Universe 25

The Universe-25 Experiment
American ethologist John Calhoun conducted many interesting experiments in the 1960s and 1970s. He used rats and mice for his experiments. Calhoun tried to understand what the future held for mankind.

As a result of his many studies on mice, the scientist formulated a new concept, the «behavioral shell. This expression implied a transition to destructive and deviant behavior under conditions of overpopulation and overcrowding.

The ethologist’s experiments aroused great interest in the scientific world. Special concern was expressed by specialists living in Western countries, because after the end of World War II (1939-1945) there was a real baby boom. Scientists were for the first time thinking seriously about how overpopulation on the planet could affect the way people lived.

Universe 25, or How Heaven Became Hell
John’s greatest popularity came from the Universe-25 experiment, conducted with mice in 1972. The goal was to study and understand how population density could affect rodent life. The experimenter created the perfect conditions for the mice to live and breed fully.

A large structure of 2×2 m and 1.5 m high was built. The temperature inside it was always kept as comfortable as possible for the mice (+20°C). The mice were never short of food or water. In addition, nests were made for the mice to raise their young.

The author of the experiment made sure that the pen was kept clean at all times. Special attention was paid to the safety of the mice. They were regularly examined by veterinarians to rule out the appearance of any epidemic.

It is interesting that more than 6,140 mice could drink water and eat up to 9,500 at a time in the enclosure. At the same time, the rodents could have had problems with «housing» only if their number had exceeded 3,840 individuals. However, this has never happened. The maximum number of mice did not exceed 2200 specimens.

Mouse Paradise
At the very beginning of the Universe-25 experiment, four pairs of healthy mice were placed inside the enclosure. They quickly adapted to the new surroundings and began to reproduce actively. John labeled this period of assimilation phase A.

Phase B began when the offspring began to appear in the «Mouse State». At that time, the number of rodents doubled every 55 days. However, after 10 months, the situation changed — phase C began.

Starting on day 315 of the Universe-25 experiment, the rate of birth of mice decreased significantly: the number of rodents doubled every 145 days.

By this time there were about 600 individuals living in the enclosure, among which a hierarchy and a certain social life were formed. At the same time, the space was getting smaller and smaller.