In the 1830s, around 20,000 Cherokee Indians were uprooted from their traditional territories around the Smokey Mountains in Georgia, Alabama, and Tennessee and forced to begin a long march to a new home in Oklahoma. Infamously, many thousands would die on the trail. As the white settlers had expanded west in search of land and profits, the weaker natives were left with no choice but to take their chances and move, leaving rich and empty territory for the newcomers. This was the “Trail of Tears”, a brutal displacement of an entire people that has more or less been consigned to history.

Yet competition, conflict, and war between peoples have not been consigned to history. While major wars between nation states have declined in recent decades, levels of inter-group violence within states in civil wars and between competing non-state actors, armed groups, and criminal organizations has remained at staggering levels.

There is a new Trails of Tears, for example, taking place in Europe, as hundreds of thousands of Syrians flee the civil war there, hounded by multiple warring factions behind them and hindered by the increasingly parochial interests of the European states ahead of them. After last summer’s free-for-all migration across the EU’s open borders, one by one countries have erected razor-wire fences and locked down their borders. Thousands have died on this trail too, especially crossing the Mediterranean in flimsy and overloaded boats, in the outflow of territorial aggression that is hauntingly reminiscent of the ordeals of the Cherokee—and all too many other historical examples. 

Knoxville Workshop on Evolution and War
In September 2015, a group of scholars gathered in Knoxville, Tennessee, close to the origins of the Trail of Tears, to consider the deep origins and persistence of war. Cognizant of our historical surroundings, we had come together to ask whether new light could be shed on the unending phenomenon of inter-group conflict and war from a different perspective: evolution. The workshop was hosted by University of Tennessee’s National Institute for Mathematical and Biological Synthesis (NIMBioS), whose mission is to bring together cross-disciplinary teams to develop mathematical and biological approaches to understanding a variety of complex systems—of which war is a good example. Our group included anthropologists, economists, historians, modelers, primatologists, psychologists, political scientists, and physicists, including many leaders in these fields such as Richard Wrangham, Kim Hill, and Polly Wiesner, as well as new blood in a competitively selected group of graduate students and post-docs.

But what could an evolutionary perspective on war offer that other approaches could not? Two broad themes emerge. First, war may have been evolutionarily adaptive in our past, meaning that, although on the face of it war seems such a costly activity, fighting other groups brought net benefits to Darwinian fitness (reproductive success).[1] If so, then we would expect natural selection to have favored the evolution of adaptations that helped people to prepare, coordinate, and fight more effectively in inter-group conflicts (and this may have occurred via the processes of genetic selection among individuals, and/or as cultural evolution among groups). Hence, an evolutionary perspective may help us understand war as an adaptive strategy, just as it has helped us understand many other “nasty” traits such predation or fighting between individuals. It’s never good for the loser, but it can be a strategy that pays off on the average over the long term for the genes or groups that live on.

Second, whether or not war was adaptive in our past, in today’s world it may incur net costs to all involved. Operating on such a large scale and with such lethal weapons, the marginal benefits may be outweighed by its enormous costs for winners and losers alike. But even or especially here, an evolutionary perspective can be helpful to understanding war, because it helps us to explain the conditions under which human beings become more or less motivated to fight. We can make predictions about how many of our evolved dispositions may cause or exacerbate conflict, ranging from well-known biases such as distrust of out-groups and overconfidence, to the desire for status and revenge). An evolutionary understanding of human nature helps us understand the contemporary conditions that encourage people to fight.

But What’s New?
While there has been a long history of applying biological and evolutionary ideas to warfare (Nazi sympathizers among them, but later on a much more serious group of sociobiology scholars), things are quite different today—and for the better. The gains have been threefold: concepts are better defined, theories are more nuanced, and the evidence is more abundant.

