A History of Violence

Two perennial and obviously closely related questions in the biosocial sciences are whether human beings are violent by nature and whether our close relatives among the great apes are violent by nature.  It is obvious that human beings and chimpanzees display violent behavior in fact, both within groups (politics) and between groups (war).  For those inclined to believe that such violence is not the produce of evolution but instead a result of unnatural environmental factors (which is to say, factors that did not constitute substantial selection pressures during their evolution), there are a number of available arguments. 

One is that the last twelve thousand years have seen the rise of social conditions among human beings that are very different from those in which any primate ever lived before.  Large surpluses and the social stratification that was made possible by those surpluses gave human beings something to fight about.  That is the most plausible case for the thesis that violence is accidental rather than natural to our species.  It flies in the face of evidence that human beings were more violent in hunter-gatherer societies that approximate the environment of evolutionary adaptation. 

A second argument is that human beings are largely responsible for chimpanzee violence.  Humans have put enormous stress on chimpanzees (by restricting their foraging ranges, etc.) and this, not their nature, is to blame.  For a third argument, one may look to our other cousins, the bonobos.  These animals do not fight wars, organize hunts, or display much interpersonal violence in their groups. 

To make the bonobo argument plausible, one would have to explain why the same artificial pressures that make chimpanzees violent have not had the same effect on bonobos.  If it has, I have not seen it reported.  The absence of violence among bonobos is thought to result from the power of female coalitions.  These coalitions are built upon networks of sexual partnerships among the females and function to protect the sons of the coalition partners. 

The problem with using bonobos to argue that the three species are not inherently violent is that is raises the question of what the female coalitions arose to do in the first place.  Mothers collective protect their sons, which they would not have to do if their sons did not need protection.  That this has been going on for long enough to modify the bonobo’s evolution is evident from the fact that bonobo males are considerably smaller and less robust than chimpanzee males. 

Competition for status among males is less intense and largely nonviolent but it is not absent.  Males who have living mothers are apparently advantaged in status competition over motherless males.  Motherless males are also subject to much more aggression by other males, especially when they are young.  It appears that bonobos are the exception that proves the rule.  Their tendencies to interpersonal violence are not absent, they are merely suppressed by a special feature of pan paniscus evolution. 

As for chimpanzees, a study published in Nature does short work with the excuses for violence in this species.  From a summary in The Washington Post:

The paper, which analyzed data from 426 combined years of observation and 18 separate chimp sites, argues chimps are not driven to violence by their contacts with humans, which some scientists have previously contended. Chimps, rather, are natural born killers.

“Variation in killing rates was unrelated to measures of human impacts,” said the paper, which was researched by an international team of 30 scientists. “… The adaptive strategies hypothesis views killing as an evolved tactic by which killers tend to increase their fitness through increased access to territory, food, mates and other benefits.”

The research feeds into a lengthy debate over the nature of chimp violence, and what it means for humanity’s own propensity for murder. “We’re trying to make inferences about human evolution,” lead researcher Michael L. Wilson, an anthropologist at the University of Minnesota, told the New York Times. Even in areas where humanity’s hand and habitat loss were not discernible, the chimps conveyed the same bellicosity, the research found. It signified that competition over resources— even when abundant — drove the chimp wars.

So if chimpanzees are not less violent where human influences are not felt and resources are abundant and bonobos are not more violent where human influences cause stress, then it seems clear that pan troglodyte is in fact violent by nature and bonobos not.  If bonobos are less violent not because aggressive tendencies are absent but because they have been suppressed by another evolutionary adaptation, then it seems likely that the tendencies toward violent aggression have been inherited by both species from their common pan ancestors.  Finally, if human beings were more troglodyte in behavior than paniscus in their behavior before the rise of settled agriculture, then it seems likely that the history of violence stretches back to the common ancestors of all three species. 

This has significant implications for political philosophy.  Jean Jacques Rousseau argued precisely that human beings were asocial and therefore non-aggressive by nature.  It was only a terrible accident of history that drove human beings together and created the conditions for inequality and violence.  Rousseau was wrong. 

Thomas Hobbes argued not that human beings were violent by nature but that the logic of their situation when they meet drives them in the direction of violence.  I might get what I want by killing you and you, knowing this, have an incentive to kill me first.  Hobbes was closer to the truth, but failed to consider that such logic would have to be partially built-in to be effective.  The context works by triggering instincts.  If our instincts were not Hobbesian, neither would be our behavior. 

John Locke supposed that what really made us dangerous was our inherent sense of justice.  Our tendency to invoke the executive power that belongs to everyone by nature can make really enemies out of human parties, each of which thinks it has been wronged by the other.  Locke was pretty much dead spot on.  Our moral instincts are built upon the political and territorial instincts of our ape (or proto-ape) ancestors. 

