Langurs and Bonobos and Chimps

Bonobos are the new darlings of the noble savage crowd.  They were bitterly disappointed by the rest of the great apes that, as recently as the 1970’s, were all supposed to be peaceful, vegetarian, and inoffensive.  When Jane Goodall and others started actually observing great apes in the wild and, as chronicled in books such as Wrangham and Peterson’s Demonic Males, found that they occasionally displayed a few less endearing traits, such as hunting and eating meat, rape, infanticide, and the use of weapons in violent border warfare and raiding, true believers in the innate “goodness” of mankind demonstrated their own nobility by subjecting the messengers to furious ad hominem attacks.  It didn’t work.  Too many observers were reporting the same thing, and the evidence was too compelling. 

Enter the Bonobo.  They supposedly possess all the “good” traits their close relatives, the chimpanzees, so notably lack.  Occasionally their halo will slip.  For example, they compete for status, just like the other great apes.  Then, too, their hagiographers will occasionally slip up.  I was at a lecture about them once at which the speaker sought to emphasize their “feminist” nature.   It seems the females in bonobo groups tend to form alliances for self-protection, and to maintain decorum among the males.  The speaker recounted how, in one of the groups, an unruly male had attempted some aggressive behavior towards one of the females.  She and her pals ganged up on the evil-doer, giving him a thorough drubbing and, in the words of the speaker, nearly tearing his scrotum completely off.  Feminism was certainly vindicated by the incident, but the bonobo’s supposedly non-violent nature less so.

Be that as it may, apart from a few such rare lapses, bonobos do seem to be a great deal less violent and generally “demonic” than their close relatives, the chimpanzees.  If estimates that they shared a common ancestor as recently as 1.5 to 3 million years ago are correct, it would seem to demonstrate a high degree of flexibility in the evolutionary toolkit pertaining to the innate behavioral traits that characterize humans as well as other animals.  On the other hand, it may be that all these observed traits are subject to greater cultural variation within species that previously imagined.  Perhaps bonobo groups can be more “demonic” than their observed behavior to date would indicate, and chimps have taken a bum rap and are really capable of more placid behavior under the right conditions. 

The inimitable Robert Ardrey drew attention to a few data points to that effect in his The Social Contract, published in 1970.  In Chapter 7 of that book he recounted a series of observations of langurs, a leaf-eating monkey widely distributed in India.  Carried out by different researchers in different locations and environments, they revealed widely divergent information about the “typical behavior” of langurs.   The first, carried out by Phyllis Jay in an area where the creatures are fairly scarce, found that troops of 25 members more or less occupied ranges of about two square miles, and rarely contacted each other.  There appeared to be no defended territories, and no evident boundaries between groups.  A rigid rank order prevailed within the groups, and serious quarrels were almost non-existent.  As Ardrey put it, they

…seemed the ideal, sunny, non-aggressive creatures of legend, and (the) study, completed in the early year of 1959, did much to reinforce the arguments of those primate students that monkeys never fight, never defend territory, never do anything but behave themselves in a fashion rarely glimpsed in human schoolyards. It was a time when we all still said that “langurs are this way.”

Then, however, an account of another study of langurs appeared, carried out this time in Ceylon by Suzanne Ripley.  Again quoting Ardrey,

Troops were of about the same size. But nowhere did there exist those infinite distances for the happy, wandering life. The troop’s two square miles of India’s central forests became an eighth of a square mile in Ceylon. And here there were not only territories, with actively defended, unchanging borders; groups sought combat. (Like chimps! Alas, Ardrey never lived to learn the truth about them or the great apes, universally believed to all be truly peaceful, vegetarian, and inoffensive at the time he wrote his books. If only he had known how thoroughly the subsequent revelations about them vindicated his hypotheses. But I digress.) Like the howler and the callicebus, the langur is a noisy monkey. Morning treetop whoops would bring defiant answers from whooping neighbors and mobilization on the border. Ritualized displays might take place, with vast leaps through the trees. But in these combats between groups true fighting could take place, too, with chasing, wrestling, biting, tail-pulling.

But wait, there’s more.  Yukimara Sugiyama of Kyoto University also went to India to study langurs, this time in the extreme of population density among the three groups, about twice that in the Ceylon study.  What he found was what has been described by others as a “behavioral sink.”  Again quoting Ardrey,

…disorder was quite nearly perfect. There were territories, but borders were obscure and ill-defended. When troops met, leaders fought unassisted. Neither were there the rigid rank orders of dominance so characteristic of Jay’s widely separated groups. Perhaps as a consequence almost all troops had only one adult male, though there might be six or ten adult females. Sugiyama speculated that without a hierarchy regulating the relationships of males, quarrels were so disruptive that only one male usually remained. The expelled males formed their own groups in the forest.

When the sexual season approached its peak, an all-male gang, …would descend on a troop containing females, kill or drive off the leader and any sub-adult males, and fight among themselves for sexual sovereignty. Far from mourning their departed overlord, the females would respond to the action with sexual stimulation which brought on an immediate peak of copulation with the conqueror. Infants were neglected. And the episode reached its climax when the conqueror bit to death all young.

Readers of Demonic Males will note the remarkable parallels between Sugiyama’s langurs and the behavior of individual “outsider” male gorillas, which will occasionally raid the troop of a silverback, seeking to kill the infants.  If successful, the mother may follow him as her new overlord! 

But the upshot of the story is that the behavior of a given species of primate can vary widely depending on environmental conditions.  Innate behavior does not imply “deterministic” behavior.  It merely constrains the potential paths it can take.  May not the same phenomena observed among langurs be possible in the great apes?  Given the right conditions, could there be peaceful chimps and violent bonobos?  What about our own species?  Often human populations that have been peaceful for generations have also become incredibly violent in a relatively short time.  Why?  We need to learn.  There is no more important study than the study of our own nature.  Our survival depends on learning who we are.

Indian Langur

Author: Helian

I am Doug Drake, and I live in Maryland, not far from Washington, DC. I am a graduate of West Point, and I hold a Ph.D. in nuclear engineering from the University of Wisconsin. My blog reflects my enduring fascination with human nature and human morality.

2 thoughts on “Langurs and Bonobos and Chimps”

  1. I often think that our fear of what we will actually discover is the greatest obstacle to an honest study of human nature. The concept of the noble savage is simply too appealing and has influenced Western minds for too long to be discarded easily.
    I’m a cop; I see human nature in its raw form daily. Most people, including most criminologists, refuse to address criminal behavior honestly. They would rather blame everything from Twinkies to Mommies than accept the possibility that human nature may be predisposed to some of these behaviors.

  2. We’ve come a long way since the “blank slate” days of the 60’s and 70’s in our study of human nature. The fact that there is such a thing, and it doesn’t always predispose us to act “nicely” is now generally accepted. Unfortunately, the truth is still inconvenient for most of what passes for the expert community in psychology, sociology, anthropogy, and the rest of the behavioral sciences. They can no longer deny the truth because of the weight of evidence against them. Instead, they ignore it. The whole field is in the process of being co-opted into a bunch of dry textbooks and obscure academic journals. That’s unfortunate, because there is no science more important or that will play a more decisive role in determining whether we manage to survive as a species or not.

    Thanks for what you do, by the way. My son and I were recently at the scene of the arrest of an intoxicated driver. He became violent, and two officers had to subdue him. I was amazed at how professional they were, actually incurring no small risk to themselves to avoid injuring the guy they were taking down. Sometimes the best way to learn to appreciate the jobs other people do is to see them in action.

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