First, and in many ways most importantly, “war” is recognized to be a broad term and numerous behaviors and dynamics play into it. Recent scholarship—as exemplified at the conference—has usefully broken down the phenomenon of war into a narrower and more explicit set of phenomena, which in turn makes operationalization possible and evolutionary hypotheses testable. For example, many presentations were actually about how humans manage to overcome the “collective action problem” facing war: although any given individual benefits from their group winning a war, why should that individual risk life and limb in participating? Without cooperation, there can be no war.[2]

Second, clearer definitions have enabled greater nuance in theory building. We have a deeper understanding of the adaptive significance of war, and a better sense of why and when it may have been favored by selection. For example, among both chimpanzees and hunter-gatherers, lethal inter-group conflict tends to be restricted to situations in which the attacker has superior numbers and an element of surprise.[3] This is significant because, far from the chaos of modern battles with vast casualties on both sides, an “imbalance of power” makes attacking others both low-risk and effective—two vital criteria if natural selection is going to favor war. Research now draws on the insights of game theory, behavioral ecology, cross-cultural studies, and cultural evolution, rather than simplistic claims of innate aggression or the so-called “killer ape” hypothesis, which is both conceptually fuzzy and basically unfalsifiable—the cardinal sin of modern science.

Third—and this is where the rubber meets the road—this scientific maturity has yielded a growing mountain of empirical evidence as to where, when, why, and how much war has been fought among pre-industrial societies around the world. These findings come not just from the accumulation of archeological and ethnographic data, but also from greater methodological rigour, new technologies, and more advanced methods of analysis. Although there are detractors,[4] a plethora of review volumes triangulating on the problem from a variety of disciplines and methods suggest that warfare is widespread among pre-industrial societies.[5] New findings include—importantly—the finding that warfare occurs among hunter-gatherer societies even when they are surrounded by other hunter-gatherer groups.[6] The old idea that inter-group conflict was imported by contact with outsiders has been resoundingly rejected for both chimpanzees and human warfare.[7] And in a stunning recent discovery, a massacre of 12 individuals at a site in Kenya 10,000 years ago has extended concrete evidence of inter-group conflict deep into our history.[8] Other work finds evidence that warfare has been instrumental in the evolution of human civilizations.[9]

Although we peer humbly ahead into many remaining puzzles of conflict and violence, we do so on the shoulders of some remarkable giants, whose research now enables a sharper image of the problems of collective action, coalitional psychology, leadership and followership, strategy, social organization, patterns of conflict across human and non-human species, the role of weapons, the costs and benefits of individual participation in war, and cross-cultural variation in patterns of conflict. An added benefit of this approach is the opportunity to integrate these aspects to generate new ideas (for example, mathematical laws of combat developed in social science generate novel implications for the evolutionary advantages of coalitions).[10]

These incremental advances do not translate into a simple consensus on why or how war evolved. However, the conference suggested at least a wide consensus that evolutionary theory offers a powerful lens for clarifying the ancient origins of war and provides a coherent deductive framework for explaining the proximate (mechanistic) and ultimate (functional) causes of war.

The Varieties of War and the Commonalities of Human Nature
One intriguing aspect of evolutionary approaches to war is its focus on individual behavior. While war takes many forms—gang violence, terrorism, insurgency, rebellion, civil war, inter-state war—an important commonality is that they are fought, and led, by human beings. This makes evolutionary approaches relevant to them all (the cognitive adaptations we all share as human beings irrevocably set the tone and shape of coalitional aggression at all levels of analysis—even in modern international relations). It also suggests important variation in its manifestation that an evolutionary perspective may help to explain. For example, inter-group conflict in our evolutionary history involved small groups of more or less voluntary warriors, united in purpose, and fighting for home territory. Modern mass armies, directed from afar by politicians that are rarely at risk themselves, represent a significant “mismatch” of evolved traits and the costs and benefits that prevail for leaders and followers today. In short, we should expect that evolved traits might easily go awry in large-scale inter-state war, but that they may well remain highly adaptive among small-scale, kin-group conflicts that arise within, say, civil wars. While contemporary wars vary in many ways, there are fundamental evolutionary mechanisms and dynamics at play (such as in-group/out-group bias, collective action problems, coalitionary psychology, and so on) that make an evolutionary perspective relevant to war in all its forms. If we want to understand the beliefs and behavior of people locked in deadly conflict with each other, we first need to consider these traits in their natural context, and that means understanding war in human evolution.

