1. Genetic pacification in Western Europe from late medieval to early modern times

My wish list for research in 2024

The State consolidates its power by monopolizing the use of violence. To this end, it will eliminate those men who use violence for personal ends. The gene pool is thus changed: directly, through the execution of violent men; and indirectly, through a new environment that makes it harder for them to live and reproduce.

Men fighting with daggers and a sword (Wikicommons)

What do I get for Christmas? Usually a box of chocolates. Or socks. If I had the choice, I’d rather get new scientific findings that interest me. Here is the first of several research proposals I hope will come to fruition in 2024.

Violence for me but not for thee

The State consolidates its power by monopolizing the use of violence. To this end, it will eliminate those men who use violence for personal ends, thus creating a new environment where social relations are peaceful and where disputes are normally settled through nonviolent means.

Pacification occurred slowly in Western Europe during the early Middle Ages. The obstacles were many: the rudimentary nature of law enforcement; the belief in a man's right to settle personal disputes as he saw fit; and the Church's opposition to the death penalty.

Those obstacles began to disappear in the eleventh century, when Church and State agreed on the need to punish the wicked so that the good may live in peace. Courts imposed the death penalty more and more often. By the late Middle Ages, 0.5 to 1.0 per cent of all men were put to death in each generation, with perhaps just as many dying at the scene of the crime or in prison while awaiting trial. Meanwhile, the homicide rate fell from a high of 20 to 40 homicides per 100,000 in the late Middle Ages to a low of 0.5 to 1 per 100,000 in the mid-twentieth century. The pool of violent men dried up until most murders occurred under conditions of jealousy, intoxication, or extreme stress (Frost and Harpending, 2015).

Did the high execution rate remove not only violent men but also their propensities for violence? Did the gene pool actually change? That scenario is plausible, given the moderate to high heritability of aggressive/antisocial behavior. Heritability is estimated at 40% by a meta-analysis of twin and adoption studies (Rhee and Waldman, 2002) and 96% by a twin study of 9 to 10 year-olds of diverse ethnic backgrounds (Baker et al., 2007). The higher figure has been attributed to the narrow age range and the use of a panel of evaluators to rate each subject. According to the latest twin study, the heritability is 40% among twins with different evaluators and 69% among those with the same evaluator (Barker et al., 2009). Finally, a review paper concludes that about half of the variance in aggressive behavior is genetic in origin (Veroude et al., 2015).

To what degree, then, could the high execution rate of late medieval and early modern times reduce the average man’s propensity for personal violence? I and Henry Harpending tried to model the impact of this selection pressure over successive generations. We concluded that the execution rate could explain a little over half of the decline in the homicide rate (Frost and Harpending, 2015). The rest could have less direct causes. Cultural norms must have shifted toward a more negative view of violent men, causing them to suffer rejection as marriage partners, discrimination in employment, exclusion from community activities, and “accidents.” By confining such men to the lower classes of society, which reproduced at a below-replacement rate in premodern times, this social exclusion would have reduced the propensity for male violence from one generation to the next.

It is possible that we underestimated the direct impact of the death penalty on homicides. Specifically, we may have erred in assuming that a propensity for homicide would cause a man to murder only once in his lifetime. It is more likely that the average executed offender had already killed more than one person and would have gone on to kill even more if allowed to live. Bandits often killed not only their victims but also any witnesses (Frost, 2015).

On the other hand, it is also possible that we overestimated the direct impact of the death penalty on the gene pool. Many violent men would have reproduced before running afoul of the law. Furthermore, men were not executed solely for acts of personal violence (Frost, 2015).

On this last point, we should understand the logic of medieval justice. The aim was not so much to find culprits for specific major crimes as to profile the criminally minded, often on the basis of minor offences. If you had crossed the behavioral threshold for a petty crime, it was assumed that you would more easily commit, or may have already committed, a crime of greater importance. Qui vole un œuf vole un bœuf.

In Western Europe, the homicide rate fell dramatically during late medieval and early modern times (Wikicommons - Max Roser, 2003)

Proposed study

The aim is to verify the above model of “genetic pacification” by examining existing data on human DNA retrieved from medieval and post-medieval sites. The datasets would be examined for changes over time in the gene pool, specifically changes in the population frequencies of alleles associated with aggressive male behavior. This evolution would be charted from the eleventh century to the early twentieth for Western Europe or for a more limited geographic area within Western Europe, such as England.

