Social ssues,Vol. 28, No. 3 (1972),pp. 21-37.58. Alexander, Darwinism nd Human Affairs, . 64.59. Campbell, "On the Genetics of Altruism nd the Counter-Hedonic Components in HumanCulture"; Eibl-Eibesfeldt, uman Ethology; rank Kemp Salter, Indoctrination s InstitutionalizedPersuasion," n Irenaus Eibl-Eibesfeldt nd Frank Kemp Salter, ds., Indoctrinability, deology, ndWarfare: volutionary erspectives New York: Berghahn Books, 1998), pp. 421-452; and Wilson,Sociobiology,. 562. Masters n Nature f Politics xplores the biological foundation f political orga-nization fully. f course the specific orm f the political organization, deology, r religion s notinformed y biology.60. See Robert Bigelow, The Dazvn Warriors: an's Evolution ozvard eace (Boston: Little, Brown,1969).61. Masters, Nature f Politics. ee also Willhoite, Primates nd PoliticalAuthority," p. 1118-1123.International olitics may also be conceived of as a dominance hierarchy: he hegemon acts likethe alpha male, and bids for hegemony resemble ontests etween alpha males defending heir e-sources.




for clearly malevolent ends.62Frank Sulloway's analysis of birth rder showsthat dominance structures within the family nfluence personality, with first-born siblings eeking to maintain onformity, nd later-borns, s subordinates,seeking to rebel against constraints.63

EVOLUTIONARY THEORY: A BETTER ULTIMATE CAUSE

Evolutionary heory rovides a better oundation or ealism han the theologi-cal or metaphysical rguments dvanced by Niebuhr or Morgenthau for hreereasons. First, t s superior s judged by the common metrics n philosophy ofscience developed by Carl Hempel and Karl Popper.64Evolutionary heorymeets all of Hempel's criteria f the deductive-nomological D-N) model of sci-entific xplanation, nlike Niebuhr's evil or Morgenthau's nimusdominandi.65Measured by Popper's criteria-developed in his theory of critical rational-ism-evolutionary theory s also superior because it is falsifiable.66 hat is,

62. Milgram acknowledges the importance of the evolutionary process for obedience: "We areborn with a potential or obedience, which then nteracts with the nfluence f society o producethe obedient man." The capacity for obedience, he argues, s like the capacity for anguage wheremental tructures nd a social milieu must be present. In explaining he causes of obedience, weneed to look both at the nborn tructures nd ... social influences.... The proportion f nfluenceexerted by each is a moot point. From the standpoint f evolutionary urvival, ll that matters sthat we end up with organisms hat an function n hierarchies." Milgram, Obedience o Authority,p. 125 (emphasis in original).63. Frank J. Sulloway, Born to Rebel: Birth Order, amily Dynamics, nd Creative ives New York:Pantheon, 1996).64. These are common standards but certainly ot the only ones; others nclude those developedby Roy Bhaskar, homas Kuhn, and Imre Lakatos. Because the D-N model and Popper's falsificat-

ion are commonly ccepted, I discuss those. If one of these alternative tandards were used, itwould not affect he result, o I do not consider them.65. More formally, heD-N model requires hat heultimate ause (the explanans) comprises tate-ments of the antecedent conditions, C, and general laws such as laws of nature L. Theexplanandum, E, is the description f whatever s being explained, predicted r postdicted. Also, Emust follow deductively from C and L.

Evolutionary heory provides a better ltimate ausal foundation ccording to the D-N modelbecause it tightly its his model. It presents theory of how nature evolves; specific evidenceabout how early primates nd humans lived and continue to do so is widely known. Proximatecauses of human behavior are deducible from t. Thus evolutionary heory rovides an adequatecausal explanation for realism because the explanans logically produces, provided the antecedentfacts, heproximate auses (explanandum)-egoism and domination. ee Carl G. Hempel, Philoso-phy f Natural cience Englewood Cliffs, .J.: Prentice-Hall, 966), pp. 49-54; and Hempel, Aspectsof Scientific xplanation, p. 174, 232-233, 247-249.66. The essence of Popper's metric s that orroboration f general theory s not possible. What sci-entists do is not to verify aws or theories but to falsify hem. Evolutionary heory s falsifiable.That s, the conditions under which the theory would be disproved are derivable from he funda-mental theory, s is the empirical vidence that would show it to be false. This is not the case forevil or animus dominandi. arl R. Popper, The Logic of Scientific iscovery London: Hutchinson,1959), pp. 40-42, 78-92, 419.




scholars know what evidence would not verify he theory.67 iebuhr's andMorgenthau's ultimate auses are noumenal i.e., outside the realm of scientificinvestigation). econd, evolutionary heory ffers widely accepted scientificexplanation of human evolution, hus giving realism the scientific oundationit has lacked.

Third, ealists an use evolutionary heory o advance arguments upportingoffensive ealism without depending on the anarchic nternational ystem. Of-fensive realists rgue that tates seek to maximize power because competitionin the nternational ystem o achieve security ompels them to do so.68 Real-ism based on evolutionary heory eaches the same conclusion, but the causalmechanism s at the first mage (the individual) rather han the third mage(the nternational ystem). tate decisionmakers re egoistic nd strive o dom-inate others. n international olitics they do so by maximizing tate power.69Focused, empirical esting s required o determine which nsights n offensiverealism based on evolutionary heory rovides. This n turn may nform xpla-nations of why state eaders choose to expand and why they re often ble togenerate popular support for xpansion with relative ase, or why external rinternal hreats have been such powerful motivators n building national soli-darity nd mobilizing a society's resources.

