Calhoun's Mice: A Mirror, Not a Prediction
In 1968, an American researcher named John Calhoun built a paradise for mice. He placed only four pairs inside. Unlimited food and water, no predators, no disease, a proper place for nests. Everything a mouse could want, provided. He named the experiment "Universe 25". It was the 25th experiment in a series of environments he built for rodents.
At first it worked great. The mice multiplied quickly, and the population doubled again and again. In early 1970 it reached a peak of about 2,200 mice.
Then something started to go wrong. Some of the males became aggressive. Some withdrew completely. Mothers neglected their pups. And there were also mice Calhoun called "the beautiful ones": they didn't fight and didn't mate. They ate, drank, slept and groomed themselves, without taking part in the social life of the colony. Births declined, pups didn't survive, and the colony slowly faded away, until it died out completely, even though food and water remained in abundance.
This story became famous, and it's usually told as a lesson about crowding: far too many mice in a single cage. But there's a detail that complicates the picture. Calhoun calculated that the nesting spots would suffice for about 3,840 mice, while the peak was about 2,200. Even then, some of the nesting spots remained empty. That doesn't mean there was no crowding. A vacant spot for a nest isn't necessarily a vacant spot within the society.
What the experiment explains, and what it doesn't
Calhoun himself spoke about crowding and the disintegration of social roles. But the experiment didn't separate all the factors that could have had an effect: a closed space, encounters the mice couldn't avoid, and difficulty finding a place in the social structure. "Universe 25" was part of extended research, but this colony alone cannot explain what caused each phenomenon. And it certainly can't be taken as a prediction of what will happen to humans in an era of Total Abundance - infinite abundance.
But within this story there's a detail that interests me in particular: the option of leaving and finding another place. Calhoun described a situation in which the young reach maturity, but struggle to find themselves a place in the social structure. In "Universe 25" they also couldn't leave and try to fit in elsewhere. The food and water were available, but the option of finding themselves a role wasn't guaranteed to the same degree.
This doesn't prove that a lack of challenge is what brought about the colony's collapse. But it raises a question we can also ask ourselves: if we have everything we need in order to live, how will we find what we want to live for? What place will we want to occupy, what will we want to do, and how will we choose it ourselves? For the mice the walls were real. For us, if there are such walls, they may look entirely different.
The question the mirror reflects back
In the book I'm writing, I talk about how if we reach AGI one day, it may solve a great many things at once. Diseases, every shortage, hard labor. I'm not afraid of that, it would be wonderful. But if that really happens, and if everything is provided, one question will remain that has nothing to do with food and water: what will be left for us to do, if we have no real challenges?
Humans are not mice. We decide, organize and change the environment. We also build stories that allow millions of people to act together for something bigger than any one of them. Protecting the environment, the vision of a business organization, nationalism, and sometimes also ultranationalism.
Not all of these goals are alike, and not every price paid for them is justified. But people are willing to invest years, give up comfort, and sometimes even risk or sacrifice their lives for an idea. The fact that it's a "story" doesn't make it meaningless. It can give a person belonging, direction and a reason to get up in the morning. It can also lead to dangerous places.
So the human question is more complex than food and water. We can invent new goals, but will we feel that they truly matter? And if the machine can also fulfill them better than us, what will our place in the story be?
Compensating culture, and what if the machine can do that too
When life started demanding less movement from us, we built ways to bring it back artificially. Gyms, morning runs, workouts. This is a compensating culture: we lift a weight that doesn't need to be moved anywhere, but the effort itself has a real purpose. It protects the body. The challenge is artificial, the benefit isn't.
Demis Hassabis, one of DeepMind's founders, has said that even as a child, after an exhausting chess game at a tournament, he asked himself whether all the brilliant minds in the room couldn't do something more useful, like help cure cancer. And yet, he didn't give up games. Later they became a training ground for systems he developed, like AlphaGo, on the way to working on scientific problems like protein structure prediction, with AlphaFold.
And today the machine doesn't just solve, in our place, exercises we already know how to solve, only faster. In 2026, for example, an AI model proposed a solution to a mathematical problem posed by Erdős and his colleagues back in the 1960s, and researchers checked and developed the proof. This isn't proof that the machine can solve everything. But it's already taking part in a breakthrough in a place where humans hadn't yet found a solution.
Now think about a world in which the machine can also handle our real challenges. Can the gym for humanity settle for exercises we choose to do to keep ourselves in shape, even if the machine already knows the answer? Or will we need an open challenge, with meaning and an outcome that still depend on us? I'm not sure I have an answer. I'm also not sure the same answer will suit everyone.
