rat experiment beautiful ones

This Old Experiment With Mice Led to Bleak Predictions for Humanity’s Future

From the 1950s to the 1970s, researcher John Calhoun gave rodents unlimited food and studied their behavior in overcrowded conditions

Maris Fessenden ; Updated by Rudy Molinek

What does utopia look like for mice and rats? According to a researcher who did most of his work in the 1950s through 1970s, it might include limitless food, multiple levels and secluded little condos. These were all part of John Calhoun’s experiments to study the effects of population density on behavior. But what looked like rodent paradises at first quickly spiraled into out-of-control overcrowding, eventual population collapse and seemingly sinister behavior patterns.

In other words, the mice were not nice.

Working with rats between 1958 and 1962, and with mice from 1968 to 1972, Calhoun set up experimental rodent enclosures at the National Institute of Mental Health’s Laboratory of Psychology. He hoped to learn more about how humans might behave in a crowded future. His first 24 attempts ended early due to constraints on laboratory space. But his 25th attempt at a utopian habitat, which began in 1968, would become a landmark psychological study. According to Gizmodo ’s Esther Inglis-Arkell, Calhoun’s “Universe 25” started when the researcher dropped four female and four male mice into the enclosure.

By the 560th day, the population peaked with over 2,200 individuals scurrying around, waiting for food and sometimes erupting into open brawls. These mice spent most of their time in the presence of hundreds of other mice. When they became adults, those mice that managed to produce offspring were so stressed out that parenting became an afterthought.

“Few females carried pregnancies to term, and the ones that did seemed to simply forget about their babies,” wrote Inglis-Arkell in 2015. “They’d move half their litter away from danger and forget the rest. Sometimes they’d drop and abandon a baby while they were carrying it.”

A select group of mice, which Calhoun called “the beautiful ones,” secluded themselves in protected places with a guard posted at the entry. They didn’t seek out mates or fight with other mice, wrote Will Wiles in Cabinet magazine in 2011, “they just ate, slept and groomed, wrapped in narcissistic introspection.”

Eventually, several factors combined to doom the experiment. The beautiful ones’ chaste behavior lowered the birth rate. Meanwhile, out in the overcrowded common areas, the few remaining parents’ neglect increased infant mortality. These factors sent the mice society over a demographic cliff. Just over a month after population peaked, around day 600, according to Distillations magazine ’s Sam Kean, no baby mice were surviving more than a few days. The society plummeted toward extinction as the remaining adult mice were just “hiding like hermits or grooming all day” before dying out, writes Kean.

Calhoun launched his experiments with the intent of translating his findings to human behavior. Ideas of a dangerously overcrowded human population were popularized by Thomas Malthus at the end of the 18th century with his book An Essay on the Principle of Population . Malthus theorized that populations would expand far faster than food production, leading to poverty and societal decline. Then, in 1968, the same year Calhoun set his ill-fated utopia in motion, Stanford University entomologist Paul Ehrlich published The Population Bomb . The book sparked widespread fears of an overcrowded and dystopic imminent future, beginning with the line, “The battle to feed all of humanity is over.”

Ehrlich suggested that the impending collapse mirrored the conditions Calhoun would find in his experiments. The cause, wrote Charles C. Mann for Smithsonian magazine in 2018, would be “too many people, packed into too-tight spaces, taking too much from the earth. Unless humanity cut down its numbers—soon—all of us would face ‘mass starvation’ on ‘a dying planet.’”

Calhoun’s experiments were interpreted at the time as evidence of what could happen in an overpopulated world. The unusual behaviors he observed—such as open violence, a lack of interest in sex and poor pup-rearing—he dubbed “behavioral sinks.”

After Calhoun wrote about his findings in a 1962 issue of Scientific American , that term caught on in popular culture, according to a paper published in the Journal of Social History . The work tapped into the era’s feeling of dread that crowded urban areas heralded the risk of moral decay.

Events like the murder of Kitty Genovese in 1964—in which false reports claimed 37 witnesses stood by and did nothing as Genovese was stabbed repeatedly—only served to intensify the worry. Despite the misinformation, media discussed the case widely as emblematic of rampant urban moral decay. A host of science fiction works—films like Soylent Green , comics like 2000 AD —played on Calhoun’s ideas and those of his contemporaries . For example, Soylent Green ’s vision of a dystopic future was set in a world maligned by pollution, poverty and overpopulation.

Now, interpretations of Calhoun’s work have changed. Inglis-Arkell explains that the main problem of the habitats he created wasn’t really a lack of space. Rather, it seems likely that Universe 25’s design enabled aggressive mice to stake out prime territory and guard the pens for a limited number of mice, leading to overcrowding in the rest of the world.

However we interpret Calhoun’s experiments, though, we can take comfort in the fact that humans are not rodents. Follow-up experiments by other researchers, which looked at human subjects, found that crowded conditions didn’t necessarily lead to negative outcomes like stress, aggression or discomfort.

“Rats may suffer from crowding,” medical historian Edmund Ramsden told the NIH Record ’s Carla Garnett in 2008, “human beings can cope.”

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Maris Fessenden | | READ MORE

Maris Fessenden is a freelance science writer and artist who appreciates small things and wide open spaces.

Rudy Molinek | READ MORE

Rudy Molinek is  Smithsonian  magazine's 2024 AAAS Mass Media Fellow.

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Universe 25: The Mouse "Utopia" Experiment That Turned Into An Apocalypse

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The utopia in all its glory. Image credit: Yoichi R Okamoto, White House photographer (public domain, via Wikimedia Commons ).

Over the last few hundred years, the human population of Earth has seen an increase, taking us from an estimated one billion in 1804 to seven billion in 2017. Throughout this time, concerns have been raised that our numbers may outgrow our ability to produce food, leading to widespread famine. 

Some –  the Malthusians  – even took the view that as resources ran out, the population would "control" itself through mass deaths until a sustainable population was reached. As it happens, advances in farming, changes in farming practices, and new farming technology have given us enough food to feed  10 billion people , and it's how the food is distributed which has caused mass famines and starvation. As we use our resources and the climate crisis worsens, this could all change  – but for now, we have always been able to produce more food than we need, even if we have lacked the will or ability to distribute it to those that need it.

But while everyone was worried about a lack of resources, one behavioral researcher in the 1970s sought to answer a different question: what happens to society if all our appetites are catered for, and all our needs are met? The answer – according to his study – was an awful lot of cannibalism shortly followed by an apocalypse.

John B Calhoun set about creating a series of experiments that would essentially cater to every need of rodents, and then track the effect on the population over time. The most infamous of the experiments was named, quite dramatically, Universe 25 .

In this study, he took four breeding pairs of mice and placed them inside a "utopia". The environment was designed to eliminate problems that would lead to mortality in the wild. They could access limitless food via 16 food hoppers, accessed via tunnels, which would feed up to 25 mice at a time, as well as water bottles just above. Nesting material was provided. The weather was kept at 68°F (20°C), which for those of you who aren't mice is the perfect mouse temperature. The mice were chosen for their health, obtained from the National Institutes of Health breeding colony. Extreme precautions were taken to stop any disease from entering the universe.

As well as this, no predators were present in the utopia, which sort of stands to reason. It's not often something is described as a "utopia, but also there were lions there picking us all off one by one". 

The experiment began, and as you'd expect, the mice used the time that would usually be wasted in foraging for food and shelter for having excessive amounts of sexual intercourse. About every 55 days, the population doubled as the mice filled the most desirable space within the pen, where access to the food tunnels was of ease.

When the population hit 620, that slowed to doubling around every 145 days, as the mouse society began to hit problems. The mice split off into groups, and those that could not find a role in these groups found themselves with nowhere to go.

"In the normal course of events in a natural ecological setting somewhat more young survive to maturity than are necessary to replace their dying or senescent established associates," Calhoun wrote in 1972 . "The excess that find no social niches emigrate."

Here, the "excess" could not emigrate, for there was nowhere else to go. The mice that found themself with no social role to fill – there are only so many head mouse roles, and the utopia was in no need of a Ratatouille -esque chef – became isolated.

"Males who failed withdrew physically and psychologically; they became very inactive and aggregated in large pools near the center of the floor of the universe. From this point on they no longer initiated interaction with their established associates, nor did their behavior elicit attack by territorial males," read the paper. "Even so, they became characterized by many wounds and much scar tissue as a result of attacks by other withdrawn males."

The withdrawn males would not respond during attacks, lying there immobile. Later on, they would attack others in the same pattern. The female counterparts of these isolated males withdrew as well. Some mice spent their days preening themselves, shunning mating, and never engaging in fighting. Due to this they had excellent fur coats, and were dubbed, somewhat disconcertingly, the "beautiful ones".

The breakdown of usual mouse behavior wasn't just limited to the outsiders. The "alpha male" mice became extremely aggressive, attacking others with no motivation or gain for themselves, and regularly raped both males and females . Violent encounters sometimes ended in mouse-on-mouse cannibalism.

Despite – or perhaps because – their every need was being catered for, mothers would abandon their young or merely just forget about them entirely, leaving them to fend for themselves. The mother mice also became aggressive towards trespassers to their nests, with males that would normally fill this role banished to other parts of the utopia. This aggression spilled over, and the mothers would regularly kill their young. Infant mortality in some territories of the utopia reached 90 percent.

This was all during the first phase of the downfall of the "utopia". In the phase Calhoun termed the "second death", whatever young mice survived the attacks from their mothers and others would grow up around these unusual mouse behaviors. As a result, they never learned usual mice behaviors and many showed little or no interest in mating, preferring to eat and preen themselves, alone.

The population peaked at 2,200 – short of the actual 3,000-mouse capacity of the "universe" – and from there came the decline. Many of the mice weren't interested in breeding and retired to the upper decks of the enclosure, while the others formed into violent gangs below, which would regularly attack and cannibalize other groups as well as their own. The low birth rate and high infant mortality combined with the violence, and soon the entire colony was extinct . During the mousepocalypse, food remained ample, and their every need completely met.

Calhoun termed what he saw as the cause of the collapse "behavioral sink".

"For an animal so simple as a mouse, the most complex behaviors involve the interrelated set of courtship, maternal care, territorial defence and hierarchical intragroup and intergroup social organization," he concluded in his study.

"When behaviors related to these functions fail to mature, there is no development of social organization and no reproduction. As in the case of my study reported above, all members of the population will age and eventually die. The species will die out."

He believed that the mouse experiment may also apply to humans, and warned of a day where – god forbid – all our needs are met.

"For an animal so complex as man, there is no logical reason why a comparable sequence of events should not also lead to species extinction. If opportunities for role fulfilment fall far short of the demand by those capable of filling roles, and having expectancies to do so, only violence and disruption of social organization can follow."

At the time, the experiment and conclusion became quite popular, resonating with people's feelings about overcrowding in urban areas leading to "moral decay"  (though of course, this ignores so many factors such as poverty and prejudice).

However, in recent times, people have questioned whether the experiment could really be applied so simply to humans – and whether it really showed what we believed it did in the first place.

The end of the mouse utopia could have arisen "not from density, but from excessive social interaction," medical historian Edmund Ramsden said in 2008 . “Not all of Calhoun’s rats had gone berserk. Those who managed to control space led relatively normal lives.”

As well as this, the experiment design has been criticized for creating not an overpopulation problem, but rather a scenario where the more aggressive mice were able to control the territory and isolate everyone else. Much like with food production in the real world, it's possible that the problem wasn't of adequate resources, but how those resources are controlled.

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Calhoun’s prophet rodents and the creation of the “behavioural sink”

Sophie Calabretto

Dr Sophie Calabretto is a mathematician specialising in fluid mechanics. She is Honorary Senior Lecturer at Macquarie University and Honorary Associate Professor, at the ACE Research Group, University of Leicester.

I first read Mrs. Fris by and the Rats of NIMH as a young’un. What I didn’t know at the time was that it was inspired by a series of experiments on population dynamics from the 1940s to the 1970s . The two studies, over a total of eight years, aimed to explore the effects of population density on behaviour.

John B Calhoun was a behavioural researcher and ethologist who spent the largest part of his career at the US National Institute of Mental Health (NIMH), in Maryland. His work spans six decades, from early experiments with rodents in the 1940s to his death in 1995. But he’s become recently spotlit for his work in 1958–62, starting with a quarter-acre pen of wild Norway rats, and a 1968–72 experiment with mice called Universe 25. Universe 25 was his research pinnacle – a “rodent utopia”.

Calhoun calculated that his pen of wild Norway rats (or brown rats, aka Parisian rats, Hanover rats, street rats, common rats, sewer rats, wharf rats… in essence, “rats” as you know them) could have a sustainable density of 5000, but the population strangely never exceeded 200. With extremely high rates of infant mortality, by the end of the 27th month of observation the population had stabilised at 150 adults.

Calhoun and his team were surprised by these unexpected results and so embarked on a more controlled experiment involving a population of domesticated Norway rats, conducted in a converted barn (a step up in luxury for the animals).

