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The Z-Curve of Human Egalitarianism

As I wrote in yesterday’s blog, Robert Bellah’s Religion in Human Evolution is a complex book that addresses many roles of religion in human social evolution. One theme that I was particularly interested in was the influence of religious developments on the evolution of human egalitarianism, especially during the Axial Age. The starting point for approaching this question is what is sometimes called as the ‘U-shaped curve of despotism’ in human evolution. We know that our closest relatives, the chimps and gorillas, live in fairly ‘despotic’ or inegalitarian societies. The chimps, for example, establish linear dominance hierarchies, in which alpha males get better food and greater access to females. We don’t know for sure whether human ancestors also lived in similarly inegalitarian societies, but it seems likely.

In contrast, as was argued by Christopher Boehm in Hierarchy in the Forest: The Evolution of Egalitarian Behavior, human hunter-gatherers, who lived in small-scale societies before agriculture, were fiercely egalitarian. High degree of equality does not simply happen because hunter-gatherers are poor and cannot accumulate much wealth (chimps also cannot accumulate wealth). No, equality requires active maintenance. People living in small-scale societies possess numerous norms and institutions designed to control ‘upstarts’ – those who attempt to set themselves as alpha-males so that they can gain control of an unfair share of resources (including females). The sanctions deployed against upstarts range from gossip and ridicule to ostracism and, ultimately, assassination.

Thus, until c.10,000 years ago, before agriculture was invented, the human evolutionary trend was that of increasing egalitarianism. The adoption of agriculture, however, enabled the rise of large-scale societies organized as states and empires with highly unequal distributions of power, wealth, and social status. In other words, the trend to greater equality reversed itself. What accounts for this U-turn? Why did humans allow inequality to develop?

The answer apparently is that the U-turn was a side effect of the transition from small-scale to large-scale societies. Small-scale societies of hunter-gatherers were integrated by face-to-face sociality. Such a diffuse, non-centralized social organization was well-suited to maintaining egalitarian ethos. However, once the size of cooperating group increases beyond 100­–200 people, even gigantic human brains are overwhelmed by the demands of face-to-face sociality (this is the argument made by Robin Dunbar). Shifting from diffuse, uncentralized social organization to hierarchical organization (as chains of command) allowed evolution to break through the upper limit on society size imposed by face-to-face sociality. A member of a hierarchically organized group needs to have face-to-face interactions with only a few individuals: a superior and several subordinates. Such links can connect everybody in a group of arbitrarily large size. The group size grows by adding additional hierarchical levels.

So far so good, but the great downside of hierarchical organization is that it inevitably leads to inequality. Once you allow a leader to order everybody around, he will use the power to feather his nest. This is sometimes known as the iron law of oligarchy.

I have argued elsewhere that conditions of endemic warfare between human groups create enormous selection pressures for larger group size (“God is on the side of big battalions”) and for effective (which means centralized) military organizations. Under such conditions, emergence of centralized military hierarchies becomes virtually inevitable. The result is the rise of increasingly complex centralized societies – chiefdoms, complex chiefdoms, and archaic states.

As Bellah notes, archaic states were characterized by enormous fusion of power in the person of the ruler. Almost invariably the rulers of such states were ‘divinized’, that is, considered to be gods as well as kings. They had literally the power of life and death over their subjects. One frequent characteristic of early centralized societies was the practice of massive human sacrifice. This naked pursuit of power and voracious appetite for consuming resources is reflected in such characterizations of rulers as a land shark who ‘eats’ island (in Hawaii), or a big rat that gobbles people’s millet (in archaic China).

Thus, although highly effective on the battlefield, a centralized military hierarchy has several drawbacks as a general way of organizing societies. A society cannot really be held together by force alone. Worse, great inequities resulting from rapacious military chiefs and their retinues alienate large segments of the population. As a result, early despotic chiefdoms and archaic states were very fragile and frequently did not outlast their founders.

The tension between the human preference for equitable outcomes and the need for centralized hierarchy brought about the “legitimation crisis of the early state” (this idea was borrowed by Bellah from Jürgen Habermas). The tension became particularly acute during the Axial Age (c.800–200 BCE), for reasons discussed in my review of Bellah’s book and other publications. One central argument in Bellah’s book is that the new world religions and philosophies that arose during the Axial Age began the long job of building more equitable societies. A large part of this evolution was imposing limits on the power of rulers and replacing power based on naked force with legitimate authority.

This is a very interesting idea. Further, whatever the explanation, it seems clear to me that empirically the post-axial period saw a general trend of human evolution away from the peak of despotism, which was achieved in archaic and early-axial states and empires. In particular, such extreme forms of inequality as human sacrifice, slavery, and distinction in legal status (such as that between nobles and commoners) have been gradually disappearing over the last 2.5 thousand years. God-kings have gone out of fashion, and what royalty are left have been relegated to an entirely ceremonial function. The spread of democracy in the last couple of centuries have imposed more effective restraints on the rulers. The only exception to this overall trend towards greater egalitarianism is that economic inequality remains as large as ever (and, in fact, has been growing over the last three decades in, for example, the US). Still, overall it appears that the peak of despotism (massive concentration of power within the hands of the ruler and the ruling clique) took place in archaic states.

If this is correct, and I believe it is, then the implication is that the evolution of egalitarianism in humans was not just a U-shaped curve, but a more complex trajectory. After ‘zigging’ to greater inequity during the pre-axial period, the trajectory than ‘zagged’ back to greater equity in the last 2.5 thousand years. I propose that we call this evolutionary pattern the Z-curve of human egalitarianism.


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  1. I found myself liking this argument, until I thought of the examples of Stalin and Mao. I would have to say that they had power nearly as absolute as the pharoahs after they had been at the top for a while. The nations with fascist dictators in the mid-20th century also found it difficult to remove their leaders once they were no longer popular. So whatever the reason for the zig-zagging on egalitarianism, it would appear to be even more convoluted than a “Z”. I’m guessing it’s something about the technology available for central control vs. the technology available for networking among non-central agents.

  2. Peter Turchin says:

    Historical dynamics is ‘fractal’, which means that on top of millennial trends (the subject of the post) are superimposed shorter cycles – secular, bigenerational, etc. More on this in my book War and Peace and War (see Chapter 11: Wheels within Wheels). For example, economic inequality waxes and wanes with the secular cycle, and the current waxing of inequality in the US fits this patterns.

    So the despotisms of the Third Reich and Stalin’s USSR should be viewed in this context. Both of them were short-term ‘blips’: Hitler’s regime lasted from 1933 to 1945, and Stalin’s from c.1930 to 1953. Note that Stalin’s regime was not defeated by external forces, but ended as a result of internal reforms.

    Similar dynamics occurred with the regimes of Mao, Pol Pot, Khomeini, Japanese fascism, etc. Just the fact that all those regimes were very short-lived suggests that they were aberrations against the ‘overall sweep of history.’