October 10, 2008
Humans Evolved Egalitarianism In Pleistocene Era

The Pleistocene era that ended 10000 years ago saw the development of human societies less hierarchical than other ape societies. How did this happen? A mathematical model of human social structures suggests that the development of egalitarian human societies came about in a small number of generations.

Although anthropologists and evolutionary biologists are still debating this question, a new study, published in the open-access journal PLoS ONE, supports the view that the first egalitarian societies may have appeared tens of thousands of years before the French Revolution, Marx, and Lenin. These societies emerged rapidly through intense power struggle and their origin had dramatic implications for humanity. In many mammals living in groups, including hyenas, meerkats, and dolphins, group members form coalitions and alliances that allow them to increase their dominance status and their access to mates and other resources. Alliances are especially common in great apes, some of whom have very intense social life, where they are constantly engaged in a political maneuvering as vividly described in Frans de Waal's "Chimpanzee politics".

In spite of this, the great apes' societies are very hierarchical with each animal occupying a particular place in the existing dominance hierarchy. A major function of coalitions in apes is to maintain or change the dominance ranking. When an alpha male is well established, he usually can intimidate any hostile coalition or the entire community.

Note that humans still place great importance in status and power. A substantial portion of human behavior is aimed at achieving and demonstrating higher status. The human shift toward a more egalitarian model has been only partial. We still have plenty of genetic influences on our brains that make us desire higher status and power. Possibly human populations differ in their frequencies of alleles for egalitarian preferences versus hierarchical tendencies based on different selective pressures in different parts of the world.

In sharp contrast, most known hunter-gatherer societies are egalitarian. Their weak leaders merely assist a consensus-seeking process when the group needs to make decisions, but otherwise all main political actors behave as equal. Some anthropologists argue that in egalitarian societies the pyramid of power is turned upside down with potential subordinates being able to express dominance over potential alpha-individuals by creating large, group-wide political alliance.

What were the reasons for such a drastic change in the group's social organization during the origin of our own "uniquely unique" species? Some evolutionary biologists theorize that at some point in the Pleistocene, humans reached a level of ecological dominance that dramatically transformed the natural selection landscape. Instead of traditional "hostile forces of nature", the competitive interactions among members of the same group became the most dominant evolutionary factor. According to this still controversial view, known as the "social brain" or "Machiavellian intelligence" hypothesis, more intelligent individuals were able to take advantage of other members of their group, achieve higher social status, and leave more offspring who inherited their parent's genes for larger brain size and intelligence. As a result of this runaway process, the average brain size and intelligence were increasing across the whole human lineage.

I like this "Machiavellian intelligence" hypothesis. But we also evolved higher intelligence in order to better manipulate tools and our physical environment. Our spatial reasoning was probably not selected for in order to better engage in Machiavellian intrigue.

As people became smarter they became more able to form alliances against dominant alpha males. So intelligence increased the bargaining power of betas? Did the rise in human intelligence then cause a selection for personality traits characteristic of betas?

Also increasing were the abilities to keep track of within-group social interactions, to remember friends and their allies and enemies, and to attract and use allies. At some point, physically weaker members of the group started forming successful and stable large coalitions against strong individuals who otherwise would achieve alpha-status and usurp the majority of the crucial resources. Eventually, an egalitarian society was established. Although some of its components are well supported by data, this scenario remains highly controversial. One reason is its complexity which makes it difficult to interpret the data and to intuit the consequences of interactions between multiple evolutionary, ecological, behavioral, and social factors acting simultaneously. It is also tricky to evaluate relevant time-scales and figure out possible evolutionary dynamics.

A paper published in PLoS ONE today makes steps towards answering these challenges. The paper is co-authored by Sergey Gavrilets, a theoretical evolutionary biologist, and two computer scientists, Edgar Duenez-Guzman and Michael Vose, all from the University of Tennessee, Knoxville.

They developed a computer model to reach their conclusions. Keep in mind that two different computer models might produce the same result (greater sharing of resources in alliances) with different assumptions and mechanisms. We can't tell whether ideas in the minds of Pleistocene humans or genes that coded for alliance-oriented behavior were the bigger driving forces. One can easily imagine these two influences feeding on each other though.

Ideas in the head of one "cave man" (or should I say "savannah man"?) could have caused that guy to look at all the other people in his group and seek out those whose personalities were most amenable to alliance formation. Any genetic alleles that favored alliances could have been there for other reasons but the thoughts in one mind could have caused one guy to reach out to those with compatible genetic alleles and get them all to behave in ways (e.g. fighting as a group and splitting spoils evenly) that promoted the spread of those alleles.

To develop egalitarian societies larger scale conflicts are needed. This puts a much more positive spin on war, doesn't it? Having external enemies to focus on helps keep alliances together.

