"Universe 25": how ideal living conditions led to extinction

In June 1972, American ethologist John Calhoun stood over a nearly empty mouse enclosure. Just seven months ago, their population numbered more than two thousand, but now there are only 122 individuals left, and they were soon to die.

The mice did not get sick, they had plenty of food and water, there were no external threats in the form of predators or bad weather. The only thing missing in their ideal conditions of detention - and what caused the death of the entire population - was the lack of free space.

So ended experiment called "Universe 25".

Who and why conducted the experiment "Universe 25"

Its author, John Calhoun, studied for several years the problem of high population density, relevant for the middle of the 20th century. Previous experiments in rats and mice did not bode well. In overcrowded enclosures, rodents became aggressive or lethargic, did not care for their offspring, demonstrated deviant sexual behavior.

However, the experiments were not completed due to lack of space. And this one, the 25th in a row, became the key one.

In 1968, a 2.5 x 2.5 x 1.3 meter square enclosure for mice was set up in the laboratory of the US National Institute of Mental Health. Tunnels and nesting rooms were made on the walls, and the very top was made of smooth metal so that the inhabitants could not get out.

Unlike the natural environment, there was plenty of food and water, there were no external threats and temperature differences. Calhoun built a real mouse garden of Eden, and then settled there with four pairs of young individuals.

The first 120 days of the experiment (phase A) were spent on getting to know mice with a new environment, the organization of the social structure and the receipt of the first offspring. This was followed by phase B, in which the population began to double every 55 days.

After the 315th day of the experiment, when the number of adult mice in the enclosure reached 620 individuals, reproduction slowed down. Phase C arrived - the population doubled in about 145 days, and its growth continued to slow down.

Animals have become extremely violent, they have abnormal sexual behavior. For example, some mice became hypersexual - they demanded sex outside of estrus, mating with individuals of the same sex. Others showed no sexual activity at all.

Moreover, mice of both sexes lost the ability to reproduce.

Males, instead of looking for a female or fighting for a place in the hierarchy, spent whole days compulsively grooming themselves. Calhoun called them "beauties".

The females did not pay attention to the cubs or even attacked their own babies, the young mice stopped get pregnant and ran away to live on the upper levels, hiding from contacts.

Calhoun called this disruption of social behavior "behavioral cesspool". Later, the term was often used to describe the decline in human society.

By day 560, there were already 2,200 individuals living in the enclosure, and phase D, the stage of gradual extinction, had begun. At this stage, the number of mice began to decline, moreover, faster and faster.

Mouse paradise turned into hell.

Why ideal conditions led to extinction

The lack of natural causes of death meant that virtually all mice reached an old age of 800 days, which is comparable to 80 years in humans. Moreover, at first, all young individuals who could and wanted to occupy a niche suitable for themselves also survived.

Overpopulation put an end to their implementation. Competition for social roles began with the older members of the mouse community, and this destroyed the normal behavior of all generations.

At first, rejected males, unable to migrate to a new place, huddled in the center of the enclosure. Their tails were bitten, their hair torn out in places. The exiles were attacked by other mice, and they themselves attacked each other, females and cubs.

Pregnant females were forced to defend the territory on their own, and their aggression shed on her own offspring. The mice stopped following them, could abandon them or kill them.

Even if the mouse survived, it was unable to form an attachment to the mother or other members of the community and at the same time was forced to constantly be among them.

Under such conditions, animals grew up autistic and infantile, capable of only the simplest actions - eating, sleeping and grooming. Such difficult behavior for mice as formation of pairs, maternal care, protection of the territory and the creation of a hierarchy within the group were not available to them.

Moreover, when Calhoun took out such infantile rodents and hooked them up with normal ones - those that did not grew up in "Universe 25" and were ready to mate, the natives of the mouse paradise could not with them to interact.

The scientist called this state "the death of the spirit" or the first death, which will inevitably lead to the death of the species.

Is it true that the same thing will happen to people as to mice in "Universe 25"

The experiment "Universe 25" came in handy: in the 60s and 70s in the United States, people were worried about the problem of the growing population and feared that this could lead to an increase in urban violence and become a source of distress.

Problems affecting rodents seemed surprisingly similar to what worried people: hypersexuality, various deviations of sexual behavior, violence, social isolation, neglect of children.

In addition, mice and rats participated in the experiments, and these species live side by side with people in cities, are not completely wild, but are not domesticated either.

Yes, and Calhoun himself was not shy about using expressions like “juvenile delinquents” to his mice, "social marginals" or "handsome" - terms that hint at similarities with certain groups of people. The scientist also warned that overpopulation could be detrimental to the future of humanity.

Given the situation at the time, the news of "Universe 25" was quickly picked up by journalists, and the results of the experiment became available to the general public. Soon there were books and films devoted to this topic, and the concept of "behavioral cesspool" was applied with might and main to the problems of modern society.

At the same time, comparing mice and humans is not a good idea.

Yes, constantly being in a crowd is tiring and an additional source of stress, but, unlike from rodents, humans have a culture, complex social organization, and technological innovations that help cope with the undesirable consequences of overpopulation.

Moreover, people can reorganize the space in such a way as to reduce the stress of crowding. So did Calhoun himself. For example, he noticed that if animals were built more rooms in which they could retire, stress levels would drop even at high population densities.

Calhoun wanted to apply his knowledge so that crowded places like prisons, hospitals, and student residences were designed correctly and provided less stress. However, he failed to complete the work and implement projects to reorganize the space.

people with enthusiasm accepted bad news about the "behavioral cesspool", but when the scientist tried to suggest a way out, no one was interested.

The reputation of the prophet of the urban apocalypse played a cruel joke on Calhoun. Nobody was going to solve the problem, and they soon forgot about it.

50 years have passed since the experiment. The world's population continues to increase, and "Universe 25" remains an evil prophecy that will apparently never come true.