Universe 25: This Was The Famous Experiment On Overcrowding With Mice
Throughout history, different experiments have been carried out to study the phenomenon of overpopulation. However, It is possible that the one in Universe 25 is the most famous of them all
For this reason, we are going to dedicate this article to studying this research and all the phenomena associated with it in depth, since its conclusions were very revealing.
To understand the implications of Universe 25, it is necessary to start from premises that place us in the context of this type of research. Therefore, before entering fully into the development of said experiment, we are going to make a short general introduction about works of this nature.
During the mid-20th century, some ethologists decided to study What were the effects that overcrowding could have on individuals in the long term? To do this, a series of experiments were developed in which a group of animals, generally rodents, were placed in a space with ideal conditions for their development and reproduction.
It could be said that a utopia was generated for these animals, since they had in advance all the resources they could need. That is, a habitat had been artificially created in which individuals would apparently have no problem feeding and reproducing, in order to increase the original population. We will see later that Universe 25 was one of these settings.
That’s where John Bumpass Calhoun, one of the most important ethologists in population density research, came in This author was one of the most prolific in terms of this type of studies. In fact, Calhoun was the creator of the so-called Universe 25, among many other scenarios of rat and mouse utopias.
The starting hypothesis for this type of experiment is that the chosen location should provide space and support, without any type of problem, until the population reached a critical point, which had been estimated by making a series of calculations and depended fundamentally on the area. of the enclosure, always taking into account that there was enough food and water for all individuals and there were no external threats.
But the results were implacable: that critical point was never reached, because the population collapsed much earlier. Because?
Creation of the Universe 25
But what happened in Universe 25? Why did what was born as a utopia end up becoming more of an apocalyptic dystopia for these rodents? To know the answer to these questions, we are going to delve fully into the development of this experiment. We will have to go back to 1968, when John B. Calhoun created a new world for a small group of mice
Universe 25 had a surface area of 6.5 m2, which originally housed a small population of 8 individuals. If there was a paradise on earth for mice, it was certainly this place. Enough food for everyone, fresh water, no predators lurking… The conditions were ideal. Apparently. According to calculations, this small world should have been able to shelter 3,500 mice. But it never reached that number.
The first eight settlers of Universe 25 soon paired up and began to reproduce, causing exponential growth in this peculiar civilization. In just over a year, the population had doubled on successive occasions until reaching a figure of 620 individuals, at which point this growth began to slow down.
Until that moment, life for the rodents had been practically perfect. They had everything they needed and nothing endangered their lives. But life in Universe 25 was about to stop being so bucolic, because, without knowing it, they were approaching a critical figure, not due to the scarcity of resources, but due to other factors, which had not been taken into account.
The decline of the project
It was then that behavioral anomalies began to appear The behavior of the mice in Universe 25 began to be erratic. It seemed that the mice no longer felt so comfortable, and although they all physically fit in the enclosure, they were beginning to feel the effects of overcrowding. They all crossed each other’s paths constantly when searching for food or water, or when returning to the nest.
There were no external threats, but internal threats began to arise. The mice were increasingly together and that implied territorial fights, constant transfers to other areas of Universe 25, etc. And the fundamental problem arose: many mice stopped playing a role in that small society. There were no roles for all individuals.
Due to this phenomenon, many of the rodents were apathetic, they stopped moving and interacting, since they did not occupy a significant role in that small world They were of no use. John B. Calhoun baptized this phenomenon with the term behavioral drainage, or behavioral sinking.
He observed that many females in Universe 25 stopped trying to reproduce. The males, likewise, moved away from the nests and simply went to the area of the enclosure where the food was found. Neighborhood conflicts were constant and it was difficult to find a mouse that did not have some wound or scar due to a territorial dispute.
Abnormal sexual behaviors were observed. There were individuals who performed these behaviors in a frenetic manner, without discrimination of sex, and then went on to not engage in copulation at all. Intra-family fights appeared Some of the mice killed their babies. Others expelled members from the nest. Cannibalistic behavior was even recorded.
It must be said that not all mice had violent behavior. There was a group, which Calhoun baptized as “the handsome ones,” whose behavior was limited to hygiene behaviors such as combing one’s hair, apart from eating and sleeping, which is the only activity to which the behavior of all the members of the group was reduced. the colony.
Collapse
The chaos in Universe 25 was absolute. The mouse paradise had turned into hell In 1970, less than two years having passed since the experiment began, the last litter of mice in this habitat was born, so the population stagnated and began to plummet.
Individuals had lost fertility, so, at this point, society had no possible salvation. What happened from then until 1973 was the progressive and inevitable death of each and every one of the mice that made up Universe 25, forever extinguishing that attempted utopia, but leaving very interesting questions behind this event.
The population progression drew a parabola whose peak was in March 1970, at which time the trend began to be negative, until reaching 1973, when Universe 25 definitively ceased to exist. Its maximum population reached 2,200 individuals. Let us remember that, ideally, it was considered that this space could have housed up to 3,500 mice.
But we have already proven that, due to behavioral drainage, a factor that the researchers had not taken into account, the population collapsed long before even approaching that figure.
Conclusions on the Universe 25 experiment
One of the first questions that usually arise after learning about the Universe 25 experiment is how extrapolated the processes that ended that small civilization are to human society itself, or at least to some of them. Logically, any conclusion in this sense must be taken with great caution, since both scenarios are far from being comparable.
John B. Calhoun himself tried to look for these parallels to try to fit what he had discovered in his study on mice into a human society Other authors, such as Jonathan Freedman, carried out their own research, this time with people, asking a series of students to perform different tasks in overcrowded conditions.
Freedman observed that the aggressive behaviors, as well as the stress and discomfort of the participants, increased as the density of people in the same space grew. In fact, some authors pointed out, regarding the Universe 25 experiment, that the key did not lie in the number of individuals that shared the same area, but in the number of interactions that all these animals were forced to carry out.
In any case, establishing a comparison with human beings is complicated since human society is substantially more complex and in no case does it have infinite resources to make the population grow indefinitely until it collapses due to other factors, such as behavioral drainage.