Calhoun’s new rat palace consisted of a 3m x 4.3m room, divided into four pens by an electrified fence. These pens contained everything a rat could possibly need: food, water, elevated burrows, winding staircases, nest boxes… a rodent wonderland. Ramps connected pen 1 to pen 2, 2 to 3, and 3 to 4, but not pen 1 to pen 4. This meant that rats tended to concentrate in pens 2 and 3, leading to the development of what Calhoun dubbed a “behavioural sink”: a sort of voluntary overcrowding that resulted from the original, involuntary overcrowding, and led to significant changes in the rats’ behaviour.

These changes weren’t at the good end of the scale.

Among the male rats, behavioural disturbances ranged from “sexual deviation”, cannibalism, and frenetic overactivity to pathological withdrawal.

As a result of the population congregation in the middle pens, the rats became unnaturally accustomed to the presence of others. Eating and undertaking other “biological activities” were transformed into social activities, which they would only do in the presence of other rats. Although fine for eating (who doesn’t love a dinner party?), this disrupted the sequence of other normal activity, such as courting, building nests, and nursing and caring for their young.

In the worst-affected rats in a series of these experiments, infant mortality was as high as 96%. Among the male rats, behavioural disturbances ranged from “sexual deviation”, cannibalism, and frenetic overactivity to pathological withdrawal.

Now decades into his rodent studies, Calhoun’s aim had morphed into extending lifespan by creating a “Mortality-inhibiting Environment for Mice”, also known as Universe 25. Universe 25, like Calhoun’s decked-out rat barn, was created to cater for the wee experimentees in every way. The 2.7m x 2.7m metal enclosure had 16 vertical mesh tunnels, each with four horizontal corridors opening off at the top, and each corridor leading to four nesting boxes.

With each of these 256 nesting boxes capable of housing up to 15 mice, Universe 25 was theoretically capable of accommodating up to 3840 mice. (I know what you’re thinking right now: “I bet it didn’t”. Me neither, dear reader.) And, of course, there was an abundance of fresh water, food, and nesting material.

This is where everything starts getting a little… Biblical.

Calhoun’s reduction of mouse mortality was based on identifying the rodent equivalent of the four mortality factors listed in Revelation – as in the Book of Revelation. Calhoun described the results of the Universe 25 experiment in a journal article titled “Death Squared: The Explosive Growth and Demise of a Mouse Population”. His text included a hefty number of biblical references for something published in the Proceedings of the Royal Society of Medicine .

His lead paragraph ends thus: “This takes us back to the white first horse of the Apocalypse which with its rider set out to conquer the forces that threaten the spirit with death. Further in Revelation ( ii.7 ) we note: ‘To him who conquers I will grant to eat the tree of life, which is in the paradise of God’ and further on (Rev. xxii.2 ): ‘The leaves of the tree were for the healing of nations.’”

And so, along with its abundance of resources, Universe 25 was cleaned every four to eight weeks, contained no predators, had the temperature maintained at a delightful 20°C, and was colonised by the finest, disease-free mice selected from the National Institutes of Health’s breeding colony. The only limitation was space.

Unfortunately, what resulted was a turbo-charged rat barn all over again. The population of Universe 25 began to steadily grow from the four original pairs of mice, until it reached a population of 2200 by Day 560. At which stage the population began its decline, and by the end of the experiment (Day 1500), there were only 27 mice remaining. The last surviving birth occurred on Day 600, after which the incidence of pregnancies declined very rapidly with no young surviving. The last conception occurred around Day 920.

While dominant males initially thrived and fathered all the offspring they could muster, the less dominant were inactive and eventually became violent towards each other. Those who were attacked would later attack others. The female counterparts of the withdrawn males simply hid. Nursing females in the presence of territorial males began to exhibit aggression, attacking and wounding their own young and forcing them to leave the nest before weaning was complete.

The next generation of mice, having never experienced healthy mouse behaviour, had no concept of mating or parenting, or even territorialism.

Consequently, the next generation of mice, having never experienced healthy mouse behaviour, had no concept of mating or parenting, or even territorialism. Some – dubbed the “beautiful ones” – spent their time eating, drinking, and grooming themselves in seclusion. Elsewhere, mice formed gangs of cannibalistic, raping plunderers.

Gradually, with a cohort of mice who would no longer actively mate or engage constructively in society, the population died out.

Calhoun was concerned with not only the death of the body (the second death) but also the death of the spirit (the first death – see Revelation ii:11 ) – an unusual inclusion in an academic paper. His thoughts are summarised with a word equation, the penultimate entry in the article:

Mortality, bodily death = the second death Drastic reduction of mortality = death of the second death = death squared = (death) 2 (Death) 2 leads to dissolution of social organisation = death of the establishment Death of the establishment leads to spiritual death = loss of capacity to engage in behaviours essential to species survival = the first death Therefore: (Death) 2 = the first death

I have considered this equation for a while, and I have a few problems from a first-year university algebra perspective.

Let’s say mortality (bodily death) is a function called M . Now, as stated before, according to Calhoun’s article, there are five mortality factors in the ecology of animals in nature: emigration, resource shortage, inclement weather, disease, and predation. So mortality would be a function of these factors: M = M(e, r s , w i , d, p) . Now, the death of the second death would be the composition* of M with M , which we denote as M ∘ M . (*Function composition is when you apply one function to the result of another: for example, if f(x) = x + 1 and g(x) = x 3 , then (f ∘ g)(x) = f(g(x)) = f(x 3 ) = x 3 + 1 .)

This is where we hit a snag, because if we assume that M is a function of real variables, what we’re looking at is the composition of a multivariable function with a multivariable function, which isn’t technically possible.

Calhoun thought that the death of the spirit, which here equates to social breakdown, is unequivocally linked to the literal end of life.

But I digress. I think the most we can conclude from this is that Calhoun thought that the death of the spirit, which here equates to social breakdown, is unequivocally linked to the literal end of life. That is: “Loss of these respective complex behaviours means death of the species.” Unfortunately, he also concludes that “for an animal so complex as man, there is no logical reason why a comparable sequence of events should not also lead to species extinction”.

Many scientists, both at the time and since, would disagree with the somewhat macabre conclusions of the experiment, arguing that Calhoun’s work was not necessarily about population density per se, but rather it about social interaction. And humans interact with each other differently to the way rodents do. As a result, “Death Squared” is predominantly cited in works about lab rodents and rodent populations, rather than in research projecting the collapse of humankind.

Maybe Calhoun himself tried to soften his conclusions. At the end of the several pages of Biblical gloom in “Death Squared” he again relied on the Bible for the article’s last passage:

“Happy is the man who finds wisdom, And the man who gains understanding. Wisdom is a tree of life to those who lay hold of her. All her paths lead to peace.                 ( Proverbs iii. 13, 18 and 17, rearranged)”

Originally published by Cosmos as Calhoun’s prophet rodents and the creation of the “behavioural sink”

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Medicine on Screen

Films and Essays from NLM

The Falls of 1972: John B Calhoun and Urban Pessimism

By Jon Adams (London School of Economics and Political Science) and Edmund Ramsden, PhD (Queen Mary University of London)

DATE: 1970-1972 LENGTH: 38 min (edited version) PRODUCER/PUBLISHER: National Institute of Mental Health, Time-Life Broadcasting CATEGORY: Research & Documentation, Sound, Color

“ F all, 1972. Scenes Include Last Survivors.” This is the text on the opening slate. What have we missed? For now, it’s enough to know we’ve arrived late in the game. This is not the event, but its aftermath. This is post-apocalypse.

We know—we think we know—what the post-apocalyptic world will look like. We’ve seen it in the movies (George Miller’s  Mad Max ), read about it (Cormac McCarthy’s  The Road ), and even played the video game (Naughty Dog’s  The Last of Us ). It’s a place where bands of ragged survivors roam over a defoliated wasteland, their engagements marked by the expression of terrible violence and unchecked sexual aggression.

For fiction, the post-apocalypse is a theatre in which to explore humanity’s barely subdued inhumanity. Functionally, it acts as a counterfactual, a reminder of the fragility of order, of how much our society depends for its continued operation upon our willing and mutual consent. Here’s how things would be if we didn’t play by the rules. Because in the post-apocalypse, nobody plays by the rules. Behaviour is as bad as it can be. The rules went away with the society they formed, everything now is pure  id . Just the base instincts survive, and survival requires just the base instincts. Kill, steal, rape. This is how the world looks from the brain stem, this is the view from the cerebellum. Post-apocalypse represents regression to pre-history, of motivational surrender to the throbbing urgency of the lizard brain.

Here’s an alternative scenario:

A world of perfectly clean and well tended inhabitants, coexisting harmoniously. No sexual violence—no sex at all. No violence, either. Lots of grooming. Regular communal meals. Because this is also a post-apocalypse. These are also the survivors of a societal collapse. They’re mice, and they’re the only living remnants of Universe 25.

Universe 25 is a nine-by-nine-foot square arena with five-foot high metal walls built within the National Institute of Mental Health (NIMH) in Bethesda, MD. Its floor is a spindle of sixteen segments split by low dividers—just tall enough to keep mice from making contact, but not so high they can’t easily climb over. Good fences make good neighbors. Its designer, NIMH scientist John B. Calhoun, climbs down into the pen, watched by the camera that McGraw-Hill educational films have brought to record the interview. The interviewer stays outside. Calhoun’s daughter would later recall the smell, above all [1] the stench of two thousand mice.

But only a few now survived—about 120 specimens. They’re clustered together around a single feeder, dumbly nuzzling and preening. Calhoun’s rodents had been through the  Mad Max  period: they had experienced their orgy of ultraviolence, sexual predation, incest, and cannibalism. Trapped inside Universe 25 with all their material needs met, the mice had bred until the stresses of over-population led them into a permanent state of fight-or-flight. Calhoun had termed this “the Behavioural Sink”—the tipping point after which all civility broke down, and the animals were drawn into an irreversible vortex of self-destruction, a frenzied mass panic from which only these huddled, withdrawn specimens now survive.

For contemporary audiences, that rapid escalation to annihilation might have brought to mind what nuclear theorist and Kennedy advisor Herman Kahn had recently called “spasm war” ( On Escalation , 1965)—the endgame of the US-Soviet  détente , the point at which everyone pressed all of their buttons.

But there was another device ticking insistently below everyday life: what Paul Ehrlich had recently called The Population Bomb (1968). The late nineteen-sixties and early seventies witnessed growing popular concern over the ability of our planet to sustain the seemingly unstoppable growth of the species. The strapline on Ehrlich’s book read: “Population Control or Race to Oblivion?” That same year, philosopher Garrett Hardin popularised the notion of the “tragedy of the commons,” a demand for regulated access to public goods that he would later revise into the altogether more troubling “lifeboat ethics” (1974). Meanwhile, an Apollo-era public mindful of the need for astronauts to carry all their own supplies were urged by Buckminster Fuller to think of our own “Spaceship Earth” as a similarly finite container. It was as if, as one commentator put it, humanity was doomed to a choice between two bombs: “we shall probably solve the population problem by nuclear extermination. In any case, the two major problems of our time—nuclear war and the population explosion—are closely linked together.” [2] Certainly, Calhoun was happy to use the language of apocalypse—quoting Revelations in the introduction to one paper from the time. [3] For what might happen aboard the airlocked Spaceship Earth; see Universe 25.

Yet if this mouse enclosure modeled our own eventual demise, then it turns out the post-apocalypse of popular culture was only a transitional phase, a station on route to this strangely calm dystopia. A blank white space, reminiscent of John Lennon’s video for 1970’s “Imagine,” or the sterile dream-rooms in the final reel of Kubrick’s recent 2001: A Space Odyssey (1968). The utopian and the dystopian osculate here. Kahn had asked: after a nuclear holocaust, “will the survivors envy the dead?” [4]

Anchoring it by the tail, Calhoun displays one of the mice on his palm, he notes its smooth pelage. It’s a balb-C albino, a common lab mouse, bred by the NIH Animal Center and more or less guaranteed disease-free and behaviourally normal. But these survivors are third- or fourth-generation descendants of those original specimens. In autopsy, their parents and grandparents had all been laced with scar tissue, tails chewed to stumps, ragged ears. Hypertrophy of the adrenal glands. These mice show none of that trauma. Calhoun and his researchers came to call them “the Beautiful Ones.”

