In the world's largest captive chimp colony at the Burger's Zoo in Arnhem, Netherlands, a struggle worthy of Machiavelli unfolded during the late 1970s. As described by primatologist Frans de Waal, the aging alpha male of the colony, Yeroen, was gradually unseated from his position of power by a younger male, Luit. Luit could not have done this on the basis of his own physical strength, but had to enter into an alliance with Nikkie, a still younger male. No sooner was Luit on top, however, than Nikkie turned on him and formed a coalition with the deposed leader to achieve dominance himself. Luit remained in the background as a threat to his rule, so one day he was murdered by Nikkie and Yeroen, his toes and testicles littering the floor of the cage.
Jane Goodall became famous studying a group of about 30 chimps at the Gombe National Park in Tanzania in the 1960s, a group she found on the whole to be peaceful. In the 1970s, this group broke up into what could only be described as two rival gangs in the northern and southern parts of the range. The biological anthropologist Richard Wrangham with Dale Peterson in their 1996 book Demonic Males describes what happened next. Parties of four or five males from the northern group would go out, not simply defending their range, but often penetrating into the rival group's territory to pick off individuals caught alone or unprepared. The murders were often grisly, and they were celebrated by the attackers with hooting and feverish excitement. All the males and several of the females in the southern group were eventually killed, and the remaining females forced to join the northern group. The northern Gombe chimps had done, in effect, what Rome did to Carthage in 146 B.C.: extinguished its rival without a trace.
There are several notable aspects to these stories of chimp behavior. First, the violence. Violence within the same species is rare in the animal kingdom, usually restricted to infanticide by males who want to get rid of a rival's offspring and mate with the mother. Only chimps and humans seem to have a proclivity for routinely murdering peers. Second is the importance of coalitions and the politics that goes with coalition-building. Chimps, like humans, are intensely social creatures whose lives are preoccupied with achieving and maintaining dominance in status hierarchies. They threaten, plead, cajole, and bribe their fellow chimps to join with them in alliances, and their dominance lasts only as long as they can maintain these social connections.
Finally and most significantly, the violence and the coalition-building is primarily the work of males. Female chimpanzees can be as violent and cruel as the males at times; females compete with one another in hierarchies and form coalitions to do so. But the most murderous violence is the province of males, and the nature of female alliances is different. According to de Waal, female chimps bond with females to whom they feel some emotional attachment; the males are much more likely to make alliances for purely instrumental, calculating reasons. In other words, female chimps have relationships; male chimps practice realpolitik.
Chimpanzees are man's closest evolutionary relative, having descended from a common chimp-like ancestor less than five million years ago. Not only are they very close on a genetic level, they show many behavioral similarities as well. As Wrangham and Peterson note, of the 4,000 mammal and 10 million or more other species, only chimps and humans live in male-bonded, patrilineal communities in which groups of males routinely engage in aggressive, often murderous raiding of their own species. Nearly 30 years ago, the anthropologist Lionel Tiger suggested that men had special psychological resources for bonding with one another, derived from their need to hunt cooperatively, that explained their dominance in group-oriented activities from politics to warfare. Tiger was roundly denounced by feminists at the time for suggesting that there were biologically based psychological differences between the sexes, but more recent research, including evidence from primatology, has confirmed that male bonding is in fact genetic and predates the human species.
THE NOT-SO-NOBLE SAVAGE
It is all too easy to make facile comparisons between animal and human behavior to prove a polemical point, as did the socialists who pointed to bees and ants to prove that nature endorsed collectivism. Skeptics point out that human beings have language, reason, law, culture, and moral values that make them fundamentally different from even their closest animal relative. In fact, for many years anthropologists endorsed what was in effect a modern version of Rousseau's story of the noble savage: people living in hunter-gatherer societies were pacific in nature. If chimps and modern man had a common proclivity for violence, the cause in the latter case had to be found in civilization and not in human nature.
A number of authors have extended the noble savage idea to argue that violence and patriarchy were late inventions, rooted in either the Western Judeo-Christian tradition or the capitalism to which the former gave birth. Friedrich Engels anticipated the work of later feminists by positing the existence of a primordial matriarchy, which was replaced by a violent and repressive patriarchy only with the transition to agricultural societies. The problem with this theory is, as Lawrence Keeley points out in his book War Before Civilization, that the most comprehensive recent studies of violence in hunter-gatherer societies suggest that for them war was actually more frequent, and rates of murder higher, than for modern ones.