Implications or nternational olitics

Scholars of nternational olitics may use evolutionary heory ogenerate newunderstanding f mportant ssues in international olitics, uch as the origins

67. Popper himself made the charge that volutionary heory was "not a testable cientific heory."Karl R. Popper, "Intellectual Autobiography," n Paul Arthur chilpp, ed., ThePhilosophy f KarlPopper, ol. 1 (La Salle, Ill.: Open Court, 1974),pp. 3-181, 134; and Popper, Objective nowledge, ev.ed. (Oxford: Clarendon, 1979),pp. 256-280. Popper's argument s incorrect, owever.Evolutionarytheory s a testable scientific heory hat possesses many falsifiable laims. See Mills and Beatty,"The Propensity nterpretation f Fitness," p. 9; M. Ruse, "Confirmation nd Falsification f The-ories n Evolution," Scientia, ol. 104, Nos. 7-8 (1969), pp. 329-357; and Sober,Philosophy fBiology,p. 47.68. The leading proponent of offensive ealism s John J. Mearsheimer. ee Mearsheimer, TheFalse Promise of nternational nstitutions," nternational ecurity, ol. 19, No. 3 (Winter 994/95),pp. 5-49; and Mearsheimer, Great ower BehaviorNew York: W.W. Norton, forthcoming). ee alsoChristopher ayne, ThePeaceof llusions: nternational elations heory nd American rand trategyin the ost-Cold WarEra Ithaca, N.Y.: Cornell University ress, forthcoming). or an analysis of of-fensive nd defensive ealism, ee Sean M. Lynn-Jones, Realism and America's Rise: A Review Es-say," nternational ecurity, ol. 23, No. 2 (Fall 1998), pp. 157-182.69. This explanation hould not be viewed as an alternative oJohn Mearsheimer's offensive eal-ism, but rather may be a complement o t. Either xplanation may be sufficient o explain state be-havior.




of war and ethnic conflict.70 volutionary heory uggests why some humansorganize attacks and why others organize to defend against such attacks. talso explains why suspicion of strangers ontributes o fitness n the course ofhuman evolution.

IMPLICATIONS FOR WARFARE

War s a phenomenon hat has been usefully tudied from multiple, ften nter-disciplinary, erspectives-psychological, regime type, and systemic, mongothers.71 lthough the causes of modern war are often omplex, ts prevalencethroughout uman history uggests that t s not caused principally y moderndevelopments, such as imperialism or militarism, lthough these no doubtcontribute o the scope, if not necessarily he intensity, f conflict.72

The human capacity for ggression nd warfare has been widely studied byeminent psychologists uch as Sigmund Freud and Erich Fromm. Freud inter-preted aggressive human behavior as the outcome of a drive that constantly

seeks release.73 or Freud, war results from many motives, some of which areopenly declared and others which are never mentioned," but "a lust for ag-gression and destruction s certainly mong them."74 Building on Freud'swork, Fromm argued that humans are subject to a unique death instinct hatleads to pathological forms of aggression beyond those found in otheranimals.75

70. I examine each in turn, but my intent here is not to provide a comprehensive nalysis, butrather o suggest how evolutionary heory may be used to generate new insights nto traditionalareas of study such as the causes of war and ethnic onflict.71. The classic studies of war remain Geoffrey lainey, The Causes of War, d ed. (New York: FreePress, 1988); and Quincy Wright, A Study of War, d ed. (Chicago: University f Chicago Press,1965). Stephen Van Evera's The Causes of War: Power nd the Roots f Conflict Ithaca, N.Y.: CornellUniversity ress, 1999) is as ambitious and thoughtful s these earlier works.72. Studies of war in the ancient world reveal that t was absolute war for those populations in-volved, and often ncluded massacres of surviving males. So warfare n the past could be no lesstotal than t s today, lthough clearly modern technology makes it easier to kill more people moreefficiently. s Thomas C. Schelling observed, "Against defenseless people there s not much thatnuclear weapons can do that annot be done with an ice pick." Schelling, Arms nd nfluence NewHaven, Conn.: Yale University ress, 1966), p. 19.73. For Freud, a desire to dominate and to aggress is a result of two diametrically pposed in-stincts: the life instinct or life force, Eros) and the death instinct sometimes referred o asThanatos). igmund Freud, TheEgo and the d, trans. Joan Riviere New York: W.W.Norton, 962).74. Sigmund Freud, "Why War?" n Melvin Small and J. David Singer, ds., International ar:AnAnthology Homewood, Ill.: Dorsey Press, 1985), p. 162. Freud's idea may be usefully omparedwith the reasons Niall Ferguson provides in his explanation of why soldiers fought n the GreatWar. Ferguson, ThePity f War:ExplainingWorldWar (New York:Basic Books,1999),pp. 339-366.75. Erich Fromm, The Anatomy f Human Destructiveness London: Jonathan Cape, 1974). For athoughtful tudy of aggression from he perspective of evolutionary psychology, ee David M.




An evolutionary perspective on war improves upon the insights of Freudand Fromm, because it explains the origin of war without depending on a"lust" for destruction s a causal mechanism. Evolutionary heory gives stu-dents of war a perspective not provided by psychological or systemic ap-proaches and offers hree mportant nsights. First, warfare s not uniquelyhuman. Second, although it may seem paradoxical, evolutionary heory x-plains how warfare ontributes o fitness. hird, volutionary heory xplainsthe role war plays in creating human societies.