All three of these early modern philosophers were, however, proceeding on the basis of a big mistake.  They supposed that man is by nature an isolated animal.  Not only political institutions but all human societies are largely accidental.  As the nature of a wall does not change much the nature of bricks, so what is natural to us is only what we bring to any society of which be become a part. 

Aristotle did not make that mistake.  Just as a biologist cannot recognize a gene except by recognizing the function it has in the cellular machinery, so we cannot understand the nature of a single human being except by recognizing how he or she shapes and is shaped by social and indeed moral and political communities.  It remains the fact that we do carry with us a nature that contains our evolutionary history within it.  The three homo species (to use a proposed and, I think, correct specification) carry with them a history of violence. 

The Natural Origin of Moral Cultures

In ancient Greek philosophy the most important dichotomy involved phusis and nomos, nature and convention.  Phusis, which is the root of our word for physics, means growth.  A phuton, or “a growth” was the Greek word for a flower or tree or something else that grew out of the soil.  It is interesting that our word “plant” names such an organism by reference to the act of putting it in the ground whereas the Greek word points to the process that defines the organism.  I will leave it to the students of Martin Heidegger to run with that one.  It is enough to say that phusis is the inner nature of anything, what makes it present itself and behave as it does, prior to any human interpretation. 

Nomos originally meant an enclosed pasture, within which animals were allowed to roam free.  The Greeks used the word metaphorically to indicate the written and unwritten laws that govern human social intercourse.  Human beings corral themselves by drawing their wagons into a circle.  The corral is merely a set of agreements or conventions made by particular communities.  We bury our dead.  They burn theirs.  We drink alcohol.  They eat pork.  Just as the pasture is enclosed by an artificial barrier, so the nomoi are human-made.  The nomoi exist by agreement or convention. 

Phusis is the same everywhere and always.  Fire always reaches toward the sky, whether in ancient Athens or today in Aberdeen, South Dakota.  Nomoi vary both between communities and within the same community over time.  For the Greek philosophers, phusis was existentially superior to nomos.  Philosophy was the attempt to replace opinions about the whole of things with knowledge.  If you properly understand something that never changes, you will never be wrong about it.  This kind of understanding is possible (at least in principle) regarding the natural things.  It is not possible even in principle to know something that is valid only by convention.  What is true by convention is worth knowing for practical reasons but uninteresting for theoretical reasons. 

Two corrections regarding the classical view are necessary in light of the modern science of phusis, which today we call biology.  First, natural things are more subject to change than the ancients had supposed.  Both modern biology and even modern physics are evolutionary sciences.  Second, it is no longer possible to view nomos and phusis as mutually exclusive explanations for human behavior.  The creation of norms and other conventions is something that human beings do by nature.  Thus nomoi are as much an expression of human nature and as revealing as the fact that we huddle around a fire when it gets cold. 

One of the things that led me to rethink this is the marvelous article by Michael Tomasello and Amrisha Vaish: “Origins of Human Cooperation and Morality.”  (Annual Review of Psychology, 2013, 64: 231-255).  Tomasello and his large collection of partners work both with apes and young children in order to understand human nature and how it is both very similar and very different from our near Darwinian relatives.  This bit (p. 246-247) jumped out at me:

Further evidence for young children’s understanding of the basic workings of social norms is provided by their selective enforcement of different types of social norms depending on group membership. Thus, children not only distinguish moral from conventional norms on multiple levels (see, e.g., Turiel 2006), but they also enforce the two distinctly.

In particular, when 3-year-old children see a moral norm being broken by an in-group member and an out-group member (as determined by their accents), they protest equivalently. But when they see a conventional norm being broken by these same agents, they protest more against an in-group member than an out-group member (Schmidt et al. 2011).

In this way as well, then, 3-year-olds have a sense of the conventional nature of conventional norms, that is, that these norms have been decided on by, and thus apply only to, one’s own group but that members of other groups may not be aware of or need not follow the same conventions. The same is not true of moral norms involving harm, toward which they take a more universalist approach.

According to this research, 3-year-old children are capable of distinguishing between conventional right (rules of conduct that are valid only because our group has agreed to them) and natural right (rules of conduct that are valid across all human associations).  Assuming that the children in the study are not students of political theory and have not been carefully coached by grad student parents, they seem to have an instinct grasp of the difference between nomoi and phusis.  They instinctively understand the difference between rules that are valid because we agreed on them and thus valid only for those who are part of the agreement and rules that bind everyone. 

If this holds up, it is dynamite for political philosophy.  It means that culture and nature are not in opposition, as social and political theory have supposed since the early moderns.  Culture, or social construction, is not something that takes place in some realm isolated or at least insulated from nature.  Instead, culture is a subcategory of nature.  Fish swim, dogs pee on fire hydrants, and human beings make table manners.  This gives full weight to the conventional nature of conventional norms and at the same time allows us to recognize universal standards by which those norms may be judged.  It makes it possible to respect and tolerate culture differences but also satisfies an apparently natural human yearning to know that some things are simply right and others wrong.