About the SA Blog Network

Guest Blog

Guest Blog

Commentary invited by editors of Scientific American
Guest Blog HomeAboutContact

Frans de Waal on the human primate: Is it “behavioral sink” or resource distribution?

The views expressed are those of the author and are not necessarily those of Scientific American.

Email   PrintPrint

Editor’s Note: This post is the second in a four-part series of essays for Scientific American by primatologist Frans de Waal on human nature, based on his ongoing research. (The first post, on our sense of fairness, can be read here.) De Waal and other researchers appear in a series of Department of Expansion videos focusing on the same topic.

In the 1960s Jack Calhoun placed an expanding rat population in a crammed room and observed how the animals killed, sexually assaulted and, eventually, cannibalized one another. The magnetism of the crowd and the behavioral deviancy led Calhoun to coin the phrase "behavioral sink."

In no time popularizers were comparing politically motivated street riots with rat packs, inner cities to behavioral sinks, and urban areas to zoos. Warning that society was heading for either anarchy or dictatorship, Robert Ardrey, a popular science journalist and author of African Genesis, remarked in 1970 on the voluntary nature of human crowding and its ill effects. These views entered mainstream thinking: The negative impact of crowding became a central tenet of the voluminous literature on aggression.

In extrapolating from rodents to people, however, these writers were making a giant leap. Compare, for instance, the per capita murder rates with the number of people per square kilometer in different nations. If things were straightforward the two ought to vary in tandem, but there is in fact no statistically meaningful relation. Among free-market nations the U.S. is an anomaly by having the highest homicide rate despite a low population density. Some seek the explanation in U.S. gun laws, but this issue remains largely taboo.

To see how other primates respond to being packed together, we compared rhesus monkeys in crowded cages with those roaming free on Morgan Island in South Carolina. We also compared chimpanzees in indoor enclosures with those living on large forested islands. Nothing like the expected crowding effects could be found. If anything, primates become more sociable in captivity, grooming each other more—probably in an effort to counter the potential of conflict, which is greater the closer they live together. Primates are excellent at conflict resolution.

For the future of the world this means that crowding by itself is perhaps not the problem it is made it out to be. Resource distribution seems the real issue. This was already true for Calhoun’s rats, the violence among them could be explained by concentrated food sources and competition. Also for humans, I would worry more about sustainability and resource distribution than population density.

For more on this topic, see: Coping with Crowding by Frans de Waal, Filippo Aureli and Peter Judge; May 2000; Scientific American.


Frans de Waal, PhD, is a Dutch-American primatologist known for his popular books, such as Chimpanzee Politics: Power and Sex among Apes (1982) and The Age of Empathy: Nature’s Lessons for a Kinder Society (2009). He teaches at Emory University in Atlanta where he directs the Living Links Center at the Yerkes National Primate Research Center. He has been elected to the National Academy of Sciences and the Royal Netherlands Academy of Arts and Sciences.

The views expressed are those of the author and are not necessarily those of Scientific American.

Video credit: Department of Expansion

Comments 8 Comments

Add Comment
  1. 1. oldvic 12:15 pm 07/21/2010

    I’m inclined to agree with your final statement, since I think that sustainability is probably aided, all else being equal, by higher densities (less soil devoted to infrastructure, fewer ecossystems destroyed or damaged by our needs, greater overall efficiencies).
    I’d merely add, as an aside, that sustainability is probably best achieved through population control, a point that we need to keep in mind (not directly related to your post, though).

    Link to this
  2. 2. Skeptikor 3:29 pm 07/21/2010

    @oldvic: I agree, population is the elephant in the room in regard to sustainability. "Control", however, may not be the optimum word as it conjures up mandated limits on family size (China) or forced sterilization (India, at one period). How we come to grips with this challenge will ultimately define our futre — or lack thereof — on this planet.

    Link to this
  3. 3. jtdwyer 5:51 pm 07/21/2010

    Yes, since essentially all of humanity’s critical issues are driven by population, our only hope is some humane means of reducing population. Since denser population of cities increases occupancy of some of the most productive croplands in the world and population driven GHGs are producing global warming, which will likely reduce crop yields and/or increase use of non-replenished ancient aquifers, and over fishing has now reduced oceanic fish species to nearly unsustainable levels, total population must be reduced from current levels to prevent resource wars, starvation, suffering and death for many hundreds of millions of people in this century.

    Relying on some form of social or even genetic engineering to produce a population that can cooperatively cooperatively survive the intolerable conditions of the near future is impractical folly.

    The world population will be reduced to at least the level that can be sustained by available resources, one way or another, with the magnitude of human suffering as the principal variable.

    Link to this
  4. 4. sfreiman 3:20 am 07/22/2010

    I wonder how the effects of crowding are related to the homogeneity of the population. Scapegoating of people who are different is a common phenomenon in cultures which see themselves under stress. I wonder whether the presence of foreigners is just a way to let off steam, or whether it contributes to the perception of stress or whether it is a cause of stress.

    Link to this
  5. 5. oldvic 4:19 am 07/22/2010

    Resource distribution is a tricky problem. For instance, should those who live in marginal lands, mostly unsuited to human needs, get free and unconditional resources from others who live in more productive lands? If so, why?
    Doesn’t such an unconditional support remove a vital stimulus for population self-control, thus making the problem worse?
    I feel that sometimes, our humanitarian impulses trick us into doing things that defeat the very purpose of our actions.
    I’m no expert, but my view on this is that as a rule most of us tend to take a rather narrow and parochial view of our needs (the "it’s people that matter" idea). Of course people matter, but we don’t exist in isolation: we live inside a complex system that needs to work properly if we are to survive. Within this mental framework and keeping in mind that social justice exists when people have what they deserve and not when everybody has the same, then yes, resource distribution is an essential step towards our well-being and our future survival.

    Link to this
  6. 6. Asterix13 3:49 pm 07/22/2010

    The rat expirements are well documented and on the long run will apply to all species as well as humanity. As why dense population and highest homicede in the USA is easy to explain. Since the formtion of USA, the average American is use to expansion, the plenty, the better than you feeling, and I want more room for growth. That demand’s expextation has slipped in the last decades, and as we found out in the real estate/ housing, the concept lead to creed and Super-Saturation. In a country as Holland the concepts of tolerence, charibility, social happiness among etnic groups is stretchedto the limit of Super-Saturation. Governing bodies in the last decades fall one after another, homicides and intolerance are escalating, diversity/ confusion over a democratic elected government / selection is getting almost inpossible with multiple interest groups and inpossible to keep the bulk satisfied. Most celebraties and high earning politicians in Holland have silently escape routes set up all over Europe (remember Europe is one) on higher and drier grounds. Bottemline, That boot is full, all are happy and Gay,and most have learned to smile in plubiek but still dislike you. Etnic clans demanded more for less in contents to the size of the group and the government can do nothing more than complie and contain profibility or damage. You be the Judge.

    Link to this
  7. 7. mdub3000 1:51 pm 07/23/2010

    We have culture. Rats do not.

    Link to this
  8. 8. Slade 3:35 am 09/14/2010

    It is ridiculous to suggest that in any situation humans would behave like a pack of rats. Are we men or are we mice? We are men of course! Humans are highest order of being on the face of the earth. Humans are the only species capable of rational thought. If we have problems like resource scarcity or overpopulation we search for a logical solution to the problem. Our actions define our environment. Our environment does not define our actions.

    Link to this

Add a Comment
You must sign in or register as a member to submit a comment.

More from Scientific American

Email this Article