WARFARE IN THE ANIMAL KINGDOM. Fromm's supposition that only hu-mans are capable of some forms f aggression s correct, ut it s perhaps onlyin this that humans are unique in the animal kingdom. Ethologists andsociobiologists gree that lthough humans may be predisposed to aggressive-ness, they are far from being the most violent animal or the only one thatwages war. Studies of numerous animals, ncluding hyenas, ions, and langurmonkeys, disclose that ndividuals engage in lethal fighting, nfanticide, ndeven cannibalism much more frequently han do humans.76 As Wilson hasdocumented n his study of nsect ocieties, alongside ants, which conduct as-sassinations, kirmishes, nd pitched battles as routine business, men are allbut tranquilized pacifists."77 e argues, n fact, hat an unbiased Martian ob-server might onclude that Homosapiens s rather eaceful when compared toother pecies.78

In perhaps the most famous of all ethological tudies, Jane Goodall observedthat ggression s part of chimpanzee behavior. n the course of her studies, hewatched not only violence associated with the struggle for male dominancebut also much intercommunal iolence, ncluding ttacks, murder, nd a four-year war between rival communities.79 lthough many species are violent, t

Buss and Todd K. Shackelford, Human Aggression n Evolutionary PsychologicalPerspective,"ClinicalPsychological eviezv, ol. 17, No. 6 (1997),pp. 605-619.76. Edward 0. Wilson, On Hulman Nature Cambridge, Mass.: Harvard University ress, 1998),pp. 103-104. For a discussion of infanticide mong primates, ncluding humans, see Michael P.Ghiglieri, heDark Side of Man: Tracing heOrigins f Male ViolenceReading, Mass.: Perseus Books,1999), pp. 129-138; and Glenn Hausfater nd Sarah Blaffer rdy, ds., Infanticide: omparative ndEvolutionary erspectivesHawthorne, N.Y.: Aldine de Gruyter, 984).77. Wilson, On Human Nature, . 104.78. Wilson, Sociobiology, . 247.79. Jane Goodall, Throuigh Windozv:My Thirty Years with the Chimpanzees f Gombe Boston:Houghton Mifflin, 990), pp. 75-84, 98-111; and Goodall, The Chimpanzees f Gombe: atterns f Be-havior Cambridge, Mass.: Harvard University ress, 1986), pp. 313-356, 503-534. She notes, "Ifthey had had firearms nd had been taught o use them, suspect they would have used them tokill." Ibid., p. 530.




this time we know that only some social insects, chimpanzees, and humanswage war (i.e., organized violence conducted to get others o yield to the desireof the attacking roup).80

WARFARE AND FITNESS. For humans, there are two sufficient xplanationsfor war: inclusive fitness nd group selection. William Hamilton's inclusivefitness heory also called kin selection) suggests that reproductive uccess is

measured not only n terms f ndividual animals but also in terms f their el-atives.81 Masters summarizes how inclusive fitness modifies traditional Dar-winian evolutionary heory: natural selection favors heability f ndividualsto transmit heir genes to posterity.... however, n organism's reproductivesuccess can sometimes be furthered y assisting others, nstead of by mat-ing."82Thus understood, n individual's self-interest an be served by assist-ing genetically elated ndividuals.83

Evolutionary heory uggests that groups may go to war to increase nclu-sive fitness.84 oing so is logical for offensive nd defensive reasons. A group

becomes more fit f t can successfully ttack to take the resources of others.85

Goodall's findings ave been confirmed or himpanzees and other primates. ee Ghiglieri, arkSide ofMan, pp. 165-166; Junichiro tani, Intraspecific illing mong Non-Human Primates," Jour-nal of Social and Biological tructures, ol. 5, No. 4 (1982), pp. 361-368; Frans de Waal, PeacemakingamongPrimates Cambridge, Mass.: Harvard University ress, 1989), pp. 61-78; and Wranghamand Peterson, DemonicMales, pp. 49-62, 127-152.80. This definition f warfare s informed y evolutionary heory nd permits he recognition hatwarfare ontributed o fitness or ertain pecies by yielding, mong other factors, more resourcesfor urvival before t was, in Clausewitz's famous observation, onducted for political ends. As Iexplain below, both nclusive fitness nd group selection can explain how warfare ontributes o

fitness. On warfarefor

nsect societies, see Edward 0. Wilson,The nsect

Societies Cambridge,Mass.: Belknap Press of Harvard University Press, 1971), pp. 447-452; for chimpanzees, seeGoodall, TheChimpanzees f Gombe, p. 530-534.81. W.D. Hamilton, The Genetical Evolution of Social Behavior. ," and Hamilton, The GeneticalEvolution of Social Behavior. I," both in Journal f Theoretical iology, ol. 7, No. 1 (July 964),pp. 1-16 and pp. 17-52, respectively. ohn Maynard Smith terms he concept kin selection n his"Group Selection and Kin Selection," Nature, March 14, 1964, pp. 1145-1147.82. Masters, "The BiologicalNature of the State," p. 165.83. Humans "should be selected to show altruism toward others n direct proportion o howclosely related they re to us genetically.... We should be willing to suffer reater isks n aidingindividuals who are more closely related and should withhold id to more distantly elated ndi-viduals.... Similarly, e should require hat distant elative e in greater eed ... in order for usto render he same assistance that we would dispense to a closer relative." Barash, SociobiologyndBehavior, . 309.84. For excellent tudies of nclusive fitness s a cause of war, see R. Paul Shaw and Yuwa Wong,"Ethnic Mobilization nd the Seeds of Warfare: n Evolutionary erspective," nternational tudiesQuarterly, ol. 31, No. 1 (March 1987), pp. 5-31; and Shaw and Wong, Genetic eeds of Warfare: vo-lution,Nationalism, nd Patriotism Boston: Unwin Hyman, 1989).85. A resource s any material ubstance that has the potential o increase survivability r fecun-dity of the population.