The Beautiful Ones of Universe 25, the Behavioural-Sink survivors, are no less selfish than the rampaging actors of McCarthy or Miller’s post-apocalyptic universes. But their particular brand of non-cooperation doesn’t involve destructive interference. Rather, they avoid the problems of unwanted contact by never developing the complex adult behaviours that lead to conflict in the first place. The Beautiful Ones broker a form of mutual peace predicated on a form of extended infantilism. In the film, Calhoun describes their arrested development: “They never learned to be aggressive, which is necessary in defense of home sites. They never learned to court, so there was no mating. Being no mating, there were no progeny.” At the time of filming, Calhoun was preparing a paper he titled “Death Squared”, in which he describes them in more existential terms:

“Autistic-like creatures, capable only of the most simple behaviors compatible with physiological survival, emerge out of this process. Their spirit has died … They are no longer capable of executing the more complex behaviors compatible with species survival.” [5]

Sartre:  L’ enfer, c’est les autres . [6]  Hell is others. In a sense, these remaining mice never fully acknowledge the existence of the other. The Beautiful Ones survive by adopting the psychological equivalent of horse blinkers.

The interview, with journalist Bill Roberts, was the second Calhoun had given to Time-Life Broadcast, a pioneering non-network television news station set up in 1958. Roberts was the Time-Life Washington bureau chief, and the cameraman is almost certainly his fellow correspondent Carl Coleman. It was Coleman who had conducted the first Calhoun interview from 1970, available (unedited) on the same reel. Time-Life Broadcasting was acquired by McGraw-Hill Educational films in 1972, and it is to McGraw-Hill that both films are credited.

The bulk of Coleman and Roberts’ work was reporting on political developments in DC, but Time-Life Broadcast encouraged them to pursue a broader agenda, drawing on the journalistic resources of  Time  magazine. As a blurb in the trade-paper  Broadcasting  (Jan 2, 1961) explained: “Not intending to duplicate other news services, Time Inc.’s bureaus and correspondents provide depth reporting that spotlights the personalities and motivations behind the news — fill out conventional coverage and give it more meaning.” Time-Life also distributed or co-produced documentary series such as Alistair Cooke’s  America  and, also in 1972, were the first to bring the BBC series  Doctor Who  to American audiences. Whether the idea of visiting Calhoun was suggested by  Time , or generated independently by Roberts and Coleman, their DC bureau was close to the laboratory. A day trip, with the camera and lights on the backseat.

As principally political journalists, you’d expect Coleman and Roberts to invite Calhoun to make connections with human society: why else would they be interested in mice? But Calhoun doesn’t need prompting: he has long seen analogies between his infested rodent pens and our increasingly populous world. He called his early enclosures “rat cities” and, in several of them, explicitly sought to recreate the vertical organisation and pressure-points (stairwells, corridors) that were characteristic of much of the post-war mass-housing projects that had sprung up across the US.

Calhoun is relatively short, mid-fifties. He seemingly hasn’t lost a strand of his hair, which is brown, mid length, greying at the sides. With his white goatee and southern manners, he might remind you of a more serious Colonel Sanders. But his eyes are narrow, wary between drooping lids, giving him more the look of a benign Charles Bronson. Sartorially, there’s the slightly-mislaid formality characteristic of a certain type of academic: in the earlier interview with Carl Coleman, Calhoun is wearing two cardigans—the first buttoned up like a vest, a second open over the top, like a jacket. As if they were a three-piece suit.

Before moving to the NIMH in 1954, Calhoun’s career had begun as an ethologist employed by the Rodent Ecology Project at Johns Hopkins between 1946-49. Charged with controlling the burgeoning rat problem in Baltimore, they noticed that increased numbers in a restricted area dampened rat population; promising a new and more effective ecological approach to rodent control through the control of space: when the animals were confined to an area such as a neighbourhood block, beyond a certain limit of numbers and resources, rat society began to break down, violence erupted, and diseases spread.

Calhoun believed that his study of rodent population dynamics had direct relevance for understanding the stresses, strains, and societal dysfunctions that troubled human populations in urban environments. Seeking to better understand the social and psychological pathologies associated with the increased population density that might be shared with the rapidly urbanizing human, Calhoun now designed a series of “rat cities.” He constructed his first “rodent universe” in a barn in Towson, MD. A ten-by-fourteen-foot pen, with an observation hatch cut through the ceiling. Each pen was divided into four by means of an electrified partition, two with a single ramp in enter and exit, and two with twin ramps. The animals wanted for little, being provided with food, warmth, bedding and housing, Calhoun describing “an always replete cafeteria … no epidemic disease, no famine.” [7]  Yet, as the population expanded, the structure of the environment began to prove critical to the well-being of the animals in each section of the pen. The animals began to suffer from the one resource they were lacking, space, and rat city became rat slum.

As the slums of the real world were cleared, and vast towerblocks built in their place, the twin strands of Calhoun’s research—population growth on the one hand, and the decline in behavioural norms under conditions of elevated social density (or more precisely, what he called “social velocity”: the frequency and volume of unavoidable social contact)—became entwined. Here in the dense urban core, human conduct seemed to exhibit aberrations disturbingly similar to those Calhoun was able to generate in his rat cities: hypersexuality, child abuse, neglect, ultraviolence. For those who sought it, Calhoun’s experiments provided a ready explanation for the criminality and social unrest that plagued the modern city. The cities weren’t just collecting bad people; they were actively turning them bad.

1972 had seen a turning point for the tower block. In March of that year, the  demolition of Pruitt Igoe  in St Louis had begun, a spectacular retreat from two decades of high-density public housing. The imploding buildings seemed a metaphor for the collapsing hopes for urban revival and, tangentially, following the assassinations of the Kennedy brothers, of Martin Luther King and Malcolm X, of the optimism that had buoyed up the Civil Rights movement of the sixties.

Faith in human nature took a more anthropological turn when Colin Turnbull’s  The Mountain People  (1972) was published that same fall to considerable acclaim. Turnbull was an anthropologist-cum-travel writer who had previously written fondly of the Mbuti pygmies of the south-western Congo in a popular book called  The Forest People . Like Margaret Mead before him, he saw in (or projected onto) the Mbuti a sort of prelapsarian innocence. But when he settled among the Ik of northern Uganda, he found a society in an altogether more Hobbesian state of nature.

As Calhoun explains in the film, according to Turnbull’s narrative (the facts of which have subsequently been contested), the Ik had been a quasi-nomadic people driven off their hunting grounds to make way for a National Park. Forced into subsistence farming on a relatively small patch of land in the lower highlands, they had experienced a sudden concentration of their population. The attendant social tensions this created, abetted by famine, led to a catastrophic breakdown of civility, internal violence, and a neglect of familial duties:

“…the people were as unfriendly, uncharitable, inhospitable and generally mean as any people can be. For those positive values we value so highly are no longer functional for the Ik; even more than in our own society they spell ruin and disaster…” [8]

For Calhoun, watching his trapped and crowded mice attack one another, what happened to the Ik must have seemed like a natural experiment, the relevance sharpened by Turnbull’s zoomorphic phrasing:

“The much vaunted gap between man and the so-called ‘lesser’ animals suddenly shrinks to nothingness, except that in this case most ‘lesser’ animals come off rather well by comparison.” [9]

Here was an ethnographic counterpart to the observations Calhoun had been making of his rodents: if the mice were analogous, the Ik were surely homologous. The three cases—rodent collapse, Ik collapse, and urban collapse—become mutually reinforcing. The phenomena of the Behavioural Sink was transcendent.

The “sober message” Bill Roberts ends on is the prospect of a community failure: of over-population leading to the sort of collapse experienced by the mice of Universe 25. But Calhoun always maintained it was the improper division of space that led to conflict, not population density per se; Pruit Igoe and Park Lane were indistinguishable in density. The difference lay in the design.

Good fences make good neighbours: the line is known from Frost’s “Mending Wall,” published in 1914, at the advent of the First World War, and three years before Calhoun was born in Monkton, TN. The poem sees two neighbours in the annual repair of a drystone boundary between their properties. Amused by their commitment to something that seems so unnecessary (“we do not need the wall,” he says, “here there are no cows”), Frost’s narrator teases his neighbor, who only replies: “Good fences make good neighbours.” The narrator is playfully stubborn:

Before I built a wall I’d ask to know What I was walling in or walling out, And to whom I was like to give offense.

The poem obliquely suggest that such divisions are a cultural imposition, one we might do well to abandon. Man builds fences, but some mysterious force of nature seeks to tear them down: “Something there is that doesn’t love a wall.” It’s as if we want to live in harmony together, but social conventions insist we keep ourselves apart from one another. The wall is a Rousseauian symbol of how civilisation diverts us from our natural happy state.

Yet Frost is rarely as simplistic as he seems, and “Mending Wall” embeds a characteristically barbed ambiguity: when you list the elements that break the wall each winter—entropy, erosion, carelessness, the hunter’s drive to kill (and, cannily, frost)—it’s hardly the stuff of hippy communes and kumbaya. The poem’s central question—“Something there is that doesn’t love a wall”—hides a dark answer. The wall is there to keep us apart, and whatever seeks to bring it down wishes to see us clash.

If Frost’s “Mending Wall” is one touchstone, another is Auden’s short poem, “The Birth of Architecture,” from 1965:

Some thirty inches from my nose The frontier of my Person goes, And all the untilled air between Is private pagus or demesne. Stranger, unless with bedroom eyes I beckon you to fraternize, Beware of rudely crossing it: I have no gun, but I can spit.

The text is quoted extant as the epigraph to the tenth chapter of Edward Hall’s  The Hidden Dimension  (1966) and it’s an even bet that it had been Hall’s earlier book,  The Silent Language  (1959) that had inspired Auden in the first instance. Travelling across Europe, Asia, the Middle East and North Africa during the thirties and forties, Hall had developed a theory of “personal space”—that “thirty inches” of perimeter Auden writes of—an extension of our corporeal being, a sort of cognitive halo, any violation of which was emotionally experienced if not physically felt. Hall befriended Calhoun in the 1960s, the two were jointly interviewed by CBS (viewable in another of the archive’s tapes), and both came to influence the landscape architect Ian McHarg, who regularly invited them to address his students in Philadelphia. McHarg’s ecological concern with the multiple uses of an environment would be instrumental in the development of what later became Geographic Information Systems, or GIS.

“Proxemics,” as Hall termed his theory, gradually faded from intellectual interest, as did the thinkers he had inspired—Marshall McLuhan and Buckminster Fuller among them. Calhoun’s work at the NIMH was phased out during the late seventies, replaced by more empirically verifiable, and commercially profitable, pharmacological research. He retired in the early eighties, and died in 1992. But Calhoun’s influence has quietly endured, even if his name has not.

It’s a peculiarly twentieth-century notion, distinctive of the urban condition, this idea that we need to be kept apart as much as we need contact; that solitude was every bit as important as company. E. B. White had, with typical precision, speared the issue in 1949, in the opening lines to his essay,  Here Is New York  (1949): “On any person who desires such queer prizes, New York will bestow the gift of loneliness and the gift of privacy.” The city concentrated and made explicit that duality. How we read Calhoun’s experiments depends, to a significant extent, on the extent to which we side with Rousseau or Hobbes. Nature’s essential goodness versus its essential brutality.

Something there is that doesn’t love a wall. The post-apocalyptic mice of Universe 25 stand as testament to this. In Calhoun’s rodent pens, we’re reminded of the dual nature of the walls we build, and of their foundational importance to the very idea of civilization, as the guarantors of both our privacy and our loneliness. Those queer prizes we collectively desire, and the vital importance of architecture to their achievement.

Bibliography

Adams, Jon, and Edmund Ramsden. “Rat Cities and Beehive Worlds: Density and Design in the Modern City.”  Comparative Studies in Society and History  53, no. 4 (October 2011): 722–756.

Biehler, Dawn.  Pests in the City: Flies, Bedbugs, Cockroaches, and Rats . Seattle: University of Washington Press, 2013.

Calhoun, John B. “A Method for Self-Control of Population Growth among Mammals Living in the Wild.”  Science  109, no. 2831 (April 1949): 333–335.

Calhoun, John B. “The Social Aspects of Population Dynamics.”  Journal Mammalogy  33,  no. 2 (1952): 139–159.

Calhoun, John B. “Social Welfare as a Variable in Population Dynamics.” in  Cold Spring Harbor Symposia   on Quantitative Biology  22 (1957): 339–356.

Calhoun, John B. “Population Density and Social Pathology.”  Scientific American  206, no.2 (February 1962): 139–148.

Calhoun, John B.  The Ecology and Sociology of   the Norway Rat .  Bethesda: U.S. Department of Health, Education, and Welfare, 1963.

Calhoun, John B. “The Social Use of Space.” In  Physiological Mammalogy , edited by William V. Mayer and Richard G. Van Gelder, 1–187. New York: Academic, 1963.

Calhoun, John B. “Control of Population: Numbers.”  Annals of the New York Academy of Sciences  184 (June 1971): 148–155.

Calhoun, John B. “Disruption of Behavioral States as a Cause of Aggression.”  Nebraska Symposium on Motivation  20 (1972): 183–260.

Calhoun, John B. “Plight of the Ik and Kaiadilt Is Seen as a Chilling Possible End for Man.”  Smithsonian Magazine  3 (Nov. 1972): 26–33.