Surveys of ethnographic data show that only 10-13 percent of primitive societies never or rarely engaged in war or raiding; the others engaged in conflict either continuously or at less than yearly intervals. Closer examination of the peaceful cases shows that they were frequently refugee populations driven into remote locations by prior warfare or groups protected by a more advanced society. Of the Yanomam" tribesmen studied by Napoleon Chagnon in Venezuela, some 30 percent of the men died by violence; the !Kung San of the Kalahari desert, once characterized as the "harmless people," have a higher murder rate than New York or Detroit. The sad archaeological evidence from sites like Jebel Sahaba in Egypt, Talheim in Germany, or Roaix in France indicates that systematic mass killings of men, women, and children occurred in Neolithic times. The Holocaust, Cambodia, and Bosnia have each been described as a unique, and often as a uniquely modern, form of horror. Exceptional and tragic they are indeed, but with precedents stretching back tens if not hundreds of thousands of years.
It is clear that this violence was largely perpetrated by men. While a small minority of human societies have been matrilineal, evidence of a primordial matriarchy in which women dominated men, or were even relatively equal to men, has been hard to find. There was no age of innocence. The line from chimp to modern man is continuous.
It would seem, then, that there is something to the contention of many feminists that phenomena like aggression, violence, war, and intense competition for dominance in a status hierarchy are more closely associated with men than women. Theories of international relations like realism that see international politics as a remorseless struggle for power are in fact what feminists call a gendered perspective, describing the behavior of states controlled by men rather than states per se. A world run by women would follow different rules, it would appear, and it is toward that sort of world that all postindustrial or Western societies are moving. As women gain power in these countries, the latter should become less aggressive, adventurous, competitive, and violent.
The problem with the feminist view is that it sees these attitudes toward violence, power, and status as wholly the products of a patriarchal culture, whereas in fact it appears they are rooted in biology. This makes these attitudes harder to change in men and consequently in societies. Despite the rise of women, men will continue to play a major, if not dominant, part in the governance of postindustrial countries, not to mention less-developed ones. The realms of war and international politics in particular will remain controlled by men for longer than many feminists would like. Most important, the task of resocializing men to be more like women -- that is, less violent -- will run into limits. What is bred in the bone cannot be altered easily by changes in culture and ideology.
THE RETURN OF BIOLOGY
We are living through a revolutionary period in the life sciences. Hardly a week goes by without the discovery of a gene linked to a disease, condition, or behavior, from cancer to obesity to depression, with the promise of genetic therapies and even the outright manipulation of the human genome just around the corner. But while developments in molecular biology have been receiving the lion's share of the headlines, much progress has been made at the behavioral level as well. The past generation has seen a revival in Darwinian thinking about human psychology, with profound implications for the social sciences.
For much of this century, the social sciences have been premised on Emile Durkheim's dictum that social facts can be explained only by prior social facts and not by biological causes. Revolutions and wars are caused by social facts such as economic change, class inequalities, and shifting alliances. The standard social science model assumes that the human mind is the terrain of ideas, customs, and norms that are the products of man-made culture. Social reality is, in other words, socially constructed: if young boys like to pretend to shoot each other more than young girls, it is only because they have been socialized at an early age to do so.
The social-constructionist view, long dominant in the social sciences, originated as a reaction to the early misuse of Darwinism. Social Darwinists like Herbert Spencer or outright racists like Madsen Grant in the late nineteenth and early twentieth centuries used biology, specifically the analogy of natural selection, to explain and justify everything from class stratification to the domination of much of the world by white Europeans. Then Franz Boas, a Columbia anthropologist, debunked many of these theories of European racial superiority by, among other things, carefully measuring the head sizes of immigrant children and noting that they tended to converge with those of native Americans when fed an American diet. Boas, as well as his well-known students Margaret Mead and Ruth Benedict, argued that apparent differences between human groups could be laid at the doorstep of culture rather than nature. There were, moreover, no cultural universals by which Europeans or Americans could judge other cultures. So-called primitive peoples were not inferior, just different. Hence was born both the social constructivism and the cultural relativism with which the social sciences have been imbued ever since.