Also, it must be able to wage a defensive war when competitors hreaten ts re-sources. 6 Evolutionary heorist William Durham argues that ntergroup g-gression develops as a behavioral adaptation to conditions of competition orresources.87War is one means by which individuals "may improve the mate-rial conditions f their ives and thereby ncrease their bility o survive nd re-produce."88According o Durham's research, group can expand its resource

base by aggressively eizing resources from ther groups. Pressure might beparticularly cute if population size is increasing faster han resources.

Ethnographer Andrew Vayda's classic study of the Iban of Borneo and theMaori of New Zealand is instructive ere. According to Vayda, the Iban case"shows the warlike extension of territory s a means whereby a group canavoidexperiencing ny very great privations due to the pressure of populationupon available resources."89 or the Maori, conquest of neighboring groupswas easier than expanding into new areas to cultivate resources: If the timeand effort equired for clearing new virgin and were considerably more than

were necessary for .. conquest and the preparation f previously used landfor cultivation, t follows that territorial onquests, such as some of those re-corded in Maori traditional istory, ould have added more efficiently o theprosperity f particular groups than would peaceful dispersion."90

Wilson's explanation of the origins and continuation f warfare dovetailswith Durham's argument and Vayda's ethnography. According to Wilson,warfare may have begun when one group of early humans considered "thesignificance f adjacent social groups and [how] to deal with them n an intelli-gent, rganized fashion. A band might hen dispose of a neighboring and, ap-

propriate its territory, nd increase its own genetic representation n the

86. I assume that ggression s logical if t does not produce a decrease in the fitness f the group.If it did-if the relative power, the size, strength, nd armament, was too great-then fleeing rbandwagoning would be rational.87. William H. Durham, "Resource Competition and Human Aggression. Part 1, A Review ofPrimitive War," Quarterly eview f Biology, ol. 51, No. 3 (September 976), pp. 385-415; and CarolR. Ember and Melvin Ember, Resource Unpredictability, istrust, nd War," Journal f ConflictResolution, ol. 36, No. 2 (June 1992),pp. 242-262.88. Durham, "Resource Competition nd Human Aggression. Part ," p. 411.89. Andrew P. Vayda, "Expansion and Warfare mong Swidden Agriculturalists," merican n-thropologist, ol. 63, No. 2 (April 1961), p. 354 (emphasis n original). Vayda's analysis s further e-

veloped in War n Ecological erspective: ersistence, hange, nd Adaptive rocessesn Three OceanianSocieties New York: Plenum Press, 1976), pp. 43-74. Noting the frequency f warfare amonghunter-gatherer ribes s Ember, Myths about Hunter-Gatherers," p. 439-448. These tribes, ndothers uch as the Mae Enga, Mendi, and Maring of Papua New Guinea and Irian Jaya, re particu-larly valuable evidence because good ethnographic tudies have been conducted, he tribes had lit-tle or no contact with colonial administration, nd all are prestate societies; thus they arecharacteristic f the great majority f human history.90. Vayda, "Expansion and Warfare mong Swidden Agriculturalists," . 348.




metapopulation."91 urthermore, his band would retain the memory of theevent and by repeating t would increase ts control f resources.92 he victo-ries of the original band "might propel the spread of the genes through he ge-netic constitution of the metapopulation. Once begun, such a mutualreinforcement ould be irreversible."93

The second argument s that war evolved through process of group selec-

tion that favors the self-sacrificing endencies of some warriors.94 his mayseem curious, but according to some evolutionary heorists, ltruistic r self-sacrificing ttributes an evolve through natural selection even though theymay appear to cause more ndividual costs than benefits.95 rom strictly vo-lutionary individual selection) or inclusive fitness perspective, ndividualsfrom ne tribe may be willing o fight ndividuals from ther ribes or he sakeof small bands of relatives n which humans have lived through most of theirevolutionary history. ighting for the tribe, either aggressing or defending,would be fighting opreserve family nd the warrior's genes. But ndividuals,

in general, hould not fight bsent these circumstances.Evolutionary heorist David Sloan Wilson's argument for group selectionsuggests why individuals would choose self-sacrifice. ccording to Wilson,group selection is the component of natural selection that operates on thedifferential roductivity f ocalpopulations within global population.96 hatis, ndividual selection favors raits hat maximize fitness within ingle groups,but group selection favors raits hat maximize the relative itness f groups.97

As human groups grew to include more distant elatives nd unrelated ndi-viduals, wars to aggress and to defend the population were still necessary-

warriors were still required. ome of these ndividuals were willing osacrificemore for the group. But for this to happen, four conditions were needed: (1)there had to be more than one group; (2) there had to be variance among