Calhoun, John B. “Death Squared: The Explosive Growth and Demise of a Mouse Population.”  Proceedings   of the Royal Society of Medicine  66, no.1 pt. 2 (1973): 80–88.

Calhoun, John B. “What Sort of Box?”  Man–Environment Systems  3 (1973): 3–30.

Calhoun, John B. “Looking Backward from ‘The Beautiful Ones.’” In  Discovery Processes in Modern Biology , edited by W. R. Klemm, 25–65. Huntington, N.Y.: Krieger, 1977.

Ehrlich, Paul.  The Population Bomb .  New York: Sierra Club/Ballantine Books, 1968.

Hall, Edward T.  The Silent Language .  New York: Doubleday, 1959.

Hall, Edward T.  The Hidden Dimension . Garden City, N.Y.: Doubleday, 1966.

Hardin, Garrett. “Lifeboat Ethics: the Case Against Helping the Poor.”  Psychology Today  8 (1974): 38–43, 123–6.

Hoagland, Hudson. “Cybernetics of Population Control.”  Bulletin of the Atomic Scientists  20, no. 2 (1964): 2–6.

Kahn, Herman.  On Thermonuclear War . Princeton, N.J.: Princeton University Press: London: Oxford University Press, 1960.

Kahn, Herman.  On Escalation: Metaphors and Scenarios . London: Pall Mall Press, 1965.

Keiner, Christine. “Wartime Rat Control, Rodent Ecology, and the Rise and Fall of Chemical Rodenticides.”  Endeavour  29 (2005): 119–125.

McHarg, Ian.  Design with Nature . New York: Doubleday, 1969.

Ramsden, Edmund. “From Rodent Utopia to Urban Hell: Population, Pathology, and the Crowded Rats of NIMH.”  Isis  102, no. 4 (Dec. 2011): 659–688.

Ramsden, Edmund, and Jon Adams. “Escaping the Laboratory: The Rodent Experiments of John B. Calhoun and Their Cultural Influence.”  Journal of Social History  42, no. 3 (2009): 761–792.

Turnbull, Colin M.  The Forest People . London: Chatto & Windus, 1961.

Turnbull, Colin M.  The Mountain People . New York: Touchstone/Simon and Schuster, 1987 [1972].

White, E. B.  Here is New York . New York: Harper & Bros, 1949.

[1]  Interviewed for  Critical Mass , dir. Mike Freedman, 2012.

[2]  Hudson Hoagland, “Cybernetics of Population Control,”  Bulletin of the Atomic Scientists  (February 1964), p.6.

[3]  Calhoun, “Death Squared,”  Proceedings of the Royal Society of Medicine , Volume 66 (January 1973): pp. 80-86.

[4]   On Thermonuclear War , Princeton, 1960; p.40.

[5]  Calhoun, “Death Squared”  Proceedings of the Royal Society of Medicine , Volume 66 (January 1973), p. 86

[6]   No Exit , 1944.

[7]  John B. Calhoun, speaking at Conference on Social and Physical Environmental Variables as Determinants of Mental Health, 22 May 1959, Washington D.C., Transcripts, p. 93, Calhoun Papers, NLM, Box 64 (“rat slum”).

[8]   The Mountain People , 1972, Touchstone/Simon and Schuster, 1987: p.32.

[9]   Ibid .

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Dr. Calhoun’s Mousery

The strange tale of a celebrated scientist, a rodent dystopia, and the future of humanity.

Lee Alan Dugatkin

240 pages | 12 halftones, 2 line drawings | 6 x 9 | © 2024

Biography and Letters

Biological Sciences: Behavioral Biology

History of Science

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“At first, scientists just wanted to figure out the best way to kill these pests. Then they decided that studying rat society could reveal the future of our own. . . . Calhoun came up with a new term to describe the process he had witnessed. The rats, he said, had fallen into a ‘behavioral sink.’ . . . Whether or not Calhoun proposed ‘an early version of the world wide web,’ as Dugatkin claims, the Internet has certainly linked ‘more and more individuals in a common communication network.’ And, it could be argued, our increasingly intelligent laptops and cell phones count as ‘thinking prostheses.’ But where, oh where is the compassion? Facebook, Yik Yak, Twitter, Twitch—each had a sunny, expansive phase, followed by a descent into flaming, catfishing, and troll wars. To the extent that Calhoun’s rats have any sociological relevance, it would seem to be in the mirror world of the Web. What, after all, could be a better description of X these days than a ‘behavioral sink?’”

Elizabeth Kolbert | The New Yorker

“The problem was overpopulation; the diagnostician was John B. Calhoun, a pioneering student of animal behavior and ecology and the subject of Dugatkin’s well-turned biography. . . . Dugatkin . . . evokes nicely the ‘eclectic, unorthodox’ trajectory of Calhoun’s career, in which he ranged with thrilling freedom across disciplines. . . . [He] animates the bureaucratic details of Calhoun’s career with dry humor. . . . And for all of the inspiration his lab work offered to city planners, prison reformers, artists and others, its scientific legacy today is slight. Partly this is because people worry less about overpopulation, but mostly—as Dugatkin notes only in the epilogue, as if gently rousing readers from a dream—it’s because the eye-catching phenomena Calhoun found in captive populations have never been documented in the wild. Behavioral sinks and beautiful ones are more suggestive metaphors than hard science, it seems, an uneasy triumph of story over data.”

Timothy Farrington | The Wall Street Journal

“A compelling biography about a groundbreaking scientist and his controversial work, using rodent cities—rodentopias—to identify and examine the potential catastrophes that might befall human overpopulation. . . . Dugatkin does an excellent job of investigating, documenting and writing about Dr. Calhoun’s life and work. . . . Drawing on previously unpublished archival research and interviews with Calhoun’s family and former colleagues, Dugatkin offers a riveting account of an intriguing scientific figure. Considering Dr. Calhoun’s experiments, he explores the changing nature of scientific research and delves into what the study of animal behavior can teach us about ourselves.”

GrrlScientist | Forbes

“A new biography nearly as quirky as its subject. . . . Dugatkin—an evolutionary biologist, science historian and prolific author who sifted through thousands of pages at the Calhoun archive in Bethesda—is an admirably thorough researcher. . . . Calhoun belonged to a generation of scientists who had no compunctions about straying from their disciplinary lane. He wrote poetry and sci-fi and consulted on humane prison design. Dugatkin captures the grand ambition of a man who gazed at rodents and saw the universe.”

Ben Goldfarb | Scientific American

“Only publishing . . . could contrive to drop two excellent books about Calhoun’s life and work into the same cycle. . . . I prefer [ Dr. Calhoun's Mousery ]. Its narrative is more straight-forward, and the author gives greater weight to Calhoun’s later career.”

Simon Ings | The Spectator

"Biologist Dugatkin’s deeply researched biography traces Calhoun’s career with close attention to the intellectual currents that directed the mouse work. Since Calhoun’s death, subsequent currents have swept a way much of what he accomplished."

Natural History

"Though labeled an animal ecologist, Calhoun worked across disciplines and incorporated science, math, urban planning, economics, and sociology into his research. . . . Few academic fields have rock stars. Yes, there were Malthus, Darwin, and Skinner, but Calhoun’s national and international fame in the 1960s and 1970s was truly dazzling. . . . Dugatkin wrote Dr. Calhoun’s Mousery to introduce new generations to a largely forgotten scientist who, although engaging in somewhat bizarre research, did so with a certain je ne sais quoi and left excellent notes concerning his work."

Washington Independent Review of Books

"Can we monitor rats' behavior and then learn anything about ourselves? Well we sure can, but we may not like what it tells us. There have been some famous experiments about all of this and our next guest has written about that actually. [Dugatkin] is . . . professor in the Department of Biology at the University of Louisville and the author of Dr. Calhoun’s Mousery: The Strange Tale of a Celebrated Scientist, a Rodent Dystopia, and the Future of Humanity ."

Mornings with Simi on 980 CKNW

"This stimulating scientific history from Dugatkin . . . recaps psychologist John B. Calhoun’s yearslong experiments on mice and rats in the 1960s and ’70s. . . . Dugatkin offers colorful accounts . . . and descriptions of the exigencies of the rat-race within them intrigue. . . . This fascinates."

Publishers Weekly

“ Dr. Calhoun’s Mousery is a brilliant reminder, from biologist and author Dugatkin, of how relevant some research remains even decades later. This story of a fascinating, complicated psychologist and his innovative, insightful, troubling studies of overpopulation in rodents is an absorbing read and a potent lesson in moral behavior—both of rodents and of humans."

Deborah Blum, Pulitzer Prize–winning author of "The Poison Squad: One Chemist’s Single-Minded Crusade for Food Safety at the Turn of the Twentieth Century"

“John Calhoun famously showed that rodential ‘society’ degenerates horrendously when rodents live at high densities. Politicians, urban planners, pundits, and criminologists then seized these findings, often distorting them when extrapolating to supposed inevitabilities about urban humans. Dugatkin gives us the life of Calhoun himself―often eccentric, with wildly expansive ideas, unclear as to just how much he wanted them interpreted imprudently. A fascinating read about an immensely influential scientist.”

Robert M. Sapolsky, author of the New York Times–bestseller “Determined: A Science of Life without Free Will”

“William Blake saw the world in a grain of sand. John Calhoun saw it in a mousery—a utopian apartment complex built for mice! Dugatkin’s brilliant, fast-paced account of Calhoun's research takes us on a whirlwind tour with stops along the way at the Royal Society in London, the Vatican, and Washington, DC. Dugatkin is both learned and lively, and his book is irresistible.”

Edward Dolnick, New York Times–best-selling author of "The Clockwork Universe" and "The Writing of the Gods"

“This engagingly written book revives the life and work of the almost-forgotten behavioral population biologist John Calhoun, whose discoveries on the crowding syndrome and social pathology in rodents had at that time far-reaching interdisciplinary implications concerning the consequences of human population growth. This book is a masterpiece of critical, scholarly biography and historical analysis of a field in behavioral biology.”

Bert Hölldobler, coauthor of the Pulitzer Prize–winning "The Ants"

Table of Contents

Zebra Stripes

Principles of animal behavior, 4th edition, the art of being a parasite.

Claude Combes

The Ark and Beyond

Ben A. Minteer

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Escaping the Laboratory: the rodent experiments of John B. Calhoun & their cultural influence.

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Infamous Universe 25 'Rodent Utopia' Experiment Is Not a Sign of the Apocalypse

Many people have used john calhoun's "rodent utopia" experiments as scientific evidence for "social decay" in humans., published may 27, 2024.

People predicting the end of world generally make those predictions without scientific evidence to support them. So when an animal-behavior researcher ran experiments in the 1960s that described "utopian" rodent societies pushing themselves into extinction, scientists and the general public alike took notice. That attention never fully went away.

Ever since the original "Universe 25" rodent utopia experiment took place, countless people have discussed the study and its findings, with some suggesting it could be an apocalyptic prediction for the future of humanity. The story pops up online every so often, and Snopes readers have written many emails over the past few years asking us about the notorious rodent utopia experiment.

The Background

Before explaining the experiment, it's important to understand why it   was performed. While environmentalism as a political theory had been around in bits and pieces since the early days of the Industrial Revolution, it was not until just after World War II that people truly began to politically organize around the environment.

One of the largest fears at the time was overpopulation — sometimes called Malthusianism after an 18th-century demographer, Thomas Malthus , who proposed that population would eventually grow faster than food production, meaning that, eventually, humanity would be unable to feed everyone. Many early environmentalists proposed similar ideas.

In the 1950s, an animal behaviorist named John Calhoun started working at the National Institute of Mental Health. He had long worked with rats, the subject of his Ph.D. thesis, and was interested in studying how a rat society would develop over time when it was limited only   by space. In other words, he wanted to test the effects of overpopulation.

In order to run his experiment, Calhoun designed complexes, which he named "Universes," that would provide his rodent subjects all they needed to survive — food, water and protection from predators and disease. The only thing that would limit the population growth would be space. 

As he watched the rodent societies grow, he began noticing strange trends:

Pregnant females began having problems raising offspring. Dominant males became incredibly territorial and overactive, while subordinate males increasingly withdrew from the larger group, coming out "to eat, drink and move about only when other members of the community were asleep." Rats became so conditioned to eating with others that they would refuse to eat alone. Some males became hypersexual and attempted to mate with anyone and everyone. Fighting was frequent. Rats began cannibalizing other rats. At one point, the infant mortality rate reached an astonishing 96%.

As one of Calhoun's assistants put it, "utopia" had turned into a "hell."

The Experiments

Calhoun published the results of his early experiments in the February 1962 edition of Scientific American, with the title " Population Density and Social Pathology ," coining the term " behavioral sink " to describe the most-crowded spots, where he observed the highest rate of antisocial behavior. In the 1960s, at the height of political discourse about so-called "social decay" in American cities, the study was a natural discussion topic. In the meantime, Calhoun continued his work.

