Henry Harpending and I have written a paper on the historical decline of personal violence in European societies. It has just been published in the journal Evolutionary Psychology. I wrote the following press release:

While war has always been with us, personal violence has been declining in Western societies over the last millennium. Is this a case of our better angels triumphing over our inner demons, as Steven Pinker has argued? Or does the change lie in our inner demons? Have they become kinder and gentler? In this newly published paper, two anthropologists, Peter Frost and Henry Harpending, argue that the last thousand years have seen a radical change in the legitimacy of personal violence. Previously, every man had the right to settle personal disputes as he saw fit, even to the point of killing, and it was only the threat of retaliation from the victim’s kinsmen that kept violence in check. This situation began to change in the 11th century throughout Western Europe with a growing consensus that the wicked should be punished so that the good may live in peace. Courts imposed the death penalty more and more often and, by the late Middle Ages, were condemning to death between 0.5 and 1.0% of all men of each generation, with perhaps just as many offenders dying at the scene of the crime or in prison while awaiting trial. Meanwhile, the homicide rate plummeted from the 14th century to the 20th, decreasing forty-fold. The pool of violent men dried up until most murders occurred under conditions of jealousy, intoxication, or extreme stress. The immediate causes were legal and cultural: harsher punishment and a shift in popular attitudes toward the violent male—who went from hero to zero. This new social environment, however, also tended to favor the survival and reproduction of individuals who would less easily resort to violence on their own initiative. Given that aggressive behavior is moderately to highly heritable, as shown by twin studies, is it possible that the high rate of capital punishment gradually removed propensities for violence from the gene pool? This hypothesis is modeled by Frost and Harpending, who conclude that such natural selection could explain a little over half of the reduction in the homicide rate. The rest of the decline may have partly resulted from violent men being increasingly marginalized in society and on the marriage market. Of course, we are still left with the original legal and cultural causes: personal violence is deterred by fear of punishment and by a cultural norm of nonviolence. But how strong are these external and internal controls today? Relaxation of these controls has caused only a modest rise in personal violence among young men of Western European background, there being no reversion to the levels that were once normal less than a millennium ago. Perhaps our inner demons have indeed changed for the better.

For the full document, please click here.

Two HBD writers, hbd chick and Jayman, have commented on the paper here. My replies are reproduced below:

Homicide decline in England before 1500

Hbd chick – their theory does not account for 1) why the homicide rates appear to have dropped significantly in england *before* 1500?

We focused on the 1500-1750 period because that was when the execution rate was at its peak, but this rate was already increasing during the previous five centuries. It would have been difficult to model the effects of this earlier period partly because we had less data to work with and partly because we didn’t know whether the execution rate increased linearly or, as is more likely, exponentially with a levelling off toward 1500.

Hbd chick – but the fact remains that the drop in homicide rates in england and germany, according to eisner, was *much* more dramatic between 1300-1500 than post-1500?

Eisner doesn’t make that claim, the pre-1500 data being too sparse and variable. I should quote the passage in question:

In the thirteenth and fourteenth century, the mean of almost 40 different estimates lies around 24 homicides per 100,000. The average homicide rates are higher for the late fourteenth century than for the thirteenth century, but it seems impossible to say whether this is due to the difference in the sources used or reflects a real increase related to the social and economic crises in the late Middle Ages. When estimates start again after a gap of some 150 years, the average calculated homicide rates are considerably lower with typical values of between 3-9 per 100,000. (Eisner, 2001)

This is another reason why we excluded the pre-1500 data. Homicide rates may have fallen more rapidly pre-1500 than post-1500 but it’s impossible to say for sure. Assuming that the decline was faster pre-1500, we may be looking at nonlinear effects in the removal of violence-prone males, i.e., if we raise the threshold for expression of impulsive, personal violence by 10%, the reduction in the homicide rate may be much more than 10%.

Hbd chick – that’s not eisner’s interpretation of the english data at all.

We may have to agree to disagree. The steep pre-1500 decline is due to a rise from the 13th century to the 14th, and Eisner notes that “it seems impossible to say whether this is due to the difference in the sources used or reflects a real increase related to the social and economic crises in the late Middle Ages.” If one looks at Figure 1 “Homicide rates in England” (p. 622), the data points are much more variable before 1400 than after 1500. If we draw a straight line from the 13th century to the 16th, the steepness of the decline is actually less than it is later on. Your argument essentially rests on a 14th century peak that may or may not be illusory.

You may be right. I just don’t have the same degree of faith in the pre-1500 data.

Increase in the execution rate before 1500

Hbd chick – it very much was – in england, anyway – a gradual, linear increase in the execution rate over the course of the medieval period, not an exponential one.

