Mind the Economy/Justice 110

Only where there is peace can there be justice. The evolutionary roots of our morality

Human evolution has shaped concepts of justice, cooperation and punishment

22 June 2025

6' min read

Justice is not born with codes. It is not born with courts, nor with constitutions. Justice, as we imagine it or seek it today, is only the most recent outcome that has seen ideas and practices go through a long, very long, evolutionary history. A history that begins long before the invention of writing, of the state, of agriculture. A story that begins in the Pleistocene, when our remote ancestors lived in small hunter-gatherer groups and had two enormous challenges in front of them: to cooperate in order to face the dangers of a hostile environment together while living together peacefully. The main obstacle to achieving these two goals lies in the opportunism, prevarication, and violence that some would be tempted to engage in to try to obtain the maximum benefit at the minimum cost. This is why our ancestors had to learn to punish those who did not respect the rules.

Christopher Boehm, an American anthropologist and primatologist, has devoted his life to the study of dozens of hunter-gatherer societies still to be found in the remotest parts of the country with the aim of reconstructing, through them, the social dynamics of our distant ancestors. The starting point of his work is in itself paradoxical: human beings are hierarchical animals, but for tens of thousands of years they lived in deeply egalitarian societies. Why? Boehm's answer is simple but counterintuitive: egalitarianism is not the absence of hierarchy, but an 'inverted' form of hierarchy. In these societies, in fact, power is there and is exercised, but this power is not concentrated in a leader. In fact, in these groups, power is de-centralised, that is, distributed among all the members of the group. This horizontal distribution of power has two main advantages: firstly, it allows effective and reciprocal monitoring of each group member's behaviour by all the other members; secondly, in the event that any violation of social norms were to emerge, it would be realised that someone was trying to impose himself on the others - the so-called 'upstart' - they would be systematically reprimanded, through a warning, by being ostracised and expelled from the group or, in the most serious cases, even by death. "Hunter-gatherer societies," writes Boehm, "are politically egalitarian because their members band together to prevent anyone from dominating others" (Hierarchy in the Forest: The Evolution of Egalitarian Behaviour, Harvard University Press, 2001). Justice, in this context, appears far from a mere philosophical abstraction, it appears rather as a social technology. To be just means to collectively protect the group, its autonomy and cohesion. Being just means acting to ensure that the greed of the few and prevarication do not get the upper hand.

Richard Wrangham, a Harvard anthropologist, has taken this insight to its extreme consequences. In his The Paradox of Goodness. The strange relationship between coexistence and violence in human evolution (Bollati Boringhieri, 2019), Wrangham argues that humans are 'self-domesticated'. Just as dogs descend from wolves that were selected for their docility, so too Homo sapiens would descend from more aggressive ancestors, selected - unwittingly - for their meekness. 'Man,' Franz Boas wrote as early as 1938, 'is not a wild form [...] but must be compared to domesticated animals. He is a self-domesticated being' (The Primitive Man. Laterza, 1995). 'Our docile behaviour,' Wrangham adds, 'is reminiscent of that of the domesticated species, and since no other species can have domesticated us, we must have done it ourselves. But how? Through physical elimination. This could take various forms: from deliberate executions in which, in the absence of prisons or police, the only way to maintain order and cooperation was to execute individuals who threatened group cohesion to the formation of coalitions whereby group members allied themselves to oppose the 'would-be despots', the alpha males. Punishments could be extremely violent - hanging, drowning, stoning, or delivery to hostile groups. The variety of methods reflected the importance of social deterrence. There could also be forms of preventive social control to ensure that aggressive behaviour was discouraged from an early age through social criticism and cultural pressures. These mechanisms would have acted as a form of natural selection. Aggressive males who were eliminated were prevented from passing on their genetic heritage to subsequent generations, and with it violent and prevaricating behavioural patterns. Generation after generation, slowly but surely this process has led to a progressive reduction of aggressiveness in our species. This sort of 'self-domestication' has left deep traces in our anatomy and behaviour. Modern humans, in fact, have a more puny body, a less prominent face, a slightly smaller brain than the Neanderthals and Homo of the Middle Pleistocene, greater 'neoteny' (the preservation of youthful traits into adulthood), reduced 'reactive' (i.e. impulsive and uncontrollable) aggression, and greater sensitivity to reputation and shame. All these traits are part of the so-called 'domestication syndrome', also observed in many other domesticated animal species. 'It is not a series of adaptive traits,' Wrangham writes, 'each shaped by evolutionary pressure to respond to a human environment. Instead, it is a series of largely useless traits that signal an evolutionary event. The domestication syndrome reveals that the species in question has recently undergone a reduction in reactive aggression'.