And now we arrive the 25th version of this study Calhoun ran, and the one he would become most well-known for: Universe 25. It was the only one of Calhoun's habitats fully studied from beginning to end. Universe 25 was populated with mice instead of rats, but most everything else remained the same. Mice had everything they needed to survive and were limited only by space.

Calhoun constructed a square box with a side length of 54 inches. He built nesting boxes, water bottles and food hoppers into the walls, with each side of the universe having 64 different nesting boxes located at various heights, 16 water bottles and four food hoppers. All of the "utilities" were accessible via a series of mesh tunnels running from the floor up the side of the wall.

Calhoun published the results of Universe 25 in 1973 in a paper called " Death Squared: The Explosive Growth and Demise of a Mouse Population ." He broke down the development and collapse of the society into four phases:

• Phase A, consisting of the first 104 days, was the adjustment phase, with "considerable social turmoil" between the eight original mice placed into the habitat. Phase A ended once the mice had their first offspring.
• Phase B, which Calhoun named the resource exploitation phase, lasted from Day 105 to Day 315. During this phase, the population grew rapidly, reaching more than 600 mice before growth began slowing. Social stratification also began to happen, with different groups of mice living in certain areas and self-selecting into their own independent groups.
• Phase C, called the stagnation phase, lasted from Day 316 to Day 560. Male mice who were not able to find room in the pre-existing social structure began to withdraw from society, violently attacking one another. Their female counterparts retreated into the highest boxes, also isolating themselves. Socially dominant males began to lose control over their territory, leaving mothers to aggressively defend their young, sometimes even abandoning them. "For all practical purposes there had been a death of societal organization by the end of Phase C," Calhoun wrote.
• Phase D was the death phase. The death rate outpaced the birth rate, and the society began to shrink. Mothers raised newborn mice for a very short time, and Calhoun proposed that the young generation's strange behaviors were a direct result of a very abnormal social upbringing that did not allow some of the more "complex behaviors," including mating rituals, to develop. Females rarely gave birth, and a large group of males, which Calhoun named the "beautiful ones," did nothing other than eat, drink, sleep and groom themselves. During Phase D, a few mice were placed in newly established universes to see whether they would relearn those social behaviors. They did not.

Calhoun's 1973 paper was not subtle. "I shall largely speak of mice, but my thoughts are on man, on healing, on life and its evolution," he wrote. He made frequent references to the Book of Revelation in the Bible and almost all of his wording aimed to personify his rodent subjects. The mice in Universe 25 lived in "walk-up apartments," and Calhoun described subgroups like "somnambulists" or the "bar flies," terms that could easily be mapped to urban life.

The conclusions felt grim, and the fears of overpopulation made their way into pop culture , like the movie "Soylent Green." There's even a book for children very loosely based around Calhoun's mouse cities (although without the doom and gloom of societal breakdown): "Mrs. Frisby and the Rats of NIMH."

The Conclusions

In modern times, Calhoun's Universe 25 experiment is often used as a way to talk about some kind of " degradation of Western society ." These analyses look at Calhoun's experiments and say, "He predicted this would happen to humans, and look at all the cultural degeneracy we see today!" For instance, here's an excerpt from a comment about the experiment we've seen repeatedly on Facebook :

According to Calhoun, the death phase consisted of two stages: the "first death" and "second death." The former was characterized by the loss of purpose in life beyond mere existence — no desire to mate, raise young or establish a role within society. As time went on, juvenile mortality reached 100% and reproduction reached zero. Among the endangered mice, homosexuality was observed and, at the same time, cannibalism increased, despite the fact that there was plenty of food. Two years after the start of the experiment, the last baby of the colony was born. By 1973, he had killed the last mouse in the Universe 25. John Calhoun repeated the same experiment 25 more times, and each time the result was the same. Calhoun's scientific work has been used as a model for interpreting social collapse, and his research serves as a focal point for the study of urban sociology. We are currently witnessing direct parallels in today's society ... weak, feminized men with little to no skills and no protection instincts, and overly agitated and aggressive females with no maternal instincts.

Scientists have repeatedly pushed back against these ideas since Calhoun's research came out. Researchers who attempted to replicate Calhoun's studies in humans found mixed results, and other scientists chastised him for extrapolating rodent behavior to humans. While the popular conception of Universe 25 focused on the apocalyptic death of society because of overpopulation, other psychologists suggested otherwise. 

In an 2008 interview with the NIH Record , Dr. Edmund Ramsden, a science historian, explained the results of a similar 1975 experiment by a psychologist Jonathan Freedman:

Freedman's work, Ramsden noted, suggested that density was no longer a primary explanatory variable for society's ruin. A distinction was drawn between animals and humans. "Rats may suffer from crowding; human beings can cope… Calhoun's research was seen not only as questionable, but also as dangerous." Freedman suggested a different conclusion, though. Moral decay resulted "not from density, but from excessive social interaction," Ramsden explained. "Not all of Calhoun's rats had gone berserk. Those who managed to control space led relatively normal lives." Striking the right balance between privacy and community, Freedman argued, would reduce social pathology. It was the unwanted unavoidable social interaction that drove even fairly social creatures mad, he believed.

But what the modern critics often carelessly and conveniently leave out is how Calhoun's research evolved after Universe 25: Up until his death in 1995, Calhoun looked for solutions to the problem he had discovered, altering his designs and controls to try to   avoid the societal collapse of Universe 25. He described rodents coming up with creative solutions to daily tasks. And it was in this way that his experiments have actually proven more useful. Architects and urban designers have taken Calhoun's experiments into consideration when designing buildings and cities. Prison researchers and reformers have also found Calhoun's studies surprisingly helpful.

So yes, while Universe 25 and Calhoun's "rodent utopias" were real experiments, they're not the apocalyptic predictions that some people make them out to be. 

Arnason, Gardar. "The Emergence and Development of Animal Research Ethics: A Review with a Focus on Nonhuman Primates."  Science and Engineering Ethics , vol. 26, no. 4, 2020, pp. 2277–93.  PubMed Central , https://doi.org/10.1007/s11948-020-00219-z.

Britannica Money . 18 Mar. 2024, https://www.britannica.com/money/Malthusianism.

Calhoun, John B. "Death Squared: The Explosive Growth and Demise of a Mouse Population."  Proceedings of the Royal Society of Medicine , vol. 66, no. 1P2, Jan. 1973, pp. 80–88.  DOI.org (Crossref) , https://doi.org/10.1177/00359157730661P202.

Calhoun, John B. "Population Density and Social Pathology."  California Medicine , vol. 113, no. 5, Nov. 1970, p. 54.  PubMed Central , https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1501789/.

---. "Space and the Strategy of Life."  Behavior and Environment: The Use of Space by Animals and Men , edited by Aristide Henri Esser, Springer US, 1971, pp. 329–87.  Springer Link , https://doi.org/10.1007/978-1-4684-1893-4_25.

Edmund Ramsden and Jon Adams. "Escaping the Laboratory: The Rodent Experiments of John B. Calhoun & Their Cultural Influence."  Journal of Social History , vol. 42, no. 3, 2009, pp. 761–92.  DOI.org (Crossref) , https://doi.org/10.1353/jsh.0.0156.

Environmentalism | Ideology, History, & Types | Britannica . https://www.britannica.com/topic/environmentalism. Accessed 17 May 2024.

Fredrik Knudsen.  The Mouse Utopia Experiments | Down the Rabbit Hole . 2017.  YouTube , https://www.youtube.com/watch?v=NgGLFozNM2o.

Garnett, Carla. "Medical Historian Examines NIMH Experiments In Crowding."  NIH Record , Vol. LX, No. 15, 25 July 2008, https://nihrecord.nih.gov/sites/recordNIH/files/pdf/2008/NIH-Record-2008-07-25.pdf.

Magazine, Smithsonian, and Maris Fessenden. "How 1960s Mouse Utopias Led to Grim Predictions for Future of Humanity."  Smithsonian Magazine , https://www.smithsonianmag.com/smart-news/how-mouse-utopias-1960s-led-grim-predictions-humans-180954423/. Accessed 17 May 2024.

Magazine, Smithsonian, and Charles C. Mann. "The Book That Incited a Worldwide Fear of Overpopulation."  Smithsonian Magazine , https://www.smithsonianmag.com/innovation/book-incited-worldwide-fear-overpopulation-180967499/. Accessed 17 May 2024.

Paulus, Paul.  Prisons Crowding: A Psychological Perspective . Springer Science & Business Media, 2012.

Ramsden, Edmund. "The Urban Animal: Population Density and Social Pathology in Rodents and Humans."  Bulletin of the World Health Organization , vol. 87, no. 2, Feb. 2009, p. 82.  PubMed Central , https://doi.org/10.2471/BLT.09.062836.

The Calhoun Rodent Experiments: The Real-Life Rats of NIMH . https://cosmosmagazine.com/science/mathematics/calhoun-rodent-experiments/. Accessed 17 May 2024.

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Woodstream, Woodstream.  What Humans Can Learn from Calhoun's Rodent Utopia . https://www.victorpest.com/articles/what-humans-can-learn-from-calhouns-rodent-utopia. Accessed 17 May 2024.

By Jack Izzo

Jack Izzo is a Chicago-based journalist and two-time "Jeopardy!" alumnus.

Article Tags

Distillations magazine

Mouse heaven or mouse hell.

Biologist John Calhoun’s rodent experiments gripped a society consumed by fears of overpopulation.

Officially, the colony was called the Mortality-Inhibiting Environment for Mice. Unofficially, it was called mouse heaven.

Biologist John Calhoun built the colony at the National Institute of Mental Health in Maryland in 1968. It was a large pen—a 4½-foot cube—with everything a mouse could ever desire: plenty of food and water; a perfect climate; reams of paper to make cozy nests; and 256 separate apartments, accessible via mesh tubes bolted to the walls. Calhoun also screened the mice to eliminate disease. Free from predators and other worries, a mouse could theoretically live to an extraordinarily old age there, without a single worry.

But the thing is, this wasn’t Calhoun’s first rodent utopia. This was the 25th iteration. And by this point he knew how quickly mouse heaven could deteriorate into mouse hell.

John Calhoun grew up in Tennessee, the son of a high school principal and an artist, and was an avid birder when young. After earning his PhD in zoology, he joined the Rodent Ecology Project in Baltimore in 1946, whose purpose was to eliminate rodent pests in cities. The project had limited success, partly because no one could figure out what aspects of rodent behavior, lifestyle, or biology to target. Calhoun set up his first utopia, involving Norway rats, in the woods behind his house to monitor rodents over time and figure out what factors drove their population growth.

Eventually Calhoun grew fascinated with the rodent behavior for its own sake and began crafting ever more elaborate and carefully controlled environments. It wasn’t just the behavior of rats that interested him. Architects and civil engineers at the time were having vigorous debates about how to build better cities, and Calhoun imagined urban design might be studied in rodents first and then extrapolated to human beings.

Calhoun’s most famous utopia, number 25, began in July 1968, when he introduced eight albino mice into the 4½-foot cube. Following an adjustment period, the first pups were born 3½ months later, and the population doubled every 55 days afterward. Eventually this torrid growth slowed, but the population continued to climb, peaking at 2,200 mice during the 19th month.

That robust growth masked some serious problems, however. In the wild, infant mortality among mice is high, as most juveniles get eaten by predators or perish of disease or cold. In mouse utopia, juveniles rarely died. As a result, there were far more youngsters than normal, which introduced several difficulties.

Rodents have social hierarchies, with dominant alpha males controlling harems of females. Alphas establish dominance by fighting—wrestling and biting any challengers. Normally a mouse that loses a fight will scurry off to some distant nook to start over elsewhere.

But in mouse utopia, the losing mice couldn’t escape. Calhoun called them “dropouts.” And because so few juveniles died, huge hordes of dropouts would gather in the center of the pen. They were full of cuts and ugly scars, and every so often huge brawls would break out—vicious free-for-alls of biting and clawing that served no obvious purpose. It was just senseless violence. (In earlier utopias involving rats, some dropouts turned to cannibalism.)

Alpha males struggled, too. They kept their harems in private apartments, which they had to defend from challengers. But given how many mice survived to adulthood, there were always a dozen hotshots ready to fight. The alphas soon grew exhausted, and some stopped defending their apartments altogether.

As a result, apartments with nursing females were regularly invaded by rogue males. The mothers fought back, but often to the detriment of their young. Many stressed-out mothers booted their pups from the nest early, before the pups were ready. A few even attacked their own young amid the violence or abandoned them while fleeing to different apartments, leaving the pups to die of neglect.

Eventually other deviant behavior emerged. Mice who had been raised improperly or kicked out of the nest early often failed to develop healthy social bonds, and therefore struggled in adulthood with social interactions. Maladjusted females began isolating themselves like hermits in empty apartments—unusual behavior among mice. Maladjusted males, meanwhile, took to grooming all day—preening and licking themselves hour after hour. Calhoun called them “the beautiful ones.” And yet, even while obsessing over their appearance, these males had zero interest in courting females, zero interest in sex.

