In 1950, John Calhoun, an American ethologist, embarked on a series of experiments with the aim of finding out how overpopulation impacted the behavior of social animals (Ramsden, & Adams, 2009). The animal chosen for the research was the mice. The reason for selecting the rodents was that they have a faster reproduction rate thus allowing him to analyze many generations of mice in a short period. Calhoun found out from the research that in a space-limited and resource-unlimited environment, the mice population would initially explode, reach the peak, and subsequently fall to extinction.
Hypothesis
John B. Calhoun sought to experiment how mice would behave when provided with everything required for their survival except space. At the helm of his experiment, which later came to be regarded as the "behavioral sink," was the behavioral change that came as a result of overcrowding or overpopulation. Therefore, the primary hypothesis for the experiment was whether insufficient space in the wake of reproduction would lead to behavioral change for the mice. It consequently aimed at assessing the cause and effect relationship between crowding and pathological behavior amongst the mice.
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The Variables
The experiment had two types of variables including the limited and unlimited resources. The team conducting the experiment ensured that the mice had a comfortable environment with unlimited food and water. The box-shaped enclosure was protected to inhibit the entry of predators and the exit of the mice. Limiting predation ensured that the mice grew in an environment free from predation and any external stress. Ramsden and Adams (2009) noted that the room that housed the mice was compartmentalized to provide the mice with different social units. The variable that was manipulated was space. As part of controlling the variables, four pairs of mice both male and female underwent screening for diseases to verify their health. The independent variable included space and resources such as food, water, and shelter. On the other hand, the dependent variable was the population numbers and changes in behavior.
The Experiment and Observations
After setting all the variables as described above, Calhoun observed the population of mice as the experiment progressed. He remained steady to note down the population and behavioral changes. As the experiment progressed, Calhoun noted that the population change went through four distinct phases. The first one was known as strive. In this phase, the mice adjusted to and explored the new environment by creating nests and setting territories. The second observable stage was known as the “exploit period” where the population of the mice exploded. According to the observation made, some compartments become populated than others meaning that some units made more resources than others. Overcrowding was also evident in some units. Lastly, the third stage was known as the equilibrium phase (Ramsden, 2009). The mice population peaked with subsequent collapse of their civilization. The new generations faced immense inhibition primarily because the available space was already socially defined. As a result, the mice started showing signs of social dysfunction such as violence. Males, for instance, began fighting each other for acceptance while others retreated as a sign of defeat. Other males became constant targets for the attacks.
Further observations indicated that the newer generations that came into the now dysfunctional unit of utopia showed signs of withdrawal. As such, they dedicated most of their time in grooming, eating, drinking, and sleeping. Due to a diverted emphasis, they faced difficulties in reproducing. The new generation of mice also showed gross unintelligence compared to others from the previous generations. As a result, the mice population began to decline as most of them began to die.
Ethics of the Experiment
Although the experiment was widely accepted and even embraced by the National Institute of Mental Health (NIH) and other scientific bodies, its ethics came into question. Important to note is that during the 1960s when the experiment was done, little consideration of animal rights was upheld. However, with those standards, the experiment provided extreme conditions for the rodents. The cages were small, and the animals became severely stressed. According to the 3Rs (replacement, reduction, refinement), the experiment disregarded refinement which asserts that scientists must not use strategies that increase suffering but rather utilize those that improve welfare. The death of the rodents at the end was a sign of animal cruelty (Ramsden, 2009).
Significance to Humans
The experiment conducted by Calhoun had space as the limiting factor. As time continued to move, the embattled mice passed their negative behavioral characteristics to the next generations, and the sequence continued (Fredrick, 2017). Therefore, this ensured that the continuation of the antisocial behavior remained evident. The principal question raised, therefore, was what made space or lack of thereof such an essential factor in the life of social animals. It, therefore, reflected on the problems of population condensation as experienced in human beings. A high population density amongst human beings can be a dangerous thing. It leads to many inconveniences some of which can be dangerous to the lives of humans. Fredrick, (2017) asserted that a lack of social amenities and vital resources for survival would eventually lead to competition thereby leading to a behavioral sink. Once cities and towns are faced with overcrowding, social unrest and other undesirable behaviors will set in. Due to the inconveniences caused, people will be less likely to engage in reproductive behavior, therefore, leading to a deep in the population. Just as the mice in the cages fought each other for due to stress that came with space, human beings will engage in a plethora of antisocial acts as crime that could potentially cause death.
References
Ramsden, E., & Adams, J. (2009). SECTION IV: SCIENCE IN SOCIAL HISTORY: ESCAPING THE LABORATORY: THE RODENT EXPERIMENTS OF JOHN B. CALHOUN & THEIR CULTURAL INFLUENCE. Journal of Social History , 42 (3), 761-792.
Fredrick, K. (2017). In rat research, a warning for human society. Washington Post, The .
Ramsden, E. (2009, February). The urban animal: population density and social pathology in rodents and humans. Bulletin of the World Health Organization . p. 82.