Darwin had also noticed something similar. In The Origin of Man he wrote 'Man may in many respects be compared to those animals which have long since been domesticated'. But the insight was never followed by a convincing explanation and so he ended up considering it a weak hypothesis. Yet, in another passage in the same book, Darwin suggests that social selection - through the exclusion or execution of aggressive individuals - may have played a role, for 'In mankind,' Darwin writes, 'some of the worst characters, which without any apparent cause sometimes appear in families, may represent reversions to the savage state, from which we are not many generations removed.

If Christopher Boehm has shown that justice is a social technology created to preserve egalitarian social structures and thus group cohesion, Richard Wrangham has made us realise that it also exerts evolutionary pressure. Justice, in this sense, is not just a set of norms: it is a selection mechanism. A way of rewarding the cooperative and punishing the overbearing. A moral filter that has shaped our species. And this filter has worked because human beings are deeply social animals. As Wrangham writes, 'We have evolved to be an affable and cooperative species, whose selfish impulses are more muted than in the past. We are fortunate to be better equipped to resist the temptation of violence than a chimpanzee or a Middle Pleistocene Homo'.

But self-domestication also has a dark side. For while it has contributed to the reduction of impulsive violence - the 'reactive aggression' of which Wrangham speaks - it has also left intact, or even enhanced, 'proactive aggression', that which is planned, cold, instrumental. It is the aggression of wars, genocides, ideological persecutions. "Human beings," he writes in this regard, "are neither entirely good nor entirely bad. We have evolved in both directions simultaneously. Both tolerance and violence are adaptive tendencies that have been instrumental in getting us where we are. The idea that human nature is both virtuous and evil creates some problems for us, since we would probably all prefer simplicity (...) The moral contradictions of our ancestors should not prevent us from making a realistic assessment of who we are. If we succeed, we still have hope'.

The transition from Palaeolithic to modern justice is not linear. But some continuities are surprising. The centrality of reputation, for example: today as then, being perceived as righteous is often more important than actually being so. The role of shame, a social emotion to which we often give more weight than the punishment itself. The role of the latter, then, understood not so much as revenge, but as a deterrent. Moral conscience, that which makes us capable of feeling shame, guilt, empathising with others, would thus be the result of a long process of social selection. It is not a divine gift, nor a rational invention: it is an adaptation. A way of living together without annihilating each other.

Even today, as in the Pleistocene savannahs, justice represents an unstable balance that constantly sways between cooperation and control, between individual freedom and collective order. And today, as then, its effectiveness depends on the ability of the group - whatever its scale - to recognise and sanction anti-social behaviour.

Thinking of justice as a product of evolution does not diminish it, on the contrary, it entrenches it. It reminds us that it is not a luxury of advanced civilisations, but a necessity of all communities. That it does not arise from a code written by rulers, but from an innate and ancient need: to live together to enjoy the benefits of cooperation, without, at the same time, destroying each other. It also reminds us that justice is never given once and for all but is a fragile achievement. It requires vigilance, adaptation, creativity, continuous moral tension. As Joshua Greene reminds us, 'The philosophy of one century is the common sense of the next' (Moral Tribes. Emotion, Reason, and the Gap Between Us and Them. Penguin, 2013) Perhaps it is time to update our common sense. And to recognise that, to meet the challenges of the present, we must first rediscover the moral roots of our distant past.

(*) Professor of Economics, University of Cagliari