How could Mouse Heaven go so terribly wrong?
In 1968 John Calhoun, a scientist and animal behavioralist, decided to create a "utopia" for mice. It would have unlimited food and water, with beautiful nesting spaces and plenty of materials for the mice to make cozy homes with. Sweet experiment! the mice were probably thinking. Much better than the Maybelline trials we're used to.
However, there was a catch, of course. There was one thing the utopia would be lacking, and that would be physical space. As the mouse population grew, overcrowding would become an issue, and Calhoun wanted to study the problems this would potentially cause. That sound you hear is the collective sigh of the disappointed mice who were stoked about the 24/7 all-you-can-eat buffet.
The experiment, dubbed Universe 25, began when Calhoun introduced four mouse "couples" into the utopian complex. A year or so later, it was overrun and the conditions had turned hellish, even though the mice had not run out of food or water.
"The conditions had turned WHAT?" Giphy
Initially, for just the eight original mice, the square box Calhoun built included 256 nesting boxes (or apartments) stacked on top of one another. Water bottles and food dispensers were located all along the nesting spots, and mice could travel throughout the complex at will via mesh tunnels. The starter mice were also screened for diseases and the population was obviously protected from predators. The climate was controlled and comfortable. Conditions were perfect.
The first mouse pups showed up a little over three months later, with the population of the colony doubling every 55 days. Nineteen months later, there were 2,200 mice living inside the box. With such perfect surroundings, the infant mortality rate was practically zero, leading to the rapid rise in numbers.
John Calhoun poses with his rodents inside the mouse utopia. Yoichi R Okamoto, Public Domain
By month 19, this rodent utopia had become an overcrowded hellscape. Calhoun noticed three alarming trends, in particular.
In short, everything was devolving into chaos and the very society of the mice began to collapse at a rapid rate.
The "Beautiful Ones" and the "Dropouts": Mice have a complex social hierarchy ruled by dominant alpha males. Sam Kean of Science History Institute Museum & Library notes that, in the wild, non-dominant males (the ones who lose macho showdowns) can skip town and start over somewhere else. But in the close quarters of Calhoun's experiment, with nowhere to hide, they were forced to hang around and viciously battle with each other over scraps. Eventually, non-dominant male mice, which Calhoun called the "Beautiful Ones," withdrew from society completely and only ate, slept, and groomed themselves.
Though resources were unlimited, certain aggressive males hoarded them anyway: The alpha males ruled over everything in the once-utopian mouse society. They kept harems of females in the apartments to mate with and fought fiercely to defend their territory. But new waves of hungry young male mice kept coming and coming, and eventually even the most dominant alphas abandoned their posts. This led to more attacks on nursing females, which in turn led to more mothers kicking their pups out of the nest early.
Birth rate declined dramatically: With the non-dominant males giving up completely and focusing on #SelfCare, dominant males too exhausted from endless battles, and females sick and tired of it all (many became asexual hermits by the end), stopped mating and giving birth entirely. Once this happened, the society was doomed. Even with plenty of food still available, cannibalism was rampant.
Calhoun was not shy about drawing parallels between his research and humanity. "I shall largely speak of mice, but my thoughts are on man, on healing, on life and its evolution," he once wrote.
Alpha male mice, anyone? Photo by Kanashi on Unsplash
There are aspects of his wild experiment that certainly sound familiar.
We live in a world with plenty of resources for everyone, but a few select people hoard more than their fair share. When you think of the rodent "apartments," it's hard not to picture densely packed urban environments where people are stacked on top of each other at every turn. Maybe on some level some of us can relate to the “Beautiful Ones” and their urge to not participate in all the ugliness and just sequester and groom themselves. You can make an argument that when the mice stopped having to worry about food and shelter, it removed the element of challenge from their lives and left them lost. Similarly, many of us are lucky enough to not have to wonder where our next meal comes from, and maybe that has something to do with our never-ending search for meaning. Some even go so far as to link more people choosing to delay having children, or not have children at all, with the collapsing society of the mice.
But Calhoun's work has also been heavily scrutinized, with some claiming it's based on shaky science. And in the end, there’s the small matter that humans are not mice. We are infinitely more complicated, and so much better suited to adapting to our environments. Kean writes, "Ultimately Calhoun’s work functions like a Rorschach blot—people see what they want to see."
It's fascinating and thought-provoking nonetheless. Watch this breakdown of the experiment shared by the National Library of Medicine in the early 1970s.
- YouTube youtu.be
This article originally appeared in April. It has been updated.
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