Intriguingly, Calhoun had noticed in earlier utopias that such maladjusted behavior could spread like a contagion from mouse to mouse. He dubbed this phenomenon “the behavioral sink.”

Between the lack of sex, which lowered the birth rate, and inability to raise pups properly, which sharply increased infant mortality, the population of Universe 25 began to plummet. By the 21st month, newborn pups rarely survived more than a few days. Soon, new births stopped altogether. Older mice lingered for a while—hiding like hermits or grooming all day—but eventually they died out as well. By spring 1973, less than five years after the experiment started, the population had crashed from 2,200 to 0. Mouse heaven had gone extinct.

Universe 25 ended a half century ago, but it continues to fascinate people today—especially as a gloomy metaphor for human society. Calhoun actively encouraged such speculation, once writing, “I shall largely speak of mice, but my thoughts are on man.” As early as 1968, journalist Tom Wolfe titled an essay about New York “O Rotten Gotham—Sliding Down into the Behavioral Sink.” Oddly, though, none of the prognosticators could agree on the main lesson of Universe 25.

The first people to fret over Universe 25 were environmentalists. The same year the study began, biologist Paul Ehrlich published The Population Bomb , an alarmist book predicting imminent starvation and population crashes due to overpopulation on Earth. Pop culture picked up on this theme in movies, such as Soylent Green , where humans in crowded cities are culled and turned into food slurry. Overall, the idea of dangerous overcrowding was in the air, and some sociologists explicitly drew on Calhoun’s work, writing: “We . . . take the animal studies as a serious model for human populations.” The message was stark: Curb population growth—or else .

More recently scholars saw similarities to the Industrial Revolution and the rise of modern urban society. The 19th and 20th centuries saw population booms across the world, largely due to drops in infant mortality—similar to what the mice experienced. Recently, however, human birth rates have dropped sharply in many developed countries—often below replacement levels—and young people in those places have reportedly lost interest in sex. The parallels to Universe 25 seem spooky.

Behavioral biologists have echoed the eugenics movement in blaming the strange behaviors of the mice on a lack of natural selection, which in their view culls those they consider weak and unfit to breed. This lack of culling resulted in supposed “mutational meltdowns” that led to widespread mouse stupidity and aberrant behavior. (The researchers argued that the brain is especially susceptible to mutations because it’s so intricate and because so many of our genes influence brain function.)

Extrapolating from this work, some political agitators warn that humankind will face a similar decline. Women are supposedly falling into Calhoun’s behavioral sink by learning “maladaptive behaviors,” such as choosing not to have children, which “destroy[s] their own genetic interests.” Other critics agonize over the supposed loss of traditional gender roles, leaving effete males and hyperaggressive females, or they deplore the undermining of religions and their imperatives to “be fruitful and multiply.” In tandem, such changes will lead to the “decline of the West.”

Still others have cast Universe 25’s collapse as a parable illustrating the dangers of socialist welfare states, which, they argue, provide material goods but remove healthy challenges from people’s lives, challenges that build character and promote “personal growth.” Another school of thought viewed Universe 25 as a warning about “the city [as] a perversion of nature.” As sociologists Claude Fischer and Mark Baldassare put it, “A red-eyed, sharp-fanged obsession about urban life stalks contemporary thought.”

Most critics who’ve fretted over Calhoun’s work cluster on the conservative end of the political spectrum, but self-styled progressives have weighed in as well. Advocates for birth control repeatedly invoked Calhoun’s mice as a cautionary tale about how runaway population growth destroys family life. More recent interpretations see the mice collapse in terms of one-percenters and wealth inequality; they blame the social dysfunction on a few aggressive males hoarding precious resources (e.g., desirable apartments). In this view, said one critic, “Universe 25 had a fair distribution problem” above all.

Given these wildly varying (even contradictory) readings, it’s hard to escape the suspicion that personal and political views, rather than objective inquiry, are driving these critics’ outlooks. And indeed, a closer look at the interpretations severely undermines them.

When forecasting population crashes among human beings, Population Bomb –type environmentalists invariably predicted that overcrowding would lead to widespread shortages of food and other goods. That’s actually the opposite of what Universe 25 was like. The mice there had all the goods they wanted. This also undermines arguments about unfair resource distribution.

Perhaps, then, it was the lack of struggles and challenges that led to dysfunction, as welfare critics claimed. Except that the spiral of dysfunction began when hordes of “dropout” mice lost challenges to alpha males, couldn’t escape elsewhere, and began brawling in the middle of the pen. The alpha males in turn grew weary after too many challenges from youngsters. Indeed, most mice faced competition far in excess of what they would encounter in the wild.

The appearance of the sexless “beautiful ones” does seem decadent and echoes the reported loss of interest in sex among young people in developed countries. Except that a closer look at the survey data indicates that such worries might be overblown. And any comparison between human birth rates and Universe 25 birth rates is complicated by the fact that the mouse rates dropped partly due to infant neglect and spikes in infant mortality—the opposite of the situation in the developed world.

Then there are the warnings about the mutational meltdown and the decline of intelligence. Aside from echoing the darkest rhetoric of the eugenics movement, this interpretation runs aground on several points. The hermit females and preening, asexual males certainly acted oddly—but in doing so, they avoided the vicious, violent free-for-alls that beset earlier generations. This hardly seems dumb. Moreover, some of Calhoun’s research actually saw rodents getting smarter during experiments.

This evidence came from an earlier utopia involving rats. In that setup, dropout rats began digging new burrows into the dirt floor of their pen. Digging produces loose dirt to clear away, and most rats laboriously carried the loose dirt outside the tunnel bit by bit, to dump it there. It’s necessary but tedious work.

But some of the dropout rats did something different. Instead of carrying dirt out bit by bit, they packed it all into a ball and rolled it out the tunnel in one trip. An enthused Calhoun compared this innovation to humankind inventing the wheel. And it happened only because the rats were isolated from the main group and didn’t learn the dominant method of digging. By normal rat standards, this was deviant behavior. It was also a creative breakthrough. Overall, then, Calhoun argued that social strife can sometimes push creatures to become smarter, not dumber.

(Incidentally, after Universe 25’s collapse, Calhoun began building new utopias to encourage creative behavior by keeping mice physically and mentally nourished. This research, in turn, inspired a children’s book named after Calhoun’s workplace— Mrs. Frisby and the Rats of NIMH , wherein a group of rats escape from a colony designed to stimulate their intelligence.)

So if all these interpretations of Universe 25 miss the mark, what lesson can we draw from the experiment?

Calhoun’s big takeaway involved status. Again, the males who lost the fights for dominance couldn’t leave to start over elsewhere. As he saw it, they were stuck in pathetic, humiliating roles and lacked a meaningful place in society. The same went for females when they couldn’t nurse or raise pups properly. Both groups became depressed and angry, and began lashing out. In other words, because mice are social animals, they need meaningful social roles to feel fulfilled. Humans are social animals as well, and without a meaningful role, we too can become hostile and lash out.

Still, even this interpretation seems like a stretch. Humans have far more ways of finding meaning in life than pumping out children or dominating some little hierarchy. And while human beings and mice are indeed both social creatures, that common label papers over some major differences. Critics of Calhoun’s work argued that population density among humans—a statistical measure—doesn’t necessarily correlate with crowding —a feeling of psychological stress. In the words of one historian, “Through their intelligence, adaptability, and capacity to make the world around them, humans were capable of coping with crowding” in ways that mice simply are not.

Ultimately Calhoun’s work functions like a Rorschach blot—people see what they want to see. It’s worth remembering that not all lab experiments, especially contrived ones such as Universe 25, apply to the real world. In which case, perhaps the best lesson to learn here is a meta-lesson: that drawing lessons itself can be a dangerous thing.

Sam Kean is a best-selling science author. His latest book is  The Icepick Surgeon: Murder, Fraud, Sabotage, Piracy, and Other Dastardly Deeds Perpetrated in the Name of Science .

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The Behavioral Sink

The mouse universes of john b. calhoun.

How do you design a utopia? In 1972, John B. Calhoun detailed the specifications of his Mortality-Inhibiting Environment for Mice: a practical utopia built in the laboratory. Every aspect of Universe 25—as this particular model was called—was pitched to cater for the well-being of its rodent residents and increase their lifespan. The Universe took the form of a tank, 101 inches square, enclosed by walls 54 inches high. The first 37 inches of wall was structured so the mice could climb up, but they were prevented from escaping by 17 inches of bare wall above. Each wall had sixteen vertical mesh tunnels—call them stairwells—soldered to it. Four horizontal corridors opened off each stairwell, each leading to four nesting boxes. That means 256 boxes in total, each capable of housing fifteen mice. There was abundant clean food, water, and nesting material. The Universe was cleaned every four to eight weeks. There were no predators, the temperature was kept at a steady 68°F, and the mice were a disease-free elite selected from the National Institutes of Health’s breeding colony. Heaven.

Four breeding pairs of mice were moved in on day one. After 104 days of upheaval as they familiarized themselves with their new world, they started to reproduce. In their fully catered paradise, the population increased exponentially, doubling every fifty-five days. Those were the good times, as the mice feasted on the fruited plain. To its members, the mouse civilization of Universe 25 must have seemed prosperous indeed. But its downfall was already certain—not just stagnation, but total and inevitable destruction.

Calhoun’s concern was the problem of abundance: overpopulation. As the name Universe 25 suggests, it was not the first time Calhoun had built a world for rodents. He had been building utopian environments for rats and mice since the 1940s, with thoroughly consistent results. Heaven always turned into hell. They were a warning, made in a postwar society already rife with alarm over the soaring population of the United States and the world. Pioneering ecologists such as William Vogt and Fairfield Osborn were cautioning that the growing population was putting pressure on food and other natural resources as early as 1948, and both published bestsellers on the subject. The issue made the cover of Time magazine in January 1960. In 1968, Paul Ehrlich published The Population Bomb , an alarmist work suggesting that the overcrowded world was about to be swept by famine and resource wars. After Ehrlich appeared on The Tonight Show with Johnny Carson in 1970, his book became a phenomenal success. By 1972, the issue reached its mainstream peak with the report of the Rockefeller Commission on US Population, which recommended that population growth be slowed or even reversed.

But Calhoun’s work was different. Vogt, Ehrlich, and the others were neo-Malthusians, arguing that population growth would cause our demise by exhausting our natural resources, leading to starvation and conflict. But there was no scarcity of food and water in Calhoun’s universe. The only thing that was in short supply was space. This was, after all, “heaven”—a title Calhoun deliberately used with pitch-black irony. The point was that crowding itself could destroy a society before famine even got a chance. In Calhoun’s heaven, hell was other mice.

So what exactly happened in Universe 25? Past day 315, population growth slowed. More than six hundred mice now lived in Universe 25, constantly rubbing shoulders on their way up and down the stairwells to eat, drink, and sleep. Mice found themselves born into a world that was more crowded every day, and there were far more mice than meaningful social roles. With more and more peers to defend against, males found it difficult and stressful to defend their territory, so they abandoned the activity. Normal social discourse within the mouse community broke down, and with it the ability of mice to form social bonds. The failures and dropouts congregated in large groups in the middle of the enclosure, their listless withdrawal occasionally interrupted by spasms and waves of pointless violence. The victims of these random attacks became attackers. Left on their own in nests subject to invasion, nursing females attacked their own young. Procreation slumped, infant abandonment and mortality soared. Lone females retreated to isolated nesting boxes on penthouse levels. Other males, a group Calhoun termed “the beautiful ones,” never sought sex and never fought—they just ate, slept, and groomed, wrapped in narcissistic introspection. Elsewhere, cannibalism, pansexualism, and violence became endemic. Mouse society had collapsed.

On day 560, a little more than eighteen months into the experiment, the population peaked at 2,200 mice and its growth ceased. A few mice survived past weaning until day six hundred, after which there were few pregnancies and no surviving young. As the population had ceased to regenerate itself, its path to extinction was clear. There would be no recovery, not even after numbers had dwindled back to those of the heady early days of the Universe. The mice had lost the capacity to rebuild their numbers—many of the mice that could still conceive, such as the “beautiful ones” and their secluded singleton female counterparts, had lost the social ability to do so. In a way, the creatures had ceased to be mice long before their death—a “first death,” as Calhoun put it, ruining their spirit and their society as thoroughly as the later “second death” of the physical body.

