Among scientists there has been a long debate about whether human violence toward other humans is inherent, cultural or a mix of both. The question is: Are we natural-born killers, notes Lawrence Davidson.
By Lawrence Davidson
A new study, published in the journal Nature and entitled “The Phylogenetic Roots of Human Lethal Violence,” argues two points: (1) along with many other mammals and particularly primates, human lethal violence is innate because it is part of a long “evolutionary history”; and (2) for humans, however, it is also a behavior that is responsive to our cultural environment. So, over time, “culture modulates our bloodthirsty tendencies.”
What is particularly original about this study is that it places human violence against the backdrop of general mammalian and primate lethal behavior. The researchers found that there is a correlation between the level of intra-group violence of those species that lie close to each other on the evolutionary tree.
In order to come to this conclusion the authors of the study (who are evolutionary biologists) looked at the available data on in-group violent deaths in 1,020 mammal species. From this information they tried to approximate how murderous each group is. For conclusions about the human propensity for murder, the researchers looked at 600 human groups stretching back as far as 50,000 years ago. It turns out we are less violent than baboons and more violent than bonobos, while about as violent as chimpanzees.
Just for the reader’s information, it seems that killer whales almost never hurt each other, and bats and anteaters are quite peaceable to others of their kind. On the other hand, if you’re a cougar, chinchilla or marmot, things can get very dangerous and one has to stay wary of the neighbors.
Getting back to humans, almost every serious historian knows that our propensity for lethal violence has been around for as far back as we can go. Thus the proposition that this behavior is inherited from our pre-human ancestors seems reasonable. However, there is an effort on the part of some researchers in this field, including those who wrote the Nature article, to make the argument that humans are getting less violent.
For instance, this study claims that among Paleolithic hunter-gather groups, roughly 2 percent of deaths were the result of lethal violence. Later, in medieval times, this allegedly jumps to 12 percent. But in the modern age, with “industrialized states exerting the rule of law,” the rate appears to have fallen to 1.3 percent. Is all of this really accurate?
The authors are not the first to make this claim. The Harvard psychologist Steven Pinker, in a 2011 book entitled The Better Angels of Our Nature, argues that humans can and have lowered their level of interpersonal violence through creating institutions and laws that discourage such behavior.
As a general rule we should be wary of such sweeping claims about behavior over such large expanses of time. As one observer of the Nature study commented, much of the data [sources range from archeological digs to modern crime statistics] is “imprecise.” The same is true of Pinker’s evidence. It is due to just such challenges that such studies present these claims in terms of statistical models.
Evolution and Culture
There is much more that can be said about what may well be our species’ “innate tendency to solve problems with violence.” For one thing, it often appears to be territorial. Human beings, nomadic or otherwise, stake out territory and then defend it. This is obviously similar to what certain other primates, close to us on the evolutionary tree, do and so it is reasonable to assume an evolutionary derivation for this behavior.
As societies developed – got larger and more complex – efforts arose to control destructive behavior within in-groups. These took the form of the laws referred to by Steven Pinker as well as the present authors. However, sometimes the data seems to belie this claim.
For instance, why should the medieval period be so much more violent than the Paleolithic if societal institutions and laws were so much more developed at that later time? There might be extenuating circumstances to explain this, but the glitch does suggest that an overall answer to why the rates of lethal human violence go up and down is complicated and multifaceted.
And, what can we say of the modern era, which is supposed to be humankind’s least murderous epoch? If the statistics are correct – which seems counterintuitive – we should be reassured. However, less reassuring is the fact that our technological know-how has also supplied modern mankind with nuclear weapons and thus the ability to wipe out our species, and most all the others too.
There may be a glimmer of hope for a more peaceful future if indeed our violent inclinations are tied to acquisition of territory, and within those territories we usually make efforts to minimize intra-group violence. Under those circumstances one can speculate that the development of ever larger states (culminating in a world state) with ever larger in-groups (culminating in humanity as a single in-group) seems the way to go. Then, in theory, law and order within these expanding categories would make for a more peaceful world.
Just to interpose this part of the analysis into today’s U.S. politics, we can note that the Republican presidential candidate, Donald Trump, wants to make the country’s collective in-group smaller by deporting hundreds of thousands and closing the borders to thousands more. Such a policy can only make the United States more insular and subject to the paranoia of a heightened us-versus-them worldview.
On the other hand, the Democratic candidate, Hillary Clinton, seems to be advocating a hawkish foreign policy that emphasizes the need to control foreign territory directly or by proxy but with no inclination to increase the in-group. This too can only make the world a more dangerous place. The view of one candidate or the other being a “lesser evil” might depend on whether you are focused on domestic or foreign policy.
Whatever the optimistic claim of the Nature study about today’s comparative level of lethal violence, it seems pretty clear that our laws are not doing well enough to supply the peaceful future most of us hope for. For instance, international human rights laws are so infrequently enforced as to be of minimal effect. And, as current migrant crises around the world make clear, the prospects for ever larger in-groups are but a dream.
All of this only gives added credence to the notion that our willingness to slaughter each other is innate – an adaptive habit of a long evolutionary history. This conclusion is offered as an explanation rather than an excuse. For, as the Nature study authors recognize, culture can impact such behavior – tamping it down at least within a designated in-group.
Yet it is hard to shake the feeling that our addiction to lethal violence is our evolutionary fate, and that it hangs there, like a sword of Damocles, always ready to impose itself should the delicate strand of law snap.
Lawrence Davidson is a history professor at West Chester University in Pennsylvania. He is the author of Foreign Policy Inc.: Privatizing America’s National Interest; America’s Palestine: Popular and Official Perceptions from Balfour to Israeli Statehood; and Islamic Fundamentalism.