An even greater number, after successfully giving birth, fell short in their maternal functions.
#Rat utopia full#
“Many were unable to carry pregnancy to full term, or to survive delivery of their litters if they did. Some males became repeated targets of attacks.Ĭalhoun had noted during his experiments: Males fought each other for acceptance, those that where defeated withdrew. The mice showed different types of social dysfunctions. He noted that the new generations were inhibited since most space was already socially defined. During the third phase Calhoun observed the collapse of the mice civilisation. During this phase, the mice population peaked at 2200 individuals, although there was space for 3000. The third phase was named the ”equilibrium phase”. It was also observed that some units started to become crowded. The second stage was named the ”exploit period”. During this stage the mice population exploded. Calhoun observed that some compartments became more populated than others, and therefore some units used more resources. He noted down behavioural changes and population numbers. He found that there were four distinct phases of population change observed during the experiment. The first stage, named “Strive”, was a phase in which the mice explored and adjusted to their new habitat, set territories and created nests. Upon verifying that they were healthy they were introduced into the enclosure.Ĭalhoun observed the mice population over the course of the experiment.
#Rat utopia free#
By removing the risk of predation, the mice could grow in an environment free from external stress. The room was then compartmentalised into different units, this allowed Calhoun to identify how different social groupings formed.įour pairs of mice were screened for diseases (four male and four female). The room was closed off so that neither the mice could get out nor predators get in. This was achieved by fitting a pen (box-shaped enclosure) with unlimited food and water. His team created a comfortable environment ideal for the mice. John Calhoun’s experiments gained world-wide recognition and his expertise was sought after by government bodies such as NASA. They present a useful yet grim insight into what could be our own future, for no matter how many times Calhoun repeated the experiment, the results led to the same inevitable conclusion: extinction. The social decay led to unrest in the environment, which in turn led to sub replacement fertility. It was concluded that nature has a limit in which social animals can interact.
He chose rodents as these reproduce rapidly thus allowing him to observe the development of several generations of mice in a relatively short space of time.Ĭalhoun and his researchers found that in a space-limited/resource unlimited environment, the population of mice would explode peak-out and then collapse to extinction. This test was replicated several times and it was found that these led to the same outcome each time. The reason for this phenomenon was found to derived from social decay which worsened with each generation.
#Rat utopia series#
In 1950, an American ethologist named John Calhoun created a series of experiments to test the effects of overpopulation on the behaviour of social animals. The animals which Calhoun chose for his experiments where mice (and later on rats).