But there has been a revolution in modern evolutionary thinking. It has multiple roots; one was ethology, the comparative study of animal behavior. Ethologists like Konrad Lorenz began to notice similarities in behavior across a wide variety of animal species suggesting common evolutionary origins. Contrary to the cultural relativists, they found that not only was it possible to make important generalizations across virtually all human cultures (for example, females are more selective than males in their choice of sexual partners) but even across broad ranges of animal species. Major breakthroughs were made by William Hamilton and Robert Trivers in the 1960s and 1970s in explaining instances of altruism in the animal world not by some sort of instinct towards species survival but rather in terms of "selfish genes" (to use Richard Dawkins' phrase) that made social behavior in an individual animal's interest. Finally, advances in neurophysiology have shown that the brain is not a Lockean tabula rasa waiting to be filled with cultural content, but rather a highly modular organ whose components have been adapted prior to birth to suit the needs of socially oriented primates. Humans are hard-wired to act in certain predictable ways.
The sociobiology that sprang from these theoretical sources tried to provide a deterministic Darwinian explanation for just about everything, so it was perhaps inevitable that a reaction would set in against it as well. But while the term sociobiology has gone into decline, the neo-Darwinian thinking that spawned it has blossomed under the rubric of evolutionary psychology or anthropology and is today an enormous arena of new research and discovery.
Unlike the pseudo-Darwininsts at the turn of the century, most contemporary biologists do not regard race or ethnicity as biologically significant categories. This stands to reason: the different human races have been around only for the past hundred thousand years or so, barely a blink of the eye in evolutionary time. As countless authors have pointed out, race is largely a socially constructed category: since all races can (and do) interbreed, the boundary lines between them are often quite fuzzy.
The same is not true, however, about sex. While some gender roles are indeed socially constructed, virtually all reputable evolutionary biologists today think there are profound differences between the sexes that are genetically rather than culturally rooted, and that these differences extend beyond the body into the realm of the mind. Again, this stands to reason from a Darwinian point of view: sexual reproduction has been going on not for thousands but hundreds of millions of years. Males and females compete not just against their environment but against one another in a process that Darwin labeled "sexual selection," whereby each sex seeks to maximize its own fitness by choosing certain kinds of mates. The psychological strategies that result from this never-ending arms race between men and women are different for each sex.
In no area is sex-related difference clearer than with respect to violence and aggression. A generation ago, two psychologists, Eleanor Maccoby and Carol Jacklin, produced an authoritative volume on what was then empirically known about differences between the sexes. They showed that certain stereotypes about gender, such as the assertion that girls were more suggestible or had lower self-esteem, were just that, while others, like the idea that girls were less competitive, could not be proven one way or another. On one issue, however, there was virtually no disagreement in the hundreds of studies on the subject: namely, that boys were more aggressive, both verbally and physically, in their dreams, words, and actions than girls. One comes to a similar conclusion by looking at crime statistics. In every known culture, and from what we know of virtually all historical time periods, the vast majority of crimes, particularly violent crimes, are committed by men. Here there is also apparently a genetically determined age specificity to violent aggression: crimes are overwhelmingly committed by young men between the ages of 15 and 30. Perhaps young men are everywhere socialized to behave violently, but this evidence, from different cultures and times, suggests that there is some deeper level of causation at work.
At this point in the discussion, many people become uncomfortable and charges of "biological determinism" arise. Don't we know countless women who are stronger, larger, more decisive, more violent, or more competitive than their male counterparts? Isn't the proportion of female criminals rising relative to males? Isn't work becoming less physical, making sexual differences unimportant? The answer to all of these questions is yes: again, no reputable evolutionary biologist would deny that culture also shapes behavior in countless critical ways and can often overwhelm genetic predispositions. To say that there is a genetic basis for sex difference is simply to make a statistical assertion that the bell curve describing the distribution of a certain characteristic is shifted over a little for men as compared with women. The two curves will overlap for the most part, and there will be countless individuals in each population who will have more of any given characteristic than those of the other sex. Biology is not destiny, as tough-minded female leaders like Margaret Thatcher, Indira Gandhi, and Golda Meir have proven. (It is worth pointing out, however, that in male-dominated societies, it is these kinds of unusual women who will rise to the top.) But the statistical assertion also suggests that broad populations of men and women, as opposed to exceptional individuals, will act in certain predictable ways. It also suggests that these populations are not infinitely plastic in the way that their behavior can be shaped by society.