The Added Value of an Evolutionary Perspective
War is a complex process involving multiple interacting agents and institutions that defies simple explanation. However, the potentially powerful insights of evolutionary theory (the single best theory for understanding the behavior of any organism) is entirely omitted from the toolbox of most contemporary scholars and practitioners of war. This is not to exclude the all important political science, economics, and historical perspectives that have accumulated considerable data and theories on the causes of war already.[11] Nevertheless, evolution offers vital new perspectives and often counter-intuitive theories that add explanatory power over and above existing theories on why people are motivated to fight, and the conditions under which they are more likely to organize to do so.

Given the unending list of conflicts around the globe, and the many failures of conflict resolution efforts, evolutionary approaches offer a range of novel predictions and empirical data that shed new light on the old problem of war. Steven Pinker is right that wars between nation states are in decline (at least for the moment), but conflict on the whole continues unabated, expanding in other forms as civil wars, non-state armed conflicts, and terrorism spread, and also finding new forms in cyber warfare and the geopolitics of outer space.[12] With conflicts raging in the Ukraine, Syria, Nigeria, Israel-Palestine, and future ones looming over Kashmir, the Arctic, and the South China Sea, social science theories are failing to fully succeed in explaining, predicting, or avoiding war.

In what some hail as the century of biology, we and many leading experts gathered at the conference in Knoxville suggest that the simple step of recognizing humans as evolved organisms with a long history of war can only help, in some way big or small, to understand when and why people fight.


[1] Chagnon, N. A. (2014) Noble Savages: My Life Among Two Dangerous Tribes – The Yanomamo and the Anthropologists. New York: Simon & Schuster.

[2] Tooby, J. & Cosmides, L. (1988) The evolution of war and its cognitive foundations. Institute for Evolutionary Studies Technical Report #88-1.

[3] Wrangham, R. W. (1999) The Evolution of Coalitionary Killing, Yearbook of Physical Anthropology, 42: 1-30.

[4] Fry, D. P. (Ed.). (2013) War, Peace, and Human Nature: The Convergence of Evolutionary and Cultural Views. New York: Oxford University Press.

[5] Allen, M. W. & Jones, T. L. (Eds.) (2014) Violence and Warfare among Hunter-Gatherers. Left Coast Press.

[6] Wrangham, R. W. & Glowacki, L. (2012) Intergroup Aggression in Chimpanzees and War in Nomadic Hunter-Gatherers: Evaluating the Chimpanzee Model, Human Nature, 23: 5-29.

[7] Wilson, M.L., et al. (2014) Lethal Aggression in Pan Is Better Explained by Adaptive Strategies Than Human Impacts, Nature, 513(7518): 414-417;

[8] Mirazón Lahr, M., et al. (2016) Inter-group violence among early Holocene hunter-gatherers of West Turkana, Kenya, Nature 529: 394–398.

[9] Turchin, P., et al. (2013) War, space, and the evolution of Old World complex societies. PNAS, 110, 16384–16389

[10] Johnson, D.D.P. & MacKay, N.J. (2015) Fight the power: Lanchester’s laws of combat in human evolution, Evolution and Human Behavior, 36 (2): 152-163.

[11] Levy, J. S., & Thompson, W. R. (2010) Causes of War. Oxford: Wiley-Blackwell.

[12] Pinker, S. (2011) The Better Angels of Our Nature: Why Violence Has Declined. New York: Viking.

Published On: March 4, 2016

Dominic Johnson

Dominic Johnson

Dominic Johnson is Alistair Buchan Professor of International Relations at the University of Oxford. He received a D.Phil. from Oxford in evolutionary biology, and a Ph.D. from Geneva University in political science. Drawing on both disciplines, he is interested in how new research on evolution and human biology is challenging theories of international relations, conflict, and cooperation. For the 2012-2013 academic year, he is co-leading a project on evolution and human nature at the Center of Theological Inquiry in Princeton.

