Hammurabi in the genome

Laypeople can intuitively recreate the criminal laws of ancient, culturally unfamiliar societies.

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Daniel Sznycer & Carlton Patrick

Criminal justice systems are complex. To give an example, the federal criminal code of the United States has hundreds of sections with provisions regarding robbery and burglary, racketeering, drive-by shootings, child support, extortionate credit transactions, obscenity, and many others. This is a behemoth of an institution.

But we might grasp it if we reduce it to its minimal expression. Say, two individuals locked in conflict. Lacking the benefit of courts or criminal laws—what we want to understand—our two individuals have only themselves to sort things out. Our characters might resolve their conflict by mutual compromise. Or our characters might resolve their conflict by force. Our characters can do this because humans come factory-equipped with mental software to navigate conflict: concepts (e.g., wrong), intuitions (e.g., a wrong deserves a punishment), emotions (e.g., anger).

These human intuitions of justice give us a key to understand criminal laws. But they also give us a theory of the origin of criminal laws. To wit, the making of laws is steered by the justice intuitions of lawmakers. Of course, it takes many other ingredients to make laws. Writing, for instance.

This theory of the origin of criminal laws is attractive because it can begin to explain a complex institution naturalistically as part of a causal network that is linked to the rest of the physical world.

This theory has empirical support. Past research has shown that laypeople rank the seriousness of various criminal offenses in a way that agrees with the punishments that actual laws provide for those offenses. This is what you expect if justice intuitions run the show—if justice intuitions govern how lawmakers make laws and how laypeople perceive offenses.

But there’s a potential problem with this theory. Laws vary across cultures. For example, cross-race marriage, homosexuality, selling alcohol, and selling gum are legal offenses in some places and times but not others. So perhaps criminal laws originate in cultural norms, not human nature.

There’s also a potential problem with the evidence. In previous research, the study participants, the offenses evaluated by participants, and the punishments dictated by law for those offenses all originated in similar cultures: contemporary mass societies that are in close commercial and media contact. So maybe the previous research simply demonstrates participants’ cultural familiarity with the study materials—ask people to guess the laws of unfamiliar cultures and they’ll be clueless. Or, will they?

In our new paper, The origins of criminal law, we show that laypeople with no training in law can intuitively recreate the criminal laws of ancient, culturally unfamiliar societies.

Participants saw various offenses from the Laws of Eshnunna (Sumer, 3,800 years ago), one of humanity’s most ancient legal codes and a cousin of the famous Code of Hammurabi. For replication purposes, other participants saw offenses from the Tang Code (China, 1,400 years ago). Participants saw the offenses but not their corresponding legal punishments. Their task was to judge the severity of each offense. We found that participants’ ratings of the severity of these offenses correlate positively with the actual punishments dictated for the offenses by the ancient legal codes.

Justice intuitions don’t guarantee cultural accuracy. Take this Tang offense: “All cases of a master who kills a slave who has not committed an offense are punished by one year of penal servitude (NB: redeemable by paying a fine of 20 copper chin)”. This offense was considered mild by the Tang Code but very serious by the study participants. Yet, despite this big discordance, participants’ intuitions were generally accurate. For example, participants echoed the Tang Code’s stipulation that beating and killing a person in a fight is a more serious offense than betting goods and articles in games of chance. This suggests that the brain machinery that generates justice intuitions combines universal principles with open parameters tunable to local information. The principles may explain why participants generally saw eye to eye with the Tang lawmakers. The parameters may explain cultural variation.

Identifying ancient codes with the right characteristics was a challenging adventure. We had to rule out fragmentary codes whose tablets got mangled in their journey to the present. We also ruled out codes that dictate punishments in multiple, incommensurable metrics (e.g., exile, burning). Luckily, the Laws of Eshnunna preserve enough offenses punished on a common metric (fines). The Tang Code—the earliest Chinese code that we know of—is geographically and culturally remote from both Eshnunna and our participants, so this code was good too.

Working with these ancient legal codes was very rewarding. You can recognize the human anatomy in Tang portraits, in Eshnunna figurines, in 200,000-year-old skeletal remains. But behavior doesn’t fossilize, so the lives of our human ancestors are shrouded in epistemic fog. The Eshnunna and Tang laws gave us an unusually precise glimpse into the moral and institutional lives of ancient peoples. Doing research with these laws was the next best thing to time travel.

Human social life is intensely evaluative. We are consumed by what’s hot and what’s not, what’s cool and what’s uncool. We suspect that the human psychology of social evaluation is the same everywhere. We also suspect that social evaluations shape various institutions, including criminal justice systems, via emotions, moral judgments, punishment decisions, and other elements of our psychology. If those things are true, then there may be structural correspondences between thoughts, behaviors, and institutions when those are based on social evaluations. And these correspondences may be seen across cultures that are mutually remote in space and time. In our paper we show a handful of these correspondences. But a vast space remains to be explored. As they say, more research is needed.

Daniel Sznycer

Assistant Professor of Psychology, University of Montreal