Wednesday, June 30, 2010

Social stability, population growth and the experiments of John B. Calhoun

By Steve Rensberry   

As far along as we may be on the pathway to a singularity, it's hard to deny the acceleration that has taken place over the past century in terms of population growth, and the chance that it could leave a vast majority of us shaking our heads in disbelief when it's all said and done.
   Consider the compounding effects, and a total world population that was only around 1 million in 10,000 BCE. By the year 1,000 CE it had multiplied to 300 times that size, to 310 million. We surpassed the 1 billion mark in the early 1800s, then grew to some 1.26 billion in 1850 and to 2.5 billion in 1950.
   Now, just 60 years later, we’re at an incredible 6.8 billion. That's according to estimates put together by the United Nations. That's 4.3 billion more human beings living on this magnificent floating ball of rock in 2010 than there were at the time my parents pledged their lives to one another!  The rate of growth has slowed, fortunately, with speculation that total world population will peak at about 9 billion people sometime between 2040 and 2050.
   Much has been written about the threat to the earth's ecosystem and environment, but the positive and cumulative effects in terms of increasing knowledge, together with the possible, but uncertain ways in which it could affect social and psychological aspects of the human race may be two commonly overlooked dynamics.
   American research psychologist John Calhoun was an exception. Calhoun died in 1995 but was widely known for his studies of population density and its effects on animal behavior, in particular rats. He had worked in the division of neuropsychiatry at Walter Reed Army Medical Center before joining the National Institutes of Health in 1954, where he remained for more than 30 years.
   But it was in 1946 and 1947 at Johns Hopkins University that Calhoun began a massive study of a colony of Norway rats, maintained in an outdoor pen that was some 10,000 square feet in size. Despite the ability for the five pregnant females in the group to produce more than 50,000 offspring within the space provided, the total population in the pen never surpassed 200 rats. The rats also broke up into colonies of only about a dozen each instead of spreading themselves throughout the pen, pointing to a maximum size before which the rats succumbed to forces and stresses which would work to their detriment. See: Escaping the Laboratory
   Calhoun continued his behavioral experiments in a Maryland barn in 1954, and again in the 1960s in another elaborate arrangement on property owned by the National Institutes of Mental Health. Here he constructed what was known as his "mouse universe," a 9-foot square, 54-inch tall, meticulously designed and constructed living environment. Space was the only limitation.
   What he found was a total, eventual breakdown in social structure within the colony, leading to extinction. Male rats would withdraw, tending only to themselves, and the females would all but stop reproducing.
  "The conclusions drawn from this experiment were that when all available space is taken and all social roles filled, competition and the stresses experienced by the individuals will result in a total breakdown in complex social behaviors, ultimately resulting in the demise of the population," the entry on Wikipedia says. See: John Calhoun.
   Human civilization and the cognitive complexity of  humans far exceeds that of rodents, but do we really know what the future holds? Were Calhoun's experiments relevant to our understanding of human culture and population growth? As time marches on, we might do well to keep matters related to adaptability and that tremendously creative, inventive spark that sets us apart from so much of the animal kingdom well in mind.

Carl Sagan on God, Faith and Religion