The model also highlights the importance of the presence of outsiders (or "scapegoats") for stability of small alliances. The researchers suggest that the establishment of a stable group-wide egalitarian alliance should create conditions promoting the origin of conscience, moralistic aggression, altruism, and other cultural norms favoring group interests over those of individuals. Increasing within-group cohesion should also promote the group efficiency in between-group conflicts and intensify cultural group selection.

A better organized group is going to wipe out less organized groups. Once group-level organization gets a foothold any genetic variants that helped favor it would get selected for and spread. Higher intelligence might have catalyzed the spread of alleles for higher intelligence and alleles for greater egalitarian behavior.

Is communism not possible because the spread of egalitarian alleles hasn't gone far enough? Too many of the old hierarchical alleles are still around? I suspect another explanation: The egalitarian alleles were selected for to enable groups to compete with other groups. Humans competed for resources and for the vast bulk of human history resource limitations made hunger widespread and the competition for resources fierce. Egalitarianism and competitive urges are key elements of human nature and egalitarianism's development came about to help people compete more effectively.

See also Cochran And Harpending See Human Evolution Acceleration and Cochran And Hawks Detect Human Evolution Acceleration.

Share |      Randall Parker, 2008 October 10 12:15 PM  Evolution Human Nature

Kralizec said at October 10, 2008 7:09 PM:

"The people, being unable to govern themselves, must first choose leaders." (Allan Bloom, The Closing of the American Mind)

"We call ourselves citizens, but most of us are, at best, voters." (Harvey C. Mansfield)

"Every democracy is really an oligarchy, unless it verges on anarchy." (Leo Strauss)

Randall Parker said at October 10, 2008 7:20 PM:


I think what egalitarian democratic voters try to do is to select someone who won't take as much from them. Egalitarians know they aren't going to achieve perfect equality. They seek to avoid the more extreme forms of being dominated.

Kralizec said at October 10, 2008 7:51 PM:

Hi Randall,

I agree with you that there are sensible sorts of egalitarianism and egalitarian arrangements. I'm often moved to make tart remarks about egalitarianism by my fear and loathing of the sorts of radical "egalitarians" whose desires and doctrines actually tend to increase the power of a few men who present themselves as egalitarian saviors or experts. It's the "egalitarian" vanguard I loathe, the men who think they should rule the rest because of their superior egalitarianism.

averros said at October 10, 2008 8:50 PM:

Communism (socialism, to be more precise, for communism is a kind of socialist eschatology, totally impossible in the physical world) is impossible because it cannot exist economically. That was proven back in 1920 by von Mises.

And "the scientists" seem to be curiously ignorant about primatology (and zoology in general). Bonobos, for example, are a lot more "egalitarian" (meaning network-shaped socium rather than hierarchial) than humans.

The true "egalitarism" is found only in eusocial species - but is always based on firm reproductive control, so the entire population is, basically, a bunch of clones.

James Bowery said at October 10, 2008 10:31 PM:

Don't confuse egalitarianism with individualism.

Don't confuse competition with alpha males by beta males with escape from alpha males by those that expand humanity's ecological range with technology.

Tj Green said at October 11, 2008 8:17 AM:

The predator prey arms race, where survival strategies become the dominant creative force within the constraints of environmental factors, starts to break down for our species. With the emergence of psychopathic leaders, the predator prey arms race continues within a species. You have to be intelligent to survive endless tribal conflicts. David (probably psychopathic) and Goliath, brain against brawn.

Ken Hahn said at October 11, 2008 1:53 PM:

Cooperation is most effective when applied to competition. From sports teams to business enterprises to families, humans best cooperate to compete with other groups. Communism cannot work because it eliminates competition and demands cooperation without competitive rewards. The new socialist man does not and cannot exist because rewards for hard work and cooperation become counterproductive to what matters to humans, family, group or personal advancement. When rewards are equally distributed, regardless of effort, the incentive is to put in as little effort as possible.

James Bowery said at October 11, 2008 2:04 PM:

When rewards are equally distributed, regardless of effort, the incentive is to put in as little effort as possible.

Likewise, when rewards are distributed by windfall to those in possession of "land" -- economic rent -- then the incentive is to acquire property and prevent the creation of alternative "land". This is essentially what prematurely terminated the opening of frontiers like the ocean and space.

The solution is to distribute economic rent as citizens' dividends so people don't engage in zero-sum games in either the public or private sectors.

Geoff said at October 11, 2008 3:52 PM:

Honestly, evolutionary conjectures like these have almost no real explanatory power.

Evolution can explain adultery and monogamy. Hierarchy and egalitarianism. Being mean and being nice.

It explains nothing because it can predict nothing. It is just a tautology with a post hoc explanations. Whatever survives survives.