Calhoun had built his career on this basic experiment and its consistent results ever since erecting his first “rat city” on a quarter-acre of land adjacent to his home in Towson, Maryland, in 1947. The population of that first pen had peaked at 200 and stabilized at 150, when Calhoun had estimated that it could rise to as many as 5,000—something was evidently amiss. In 1954, Calhoun was employed by the National Institute of Mental Health in Rockville, Maryland, where he would remain for three decades. He built a ten-by-fourteen-foot “universe” for a small population of rats, divided by electrified barriers into four rooms connected by narrow ramps. Food and water were plentiful, but space was tight, capable of supporting a maximum of forty-eight rats. The population reached eighty before succumbing to the same catastrophes that would afflict Universe 25: explosive violence, hypersexual activity followed by asexuality, and self-destruction.

In 1962, Calhoun published a paper called “Population Density and Social Pathology” in Scientific American , laying out his conclusion: overpopulation meant social collapse followed by extinction. The more he repeated the experiment, the more the outcome came to seem inevitable, fixed with the rigor of a scientific equation. By the time he wrote about the decline and fall of Universe 25 in 1972, he even laid out its fate in equation form:

Mortality, bodily death = the second death Drastic reduction of mortality = death of the second death = death squared = (death) 2 (Death) 2 leads to dissolution of social organization = death of the establishment Death of the establishment leads to spiritual death = loss of capacity to engage in behaviors essential to species survival = the first death Therefore: (Death) 2 = the first death

This formula might apply to rats and mice—but could the same happen to humankind? For Calhoun, there was little question about it. No matter how sophisticated we considered ourselves to be, once the number of individuals capable of filling roles greatly exceeded the number of roles,

only violence and disruption of social organization can follow. ... Individuals born under these circumstances will be so out of touch with reality as to be incapable even of alienation. Their most complex behaviors will become fragmented. Acquisition, creation and utilization of ideas appropriate for life in a post-industrial cultural-conceptual-technological society will have been blocked.

If its growth continued unchecked, human society would succumb to nihilism and collapse, meaning the death of the species. Calhoun’s death-squared formula was for social pessimists what the laws of thermodynamics are for physicists. It was a sandwich board with “The End Is Nigh” written on one side, and “QED” on the other. Indeed, the plight of Calhoun’s rats and mice is one we easily identify with—we put ourselves in the place of the mice, mentally inhabit the mouse universe, and cannot help but see ways in which it is like our own crowding world.

This is precisely what Calhoun intended, in the design of his experiments and the language he used to describe them. Universe 25 resembles the utopian, modernist urban fantasies of architects such as Ludwig Hilberseimer. Calhoun referred to the dwelling places within his Universes as “tower blocks” and “walk-up apartments.” As well as the preening “beautiful ones,” he refers to “juvenile delinquents” and “dropouts.” This handy use of anthropomorphism is unusual in a scientist—we are being invited to draw parallels with human society.

And that lesson found a ready audience. “Population Density and Social Pathology” was, for an academic paper, a smash hit, being cited up to 150 times a year. Particularly effective was Calhoun’s name for the point past which the slide into breakdown becomes irretrievable: the “behavioral sink.” “The unhealthy connotations of the term are not accidental,” Calhoun noted drily. The “sink,” a para-pathology of shared hopelessness, drew in pathological behavior and exacerbated its effects. Once the event horizon of the behavioral sink was passed, the end was certain. Pathological behavior would escalate beyond any possibility of control. The writer Tom Wolfe alighted on the phrase and deployed it in his lament for the declining New York City, “O Rotten Gotham! Sliding Down into the Behavioral Sink,” anthologized in The Pump House Gang in 1968. “It got to be easy to look at New Yorkers as animals,” Wolfe wrote, “especially looking down from some place like a balcony at Grand Central at the rush hour Friday afternoon. The floor was filled with the poor white humans, running around, dodging, blinking their eyes, making a sound like a pen full of starlings or rats or something.” The behavioral sink meshed neatly with Wolfe’s pessimism about the modern city, and his grim view of modernist housing projects as breeding grounds for degeneration and atavism.

Wolfe wasn’t alone. The warnings inherent in Calhoun’s research fell on fertile ground in the 1960s, with social policy grappling helplessly with the problems of the inner cities: violence, rape, drugs, family breakdown. A rich literature of overpopulation emerged from the stew, and when we look at Calhoun’s rodent universes today, we can see in them aspects of that literature. In the 1973 film Soylent Green , based on Harry Harrison’s 1966 novel Make Room! Make Room! , the population of a grotesquely crowded New York is mired in passivity and dependent on food handouts which, it emerges, are derived from human corpses. In Stand on Zanzibar , John Brunner’s 1972 novel of a hyperactive, overpopulated world, society is plagued by “muckers,” individuals who suddenly and for no obvious reason run amok, killing and wounding others. When we hear of the death throes of Universe 25—the cannibalism, withdrawal, and random violence—these are the works that come to mind. The ultraviolence-dispensing, gang-raping, purposeless “droogs” of Antony Burgess’s novel A Clockwork Orange , which appeared in the same year as Calhoun’s Scientific American paper, are the very image of some of the uglier products of mouse utopia.

Calhoun’s research remains a touchstone for a particular kind of pessimistic worldview. And, in the way that writers like Wolfe and the historian Lewis Mumford deployed reference to it, it can be seen as bleakly reactionary, a warning against cosmopolitanism or welfare dependence, which might sap the spirit and put us on the skids to the behavioral sink. As such, it found fans among conservative Christians; Calhoun even met the pope in 1974. But in fact the full span of Calhoun’s research had a more positive slant. The misery of the rodent universes was not uniform—it had contours, and some did better than others. Calhoun consistently found that those animals better able to handle high numbers of social interactions fared comparatively well. “High social velocity” mice were the winners in hell. As for the losers, Calhoun found they sometimes became more creative, exhibiting an un-mouse-like drive to innovate. They were forced to, in order to survive.

Later in his career, Calhoun worked to build universes that maximized this kind of creativity and minimized the ill effects of overcrowding. He disagreed with Ehrlich and Vogt that restrictions on reproduction were the only possible response to overpopulation. Man, he argued, was a positive animal, and creativity and design could solve our problems. He advocated overcoming the limitations of the planet, and as part of a multidisciplinary group called the Space Cadets promoted the colonization of space. It was a source of lasting dismay to Calhoun that his research primarily served as encouragement to pessimists and reactionaries, rather than stimulating the kind of hopeful approach to mankind’s problems that he preferred. More cheerfully, however, the one work of fiction that stems directly from Calhoun’s work, rather than the stew of gloom that it was stirred into, is optimistic, and expands imaginatively on his attempts to spur creative thought in rodents. This is Robert C. O’Brien’s book for children, Mrs. Frisby and the Rats of NIMH , about a colony of super-intelligent and self-reliant rats that have escaped from the National Institute of Mental Health.

Cabinet and the author regret that a previous version of this article omitted its sources.

See press about “The Behavioral Sink” on Longreads.com and theatlantic.tumblr.com .

Will Wiles is a London-based author and journalist. He is deputy editor of Icon , a monthly architecture and design magazine. His debut novel, Care of Wooden Floors , will be published by HarperPress in February 2012.

Home → Health → Mind & Brain

Neuroscientist teaches rats to drive − their joy suggests how anticipating fun can enrich human life

Equipped with a rodent version of a Cybertruck, these driving rats reveal that positive experiences may sculpt the brain just as powerfully as stressful ones.

We crafted our first rodent car from a plastic cereal container. After trial and error, my colleagues and I found that rats could learn to drive forward by grasping a small wire that acted like a gas pedal. Before long, they were steering with surprising precision to reach a Froot Loop treat.

As expected, rats housed in enriched environments – complete with toys, space and companions – learned to drive faster than those in standard cages. This finding supported the idea that complex environments enhance neuroplasticity : the brain’s ability to change across the lifespan in response to environmental demands.

After we published our research, the story of driving rats went viral in the media . The project continues in my lab with new, improved rat-operated vehicles, or ROVs, designed by robotics professor John McManus and his students. These upgraded electrical ROVs – featuring rat-proof wiring, indestructible tires and ergonomic driving levers – are akin to a rodent version of Tesla’s Cybertruck.

As a neuroscientist who advocates for housing and testing laboratory animals in natural habitats, I’ve found it amusing to see how far we’ve strayed from my lab practices with this project. Rats typically prefer dirt, sticks and rocks over plastic objects. Now, we had them driving cars.

But humans didn’t evolve to drive either. Although our ancient ancestors didn’t have cars, they had flexible brains that enabled them to acquire new skills – fire, language, stone tools and agriculture. And some time after the invention of the wheel, humans made cars.

Although cars made for rats are far from anything they would encounter in the wild, we believed that driving represented an interesting way to study how rodents acquire new skills. Unexpectedly, we found that the rats had an intense motivation for their driving training, often jumping into the car and revving the “lever engine” before their vehicle hit the road. Why was that?

The new destination of joy

Concepts from introductory psychology textbooks took on a new, hands-on dimension in our rodent driving laboratory. Building on foundational learning approaches such as operant conditioning , which reinforces targeted behavior through strategic incentives, we trained the rats step-by-step in their driver’s ed programs.

Initially, they learned basic movements, such as climbing into the car and pressing a lever. But with practice, these simple actions evolved into more complex behaviors, such as steering the car toward a specific destination.

The rats also taught me something profound one morning during the pandemic.

It was the summer of 2020, a period marked by emotional isolation for almost everyone on the planet, even laboratory rats. When I walked into the lab, I noticed something unusual: The three driving-trained rats eagerly ran to the side of the cage, jumping up like my dog does when asked if he wants to take a walk.

Had the rats always done this and I just hadn’t noticed? Were they just eager for a Froot Loop, or anticipating the drive itself? Whatever the case, they appeared to be feeling something positive – perhaps excitement and anticipation.

Behaviors associated with positive experiences are associated with joy in humans, but what about rats? Was I seeing something akin to joy in a rat? Maybe so, considering that neuroscience research is increasingly suggesting that joy and positive emotions play a critical role in the health of both human and nonhuman animals.

With that, my team and I shifted focus from topics such as how chronic stress influences brains to how positive events – and anticipation for these events – shape neural functions.

Working with postdoctoral fellow Kitty Hartvigsen , I designed a new protocol that used waiting periods to ramp up anticipation before a positive event. Bringing Pavlovian conditioning into the mix, rats had to wait 15 minutes after a Lego block was placed in their cage before they received a Froot Loop. They also had to wait in their transport cage for a few minutes before entering Rat Park, their play area. We also added challenges, such as making them shell sunflower seeds before eating.

This became our Wait For It research program. We dubbed this new line of study UPERs – unpredictable positive experience responses – where rats were trained to wait for rewards. In contrast, control rats received their rewards immediately. After about a month of training, we expose the rats to different tests to determine how waiting for positive experiences affects how they learn and behave. We’re currently peering into their brains to map the neural footprint of extended positive experiences.

Preliminary results suggest that rats required to wait for their rewards show signs of shifting from a pessimistic cognitive style to an optimistic one in a test designed to measure rodent optimism. They performed better on cognitive tasks and were bolder in their problem-solving strategies. We linked this program to our lab’s broader interest in behaviorceuticals , a term I coined to suggest that experiences can alter brain chemistry similarly to pharmaceuticals.

This research provides further support of how anticipation can reinforce behavior. Previous work with lab rats has shown that rats pressing a bar for cocaine – a stimulant that increases dopamine activation – already experience a surge of dopamine as they anticipate a dose of cocaine.

The tale of rat tails

It wasn’t just the effects of anticipation on rat behavior that caught our attention. One day, a student noticed something strange: One of the rats in the group trained to expect positive experiences had its tail straight up with a crook at the end, resembling the handle of an old-fashioned umbrella.

I had never seen this in my decades of working with rats. Reviewing the video footage, we found that the rats trained to anticipate positive experiences were more likely to hold their tails high than untrained rats. But what, exactly, did this mean?

Curious, I posted a picture of the behavior on social media. Fellow neuroscientists identified this as a gentler form of what’s called Straub tail , typically seen in rats given the opioid morphine. This S-shaped curl is also linked to dopamine . When dopamine is blocked, the Straub tail behavior subsides.

Natural forms of opiates and dopamine – key players in brain pathways that diminish pain and enhance reward – seem to be telltale ingredients of the elevated tails in our anticipation training program. Observing tail posture in rats adds a new layer to our understanding of rat emotional expression, reminding us that emotions are expressed throughout the entire body.

While we can’t directly ask rats whether they like to drive, we devised a behavioral test to assess their motivation to drive. This time, instead of only giving rats the option of driving to the Froot Loop Tree, they could also make a shorter journey on foot – or paw, in this case.

Surprisingly, two of the three rats chose to take the less efficient path of turning away from the reward and running to the car to drive to their Froot Loop destination. This response suggests that the rats enjoy both the journey and the rewarding destination.

Rat lessons on enjoying the journey

We’re not the only team investigating positive emotions in animals.

Neuroscientist Jaak Panksepp famously tickled rats , demonstrating their capacity for joy .