Anthony Lopez

Anthony Lopez

Anthony C. Lopez received a Ph.D. from Brown University in Political Science and is Assistant Professor of International Relations and Political Psychology at Washington State University. His research investigates war as the product of an evolved coalitional psychology, and examines the relationship between inter-group conflict and intra-group cooperation from an adaptationist perspective. Anthony also received training as a Research Affiliate with the Center for Evolutionary Psychology at the University of California, Santa Barbara.


  • Carmi Turchick says:

    There is really nothing similar between the forced removal and forced violent march of the peaceful Cherokee and the refugees fleeing Syria.

    As for the rest, looks like some small progress is being made. I applied for this conference and was disappointed not to be invited because I believe I am well ahead in my progress on a number of the issues you all discussed. For example, I can explain how to predict most group level conflict before it occurs using universal linguistic patterns of incitement, and why those patterns are universal.

    I also have to say that cultural evolution as currently conceived is a dead end, it will not be a productive avenue for investigation. The failure to properly understand group level selection has lead some to go this unproductive route. I could have helped here too.

    Next time you have this kind of conference, invite me.

  • Pete Richerson says:

    I’m surprised that evolutionists would look for adaptive explanations for war. Evolutionary game theory is as much about mal-adapation as adaptation. Take Hamilton’s theory of inclusive fitness. The famous B/C > 1/r rule predicts that evolution can solve the dilemma of cooperation only in situations where r is appreciable. In most pairs of individuals r ~ 0. Evolution is a very inefficient mechanism for solving the dilemma of cooperation at large scales. The fitness of potential cooperators would increase up to the limit of B/C > 1, but genetic evolution by natural selection leaves most of these potential gains unrealized, as we generally see in nature.

    Humans routinely solve the dilemma of cooperation on a much larger scale than most other organisms perhaps because we are subject to multi-level selection on cultural variation. But even when human political systems are fairly efficient at solving dilemmas of cooperation at say the tribal or national level, they have often failed to solve it at the next scale up. Hence, relations between tribes or nations are often not governed by functional institutions. Alliances are often unstable if they exist at all and violent conflict, war, sometimes breaks out.

    In the aftermath of wars, the peace-makers often strive to innovate institutions that will solve the problem of conflict at the level of the last war. Sometimes these are successful and fairly durable, such as the peace in Europe and the circum-Mediterranean region enforced by the Roman Empire. Other attempts, like the post WWI League of Nations, fail. But we don’t look to adaptive explanations for these failures, but maladaptive ones.

  • John Strate says:

    Thanks for this very insightful and interesting update. I’ve always wondered what traces the lengthy history of warfare have left in the human genome and how researchers would go about identifying them. It’s difficult to think of any cause that is more deserving of the label “prime mover” than warfare, both for human biological and cultural evolution.

  • Robert Trivers says:

    I too regret that Turchick was not invited for the reasons Turchick gives. As for Richerson, as usual he obfuscates rather than clarifies. Hamilton’s rule dealt with altruism not cooperation and there is something called ‘reciprocal altruism’ that gets us much closer to human cooperation; once you have a medium of exchange (=money) you can quickly expand beyond two-party interactions with enormous potential economies of scale (see Adam Smith). As for his gibberish about ‘evolutionary game theory’ being as much about mal-adaptation as adaptation, thank God the rest of us don’t waste half our time on understanding what is maladaptive.