Kralizec said at October 12, 2008 1:01 AM:
The solution is to distribute economic rent as citizens' dividends so people don't engage in zero-sum games in either the public or private sectors. (James Bowery, on October 11, 2008, at 02:04 PM)
It seems that either one can talk about a problem in everyday language or one cannot. If one can, then it seems better to do so. If one cannot, it nevertheless seems necessary to begin with the listener's or reader's own language and help him develop it in ways one thinks will deepen his understanding of the problem.
Boulis said at October 12, 2008 2:52 AM:

Hm, I am far from an expert on the topic of human evolution, but as a historian I have to say I am more than a little confused by some of the suppositions drawn in this article. For example, many researchers believe that the entire world population at the very end date of the period you are describing (i.e. 10,000 B.C.) hovered somewhere between 1 and 10 million people, presumably divided into relatively small hunter-gatherer bands/tribes. (See http://www.census.gov/ipc/www/worldhis.html) So even at this late date, intra-band contact (much less conflict) would have been rare. Moreover, the incentive for prolonged conflict between bands (you mention the word "war") would have been negligible since the nomadic nature of hunting and gathering would make it more likely the weaker band would simply migrate somewhere else rather than risk extinction at the hands of the stronger one.

There was competition for resources of course: competition that may have occasionally resulted in mini-wars of "extinction." But such events would have been exceedingly rare before the advent of settled agriculture (Neolithic Revolution - also 10,000 B.C.) given that you could always hunt and gather somewhere else. It is the sedentary nature of agriculture that tied people to parcels of territory and made war commonplace. Incidentally, farming also led to population growth and increasingly complex societies that were far more hiearchical than hunter-gatherer societies. Even if cooperation assured survival before the Neolithic Revolution, a society of orders and ranks became the norm after the arrival of agriculture.

lvt_fan said at October 12, 2008 3:30 AM:

It seems that either one can talk about a problem in everyday language or one cannot.

No, for once Jim Bowery is absolutely right - see Land value tax and Economic rent for an "everyday language" explanation of these issues. Levying a LVT is THE most effective way to cool down a bubbling real-estate market - the Chinese did exactly this and they had no real estate crisis, despite a savings rate among the highest in the world. Japan's real-estate and banking crisis in the 80's occurred when they started phasing out their traditional land tax.

Really, it's yet another example of an economically beneficial policy which has no chance in hell of being enacted here, for purely political reasons.

Bill White said at October 12, 2008 9:10 AM:

Current events (Obama vs McCain in Florida) gives us one example of this:

A better organized group is going to wipe out less organized groups.

Recent reports of infighting within the Florida GOP appear to be hampering united efforts to defeat Obama.

For example, Charlie Crist's people are blaming McCain for choosing Palin rather than Crist himself and there was a publicized spat over party leader Greer being refused a seat on Palin's charter, so he chartered his own plane at Party expense.

Thus we see the self interest of various Florida politicians weakening McCain's efforts to defeat Obama.

Faruq Arshad said at October 12, 2008 1:44 PM:

This strikes me as conjecture. I mean, there are many theories regarding depression,such as rank theory,chemical theory etc,etc. In a similar way these theories about human in the distant past are not really tested,but just theories.

Kralizec said at October 13, 2008 1:06 AM:
Geoff said at October 11, 2008 03:52 PM:

Honestly, evolutionary conjectures like these have almost no real explanatory power.

Evolution can explain adultery and monogamy. Hierarchy and egalitarianism. Being mean and being nice.

It explains nothing because it can predict nothing. It is just a tautology with a post hoc explanations. Whatever survives survives.

These remarks seem quite offhand, even flippant. They don't seem to be intended to raise problems in one's reasoning in such a way that one can continue and improve one's inquiry; instead, they seem intended merely to stop the inquiry and dismiss it altogether. One perhaps could not have predicted that these particular remarks would be such a confused mess, but an explanation for the mess is readily available: For the sake of bringing the inquiry to a grinding halt, self-contradiction and disorderliness work better than coherency and order.
Randall Parker said at October 13, 2008 6:14 PM:


Geoff is dismissing the power of natural selection by saying basically it is all an accident. Some people do not want to accept that we were shaped by evolution and that we are capable of figuring out how we were shaped by evolution.

Take adultery and monogamy for example. We already have candidate alleles for influencing this. Vasopressor receptor variations control whether voles are monogamous. Well, for humans a similar mechanism appears to be at work:

Hasse Walum at the Karolinska Institute in Stockholm, Sweden, and colleagues looked at the various forms of the gene coding for a vasopressin receptor in 552 Swedish people, who were all in heterosexual partnerships. The researchers also investigated the quality of their relationships.

They found that variation in a section of the gene called RS3 334 was linked to how men bond with their partners. Men can have none, one or two copies of the RS3 334 section, and the higher the number of copies, the worse men scored on a measure of pair bonding.

Not only that, men with two copies of RS3 334 were more likely to be unmarried than men with one or none, and if they were married, they were twice as likely to have a marital crisis.

And yet some claim our evolutionary past has no explanatory power.

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