Murders in the USA – the “Behavioral Sink” in action?

Back in the 1950’s and 1960’s, ethologist John C. Calhoun experimented with rats to find out how their behavior changed when their population density (i.e the number of rats in a confined space) was increased.  He described their behavior in two papers that have become seminal in their field:

He called their reactions the “Behavioral Sink“, observing that normal interactions became pathologically warped under the stress of overcrowding, resulting in violence, cannibalism, and the breakdown of normal social interaction.  The term (and his experiments) have been used as a metaphor for human interaction under the stress of increasing density of urban population.

One wonders whether it isn’t the primary factor behind the distribution of murders in the USA.

Murders in US very concentrated: 54% of US counties in 2014 had zero murders, 2% of counties have 51% of the murders

The United States can really be divided up into three types of places. Places where there are no murders, places where there are a few murders, and places where murders are very common.

In 2014, the most recent year that a county level breakdown is available, 54% of counties (with 11% of the population) have no murders.  69% of counties have no more than one murder, and about 20% of the population. These counties account for only 4% of all murders in the country.

The worst 1% of counties have 19% of the population and 37% of the murders. The worst 5% of counties contain 47% of the population and account for 68% of murders. As shown in figure 2, over half of murders occurred in only 2% of counties.

Murders actually used to be even more concentrated.  From 1977 to 2000, on average 73 percent of counties in any give year had zero murders.

. . .

In 2014, the murder rate was 4.4 per 100,000 people.  If the 1% of the counties with the worst number of murders somehow were to become a separate country, the murder rate in the rest of the US would have been only 3.4 in 2014. Removing the worst 2% or 5% would have reduced the US rate to just 3.06 or 2.56 per 100,000, respectively.

. . .

Murder isn’t a nationwide problem.  It’s a problem in a very small set of urban areas, and any solution must reduce those murders.

There’s more at the link.  Very interesting and highly recommended reading.

There are a number of things that I take away from this study, including (but not limited to):

  1. “Gun violence” or “knife violence” or any other “kind” of violence might be better described as “urbanized violence”.  That’s where it’s far more prevalent, after all.  Basically, the greater the population density in a given area, the greater the likelihood of crime and violence.
  2. Those of us who live in or near urbanized areas should be more on our guard, and more willing (and able) to defend ourselves and our loved ones, against such urbanized violence.  That’s not to say that people living in less population-dense areas don’t need to be on their guard;  they’re just less likely to have to put their precautions into practice. 
  3. If, in a crisis (e.g. hurricane evacuations, etc.) urban populations spread out into other areas, they’re going to take their urban background (including a possible propensity for crime and violence) with them.  Be prepared to respond accordingly.  (See my after-action reports on that situation in 2005.)
  4. When we see news footage of riots, criminal “flash mobs” and other urban phenomena, let’s remember the studies referred to above, and comport ourselves accordingly – including being prepared to deal with the problem.
  5. When politicians pontificate about the need for solutions to urbanized violence, fundamentally, they’re either mistaken or they’re lying, because population density will, in and of itself, defeat many measures to reduce urban crime and violence.  Population density is a primary cause of the problem.  You won’t solve the latter without dealing with the former.  It’s simply not possible.

Food for thought.



  1. Makes you wonder about the blindness or maliciousness of those who wish to radically increase the population density of the country.

    1. Their desire to move people into large urban areas is all about creating a technocratic panopticon control grid police state. The fact that more murders occur only makes it easier to ban Things and create more onerous laws creating even more control.

  2. Recalling that the Democrat/Socialists desperately want ALL of the US population contained in cities, let us connect the dots: the cooperative MSM and university publications will NEVER refer to "Behavioral Sink."

  3. Rats don't learn new rules of socialization. People can. What we're seeing is unsocialized barbarians in high concentrations, for which LBJ's Great Society and the destruction of the black family by feel-good social policies must take a very large share of the blame. Much of the rest comes from the insane immigration policies since the 1960's and illegal immigration, plus the never-ending failure of the War on Drugs.

  4. Interesting idea. Curious how it applies in places that have much greater density yet fewer homicides, e.g. Japan or a place I know well, Poland. Poland has 40 million packed into a relatively small land area. Homicide rates there are miniscule. Makes me think that more study is needed, something alters human behavior in dense settings that does not impact rats….

  5. The rat theory and accompanying study is badly flawed. For openers, people aren't rats (and I'm dodging the obvious label here); people are close to Chimpanzees and other primates – some people more than others. Secondly, the study doesn't explain cities like Amsterdam, Hong Kong, Melbourne, Osaka, Singapore, Stockholm, Sydney, Tokyo, Toronto, or Zurich. All of these have a high population density, yet are peaceful places to live.

  6. Eliminate the top 5 murder capitols of the USA (a feature of all is Democrat rule and draconian gun ownership laws), and eliminate all the American african-perpetrated murders in the USA from the statistics, and I bet the USA has nearly the lowest murder rate or even raw numbers in the world.

  7. It has nothing to do with Skinner's "behavioral sink" due to population density.

    Skinner found the sink did not occur if the rats had private areas to retreat to to eat… private homes and apartments would qualify easily.

    As others have said, there are many extremely high density cities with very low murder rates… Hong Kong, Singapore, and Tokyo are ones I can think of off hand.

    It has nothing to do with population density, and everything to do with the culture of the people who live there.

  8. Studies of rats are valid.

    For rats.

    The reason Los Angeles and Cook counties (L.A. and Chicongo) have 51% of the murders in the entire country is that they are concentrated deposits of human refuse, with Democrat city governments, and shoddy, corrupt under-policing of those same protected Diversity candidates, in most cases with the same 1% of the population committing 99% of the crime.

    The population density is the same in nearby rich suburbs as it is in Watts, East L.A., or the South Side of Chicongo, and yet the (non-existent) murder rates there are infinitesimally small, unless visited by the wastes of skin and oxygen from those same urban $#!^holes.

    Prove this for yourself.
    Look at the population density at baseball and football games during the game, and tell me the murder rate extrapolated to a 365-day year.

    Some rats need some rat killin'.
    It's no more complicated than that.

    If we simply executed the violent incorrigibles, the murder rates in South Central or South Chicago would drop to the levels found in Monaco and Luxembourg, and recidivism would drop to 0%.

  9. Never ceases to amaze me the way people can, with a straight face, attempt to extrapolate animal studies over to people, especially with the sociological/psychological stuff. Sure, some behaviors are going to have a certain amount of correlation and contiguity, but given the massive difference in sophistication and complexity between human behavior and animal models, can we really take this sort of thing seriously?

    After all, if it were merely density, then the average college dorm and military barracks ought to be veritable hotbeds of violence and social dysfunction, right…?

    Some things coming out of academia are so ridiculous as to be indistinguishable from satire and parody. Density in human populations resulting in the same effects as rats…? How about taking a look at the historical record, and examining what went on in Kowloon Walled City? If the government of Hong Kong hadn't shut the place down, it would still be going strong, and probably still be the highest human-density locale on the planet. Precisely none of what the animal models would predict went on there, in terms of population crashing, soooo… What does that tell us about animal models and human behavior?

  10. All human studies are bullshit, designed to justify legislation rather than to describe reality. Pardon my cynicism.

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