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:

• Population Density and Social Pathology
• Death Squared:  The Explosive Growth and Demise of a Mouse Population

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.

Peter