91. Wilson, Sociobiology, . 573.92. Ibid.93. Ibid.94. Group and individual selection re not necessarily ncompatible; oth may be operative n apopulation simultaneously. roup selection was largely developed by Ronald A. Fisher nd V.C.Wynne-Edwards. ee Fisher, The Genetical heory f Natural Selection Oxford: Clarendon, 1930);

and Wynne-Edwards, Animal Dispersion n Relation o Social Behaviour Edinburgh: Oliver andBoyd, 1962).95. Classic studies are Robert L. Trivers, The Evolution of ReciprocalAltruism," Quarterly eviewofBiology, ol. 46, No. 1 (March 1971), pp. 35-57; and David Sloan Wilson, The Natural Selection fPopulations nd CommunitiesMenlo Park, Calif.: Benjamin/Cummings, 980).96. Wilson, Natural Selection f Populations nd Communities, . 45.97. As Sober and Wilson submit, Altruism s maladaptive with respect o individual selection butadaptive with respect o group selection." Sober and Wilson, Unto Others, . 27.




groups for a particular rait, o some groups had to have more altruists hanothers; 3) there had to be a direct relationship between the proportion ofaltruists n the group and the offspring f the group; and (4) the altruists ad toreproduce with other groups.98 n conflict, he group that prevailed couldconquer others because it had more warriors. t had more warriors ecause thepopulation had more altruists. ecause the warriors eproduced, he "warrior"

genetic ype continued, hough t may have declined relative o the other mem-bers of the group during episodes of warfare. Thus group selection explainshow altruism ontributes o warfare.99

While the origin f warfare s informed y evolutionary heory, arfare tselfhas multiple forms nd is greatly nfluenced by culture nd the internationalsystem. To understand why, ne must move from ltimate auses of warfare oproximate auses. E.O. Wilson explains, "The particular orms f organized vi-olence are not nherited. No genes differentiate .. headhunting rom annibal-ism, the duel of champions from genocide."100 Thus each culture gives a

specific orm o warfare-from he Greek phalanx to the precision weaponry ofinformation arfare-and the competitive ressure f the nternational ystemforces ocialization.101 nd of course the effect f culture or more broadly thesocial environment) s not imited o the form warfare akes;culture nfluencesthe suppression or exacerbation f conflict.

WAR AND THE CREATION OF SOCIETIES. Evolutionary heory an explain thekey role of war in the creation f societies. Evolutionary heorist ichard Alex-ander proposes the "balance of power" theory f human social organization.102He argues that human society originated n three tages: (1) small groups de-

veloped early n human history orprotection gainst predators; 2) over timethese groups began killing arge animals for food; and (3) increasingly argebands had to stay together o counter he threat osed by other groups of hu-mans. For Alexander, the threat f war and the need for protection hroughbalancing the power of proximate groups gave rise to human society.

98. The four criteria f group selection re drawn from bid., p. 26.99. Also noting the relationship etween group selection nd warfare re Peter A. Corning, AnEvolutionary Paradigm for the Study of Human Aggression," in Martin A. Nettleship,R. Dalegivens, and Anderson Nettleship, ds., War, ts Causes and CorrelatesThe Hague: Mouton,

1975), pp. 359-387; Irenaus Eibl-Eibesfeldt, Us and the Others," n Eibl-Eibesfeldt nd Salter,Indoctrinability,deology, nd Warfare, p. 21-53; Eibl-Eibesfeldt, Warfare, Man's Indoctrinability,and Group Selection," Zeitschrift ar Tierpsychologie, ol. 60, No. 3 (1982), pp. 177-198; and JosephSoltis,Robert Boyd, and Peter J. Richerson, Can Group-Functional ehaviors Evolve by CulturalGroup Selection?" Current nthropology, ol. 36, No. 3 (June 1995), pp. 473-483.100. Wilson, On Human Nature, . 114.101. Waltz, Theory f nternational olitics, p. 74-77, 127-128.102. Alexander, Darwinism nd Human Affairs, p. 222-223.




Physiologist Jared Diamond provides a similar explanation of this process:"The amalgamation of smaller units into larger ones has often been docu-mented historically r archaeologically. Contrary o Rousseau, such amalga-mations never occur by a process of unthreatened ittle societies freelydeciding to merge."''03 ather uch amalgamation occurs n either f two ways:"by merger under the threat f external force, r by actual conquest."'104

Population density s critical or understanding why the external hreat romneighboring roups increased around 13,000 years ago. Diamond argues thatwhere population densities re low-for example, n hunter-gather ocieties-groups may migrate way from he external hreat osed by others, s they didin the Amazon, New Guinea, and North America.105Hunter-gathers re betterable to move around because they are less tied to a specific erritory. heredensities are moderate, as in simple agricultural, ribal societies, there arefewer places for urvivors o flee. Furthermore, iamond submits, with ittlefood surplus in these societies, the victors have little use for the survivors.

Thus began the pattern hat defined war in the ancient world: Men are killed,women and children become captives, and territory s occupied.106 inally,where population densities re high, hesurvivors have nowhere to go, but thevictors an more effectively xploit he defeated by making hem pay tribute rabsorbing them nto their ociety.

