Self-Domestication in Bonobos and Other Animals

Self-domestication happens when the benefits of cooperation outweigh the costs:

But why and how could natural selection tame the bonobo? One possible narrative begins about 2.5 million years ago, when the last common ancestor of bonobos and chimpanzees lived both north and south of the Zaire River, as did gorillas, their ecological rivals. A massive drought drove gorillas from the south, and they never returned. That last common ancestor suddenly had the southern jungles to themselves.

As a result, competition for resources wouldn't be as fierce as before. Aggression, such a costly habit, wouldn't have been so necessary. And whereas a resource-limited environment likely made female alliances rare, as they are in modern chimpanzees, reduced competition would have allowed females to become friends. No longer would males intimidate them and force them into sex. Once reproduction was no longer traumatic, they could afford to be fertile more often, which in turn reduced competition between males.

"If females don't let you beat them up, why should a male bonobo try to be dominant over all the other males?" said Hare. "In male chimps, it's very costly to be on top. Often in primate hierarchies, you don't stay on top very long. Everyone is gunning for you. You're getting in a lot of fights. If you don't have to do that, it's better for everybody." Chimpanzees had been caught in what Hare called "this terrible cycle, and bonobos have been able to break this cycle."

This is the sort of thing I write about in my new book. And with both bonobos and humans, there's an obvious security problem: if almost everyone is non-aggressive, an aggressive minority can easily dominate. How does society prevent that from happening?

Posted on February 17, 2012 at 6:25 AM • 23 Comments


JanneFebruary 17, 2012 7:33 AM

My guess: ostrasization. Once a large majority of individuals are nominally non-aggressive, then the rare individual that tries to use violence will be rapidly beat up, shunned and expelled from the group. Left to fend for themselves with no help from the group they will fare very poorly. Remember, just because you're nice to others in your group it doesn't mean you are not capable of serious violence if needed.

Or, in other words, being nice is an evolutionary stable strategy once it gets to dominate the pool of strategies.

bvFebruary 17, 2012 7:55 AM

Isn't the problem of emergent aggressive sub-group in a non-aggressive group studied in evolutionary biology as the hawk-dove game?

John Maynard-Smith had worked on the Evolutionary Stable Strategy for the Hawk-Dove game, IIRC.

bobFebruary 17, 2012 7:59 AM


Ostracism only works in small isolated groups.

Once the ostracised get to a certain number, you're back with the original problem again.

Ostracism can work in non-isolated groups as long as the ostracised can escape, eg, Mennonites or as in the book, "The Dispossessed".

VadimFebruary 17, 2012 8:06 AM

Replace elections by sortition this way the percentage of dominant individuals in the elites will be the same as in the rest of population.

CreosoteFebruary 17, 2012 8:17 AM

> if almost everyone is non-aggressive, an aggressive minority can easily dominate

Aggressiveness has a cost in terms of competitiveness (intended as ability to survive and breed) because it brings more risks: even if inter-specific fights rarely ends with death, a serious injury can prevent food gathering, and a scratch can easily result fatal by septicemia.
Even reduced cooperation may be a serious issue for social animals that rely on the pack for improving protection and food gathering.

Above the average aggressiveness in some conditions may easily become a disadvantage, when its costs outweigh the benefits that a dominant position in the pack would bring.

phred14February 17, 2012 8:39 AM

I first read about bonobos many years ago, about the time one of the early Linux GNOME releases was named after them.

The way that article put it, bonobos were brachiating apes (swinging from the trees) living with plenty of food, and therefor got as big as they could be. Their size was limited by the ability to swing from branches, not by food availability, etc. As a result, females were as big and powerful as males, and didn't have to put up with any guff. They could accept sexual advances they liked and reject those that they didn't like. Rude males were rejected, and the rest was history, breeding, evolution, and that kind of thing.

But the key to it all was the equal size and power forced by an external limit.

Carl February 17, 2012 8:47 AM

"How does society prevent that from happening?"

RKBA, and remembering the difference between aggression and defense.

VlesFebruary 17, 2012 8:50 AM

Excuse double post..but the above means I contradicted myself in an earlier post comparing the prison system to a poor implementation of ostracism. Justice used to be something far more straightforward: an eye for an eye or a tooth for a tooth, pay monies or chop some body part off. Somewhere, somehow punishment (by law) morphed into this friendly version of ostracism called imprisonment...did we error?
(A prison used to be the place you were placed in while awaiting your punishment. Now it has become the punishment...)

Bob TFebruary 17, 2012 8:55 AM

We love them until they can love themselves.

"Because, I’m good enough, I’m smart enough, and dog-gone it, people like me." Stuart Smalley

ChuckFebruary 17, 2012 8:56 AM

I don't understand the statement, "As a result, competition for resources wouldn't be as fierce as before."

What limits the bonobo population if not some finite resource---food, living space?

Many species exist on the Malthusian edge, why not bonobos? If on that edge, would there not be competition for resources?

ankleFebruary 17, 2012 9:34 AM

The problem with the non-aggressors trying to get the aggressors to do anything (like stay out for 10 years because they're being ostracized) is that the non-aggressors aren't aggressive, and thereby have no power over the aggressors.

carlFebruary 17, 2012 10:30 AM

I think the most important point is
the forming of alliances by the females

I am not sure how exactly it developed but I think the mechanism is clear:

-more food resources means bigger groups,
means more potential for alliances,

-allied individuals are more powerful than the strongest single,
females with natural close mother-child relationships are better at forming relationships
The hierarchy is not formed through who is strongest in a "duel",but by who can call more allied friends in a conflict.
So even a physically weak male who has a powerful mother with lots of allied females has a higher rank than a physically stronger male with a lower ranking mother.