    • Helga Vierich says:

      What to make of suggestions in the literature of late, reporting evidence that there are hormones, especially oxytocin, that explain affiliation to an “in-group” but also aggression to an “out-group”. For example, Carsten de Drue et. al. suggest:

      “Humans regulate intergroup conflict through parochial altruism; they self-sacrifice to contribute to in-group welfare and to aggress against competing out-groups. Parochial altruism has distinct survival functions, and the brain may have evolved to sustain and promote in-group cohesion and effectiveness and to ward off threatening out-groups. Here, we have linked oxytocin, a neuropeptide produced in the hypothalamus, to the regulation of intergroup conflict. In three experiments using double-blind placebo-controlled designs, male participants self-administered oxytocin or placebo and made decisions with financial consequences to themselves, their in-group, and a competing out-group. Results showed that oxytocin drives a “tend and defend” response in that it promoted in-group trust and cooperation, and defensive, but not offensive, aggression toward competing out-groups.” (my emphasis)

      This interpretation of the function of oxytocin, as representing an innate capacity for ethnocentrism, is particularly problematical when they try to put this into an evolutionary context. Sure, people might be driven to defend their loved ones, and others with whom they identify, from danger. But this does not translate into aggressive attacks… only defensive action. Oxytocin might explain why people act to defend, but it is clear that more complex explanations are needed for wars of aggression.

      Speculations about some kind of innate “tribal” tendency in human beings have been over-played, while evidence of compliance and hyper-cooperation have been down-played, all in support of the idea that innate human tendencies are responsible for mutual hostility, war, and even genocide.

      This ignores or minimizes the role of political propaganda and the role of conscious decisions by leaders, to use force in defense and offense. It (often literally) shifts attention away from the theft of economic resources and displacement of peoples. By asserting the imperative naturalness of territorial expansion and warfare between human groups, leaders mystify and mislead. In this light, soldiers all over the world have fought for imperial expansion as often as they fought against it. The cause is not human nature, it is political and economic ambition and expediency, which sometimes uses the myth that warfare is a “natural” human tendency. It is interesting to note that assumptions that humans are innately territorial and hostile to “out-groups” are in direct contradiction to ideology explicitly exploitative and contemptuous of the “fighting man” or of “the people”, which suggest that people must be manipulated into fighting.

      Recently, research on what motivates men to fight, has been done in a very difficult theatre: the ISIS insurgency in Iraq. David Berreby summarized work by Scott Atran, Lydia Wilson, and Hammad Sheikh on the motivations of ISIS fighters, Palestinians, Iranians, and other groups involved in various conflicts in the region. They have identified something very striking about the “banality of evil” that permits people to kill one another without moral scruples: for ordinary people, sacred values are important enough to die for and kill for.

      It is note-worthy that “…all sacred values appear to be defined by a taboo against material trade­-offs.” This last statement was what really jumped out at me. In particular, it suddenly clarified reasons for something that always happened during the inter-group meetings I observed between hunter-gatherers who spoke different languages – and thus identified themselves as being from different, named groups.

      They almost NEVER traded, in the sense of offering exchange of one object for another. It was a taboo. Even gifts were suspect, and could be seen as “seeking advantage”, hinting at hidden agendas beyond friendly conduct. Signals of self-interest were avoided – although sometimes actually joked about, so that the participants were left in no doubt that their meeting was not about seeking material benefit. Thus, potential hostility was not even possible, if the contact did not yield expected benefits, since neither side saw much they wanted to possess. Instead, they used signs and their knowledge of one another’s languages to invite each other to spontaneous rituals, where, in the course of singing songs and dancing, they freely offered each other the latest tunes and moves. In fact, among the Kua, I was told that all songs were sacred: they were prayers or hymns that conjured the spirit of the creators of the world. So were the best stories, those from the long ago past. Stories were told during quieter evenings, often translated on the run for the benefit of less bi-lingual persons.

      One on one, they told one another the latest jokes but also laughed generously at the oldest and more jaded ones. The children and young adults played and pranked and laughed, young people flirted across the ethnic divide, and what tiny gifts did get passed between individuals were off-handedly, and even shyly, offered, often privately. All available meat brought into camp was shared, mostly without comment. What comment there was, often was to disparage such contributions.

      What was sacred, here? Judging by other statements and historical events, and what was NEVER spoken of, it seems that the sacred thing was peace. Common values underwrote peaceful politics and thus made possible a further the unspeakable promise of mutual help if it was ever needed. These contacts implied relatedness that went beyond known kinship, even to the point of long chats, which sometimes even resorted to inventing common ancestors to further emphasize similarities over differences.