You’re using soft sources. Before 1500, we don’t have good data on execution rates, although the rates were clearly lower. I’m not really arguing with you. I just don’t have much confidence in the pre-1500 data.

Why did homicide rates remain higher in Italy?

Hbd chick – the homicide rates remained much higher in italy even though italy had some very strong states in the medieval period (city-states) – ones that that *did* execute murderers (although i don’t know at what rates)

We tried to locate data on execution rates from elsewhere in Europe but were unsuccessful. In any case, the selection pressure was not simply court-ordered executions but also extrajudicial executions, i.e., killing of the offender at the scene of the crime or death while awaiting trial. Extrajudicial executions seem to have been frequent. There is evidence that trials were often deliberately postponed so that the accused would conveniently die in prison while awaiting trial (life in prison was no great shakes if you had no friends on the outside).

I suspect that there were cultural differences between Northwest Europe and Italy in popular willingness to collaborate with authorities in the “war on murder.” A parallel can be made with witch-hunting, which reached unusually high levels in the Holy Roman Empire while being much less common elsewhere. The difference was due to grassroots participation in the war on witches. I suspect that the “war on murder” in Italy was largely carried out by civil authorities with much less popular support than was the case in England or Flanders. These are just my impressions, however.

Hbd chick – and that pattern, as i’ve said, is in stark contrast to Italy

I agree, although there are significant regional differences within that country. Keep in mind that Italy experienced the State’s monopoly on violence for a much longer time than did Northwest Europe, which went from barbarism to pacified social relations over a much shorter time. In addition, the Italian trajectory of pacification is probably different both quantitatively and qualitatively.

Other reasons for the homicide decline

Hbd chick – i bet that the reduction in homicide rates from 1200-1500 has more to do with that [increased outbreeding and decline of clannishness] than with a strong state enforcing its laws.

It may be both with a synergy effect as well. Grassroots support was a critical factor in the “war on murder.” The alliance between Church and State was also a factor in getting people to internalize this new cultural norm.

Hbd chick – Durkheim saw the decline of homicide rates as resulting from the liberation of the individual from collective bonds rather than as the consequence of the coercive potential of the state.

I see the arrow of causality running in the opposite direction. Pacification of social relations made it possible for individuals to survive as individuals in a much larger, freer and more anonymous social environment. People no longer had to turn to their kinsmen for help and protection.

Jayman – Frost and Harpending admit in their paper that their scenario cannot on its own explain the results we see.

I agree that the execution rate was not the sole factor in the removal of violence-prone males. Once nonviolence became the desired norm, the violent male went from hero to zero. He became marginalized on the marriage market and in opportunities for social and economic advancement à la Clark and Unz (Clark, 2007; Clark, 2009; Unz, 1980; Unz, 2013).

Global variation in homicide

Jayman – We see that around the world, all Europeans and their offshoots (with the exception of the East Slavs, and the Sami, apparently) as well as Northeast Asians stand out as being particularly less violent, at least as gauged by homicide rates. These are the pacified peoples. Whatever processes that operated, some or all of them must have operated in all these places.

[…] There are regional high points in Europe. All are the usual suspects: Scotland and Northern Ireland, southern Portugal, southern Italy, Greece, Albania (i.e., the PIIGS). The West and the South Slavs, while not as far gone as their East Slavic cousins, do stand out for themselves.

I would suggest some caution in interpreting the world map of homicide rates. In many countries, some homicides end up being reported as “accidents.” This is especially so in the case of domestic disputes or in cases where the murderer is the top dog in the village. With that caveat, the map is not too far from reality. We see an east-west cline in Europe, which may be related to the relative lateness of state formation in Eastern Europe.

Even within European-descended societies, we see interesting variations (which don’t always appear on the map). There is good evidence that personal violence is more common in the U.S. among white southerners than among white northerners. Southern whites are descended disproportionately from settlers who came from the northern English borderlands, where endemic violence persisted until the 18th century and where any encounter with non-kin, however innocent, could turn violent. ” In a world of treachery and danger, blood relationships became highly important. Families grew into clans, and kinsmen placed fidelity to family above loyalty to the crown itself” (Fischer, 1989, p. 628).

White southerners also tend to attach more importance to “honor.” Disputes over honor (insults, slights on one’s reputation or the reputation of one’s family, etc.) are a major cause of personal violence. The homicide rate could not have easily declined without a reduction in the importance of honor.

Jayman – Indeed. That’s a key point in support of “HBD Chick selection”: clannish societies are hard to pacify because individuals have to be ready to defend kin.

Yes, I see the two processes as being complementary. The dissolution of clannishness was both a cause and an effect of the pacification of social relations.