According to the United Nations Population Fund (UNFPA), 2008 was the first year in human history that more than half of the worlds population was living some kind of urban center (towns or cities). This trend of increasing urbanization is expected to continue well into the future with over 5 billion people living in increasingly dense population centers. This will have more impacts on a broader range of issues than can possibly be predicted with any meaningful expectation of accuracy. The implications range from environmental and conservation concerns to physical and mental health issues and so much more.
Lets take a look at some very interesting animal research and see how it might apply to our current situation as well as our future. In the late 1940's a scientist named John, B Calhoun began a series of experiments looking at the effects of crowding on rat populations. Calhoun built increasingly impressive enclosures for his test subjects coming in at approximately a quarter acre. This enclosure designed to provide the test subjects with everything they needed to survived in complete abundance. The only limiting factor the rat population faced was physical space. Once the enclosure was set up Calhoun placed 5 pregnant female rats in the enclosure to start the population.
Once the founder population's were introduced the the enclosures they began to breed extremely rapidly. As the population density continued to increase psychological/behavioral issues began to arise eventually resulting in an environment that one of Calhoun's assistants described as "hell". Over time males became increasingly aggressive and even began roaming in "gangs" and attacking females and young rats .
indiscriminately. Mating behaviors became severely out of whack with homosexuality, pansexuality, and hypersexuality running rampant. Some rats attempted to mount every rat they encountered. At the same time female rats began to experience difficulties in constructing their nests and caring for their young. The situation eventually devolved to the point that mothers were abandoning and attacking their own pups leading to an astonishingly high infant morality rate of 96%. Interestingly, even with food in absolute abundance many animals engaged in cannibalization of the dead.
With the population unable to effectively reproduce the populations eventually plummeted and although the issue of density was resolved by the mass die off the animals had lost much of the behavior that is necessary for a functioning population. Seemingly changed forever the rats never recovered and eventually died out. Calhoun coined a phrase to describe the accelerating degeneration of behavior observed in his experiment. He called it "the behavioral sink". The behavioral sink arises from the behavior of individual animals within a crowd. The behavior of these individuals disrupts the normal functioning of those around them leading to behavioral issues in more and more animals and of greater and greater severity. According to Calhoun the behavioral sink emerges from this erratic behavior like a vortex aggravating all other pathologies found in the group.
Absolutely there are profound differences between rat populations and human populations and one should be careful not to draw too strong a conclusion regarding human behaviors and our future from animal behavior experiments. However, my main concern is more on the general idea of feedback loops within emergent pathologies of dense populations. We have in place the structures necessary to keep at bay those first few individuals to react adversely to various influences. Either through police or healthcare we do what we can to isolate and treat the individuals who pose a threat to the group as a whole. My concern is regarding what might happen if things go wrong, even for a little while. If there is a big enough event to disrupt the system for a few weeks maybe, then what happens? Are we already at a density that if our societal controls are removed that we will enter a behavioral sink loop and degenerate past the point of return?
Let me know what you think in the comments! Also, please look to the right and click the "like" button. I just set up a facebook page for the blog and would appreciate any support!
I retrieved much of my information for this article from the following paper: http://eprints.lse.ac.uk/22514/