      The typical fluid and temporary nature of cooperative groups seen in modern hunter-gatherers makes it very difficult to find any clear cut “in” and “out” groups below the level of a whole language or dialect. Furthermore, as my previous example shows, the maintenance of mutual cordiality can be elevated to a kind of sacred value between such groups. Taboos on inter-group violence and conflict make sense among most hunter-gatherers: it is stupid to alienate people who might tell you a new joke, show you a new way of making an arrow, or lighting a fire. It is especially stupid if they are neighbors, and might, someday, during a catastrophic drought, offer you refuge, on the unspoken assumption that you would do likewise.

      So is the defusing of any potential threat offered to an “out-group” always a sacred value? No. When contact with that group leads to harm, reaction can be swift and comprehensive. Even children can swiftly shift from friendship to enmity based on negative information about other persons. Slander and gossip over misdemeanors, so effective against freeloaders, mischief-makers, and other miscreants within a community, can be channeled against whole “other” communities. Individuals tagged as members of the despised “others“ will not be shown much mercy.

      However, what this means is that an “out-group” is created, not intrinsic. As history shows, an “out-group”, in fact, can be created that divides families, turns lovers into enemies, severs lifelong friendships, just as easily as it replaces curiosity about newcomers with loathing. In other words, human collective aggression is not about territorial imperatives, it is about social rejection. It is about the fact that protecting a mutuality of cooperation trumps individual advantage. If the first sacred value is finding joy in common humanity (an adaptation via species imprinting and a very ancient) the second is the merger of individual identity with a larger entity, consisting not just of known companions but of all others, even strangers, who share a common cause.

  • Helga Vierich says:

    I was concerned about the lack of analysis that appears to have gone into the presented papers.

    I think that the origins of warfare is a topic of great importance, and deserves open discussion. Not innuendo, not the apparently deliberate confounding of mere “human violence” (a given in any large social primate species under certain circumstances) social control (redress of grievances and execution of murderers), with the kind of coalitional violence resulting in clashes between people whose aim is to kill and defeat those fighting for the “other side”. people who might be complete strangers meeting on a field of battle to kill each other.

    Whether this is a culturally orchestrated use of the potential for human violence, was, I thought, not even in question. But the essay sited below does just that – it implies that war is an aspect of our evolved behavioural biology. This flies in the face of the general scientific consensus.

    Richard Wrangham persists in jumping straight from a very questionable model of “war” in chimps to WWII: all explained by out innate evolved behavioural drivers. It is only possible to even consider this sort of model if you completely ignore both the dangers of inbreeding depression and cultural stagnation.

    I have no doubt there were violent episodes throughout human evolutionary history, but I doubt that genocidal attacks of the kind perpetrated during warfare constituted a successful strategy in a world of low population density and mobile foraging.

    We have much more evidence – archaeological and ethnographic – for a slow onset of warfare after the transition to sedentism based on fixed or stored resources, during the early Holocene, in certain places, there is increased skeletal evidence of malnutrition and violent injuries, even occasional massacres.

    For a particular group to become dominated by such ideas, the ideas must have caught on for some reason – because, for example, they had overpopulated their lands and begun to experience worsening living conditions and heightened risk. Under such conditions people who find they can solve their problems by means of violent predatory expansion – either through warfare to subjugate or by genocide – they can improve their own lives and reduce risk of famine.

    The former option (colonization and subjugation) is of course basically a protection racket – “we will take stuff off you as needed, but mostly will leave you alone to operate your business as long as you pay us off regularly” while the other is the standard operating procedure of expansion prescribed by the God of Abraham “We are going to kill all of you and drive you into the sea” and it essentially a replacement “we are taking over your whole business and if you don’t like it we will kill you”.