FEMINISTS AND POWER POLITICS
There is by now an extensive literature on gender and international politics and a vigorous feminist subdiscipline within the field of international relations theory based on the work of scholars like Ann Tickner, Sara Ruddick, Jean Bethke Elshtain, Judith Shapiro, and others. This literature is too diverse to describe succinctly, but it is safe to say that much of it was initially concerned with understanding how international politics is "gendered," that is, run by men to serve male interests and interpreted by other men, consciously and unconsciously, according to male perspectives. Thus, when a realist theorist like Hans Morganthau or Kenneth Waltz argues that states seek to maximize power, they think that they are describing a universal human characteristic when, as Tickner points out, they are portraying the behavior of states run by men.
Virtually all feminists who study international politics seek the laudable goal of greater female participation in all aspects of foreign relations, from executive mansions and foreign ministries to militaries and universities. They disagree as to whether women should get ahead in politics by demonstrating traditional masculine virtues of toughness, aggression, competitiveness, and the willingness to use force when necessary, or whether they should move the very agenda of politics away from male preoccupations with hierarchy and domination. This ambivalence was demonstrated in the feminist reaction to Margaret Thatcher, who by any account was far tougher and more determined than any of the male politicians she came up against. Needless to say, Thatcher's conservative politics did not endear her to most feminists, who much prefer a Mary Robinson or Gro Harlem Brundtland as their model of a female leader, despite -- or because of -- the fact that Thatcher had beaten men at their own game.
Both men and women participate in perpetuating the stereotypical gender identities that associate men with war and competition and women with peace and cooperation. As sophisticated feminists like Jean Bethke Elshtain have pointed out, the traditional dichotomy between the male "just warrior" marching to war and the female "beautiful soul" marching for peace is frequently transcended in practice by women intoxicated by war and by men repulsed by its cruelties. But like many stereotypes, it rests on a truth, amply confirmed by much of the new research in evolutionary biology. Wives and mothers can enthusiastically send their husbands and sons off to war; like Sioux women, they can question their manliness for failing to go into battle or themselves torture prisoners. But statistically speaking it is primarily men who enjoy the experience of aggression and the camaraderie it brings and who revel in the ritualization of war that is, as the anthropologist Robin Fox puts it, another way of understanding diplomacy.
A truly matriarchal world, then, would be less prone to conflict and more conciliatory and cooperative than the one we inhabit now. Where the new biology parts company with feminism is in the causal explanation it gives for this difference in sex roles. The ongoing revolution in the life sciences has almost totally escaped the notice of much of the social sciences and humanities, particularly the parts of the academy concerned with feminism, postmodernism, cultural studies, and the like. While there are some feminists who believe that sex differences have a natural basis, by far the majority are committed to the idea that men and women are psychologically identical, and that any differences in behavior, with regard to violence or any other characteristic, are the result of some prior social construction passed on by the prevailing culture.
THE DEMOCRATIC AND FEMININE PEACE
Once one views international relations through the lens of sex and biology, it never again looks the same. It is very difficult to watch Muslims and Serbs in Bosnia, Hutus and Tutsis in Rwanda, or militias from Liberia and Sierra Leone to Georgia and Afghanistan divide themselves up into what seem like indistinguishable male-bonded groups in order to systematically slaughter one another, and not think of the chimps at Gombe.
The basic social problem that any society faces is to control the aggressive tendencies of its young men. In hunter-gatherer societies, the vast preponderance of violence is over sex, a situation that continues to characterize domestic violent crime in contemporary postindustrial societies. Older men in the community have generally been responsible for socializing younger ones by ritualizing their aggression, often by directing it toward enemies outside the community. Much of that external violence can also be over women. Modern historians assume that the Greeks and Trojans could not possibly have fought a war for ten years over Helen, but many primitive societies like the Yanomamo do exactly that. With the spread of agriculture 10,000 years ago, however, and the accumulation of wealth and land, war turned toward the acquisition of material goods. Channeling aggression outside the community may not lower societies' overall rate of violence, but it at least offers them the possibility of domestic peace between wars.
