Things can only get better (Image: Rex Features)

Pessimists, anti-capitalists, conservatives and greens, take note – we are much more peaceful now than we used to be, says the psychologist

Interactive graphic: The 20 worst things people have done to each other

What got you interested in the history of violence?

I was struck by a graph I saw of homicide rates in British towns and cities going back to the 14th century. The rates had plummeted by between 30 and 100-fold. That stuck with me, because you tend to have an image of medieval times with happy peasants coexisting in close-knit communities, whereas we think of the present as filled with school shootings and mugging and terrorist attacks.


Then in Lawrence Keeley’s 1996 book War Before Civilization I read that modern states at their worst, such as Germany in the 20th century or France in the 19th century, had rates of death in warfare that were dwarfed by those of hunter-gatherer and hunter-horticultural societies. That too, is of profound significance in terms of our understanding of the costs and benefits of civilisation.

Isn’t this topic a departure for you? Your earlier books focus on how the mind and brain work…

Two of my earlier books, How The Mind Works and The Blank Slate, were not about language or even cognition, narrowly, but about human nature. In them I talked about violence, for example, the abolition of barbaric customs such as torturing people to death for religious heresy, to reinforce the point that human nature comprises many components, some of which incline us toward violence, some of which pull us away from it. The fact that violence has declined and what this implied for human nature were spelled out in both books, but I decided that those paragraphs deserved to be expanded into a book of their own.

Where did you find evidence for how violence has changed over time?

For prehistoric times, the main evidence is from forensic archaeology: the proportion of skeletons that had bashed-in skulls, or arrowheads embedded in bones, together with archaeological evidence such as fortifications. For homicide over the last millennia or so, there are records in many parts of Europe that go back to the Middle Ages. And we know from documents of the era that crucifixions and all manner of gory executions took place in the ancient world.

For data about wars, there are many databases that estimate war deaths, and in recent eras, governments and social scientists have tracked just about every aspect of life, so we really can get a clear view of things like child abuse, spousal abuse, rape and so on.

How do you explain the decline in violence?

I don’t think there is a single answer. One cause is government, that is, third-party dispute resolution: courts and police with a monopoly on the legitimate use of force. Everywhere you look for comparisons of life under anarchy and life under government, life under government is less violent. The evidence includes transitions such as the European homicide decline since the Middle Ages, which coincided with the expansion and consolidation of kingdoms; the transition from tribal anarchy to the first states. Watching the movie in reverse, in today’s failed states violence goes through the roof.

Do you think commerce helps too?

Commerce, trade and exchange make other people more valuable alive than dead, and mean that people try to anticipate what the other guy needs and wants. It engages the mechanisms of reciprocal altruism, as the evolutionary biologists call it, as opposed to raw dominance.

Trade and exchange make other people more valuable alive than dead

What else has contributed to the decline?

The expansion of literacy, journalism, history, science – all of the ways in which we see the world from the other guy’s point of view. Feminisation is another reason for the decline. As women are empowered, violence can come down, for a number of reasons. By all measures men are the more violent gender.

Has human nature, specifically our inclination toward violence, changed? Or is it more a change in how this inclination manifests itself?

I argue for the latter, although it’s not inconceivable that the former has taken place, that we have literally evolved so that the more pacific parts of human nature have been strengthened, at least over a span of centuries or millennia. I have a lengthy discussion in the book for how that could happen: it’s certainly biologically possible.

But some of the declines are far too recent to be explicable by natural selection, which has a speed limit measured in generations. So the most parsimonious explanation is that all the changes are environmental rather than genetic, while not ruling out the possibility of genetic changes.

Why do so many people think we live in incredibly violent times?

I think there are a number of systematic biases, what I call “historical myopia” being one of them. The closer you get to the present, the better the records are, and I think this is a major distorter of our impressions of violence. We know about every massacre that has taken place close to the present, but the ones in the distant past are like trees falling in the forest with no one to hear them.

So you think that we care more about violence than we used to?

Yes. Forms of violence that would once have been off people’s radar are now characterised as violence. Capital punishment was just a part of life. Pickpockets would be hanged. Now the most vicious serial murderer is executed painlessly after an appeal process that lasts decades and you’ve got nuns holding candles.

Also the human mind loves to learn about violence. Blood sells. The media don’t report that yesterday in Buenos Aires several hundred people died peacefully in their sleep, but if five of them were blown up, that would be news. More generally, when conflicts peter out it never makes the headlines. Unless you systematically tabulate violent deaths as a proportion of all deaths or as a proportion of population size, you will be misled.

What would you say to someone who doesn’t understand how a society capable of fighting the second world war could be less violent than ancient societies?

I would say look at the numbers. In the book I present a table where the second world war only comes in ninth place in the world’s atrocities. And one point is not a trend – the second world war, in terms of history, was very much an outlier.

Isn’t it simplistic to just compare the numbers of deaths in ancient wars and modern wars? How do you account for the difference in the nature of warfare and the technologies used?

That is part and parcel of the question that I am asking: namely, assuming that being killed is equally bad in all societies and at all times, was the tribal way of warfare more quantitatively destructive of human life than modern forms of warfare? They are qualitatively different, but in a way that is my point: knowing these differences, which was a worse time to be a human being?

What do you want readers to take away from your new book?

To be grateful for some of the institutions we take for granted, such as government and the court system. That, as much as we are irritated by lawyers, cops and government, the alternative is worse. The forces of reason, enlightenment, cosmopolitanism, women’s empowerment – we should be grateful for all this and not nostalgic for a time in which everyone’s world was far more constricted.

This goes for trade and commerce too. Capitalism is a dirty word for many intellectuals but there are a number of studies showing that open economies and free trade are negatively correlated with genocide and war. I would lump all of these things together under “modernity”.

So modernity tends to result in less violence?

Yes. There is an enormous current of romantic nostalgia among many sectors of intellectual life – the religious right, the green left. What I hope to remind people is that modernity, for all its problems, has brought us many gifts. Foremost is one that few people appreciate, namely a reduction in overall violence.