According oDiamond, an example of a tribe hat merged with nother ribeunder external force s the Cherokee ndian confederation hat formed n theeighteenth entury o counter ncreasing ressure from white ettlers.107 ater,facing similar pressure, the Sioux adopted the same response. The United

States also faced pressure from xternal foes-the British-as well as internalfoes, as Shays's Rebellion llustrated. oth were instrumental n replacing theArticles of Confederation with the Constitution, which provides for a strongcentral government o deal with enemies both foreign nd domestic. n the

103. Diamond, Guns, Germs, nd Steel, p. 289.104. Ibid., p. 289. See also Robert Bigelow, The Role of Competition nd Cooperation n HumanEvolution," n Nettleship, Dalegivens, and Nettleship, War, ts Causes and Correlates, p. 235-258;and Keeley, War before ivilization.105. Diamond, Guns, Gerns, nd Steel, p. 291-292; and Robert L. Carneiro, A Theory of the Ori-gin of the State," Science, August 21, 1970, pp. 734-737.106. Wilson calls attention o this pattern when he recalls Moses' instructions n the occasion ofthe victory ver the Midanites: "Now kill every male dependent, nd kill every woman who hashad intercourse with a man, but spare for yourselves very woman among them who has not hadintercourse." umbers 31:7,17,18. Wilson, Sociobiology,. 573. Wilson notes that ggression nd ge-netic usurpation occurs among other primates s well.107. Diamond, Guns, Germs, nd Steel,pp. 289-290.




nineteenth entury, espite the strong pposition of some Germans, Germanyunified n response to increasing hreats rom arger, nified tates around it.

Diamond's second cause of population aggregation i.e., by conquest) isbetter tudied.108 harles Tilly, erhaps the foremost ontemporary cholar ofwar's effect n state formation, uccinctly bserved, "War made the state, ndthe state made war."109 ut as Robert Carneiro has demonstrated, war created

complex societies ong before European state formation n the sixteenth ndseventeenth enturies, nd in non-European cultures s well.110 tates createdby conquest nclude the Zulu state n southeastern Africa, heAshanti state ofwest Africa, heAztec and Inca empires, s well as Rome and the MacedonianEmpire under Alexander.

IMPLICATIONS FOR THE ULTIMATE CAUSES OF ETHNIC CONFLICT

The frequency of ethnic conflict ince the end of the Cold War, includingconflicts n Bosnia,Chechnya, Kashmir, Kosovo, Rwanda, Sri Lanka, and Tur-

key, has led to considerable research nto ts causes.111 learly the slaughter f800,000-1million Tutsis nd moderate Hutus in Rwanda, and the widespreadethnic leansing n the former ugoslavia, demonstrate he need to understandethnic onflict. eferring othe Serb ethnic leansing of Kosovo in 1999,Presi-dent Bill Clinton said that a bright uture or humanity s threatened by theoldest problem of human society: ur tendency ofear nd dehumanize peoplewho are different rom urselves."112 his comment s understandable f t isperceived s a justification o a liberal ociety f NATO's actions against Serbia.Considered from the perspective of evolutionary heory, owever, Clinton's

words seem to suggest that only if humans stop being human can they enjoythe bright uture he envisions.Clinton has identified heproblem. Xenophobia-the fear of strangers-and

ethnocentrism-the belief in the superiority r preference or members ofone's own ethnic group-exist among almost all peoples, and both contribute

108. For classic considerations, ee Carneiro, "A Theory of the Origin of the State"; and FranzOppenheimer, TheState, rans. John Gitterman New York: Free Life Editions, 1975).109. Charles Tilly, Reflections n the History f European State-Making," n Tilly, d., TheForma-

tion f National tates n Western urope Princeton, N.J.:Princeton University ress, 1975), p. 42.110. Carneiro, A Theory of the Origin of the State," pp. 734-737.111. Michael E. Brown has identified our underlying auses of ethnic conflict. He argues thatstructural, olitical, conomic, r cultural factors may be triggered y elite or mass movements, rby nternal r external olitics. Brown, The Causes of nternal Conflict:An Overview," n Brown,Owen R. Cote, Jr., ean M. Lynn-Jones, nd Steven E. Miller, ds., Nationalism nd EthnicConflict:An International ecurity Reader Cambridge, Mass.: MIT Press, 1997), pp. 3-25.112. "Clinton: U.S. Is Fighting or he World's Future," New York imes,April 17, 1999, p. A6.




to the ubiquity nd scale of ethnic iolence.113Evolutionary heory ermits tu-dents of ethnic conflict o understand xenophobia and ethnocentrism s ulti-mate, though not direct, auses of ethnic conflict, hich, ike war, may resultfrom multiple causes.

Also like war, xenophobia is found in nonhuman animals, which suggeststhat evolutionary heory an help explain xenophobic behavior.114 The empiri-

cal evidence for his s strong. Barash has found n his studies of humans andother nimals that both .. tend to reserve heir most ferocious ggression o-ward strangers."115 iologist John Fuller concludes that "xenophobia is ascharacteristic f humans as of ants, mice, or baboons."116

The individual and group selection processes of evolution explain why xe-nophobia contributes o fitness nd why humans may react negatively o peo-ple of different eographic origins, or those with different morphologicalfeatures, uch as facial traits r skin color. f the genetic difference s physical,then dentification f difference s obvious, such as that between Africans nd

Europeans, but xenophobia can be triggered y even small differences etweenneighboring ribes or populations.117 For example, Slavs typically ave broadfaces and Anglo-Saxonsnarrow ones; Tutsis end to be tall, nd Hutus short.118

According othe theory f nclusive fitness, or lmost all of their volution-ary history, umans have lived in bands of genetically imilar ndividuals. As aresult, trangers were unlikely to be relatives of an area's residents. ndeed