The core of the feminist agenda for international politics seems fundamentally correct: the violent and aggressive tendencies of men have to be controlled, not simply by redirecting them to external aggression but by constraining those impulses through a web of norms, laws, agreements, contracts, and the like. In addition, more women need to be brought into the domain of international politics as leaders, officials, soldiers, and voters. Only by participating fully in global politics can women both defend their own interests and shift the underlying male agenda.
The feminization of world politics has, of course, been taking place gradually over the past hundred years, with very positive effects. Women have won the right to vote and participate in politics in all developed countries, as well as in many developing countries, and have exercised that right with increasing energy. In the United States and other rich countries, a pronounced gender gap with regard to foreign policy and national security issues endures. American women have always been less supportive than American men of U.S. involvement in war, including World War II, Korea, Vietnam, and the Persian Gulf War, by an average margin of seven to nine percent. They are also consistently less supportive of defense spending and the use of force abroad. In a 1995 Roper survey conducted for the Chicago Council on Foreign Relations, men favored U.S. intervention in Korea in the event of a North Korean attack by a margin of 49 to 40 percent, while women were opposed by a margin of 30 to 54 percent. Similarly, U.S. military action against Iraq in the event it invaded Saudi Arabia was supported by men by a margin of 62 to 31 percent and opposed by women by 43 to 45 percent. While 54 percent of men felt it important to maintain superior world wide military power, only 45 percent of women agreed. Women, moreover, are less likely than men to see force as a legitimate tool for resolving conflicts.
It is difficult to know how to account for this gender gap; certainly, one cannot move from biology to voting behavior in a single step. Observers have suggested various reasons why women are less willing to use military force than men, including their role as mothers, the fact that many women are feminists (that is, committed to a left-of-center agenda that is generally hostile to U.S. intervention), and partisan affiliation (more women vote Democratic than men). It is unnecessary to know the reason for the correlation between gender and antimilitarism, however, to predict that increasing female political participation will probably make the United States and other democracies less inclined to use power around the world as freely as they have in the past.
Will this shift toward a less status- and military-power-oriented world be a good thing? For relations between states in the so-called democratic zone of peace, the answer is yes. Consideration of gender adds a great deal to the vigorous and interesting debate over the correlation between democracy and peace that has taken place in the past decade. The "democratic peace" argument, which underlies the foreign policy of the Clinton administration as well as its predecessors, is that democracies tend not to fight one another. While the empirical claim has been contested, the correlation between the degree of consolidation of liberal democratic institutions and interdemocratic peace would seem to be one of the few nontrivial generalizations one can make about world politics. Democratic peace theorists have been less persuasive about the reasons democracies are pacific toward one another. The reasons usually cited -- the rule of law, respect for individual rights, the commercial nature of most democracies, and the like -- are undoubtedly correct. But there is another factor that has generally not been taken into account: developed democracies also tend to be more feminized than authoritarian states, in terms of expansion of female franchise and participation in political decision-making. It should therefore surprise no one that the historically unprecedented shift in the sexual basis of politics should lead to a change in international relations.
THE REALITY OF AGGRESSIVE FANTASIES
On the other hand, if gender roles are not simply socially constructed but rooted in genetics, there will be limits to how much international politics can change. In anything but a totally feminized world, feminized policies could be a liability.
Some feminists talk as if gender identities can be discarded like an old sweater, perhaps by putting young men through mandatory gender studies courses when they are college freshmen. Male attitudes on a host of issues, from child-rearing and housework to "getting in touch with your feelings," have changed dramatically in the past couple of generations due to social pressure. But socialization can accomplish only so much, and efforts to fully feminize young men will probably be no more successful than the Soviet Union's efforts to persuade its people to work on Saturdays on behalf of the heroic Cuban and Vietnamese people. Male tendencies to band together for competitive purposes, seek to dominate status hierarchies, and act out aggressive fantasies toward one another can be rechanneled but never eliminated.