Research has also shown that desirable low-stress rat environments retune their brains’ reward circuits , such as the nucleus accumbens. When animals are housed in their favored environments, the area of the nucleus accumbens that responds to appetitive experiences expands. Alternatively, when rats are housed in stressful contexts, the fear-generating zones of their nucleus accumbens expand. It is as if the brain is a piano the environment can tune.

Neuroscientist Curt Richter also made the case for rats having hope . In a study that wouldn’t be permitted today, rats swam in glass cylinders filled with water, eventually drowning from exhaustion if they weren’t rescued. Lab rats frequently handled by humans swam for hours to days. Wild rats gave up after just a few minutes. If the wild rats were briefly rescued, however, their survival time extended dramatically, sometimes by days. It seemed that being rescued gave the rats hope and spurred them on.

The driving rats project has opened new and unexpected doors in my behavioral neuroscience research lab. While it’s vital to study negative emotions such as fear and stress, positive experiences also shape the brain in significant ways.

As animals – human or otherwise – navigate the unpredictability of life, anticipating positive experiences helps drive a persistence to keep searching for life’s rewards. In a world of immediate gratification, these rats offer insights into the neural principles guiding everyday behavior. Rather than pushing buttons for instant rewards, they remind us that planning, anticipating and enjoying the ride may be key to a healthy brain. That’s a lesson my lab rats have taught me well .

Kelly Lambert , Professor of Behavioral Neuroscience, University of Richmond

This article is republished from The Conversation under a Creative Commons license. Read the original article .

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I’m a neuroscientist who taught rats to drive − their joy suggests how anticipating fun can enrich human life

We crafted our first rodent car from a plastic cereal container. After trial and error, my colleagues and I found that rats could learn to drive forward by grasping a small wire that acted like a gas pedal. Before long, they were steering with surprising precision to reach a Froot Loop treat.

As expected, rats housed in enriched environments – complete with toys, space and companions – learned to drive faster than those in standard cages. This finding supported the idea that complex environments enhance neuroplasticity : the brain’s ability to change across the lifespan in response to environmental demands.

After we published our research, the story of driving rats went viral in the media . The project continues in my lab with new, improved rat-operated vehicles, or ROVs, designed by robotics professor John McManus and his students. These upgraded electrical ROVs – featuring rat-proof wiring, indestructible tires and ergonomic driving levers – are akin to a rodent version of Tesla’s Cybertruck.

As a neuroscientist who advocates for housing and testing laboratory animals in natural habitats, I’ve found it amusing to see how far we’ve strayed from my lab practices with this project. Rats typically prefer dirt, sticks and rocks over plastic objects. Now, we had them driving cars.

But humans didn’t evolve to drive either. Although our ancient ancestors didn’t have cars, they had flexible brains that enabled them to acquire new skills – fire, language, stone tools and agriculture. And some time after the invention of the wheel, humans made cars.

Although cars made for rats are far from anything they would encounter in the wild, we believed that driving represented an interesting way to study how rodents acquire new skills. Unexpectedly, we found that the rats had an intense motivation for their driving training, often jumping into the car and revving the “lever engine” before their vehicle hit the road. Why was that?

The new destination of joy

Concepts from introductory psychology textbooks took on a new, hands-on dimension in our rodent driving laboratory. Building on foundational learning approaches such as operant conditioning , which reinforces targeted behavior through strategic incentives, we trained the rats step-by-step in their driver’s ed programs.

Initially, they learned basic movements, such as climbing into the car and pressing a lever. But with practice, these simple actions evolved into more complex behaviors, such as steering the car toward a specific destination.

The rats also taught me something profound one morning during the pandemic.

It was the summer of 2020, a period marked by emotional isolation for almost everyone on the planet, even laboratory rats. When I walked into the lab, I noticed something unusual: The three driving-trained rats eagerly ran to the side of the cage, jumping up like my dog does when asked if he wants to take a walk.

Had the rats always done this and I just hadn’t noticed? Were they just eager for a Froot Loop, or anticipating the drive itself? Whatever the case, they appeared to be feeling something positive – perhaps excitement and anticipation.

Behaviors associated with positive experiences are associated with joy in humans, but what about rats? Was I seeing something akin to joy in a rat? Maybe so, considering that neuroscience research is increasingly suggesting that joy and positive emotions play a critical role in the health of both human and nonhuman animals.

With that, my team and I shifted focus from topics such as how chronic stress influences brains to how positive events – and anticipation for these events – shape neural functions.

Working with postdoctoral fellow Kitty Hartvigsen , I designed a new protocol that used waiting periods to ramp up anticipation before a positive event. Bringing Pavlovian conditioning into the mix, rats had to wait 15 minutes after a Lego block was placed in their cage before they received a Froot Loop. They also had to wait in their transport cage for a few minutes before entering Rat Park, their play area. We also added challenges, such as making them shell sunflower seeds before eating.

This became our Wait For It research program. We dubbed this new line of study UPERs – unpredictable positive experience responses – where rats were trained to wait for rewards. In contrast, control rats received their rewards immediately. After about a month of training, we expose the rats to different tests to determine how waiting for positive experiences affects how they learn and behave. We’re currently peering into their brains to map the neural footprint of extended positive experiences.

Preliminary results suggest that rats required to wait for their rewards show signs of shifting from a pessimistic cognitive style to an optimistic one in a test designed to measure rodent optimism. They performed better on cognitive tasks and were bolder in their problem-solving strategies. We linked this program to our lab’s broader interest in behaviorceuticals , a term I coined to suggest that experiences can alter brain chemistry similarly to pharmaceuticals.

This research provides further support of how anticipation can reinforce behavior. Previous work with lab rats has shown that rats pressing a bar for cocaine – a stimulant that increases dopamine activation – already experience a surge of dopamine as they anticipate a dose of cocaine.

The tale of rat tails

It wasn’t just the effects of anticipation on rat behavior that caught our attention. One day, a student noticed something strange: One of the rats in the group trained to expect positive experiences had its tail straight up with a crook at the end, resembling the handle of an old-fashioned umbrella.

I had never seen this in my decades of working with rats. Reviewing the video footage, we found that the rats trained to anticipate positive experiences were more likely to hold their tails high than untrained rats. But what, exactly, did this mean?

Curious, I posted a picture of the behavior on social media. Fellow neuroscientists identified this as a gentler form of what’s called Straub tail , typically seen in rats given the opioid morphine. This S-shaped curl is also linked to dopamine . When dopamine is blocked, the Straub tail behavior subsides.

Natural forms of opiates and dopamine – key players in brain pathways that diminish pain and enhance reward – seem to be telltale ingredients of the elevated tails in our anticipation training program. Observing tail posture in rats adds a new layer to our understanding of rat emotional expression, reminding us that emotions are expressed throughout the entire body.

While we can’t directly ask rats whether they like to drive, we devised a behavioral test to assess their motivation to drive. This time, instead of only giving rats the option of driving to the Froot Loop Tree, they could also make a shorter journey on foot – or paw, in this case.

Surprisingly, two of the three rats chose to take the less efficient path of turning away from the reward and running to the car to drive to their Froot Loop destination. This response suggests that the rats enjoy both the journey and the rewarding destination.

Rat lessons on enjoying the journey

We’re not the only team investigating positive emotions in animals.

Neuroscientist Jaak Panksepp famously tickled rats , demonstrating their capacity for joy .

Research has also shown that desirable low-stress rat environments retune their brains’ reward circuits , such as the nucleus accumbens. When animals are housed in their favored environments, the area of the nucleus accumbens that responds to appetitive experiences expands. Alternatively, when rats are housed in stressful contexts, the fear-generating zones of their nucleus accumbens expand. It is as if the brain is a piano the environment can tune.

Neuroscientist Curt Richter also made the case for rats having hope . In a study that wouldn’t be permitted today, rats swam in glass cylinders filled with water, eventually drowning from exhaustion if they weren’t rescued. Lab rats frequently handled by humans swam for hours to days. Wild rats gave up after just a few minutes. If the wild rats were briefly rescued, however, their survival time extended dramatically, sometimes by days. It seemed that being rescued gave the rats hope and spurred them on.

The driving rats project has opened new and unexpected doors in my behavioral neuroscience research lab. While it’s vital to study negative emotions such as fear and stress, positive experiences also shape the brain in significant ways.

As animals – human or otherwise – navigate the unpredictability of life, anticipating positive experiences helps drive a persistence to keep searching for life’s rewards. In a world of immediate gratification, these rats offer insights into the neural principles guiding everyday behavior. Rather than pushing buttons for instant rewards, they remind us that planning, anticipating and enjoying the ride may be key to a healthy brain. That’s a lesson my lab rats have taught me well .

This article is republished from The Conversation , a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Kelly Lambert , University of Richmond

Cognitive flexibility is essential to navigating a changing world – new research in mice shows how your brain learns new rules

Governments are pushing teen social media bans – but behind the scenes is a messy fight over science

What is ethical animal research? A scientist and veterinarian explain

Kelly Lambert does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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Cape Canaveral, United States - October 26, 2024 A SpaceX Falcon 9 rocket carrying 22 Starlink satellites lifts off from Space Launch Complex-40 at Cape Canaveral Space Force Station.

BAKU (Reuters) -This year's U.N. climate summit - COP29 - is being held during yet another record-breaking year of higher global temperatures, adding pressure to negotiations aimed at curbing climate change. The last global scientific consensus on climate change was released in 2021 through the Intergovernmental Panel on Climate Change, however scientists say that evidence shows global warming and its impacts are unfolding faster than expected. The world may already have hit 1.5 degree Celsius (2.7 F) of warming above the average pre-industrial temperature - a critical threshold beyond which it is at risk of irreversible and extreme climate change, scientists say.

Michigan-based Mammoth Distilling has been on a mission to revive Rosen rye grown on South Manitou Island. That led them to a new adventure: Trying to revive a breed of grain that had been sitting at the bottom of Lake Huron since a ship carrying it wrecked in 1878.

A team of scientists set out to probe some of the heaviest elements in the periodic table using an advanced form of laser spectroscopy.

STORY: Methane.It's rapidly rising levels in the atmosphere could threaten efforts to curb global warming by mid-century.:: Clean Air Task ForceScientists and policymakers are urging aggressive action to stunt the output of the potent greenhouse gas.But why is controlling methane emissions so important?:: Heat-trapping power:: NASA Scientific Visualization StudioAtmospheric methane levels in the last five years have risen at their fastest rate since record-keeping began. :: Clean Air Task ForceMethane molecules are more powerful in trapping heat than carbon dioxide, or CO2, meaning it takes fewer of them to cause the same amount of warming.:: NASA Scientific Visualization StudioScientists say they have contributed around 0.5 degrees Celsius of warming so far, or roughly one third of warming experienced since pre-industrial times.Reducing methane levels could not only have a more immediate effect than reducing CO2, but according to the United Nations is likely cheaper.:: Surging emissionsMethane concentrations are also rising faster than any other major greenhouse gas.According to the 2024 Global Methane Budget, two thirds are driven largely by human activities such as agriculture, fossil fuel activities, landfill and waste.:: N2 AppliedThe report, published every five years, found methane emissions from these human activities have risen overall by 20% over the last two decades.Nearly 160 countries have pledged to cut 30% of their output levels by the end of this decade.Most of the methane mitigation efforts underway are focused on oil and gas, where emissions are easier to tackle according to the food-focused investor initiative called FAIRR.:: Natural sources are a concernThe remaining third of the world's methane emissions comes from natural sources such as thawing permafrost, peat bogs and wetlands.Animals, including humans, are also a source of methane.While it is easy to measure atmospheric methane, understanding where it comes from is crucial for tackling the problem.:: NASA's Goddard Space Flight CenterScientists are analyzing distinct isotope signatures in methane, to investigate whether the detected gas comes from biological sources or industry.

The recent boom seems a little more complicated.

Not to be outdone, Amazon Web Services has AI chips, too: Trainium, Inferentia, and Graviton. In an effort to draw attention to Trainium in particular, the company is launching a new grant program for AI research. Called Build on Trainium, the new program will award $110 million total to institutions, scientists, and students researching AI.

It looks like the record-setting pace for rocket launches from Florida’s Space Coast will continue Monday.

Scientists can't know precisely when a volcano is about to erupt, but they can sometimes pick up telltale signs. About two months before Mauna Loa spewed rivers of glowing orange molten lava, geologists detected small earthquakes nearby and other signs, and they warned residents on Hawaii's Big Island. Now a study of the volcano's lava confirms their timeline for when the molten rock below was on the move.

The Nancy Grace Roman Space Telescope will demonstrate a new generation of coronagraph technology.

Layers of volcanic rock in eastern Oregon, the Willamette Valley and the Columbia Basin have created fertile soil for farming and ranching, but in the future it could provide fruitful ground for a whole other industry designed to fight climate change. Oregon’s state geologist is pitching a novel idea of using the region’s rocky basalt […]

Florida’s Space Coast is just shy of 80 launches for the year after a pair of Veteran’s Day launches from SpaceX.