113. Noting the prevalence of xenophobia and ethnocentrism re Eibl-Eibesfeldt, Warfare, Man'sIndoctrinability, nd Group Selection," pp. 178-183; A. Michael Warnecke, Roger D. Masters, ndGuido Kempter, The Roots of Nationalism: Nonverbal Behavior and Xenophobia," Ethology ndSociobiology, ol. 13, No. 4 (1992), pp. 267-282; Pierre L. van den Berghe, The Ethnic henomenon(New York: Elsevier, 1981), pp. 15-36; and Johan M.G. van der Dennen, "Ethnocentrism nd In-Group/Out-Group Differentiation," n V. Reynolds, Vincent S.E. Falger, and Ian Vine, eds., TheSociobiologyf Ethnocentrism: volutionary imensions f Xenophobia, iscrimination, acism, nd Na-tionalism London: Croom Helm, 1987), pp. 7-8,17-20.114. A good introduction o xenophobia in animals is Charles H. Southwick et al., "Xenophobiaamong Free-Ranging Rhesus Groups in India," in Ralph L. Holloway, ed., Primate Aggression,Territoriality, nd Xenophobia: Comparative erspectiveNew York: Academic Press, 1974), pp. 185-209. See also Holloway, "Introduction," n ibid., p. 7; and Fred H. Willhoite, Jr., Evolution andCollective ntolerance," Journal f Politics, ol. 39, No. 3 (August 1977), pp. 667-684.115. Barash, Sociobiology nd Behavior, . 219.116. John . Fuller, Genes, Brains, nd Behavior," n Michael S. Gregory, nita Silvers, nd DianeSutch, eds., Sociobiology nd Human Nature San Francisco, Calif.: Jossey-Bass, 978), p. 111.

117. Alexander, Darwinism nd Human Affairs, . 126.118. These differences ontributed o the 1994 genocide in Rwanda because it made identificationof Tutsis easier. Gerard Prunier, TheRwandanCrisis:History f a Genocide New York: ColumbiaUniversity ress, 1997), pp. 5-9, 249. See also van den Berghe, Ethnic henomenon, p. 73-74. De-spite the physical differences, here were some cases of mistaken dentity: During the genocidesome persons who were legally Hutu were killed as Tutsi because they ooked Tutsi." Alison DesForges, Leave None to Tell the Story:Genociden Rwanda New York: Human Rights Watch, 1999),p. 33.




they were ikely o be competitors oth for carce resources nd for position nthe dominance hierarchy.119 n addition, s described above, many anthropolo-gists nd sociobiologists urmise that humans ived in bands who fought, irst,to protect hemselves gainst rival human bands as well as large carnivores,and second, to take resources from them. Given these conditions, humanswould consider other humans a threat, nd thus tolerance of strangers would

be low. Low tolerance of strangers ontributed o fitness. hus it spread. Al-though ike warfare nd indeed much of human behavior, xenophobia may beaugmented or weakened by psychological nd cultural forces.

Xenophobia may also have arisen through roup selection. As human com-munities grew arger, multiple groups would have reproduced, ome contain-ing genotypes that resulted in an increased suspicion of strangers. Thesegenotypes would improve fitness y increasing he survival of the group overtime. Xenophobia would not only help protect esources but would also be adefense against communicable diseases, which are often caused by contact

with strangers.120Like xenophobia, ethnocentrism may be explained by inclusive fitness.121Since arising during the Pleistocene, humans have favored those who are bio-logically related over others. n general the closer the relationship, he greaterthe preferential reatment. n a world of scarce resources and numerousthreats, he evolutionary process would select nepotism, hus promoting hesurvival of the next generation. This process is relative, however. Parents aremore willing to provide for heir hildren han they re for more distant rela-tives, nd certainly or trangers; hus the ntensity f support rapidly declines.

The essence of an inclusive fitness xplanation of ethnocentrism, hen, s thatindividuals generally should be more willing to support, privilege, andsacrifice or ne's family, ne's more distant kin, one's ethnic group, nd othersin decreasing order.122 s with warfare nd xenophobia, however, hisbehav-ior is reinforced r weakened by environmental actors uch as culture andreligion.

119. Noting the mportance f imited resources s Joel R. Peck, "The Evolution of Outsider Exclu-

sion," Journal f Theoretical iology, ebruary 2, 1990, pp. 565-571.120. The powerful effect f disease on human society is documented in William H. McNeill,Plaguesand Peoples Garden City, N.Y: Anchor, 976).121. Robin I.M. Dunbar, "Sociobiological Explanations and the Evolution of Ethnocentrism," nvan den Berghe, ociobiology f Ethnocentrism, p. 48-59; and van den Berghe, Ethnic henomenon,pp. 18-36.122. Ian Vine, "Inclusive Fitness and the Self-System," n van den Berghe, Sociobiology fEthnocentrism, p. 60-80.




Recognizing he evolutionary auses of xenophobia and ethnocentrism aybe particularly seful for scholars who have adopted a "primordialist" p-proach to the study of ethnicity nd ethnic conflict. hey argue that ethnicidentity s largely fixed haracteristic f ethnic groups and often eads to eth-nic conflict.123 or example, according to Robert Kaplan a significant ause ofethnic conflict n the former Yugoslavia is historical nmity, r "ancient ha-

treds," among Croats, Muslims, and Serbs that has existed for hundreds ofyears and occasionally results in ethnic conflict.124 volutionary theory ex-plains why xenophobia and ethnocentrism ontributed o fitness nd spread,and thus why these common traits ccount for ome of the scope and intensityof ethnic onflict hroughout istory. o "primordialists" ave a better xplana-tion of the fundamental auses of ethnic onflict hat can inform xplanationsof the origins of these conflicts, nd why they re relatively ommon, withoutasserting hat the cause is ancient hatred.