Even if we can assume peaceful relations between democracies, the broader world scene will still be populated by states led by the occasional Mobutu, Milosevic, or Saddam. Machiavelli's critique of Aristotle was that the latter did not take foreign policy into account in building his model of a just city: in a system of competitive states, the best regimes adopt the practices of the worst in order to survive. So even if the democratic, feminized, postindustrial world has evolved into a zone of peace where struggles are more economic than military, it will still have to deal with those parts of the world run by young, ambitious, unconstrained men. If a future Saddam Hussein is not only sitting on the world's oil supplies but is armed to the hilt with chemical, biological, and nuclear weapons, we might be better off being led by women like Margaret Thatcher than, say, Gro Harlem Brundtland. Masculine policies will still be required, though not necessarily masculine leaders.
The implications of evolutionary biology for the hot-button issue of women in the military is not as straightforward as one might think. The vast majority of jobs in a modern military organization are in the enormous support tail that trails behind the actual combat units, and there is no reason that women cannot perform them as well if not better than men. While men have clearly evolved as cooperative hunters and fighters, it is not clear that any individual group of women will perform less well than any individual group of men in combat. What is much more problematic is integrating men and women into the same combat units, where they will be in close physical proximity over long periods of time. Unit cohesion, which is the bedrock on which the performance of armies rests, has been traditionally built around male bonding, which can only be jeopardized when men start competing for the attention of women. Commanders who encourage male bonding are building on a powerful natural instinct; those who try to keep sexual activity between healthy 20-year-old men and women in check through "zero tolerance" policies and draconian punishments are, by contrast, seeking to do something very unnatural. Unlike racial segregation, gender segregation in certain parts of the military seems not just appropriate but necessary.
THE MARGARET THATCHERS OF THE FUTURE
The feminization of democratic politics will interact with other demographic trends in the next 50 years to produce important changes. Due to the precipitous fall in fertility rates across the developed world since the 1960s, the age distribution of countries belonging to the Organization of Economic Cooperation and Development will shift dramatically. While the median age for America's population was in the mid-20s during the first few decades of the twentieth century, it will climb toward 40 by 2050. The change will be even more dramatic in Europe and Japan, where rates of immigration and fertility are lower. Under the U.N. Population Division's low-growth projections, the median age in Germany will be 55, in Japan 53, and in Italy 58.
The graying of the population has heretofore been discussed primarily in terms of the social security liability it will engender. But it carries a host of other social consequences as well, among them the emergence of elderly women as one of the most important voting blocs courted by mid-21st century politicians. In Italy and Germany, for example, women over 50, who now constitute 20 percent of the population, will account for 31 percent in 2050. There is no way, of course, of predicting how they will vote, but it seems likely that they will help elect more women leaders and will be less inclined toward military intervention than middle-aged males have traditionally been. Edward Luttwak of the Center for Strategic and International Studies has speculated that the fall in family sizes makes people in advanced countries much more leery of military casualties than people in agricultural societies, with their surpluses of young, hotheaded men. According to demographer Nicholas Eberstadt, three-fifths of Italy's offspring in 2050 will be only children with no cousins, siblings, aunts, or uncles. It is not unreasonable to suppose that in such a world tolerance of casualties will be even lower.
By the middle of the next century, then, Europe will likely consist of rich, powerful, and democratic nations with rapidly shrinking populations of mostly elderly people where women will play important leadership roles. The United States, with its higher rates of immigration and fertility, will also have more women leaders but a substantially younger population. A much larger and poorer part of the world will consist of states in Africa, the Middle East, and South Asia with young, growing populations, led mostly by younger men. As Eberstadt points out, Asia outside of Japan will buck the trend toward feminization because the high rate of abortion of female fetuses has shifted their sex ratios sharply in favor of men. This will be, to say the least, an unfamiliar world.
LIVING LIKE ANIMALS?
In Wrangham and Peterson's Demonic Males (said to be a favorite book of Hillary Rodham Clinton, who has had her own to contend with), the authors come to the pessimistic conclusion that nothing much has changed since early hominids branched off from the primordial chimp ancestor five million years ago. Group solidarity is still based on aggression against other communities; social cooperation is undertaken to achieve higher levels of organized violence. Robin Fox has argued that military technology has developed much faster than man's ability to ritualize violence and direct it into safer channels. The Gombe chimps could kill only a handful of others; modern man can vaporize tens of millions.