There would be three tasks:

• Locate relevant aDNA datasets (Western Europe, 11th century to early 20th).

• Identify alleles that are associated with male violence, e.g., alleles at MAO-A, DAT1, DRD3, DRD4, etc. (Waldham and Rhee, 2006).

• Identify changes over time in the population frequencies of such alleles.

The last task would have two lines of enquiry:

How did genetic pacification relate to social class?

Today, personal violence is associated with low SES, but that association seems to be relatively recent. At first, the lower classes were the ones pacified through frequent use of the death penalty. Only later, as the death penalty gained public acceptance, did the courts impose it more and more equally on the entire population.

Initially, the courts were hindered by a widespread view of male violence as normal and virile. It was nonviolence that seemed abnormal and unmanly. Thus, in fourteenth century England, jurors were reluctant to convict murderers despite good evidence of guilt:

Because they preferred direct action and applauded self-help as a way of settling disputes, jurors were willing to acquit murderers even more freely than thieves. Most murders grew out of arguments that the villagers knew about. They assumed, along with the participants in the homicidal drama, that a good fight was an acceptable way of resolving the conflict. If someone got killed, that was understandable. (Hanawalt, 1979, p. 269)

The death penalty fell overwhelmingly on the poor and on outsiders without friends. Prominent people were more often prosecuted for homicide but seldom hanged (Hanawalt, 1979, pp. 53-54).

A similar situation prevailed in early Renaissance Venice, where noblemen felt entitled to use violence. They were the ones most likely to commit speech offenses, assaults, and rapes. Though making up only 4% of the population, they committed nearly a quarter of the recorded assaults. This positive correlation between SES and violent crime has been noted elsewhere in late medieval and post-medieval Europe (Eisner, 2003; Recueil, 2023; Ruggiero, 1980).

It is only from the nineteenth century onward that we begin to see a negative correlation between SES and violent crime, apparently due to in-migration from less pacified societies. With the shift from family workshops to industrial capitalism, the workforce was no longer confined to family members or even local people. Employers could cut labor costs by recruiting farther afield, typically from regions of labor surplus on the periphery of the Western world … or outside it entirely. Such workers came from regions where men had to use violence on a regular basis because the State was weak or nonexistent.

If the aDNA datasets include information on social class, it would be interesting to see how and when the correlation between SES and violent crime “flipped.”

How did genetic pacification relate to other trajectories of mental/behavioral evolution?

In this line of enquiry, the aim is to determine whether genetic pacification went hand in hand with other mental/behavioral changes, particularly an increase in cognitive ability (as measured by alleles associated with educational attainment - Edu PGS). Cognitive evolution may have required the establishment of social peace, notably to facilitate trade and other aspects of social complexity. Alternatively, the relationship may have been less direct, with social complexification acting as a shared selection pressure.

This subject has already attracted the interest of at least four researchers:

• The archaeogeneticist Davide Piffer is examining aDNA to reconstruct the cognitive evolution of Western Europe during medieval and post-medieval times (Kirkegaard, 2023).

• The economic historian Gregory Clark has documented the growth of the English middle class, which, from the twelfth century onward, made up a growing proportion of the English population. He argues that this demographic change led to a behavioral change: "Thrift, prudence, negotiation, and hard work were becoming values for communities that previously had been spendthrift, impulsive, violent, and leisure loving” (Clark, 2007, p. 166; Clark, 2009; Clark, 2023; Frost, 2022).

• The sociologist Georg Oesterdiekhoff has argued for a similar mental and behavioral evolution across Western Europe during late medieval and post-medieval times. He believes that this evolution recapitulated Jean Piaget’s stages of cognitive development:

  Medieval times - most people fail to develop mentally beyond the stage of preoperational thinking. They can learn language and social norms but their ability to reason is hindered by cognitive egocentrism, anthropomorphism, finalism, and animism.

  Sixteenth century onward - more and more people reach the stage of operational thinking. They can better understand probability, cause and effect, and the perspective of another person, whether real or hypothetical (Oesterdiekhoff, 2023).