-and also the "invention" of sex as a bonding tool
(Bonobos are famous for being sexually permissive and promiscuous using sex for fun and bonding,
reconciling etc,there are even detailed reports describing young females actively courting older females for their friendships by staying close to them, imitating them,friending them
and also having some kind of lesbian sex)

for more I recommend the books by Frans De Waal

JessFebruary 17, 2012 12:56 PM

@Chuck: "What limits the bonobo population if not some finite resource---food, living space?"

This is an insightful question. The most charitable way to understand what they're saying, if we can assume some understanding of ecology (can we assume that anthropologists have such?), is that the proto-bonobos were still food-limited, but that the value of aggression in competing for food decreased with the absence of gorillas as food competitors. It's far from obvious to me, however, that aggression would be more important in food competition with a larger, stronger species than e.g. speed, stealth, or cooperation. If this is the extent of current research, it's still at a very speculative stage.

Evo-psych is an attractive nuisance for imaginative researchers, always ready to beguile them with non-testable and non-generative etiologies. It's useful as inspiration, but rarely as a source of "truth".

ZachFebruary 17, 2012 4:05 PM

The simple answer is to indoctrinate empathy and the importance of social cohesion. There is still the problem of sociopathy (meaning individuals who lack empathy and treat other persons as expendable in pursuit of their goals), but as Vles points out above, the point of a prison is not merely to isolate undesirable or criminal individuals, but to do something with them which ends their undesirable behaviors.

Some people don't stop hurting others to get what they want. I'm already on the next question, of what to do with these people. We have sufficient resources right now to feed all humans on the planet; the problem is that some people want to confiscate and regulate most or all available resources for their own benefit at the expense of others.

AlobarFebruary 17, 2012 6:00 PM

Very interesting post.

This winter I have been doing my own domestication of wild mice experiment.

Every winter I get invaded by mice. They fight with one another. They do not cooperate. They steal my food and eat my paperwork.

This winter I decided to feed the mice until Spring when I can trap them with live traps and put them back outside.

It took a few weeks for the mice to realize that I keep their food dish full. Then the fighting and rape ceased. Mice stand shoulder to shoulder at the food dish and water dish.

They no longer steal my food or eat my paperwork.

They no longer walk thru the food dish, so the dish remains free of mouse turds.

Impossibly StupidFebruary 18, 2012 8:40 AM

Looking at humans under the same circumstances the answer seems to be: the normally non-aggressive majority gets aggressive and they line the bastards up against the wall. It hasn't become an American import just yet, but it has been popular in countries around the world.

The real problem, for humans at least, is that we seem to be aggressive by nature. After deposing a dictator, rather than saying "Oh, that was distasteful; well, back to my farm to live in peace!" too many get enamored by the immediate power of violent confrontation. For some reason, the powers-that-be never seem to figure out the long-term danger of chaos until it is far too late . . .

JardaFebruary 18, 2012 9:12 AM

"And with both bonobos and humans, there's an obvious security problem: if almost everyone is non-aggressive, an aggressive minority can easily dominate. How does society prevent that from happening?"

The question is rather: When are the humans going to learn something from bonobos?

JerryFebruary 18, 2012 1:22 PM

There was an interesting incident in some bonobo populations studied by Dr Robert Sapolsky where the alpha males of a tribe died after eating spoiled food from a garbage dump. Their alpha status gave them exclusive access to that food. The tribe learned that life without alpha males was good and systematically rejected alpha traits in new arrivals. I wonder if the bonobo tribe Dr Hare studied is a close relative to this one.

If I recall correctly the incident is mentionned in this National Geographics documentary.

VlesFebruary 19, 2012 4:10 AM

to indoctrinate empathy and the importance of social cohesion

A quality of a resilient community is the power to expel. You ostracise. Maybe the key word such communities is trust.

Flipping it (musing)
A quality of a non-resilient community is the power to include. You subue. Maybe the key word in such communities is control. Your Richard Sennett describes ample examples of the application of "Weber cages".

A community based on control that gets too large will fragment into smaller ones based on trust?

A community based on trust will only ever scale to a certain size? What size?

...The philosophy of to divide and conquer seems to pay respect to letting established communities be, for fear of upsetting a balance...

Some people don't stop hurting others to get what they want. I'm already on the next question, of what to do with these people.

...Maybe they're just in the wrong line of work. Or in the wrong type of community...

Can't find this example I once read about modern day warfare re suburban combat and the US brass realising control wasn't working so well all the way down to the platoon / squad level when operating in city streets etc. Events would so quickly evolve, that rather than controlling the OODA loop at high level, they choose to invest more trust in their sergeants and therefore give them more freedom to act. I'm sure it had Alvin and Heidi Toffler's name written on it. Maybe it was War and Anti war or the Third Wave. He around? :o)

Nancy LebovitzFebruary 22, 2012 7:25 AM

Jerry, Sapolsky studies baboons, not bonobos.

What happened is that normally young male baboons join new troupes and are mistreated by older males.

When the alphas in one troupe died of disease, new males weren't mistreated, and the culture of violence evaporated.

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