    The origin of these ideas is not mysterious. They originate in cultural systems that have begun to generate negative trophic flows in their ecosystem… in other words, they have over-populated.. leading them to cut down too many trees, cultivated too much land, and over-hunted too many species – and as wild species extinction (faunal and floral) occurs, water tables drop, soil fertility declines and erosion worsens, the only alternative to increased mortality and collapse is to organize the society into a predatory war machine (usually under some military caste that raises their children steeped in games like chess and with familiarity with battle strategy and “leadership” behaviour). Academies like Westpoint are not new, nor is the concept of elites who are rewarded for planning and executing “campaigns” of violent domination over anyone who either threatens the polity disrupts the internal economy or trade routes, and any outside attacker.

    Waves of deforestation and aggressive predatory expansion are the hallmarks of state formation throughout the archaeological record. State formation and the delicate process of eventually achieving “peace” among such entities is basically what world history consists of for the last few thousand years.

  • Helga Vierich says:

    There is one really obvious factor overlooked in the analysis as it has been presented so far in the case of Nataruk: the people who were killed clearly fit the typical profile of a hunter-gatherer camping party (band). I have looked at the range of age and sex and this appears to have been a single camping party consisting of four or five families.

    But what about the attackers? In the paper it is just ASSUMED that the killers were another group of the same composition as themselves – that these deaths were the outcome of a fight between two bands.

    I doubt this very much. First, they appear to have been left where they fell. If this had been a mix of people killed in a battle BETWEEN two “nomadic” bands, then why did none of the survivors bury their dead? Why leave young children lying among their dead mothers and fathers.. and grandmothers and grandfathers?

    No, this looks like an attack ON a band of possibly nomadic hunter-gatherers, but that does not make it an attack BY nomadic hunter-gatherers.

    There is evidence of sedentary communities along the Nile and into the richer area of Lake Turkana during this same time period In the case of Nataruk, there is evidence of pottery indicating storage in a fixed locale, and the site is located in what would have been an extremely prime fishing location. Remember Jebel Sahaba, excavated back in the 1960s? It had a cemetery with burials of over fifty people, and about half of them showed injuries similar to the ones on the Nataruk skeletons. That was dated to about the same period as Nataruk. And associated with sedentary villages.
    This particular region has a long long history of early sedentism, with some sites showing semi-permenent villages claimed to be as ld as 70,000 years http://www.archeosudan.org/index_en.html

    The distribution of ages and sexes of the dead indicate a typical hunter-gatherer camping party. This was not the result of a “battle” between two hunter-gatherer bands. This was not “war”,

    There is no way that the Nataruk massacre was the outcome of a battle between two nomadic hunter-gatherer bands. It is jumping to a hasty and unwarranted conclusion.

    • Anthony C. Lopez says:

      Thanks for the great comments, and although it has been a year since this post, I thought I’d post a few notes in response.

      First, Carmi – very sorry that space prevented you and many other qualified and interested people from attending. I know the organizers did their best to be inclusive and broad in their assembly. I look forward to seeing your predictive model in print when it’s published!

      Regarding Richerson’s surprise, I would think that Dom, myself and many others would be surprised that a dynamic such as coalitional violence would NOT be fertile ground for evolutionary explanations, particularly given the massive reproductive costs and benefits associated with its potential or actual occurrence. Even IF evolution is inefficient at solving the dilemma of cooperation at large numbers (notwithstanding Trivers’ point about reciprocal altruism and media of exchange), the point would be moot since ancestral warfare did not occur at the large scales at which evolution is purportedly inefficient. Although, of course, I am always reminded of Orgel’s second rule: “Evolution is cleverer than you are.” Instead, however, at a minimum, it would seem that the challenge is to understand the origins and nature of small scale ancestral warfare, examine its effects upon our psychology, and then examine the interaction of this psychology with modern institutions that facilitate large scale mobilization. Whether the modern effects of this evolved psychology is maladaptive, while not uninteresting, is beside the point.

      Helga raises many points in three separate posts. I’ll do my best to sort through them because they provide useful opportunities for discussion, though apologies for any omissions.