• A research team at Université catholique de Louvain is seeking to “determine the role of elite knowledge and upper-tail human capital in the rise of the West between the period 1000 and 1800 CE.” During that period, the smart fraction grew in size until it reached a critical mass where thinkers were no longer isolated individuals but rather communities of people who could interact in clubs, salons, coffeehouses, and debating societies. This intellectual ferment, “the Enlightenment,” occurred across all domains of intellectual production, not only the sciences but also literature, music, and the arts (de Courson et al., 2023).

  The above research team “will study a variety of published source materials to create a geographical grid of the density, composition and quality of upper-tail human capital across time. [The team] will also develop a new theory to understand how codified knowledge and practical skills interact and how ideas spread” (Université catholique de Louvain, 2023).

References

Baker L. A., K.C. Jacobson, A. Raine, D.I. Lozano, and S. Bezdjian. (2007). Genetic and environmental bases of childhood antisocial behavior: A multi-informant twin study. Journal of Abnormal Psychology 116: 219–235. https://psycnet.apa.org/doi/10.1037/0021-843X.116.2.219   

Barker E. D., H. Larsson, E. Viding, B. Maughan, F. Rijsdijk, N. Fontaine, and R. Plomin. (2009). Common genetic but specific environmental influences for aggressive and deceitful behaviors in preadolescent males. Journal of Psychopathology and Behavioral Assessment 31: 299–308. https://doi.org/10.1007/s10862-009-9132-6   

Clark, G. (2007). A Farewell to Alms. A Brief Economic History of the World. Princeton University Press: Princeton.

Clark, G. (2009). The domestication of man: the social implications of Darwin. ArtefaCToS 2: 64-80. https://www.researchgate.net/publication/277275046_The_Domestication_of_Man_The_Social_Implications_of_Darwin 

Clark, G. (2023). The inheritance of social status: England, 1600 to 2022. Proceedings of the National Academy of Sciences 120(27): e2300926120 https://doi.org/10.1073/pnas.2300926120

de Courson, B., V. Thouzeau, and N. Baumard. (2023). Quantifying the scientific revolution. Evolutionary Human Sciences, 5, E19. https://doi.org/10.1017/ehs.2023.6

Eisner, M. (2003). Long-term historical trends in violent crime. Crime and Justice 30: 83-142. https://doi.org/10.1086/652229

Frost, P. (2015). Supplement to: Western Europe, State Formation, and Genetic Pacification. March. https://www.researchgate.net/publication/274251025_Supplement_to_Western_Europe_State_Formation_and_Genetic_Pacification

Frost, P. (2022). Europeans and recent cognitive evolution. Peter Frost’s Newsletter, December 12.

Frost P., and H. Harpending. (2015). Western Europe, state formation, and genetic pacification. Evolutionary Psychology 13(1): 230-243. https://doi.org/10.1177%2F147470491501300114  

Hanawalt, B.A. (1979). Crime and Conflict in English Communities 1300-1348. Cambridge (Mass.): Harvard University Press.

Kirkegaard, E.O.W. (2023). Ancient genomes discussion with Davide Piffer and Emil at Lake Como. YouTube

Oesterdiekhoff, G.W. (2023). Was pre-modern man a child? The quintessence of the psychometric and developmental approaches. Intelligence 40: 470-478. https://doi.org/10.1016/j.intell.2012.05.005

Recueil, C. (2023). Jailbirds of a feather flock together. Aporia Magazine, October 5.

Rhee S.H., and I.D. Waldman. (2002). Genetic and environmental influences on antisocial behavior: A meta-analysis of twin and adoption studies. Psychological Bulletin 128: 490–529. https://psycnet.apa.org/doi/10.1037/0033-2909.128.3.490   

Ruggiero, G. (1980). Violence in Early Renaissance Venice. Rutgers University Press.

Université catholique de Louvain. (2023). Did elite human capital trigger the rise of the West? Insights from a new database of European scholars. European Research Council. Grant agreement ID: 883033 https://doi.org/10.3030/883033

Veroude, K., Zhang-James, Y., Fernàndez-Castillo, N., Bakker, M.J., Cormand, B., and Faraone, S.V. (2016). Genetics of aggressive behavior: an overview. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics 171(1): 3-43. https://doi.org/10.1002/ajmg.b.32364

Waldman, I.D., and S.H. Rhee. (2006). Genetic and Environmental Influences on Psychopathy and Antisocial Behavior. In C. J. Patrick (Ed.), Handbook of psychopathy (pp. 205–228). The Guilford Press.