Irrespective f the ultimate causes of ethnic conflict, oth the international

system nd individual states can work to suppress t. The bipolar nternationalsystem f the Cold War helped to control thnic onflict; nd the deleterious f-fect of systemic change (i.e., the end of the Cold War) in promoting thnicconflict as been well analyzed.125 tate policies may also help prevent r ame-liorate ethnic onflict. Michael Brown summarizes the principal finding f hisand Sumit Ganguly's survey of ethnic relations n sixteen Asian and Pacificstates by noting that government olicies "are often decisive in determiningwhether thnic problems, which are inherent n multiethnic ocieties, re re-solved peacefully nd equitably."126 onetheless, given the contribution f xe-

nophobia and ethnocentrism o fitness uring human evolution, thnic onflict

123. David A. Lake and Donald Rothchild use the term primordialists" o describe the scholar-ship of Walker Connor, Harold Isaacs, Robert Kaplan, and Anthony Smith. See Lake andRothchild, Spreading Fear: The Genesis of Transnational thnic Conflict," n Lake and Rothchild,eds., The nternational pread fEthnic onflict: ear,Diffusion, nd Escalation Princeton, .J.: rince-ton University ress, 1998), p. 5. See also Walker Connor, Ethnonationalism: he Quest for Under-standing Princeton, .J.: rinceton University ress, 1994); Harold R. Isaacs,Idolsof heTribe: roupIdentity nd Political hange New York: Harper and Row, 1975); Robert D. Kaplan, BalkanGhosts:Journey hrough istory New York:St. Martin's, 1993); and Anthony D. Smith, Theories fNational-ism, d ed. (New York: Holmes and Meier, 1983).124. Kaplan, BalkanGhosts.

125. See Barry R. Posen, "The Security Dilemma and Ethnic Conflict," n Michael E. Brown, ed.,Ethnic onflict nd nternational ecurity Princeton, .J.: rinceton University ress, 1993), pp. 103-124; Sandra Halperin, "The Spread of Ethnic Conflict n Europe: Some Comparative-HistoricalReflections," n Lake and Rothchild, nternational pread f Ethnic onflict, p. 151-184; and MiltonJ. Esman, Ethnic olitics Ithaca, N.Y: Cornell University ress, 1994), pp. 244-245.126. Michael E. Brown, "The Impact of Government olicies on Ethnic Relations," n Brown andSumit Ganguly, ds., Government olicies nd EthnicRelations n Asia and the Pacific Cambridge,Mass.:MITPress, 1997), p. 515.Brown s careful o note the mpact of modernization nd colonial-




This article s intended to move past the false dichotomy etween the socialenvironment nd evolution.128 learly both have profound nd simultaneouseffects n human behavior, nd each force nfluences he other. Evolutionarytheory has defined he parameters f the human condition, r that which s es-sentially permanent for an individual given the human life span. Culture, smentioned n my discussion of warfare nd ethnic onflict, an often nterdict

the powerful effects f evolution.The social environment nd evolution will continue o have a significant f-

fect n human behavior.129 he usefulness of each depends in large part on thequestion or particular ssue being addressed. The synthesis reated by Masters,E.O. Wilson, and Somit, mong others, which argues that human behavior isthe product of both human evolution and environment, makes possible ad-vances in the realist heory f nternational olitics nd, more broadly, n socialscience. 30 The application of evolutionary heory eveals insights nto humanbehavior that purely social explanations cannot. Considering ts utility more

broadly, multidisciplinary cholarship nformed y evolutionary heory rom-ises to be dynamic and rewarding for the study of international olitics.

128. This debate is usually and inaccurately haracterized s one between nature or nurture. henature/nurture onflict s now commonly een as a false dichotomy. he interaction rinciple swidely accepted n biology. This states that ll phenotypes derive from he nteraction f genotypeand environment. ee Robert A. Hinde, AnimalBehaviorNew York: McGraw-Hill, 1970).129. At the same time, few would dispute the powerful ffect hat culture has had on human de-velopment. ts power is such that n some societies, uch as Pharaonic and Ptolmaic Egypt andIncan Peru, culture vercame the ncest aboo that both sociobiologist Edward Wilson and anthro-pologist Claude Levi-Strauss have identified s universal for biological or cultural easons respec-tively. ee Wilson, On Human Nature, . 38; and Claude Levi-Strauss, The Elementary tructures fKinship, rev. ed., trans. James Harle Bell and John Richard von Sturmer London: Eyre andSpottiswoode, 1969).130. Notable efforts oproduce a theory hat aptures he biological and cultural mechanisms hatcause human attributes re William H. Durham, "Toward a Coevolutionary Theory of Human Bi-ology and Culture," n Napoleon A. Chagnon and William rons, ds., Evolutionary iology nd Hu-man Social Behavior: n Anthropological erspective North Scituate, Mass.: Duxbury Press, 1979),pp. 39-59; and Edward 0. Wilson, "Biology and Anthropology: A Mutual Transformation?" nibid., pp. 519-521. See also Charles J. Lumsden and Edward 0. Wilson, Genes,Mind, nd Culture:TheCoevolutionary rocess Cambridge, Mass.: Harvard University ress, 1981).

biological justiifcation for self-defense

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