      >> “This interpretation of the function of oxytocin, as representing an innate capacity for ethnocentrism…” The authors’ interpretation does not suggest ethnocentrism, but rather a physiological mechanism that facilitates in-group preference. Whether that preference is aimed at one’s ethnic group or one’s sports club is a different question. Robert Sapolsky has been among the loudest on this point.

      >> “…more complex explanations are needed for wars of aggression.” I don’t know why they would need to be more or less complex – although you could be right – but I absolutely agree with you on the need for separate explanations for offensive and defensive aggression.

      >> “innate ‘tribal’ tendency in human beings have been over-played…” Maybe, but does that make them wrong? Stairway to Heaven has been over-played but it remains the best rock song of all time. But I agree, this emphasis on tribalism has blinded researchers and the public to the real human capacity for peace. The solution isn’t to down-play valid findings on tribalism; rather, the solution is to examine the interactions between our aggressive and peace-building capacities.

      >> “…soldiers all over the world have fought for imperial expansion as often as they fought against it. The cause is not human nature, it is political and economic ambition and expediency…” This seems like a non-sequitur to me: “if some people fight for x and others fight against x, there must be no link to human psychology.” I think this type of thinking has been used as ammunition against evolutionary explanations by folks such as John Horgan who see variation in behavior as evidence against evolutionary explanations for it. Don’t get me wrong, I am not siding ‘with evolution’ and ‘against political ambition,’ rather I am suggesting they are not mutually exclusive. Also note that I have chosen not to use the language of “human nature” since I have no idea what that is. I’m not sure anyone does. It’s as unhelpful a construct as “culture.”

      Your points on sacred value are well-taken and I think this is an exciting avenue of research, also in light of the plasticity of group affiliations, which you note. The boundaries of groups, as you note, are created, not intrinsic, which by the way feeds back to the very first point above on why ethnocentrism is not necessarily implicated by the findings on oxytocin.

      >> “…collective aggression is not about territorial imperatives, it is about social rejection. It is about the fact that protecting a mutuality of cooperation trumps individual advantage.” Personally, I would shy away from statements such as “[choose your dynamic] is about [choose another dynamic]” since these formulations always end up being a bit too general and feel-good to be scientifically useful. Some examples: warfare is about personal ambition; warfare is about resource competition; warfare is about territorial imperatives. There is no one reason for ‘war.’ It’s an evolutionarily old practice. Some of its modern elements are shaped by an evolutionary calculus; other elements are the product of unique cultural and historical events and institutions. It’s a messy picture and we have to embrace ambiguity and complexity, not reduce it to some fundamental essence that war is ‘about.’

      My sense is that most of what is raised in Helga’s second and third posts are the product of conceptually ambiguous definitions of war. Therefore, rather than getting bogged down in the inferential possibilities contained within this or that episode of historic or pre-historic violence, let me offer some broader thoughts on terminology and methodology. First, I’d easily agree that researchers have been less that fastidious on how war is or should be defined, and that how we define warfare has massive implications for the questions we ask and the conclusions at which we arrive.

      Second, however, ‘warfare’ may not be a discrete object with discrete properties that can be carved at unique joints. But even if it was, the cultural and emotional significance of warfare as a human phenomenon makes it extremely unlikely that researchers will ever reach consensus on how warfare should be defined; i.e. what its essential nature is. Thus, it can be helpful to think of definitions of warfare as methodological instruments rather than intrinsic indicators. The evolutionary question to be asked, therefore, is the following: Can we identify forms of coalitional violence that were evolutionarily recurrent and reproductively significant, and, by extension, what selection pressures could have shaped our evolved psychology to reason about these forms of coalitional violence in ways that would have been ancestrally adaptive? Answers to this question give us a clue to the coalitional psychology that we bring to bear upon the modern world and can enable us to ask sharper questions regarding the interaction of that psychology with domestic and international institutions. But to start from the position that warfare must be X, and then take up the search for X ancestrally, is slightly backwards in my opinion and would seem to throw us into never-ending back-and-forth on what this or that episode of violence tells us about how old warfare is. Let’s not allow our labeling preferences to undermine our understanding of the evolved systems that are sitting right on top of us.

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