Maybe part of the answer lies in connection with other people. To be the person someone needs in a hard moment, to listen, to be there. It's not only a test of who solves a problem faster. But even that doesn't answer the whole question. This is what I want to examine through my Humanity-Fit, a gym for humanity: which effort is worth keeping in our own hands, and why? Yes to taking the stairs, but not 25 floors, and of course not an elevator everywhere either. Is it enough that the effort keeps us in shape, or do we need to feel that there's something in the world that won't happen without us?
And again, this is not a prophecy. Not every challenge will disappear, and not everything that feels meaningful to us has to be something only we are capable of doing. But even a hard challenge and a big goal are no guarantee that we'll feel our lives belong to us. Here another story comes in, of a man who never lacked challenges, not for a moment.
John Stuart Mill was a British philosopher and economist, who would later write "On Liberty". His father, James Mill, was himself a thinker, an associate of Jeremy Bentham. They wanted to improve society by a simple principle: increase happiness and reduce suffering. The father wanted to raise a son who could carry on that work, and designed his education accordingly. Greek from age three, Latin from age eight, and later logic and economics, with very little company from children his age.
Intellectually, the boy achieved exceptional things. But at age twenty, in the autumn of 1826, he sank into a crisis. He asked himself whether he would be happy if all the social changes he had worked for came true at once. The answer that arose in him was no. He didn't lack tasks, and he didn't lack a great purpose. And still, the things he lived for lost the power to give him joy.
The story doesn't end there. The recovery was gradual, and in 1828 books of Wordsworth's poetry helped him make room for emotion and joy that were no longer a task to analyze. Later he wrote important books on liberty and economics, and worked for women's rights. He didn't fail his father's plan. He carried it forward, and also changed direction.
Mill's story brings me back to the question that follows me too: who chose our path, and what in it is truly ours?
When I was 13, my art teacher called my father and told him that I was very talented, and that he should send me to Bezalel. At that time my father had other plans for me. Riffing on a "HaGashash HaHiver" sketch, he answered her: "You send your son to Bezalel, I'll send him to the Technion and we'll see who gets there first."
Years later, when I became a tech product manager, entrepreneur, lecturer and mentor, and my whole career revolved around high-tech, I asked myself: am I here because it's the path he paved for me, or because I made these decisions myself? What would have happened if I had gone down the path I wanted, art? What would my life look like today? Would I have been happier, or less happy? That, I'll probably never know.
But after a long process of "finding myself", I discovered that I'm still that same 13-year-old boy. Art, entrepreneurship and product management are much more similar than they seem: in all of them I imagine something that doesn't exist, take the tools and raw materials at my disposal, and create something that others will enjoy or get value from. The raw materials changed. The urge to create remained.
This is also my claim at YourMarket.Fit: each of us has a calling, a core that takes shape somewhere in the teen years and barely changes. Where it comes from is a question of personal belief: God, the universe, reincarnation or a story we tell ourselves. What changes is the way it's fulfilled - and those ways are our passions.
In the startup world, the calling parallels the company's vision. The passions are the products and categories through which the company fulfills it. Patagonia, for example, sets itself the goal of protecting the planet, and fulfills it through clothing and hiking gear while trying to reduce the harm to the environment. If it were to switch to producing renewable energy systems, that could be a pivot in fulfillment, without changing the vision. That's how I see the pivots in our lives too: not necessarily replacing the calling, but finding a new way to fulfill it.
Maybe the path my father steered me toward didn't erase the child who wanted to create. It gave him different raw materials. But I had to walk that road to recognize what in it is mine. And if AI changes the tools and the professions again, the question will also be what we want to keep creating, and for what. Not just "what's left for us to do", but "what of it do we choose to do".
If the machine can do everything, what will we need to make an effort for?
These stories don't prove the same thing, but they connect a few questions for me. Calhoun raises the question of whether satisfying all needs is enough. Mill reminds us that even a great purpose and a hard challenge don't guarantee we'll feel they're ours. And my story brings me back to what I claim at YourMarket.Fit: there's a calling in us, even when the way it's fulfilled changes. Alongside that, we're social creatures. We want to feel that what we do connects us to others, and that we're part of something bigger than us.
If one day the machine can do everything for us and better than us, this question will only get sharper. Not just working and solving problems, but also creating what we dreamed of creating and advancing the goals that give us meaning. If the goal is achieved better without us, will its very achievement be enough for us? Or is part of the meaning precisely in that we take part, make an effort and contribute?
That's the question mark hanging over the "gym for humanity". It's possible to design cognitive and emotional effort, the way we design strength training and nutrition. The fact that the workout is artificial doesn't make its benefit artificial. Maybe it will also give us a sense of meaning and belonging.
I still don't know. This is what I want to find out through the gym for humanity.
If this topic stirs something in you that's hard to put into words - a feeling that this revolution is exciting and frightening at the same time - you're not alone. I feel it too. Let's build Humanity-Fit together, a gym for our humanity, and protect what makes us human. Write to me.
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