In 1968, American ecologist Garrett Hardin published the highly influential article *The Tragedy of the Commons* in *Science*. It opens with a simple thought experiment:
> Imagine a pasture open to all herders. Each rational herder calculates: the benefit of adding one more cow goes to himself, while the cost of overgrazing is shared by everyone. So everyone adds cattle until the pasture is completely destroyed.
Hardin used this parable to illustrate a profound point: when a resource belongs to everyone, no one takes responsibility for it. Individually rational choices aggregate into collectively irrational outcomes—overgrazing, overfishing, over-pollution. For over half a century, the tragedy of the commons has been a foundational concept in environmental economics, ecology, and policy research.
But Hardin's parable told only half the story.
The Overlooked Other Half
In the real world, public resources face problems beyond "overuse." Growing evidence shows that underuse or complete abandonment can also cause ecological degradation.
- European grasslands: Centuries of low-intensity grazing maintained Europe's unique grassland biodiversity. When farmers left and livestock disappeared, shrubs and forest encroached—and open-grassland species, from meadow pipits to specific orchids, vanished with them.
- Japanese countryside: As populations age and urbanize, vast farmland and forests in Japan are being abandoned. Researchers predict large-scale "rewilding" by 2050—sounds nice, but for ecosystems dependent on human management, it means losses of biodiversity and ecosystem services.
- Mediterranean olive groves: Generations of low-intensity agriculture shaped the region's unique cultural landscapes. When land is abandoned, traditional knowledge, local species, and ecological processes die with the landscape.
- Provisioning services: direct products, like forage, timber, fish.
- Non-provisioning services: indirect functions, like carbon storage, water retention, biodiversity, landscape aesthetics.
- Aging populations and rural abandonment: Japan as a case—abandoned farmland means biocultural diversity loss, not ecological paradise.
- Post-socialist transition: Eastern European land abandonment led to landscape homogenization, invasive species spread, and higher fire risk.
- Unintended consequences of protection policies: strictly excluding humans (and fire/grazing) from some US grassland reserves let exotic shrubs replace native grasses, reducing biodiversity.
- A single tool isn't enough: quotas and protected areas alone may swing the system from one extreme to the other.
- Valuing non-provisioning services is essential: carbon markets, payments for ecosystem services, and landscape/tourism value can economically sustain low-intensity management.
- Adaptive management: with bistability and branching under convex benefits, initial conditions and small perturbations matter—early intervention is key.
- Institutional innovation for "moderate use": meaningful rural livelihoods for young people, managing semi-natural habitats, and incorporating traditional ecological knowledge.
- Shibasaki et al., *Incorporating the underuse problem in the tragedy of the commons*, arXiv:2604.27520 (2026)
- Hardin, *The Tragedy of the Commons*, Science 162, 1243 (1968)
- Ostrom, *Governing the Commons*, Cambridge University Press (1990)
- Ostrom, Nobel Prize Lecture, 2009
- Queiroz et al., *Underuse of social-ecological systems*, Land Use Policy 73, 141 (2018)
- Inoue et al., *Simulation of natural capital and ecosystem services in a watershed in Northern Japan*, Sustainability Science 14, 89 (2019)
Many ecosystems are not "natural" but "human-made"—their health and diversity depend on continuous human intervention. When intervention stops, collapse can come from the other direction.
From Hardin to Ostrom
Hardin's proposed solution was "private property or government regulation," though he later admitted the title should have been "The Tragedy of the Unregulated Commons"—because many commons are successfully managed. In 2009, political scientist Elinor Ostrom became the first woman to win the Nobel Prize in Economics, demonstrating that local communities can self-organize to manage commons successfully, through clear boundary rules, conflict resolution mechanisms, monitoring, and participatory decision-making. But her work focused on preventing overuse; underuse remained at the margins of academic attention.
A New Theoretical Framework
On April 30, 2026, a new paper offered the first systematic theoretical framework for this neglected problem:
"Incorporating the underuse problem in the tragedy of the commons" *Authors: Shota Shibasaki, Wakaba Tateishi, Shuhei Fujii, Ryosuke Nakadai* *arXiv: 2604.27520*
Core insight: overuse and underuse are not two separate problems but alternative outcomes of the same underlying evolutionary process.
The researchers built an eco-evolutionary model coupling individual resource-use strategies with resource dynamics, using adaptive dynamics—a branch of evolutionary game theory studying how traits evolve through mutation and selection. A key innovation is distinguishing two types of ecosystem services:
Convex vs. Concave: The Geometry of Destiny
The evolutionary fate of resource-use strategies depends on the shape of the provisioning benefit curve.
Concave: the victory of intermediate strategies
If provisioning benefits increase as a concave function (diminishing marginal returns), evolution converges to a unique intermediate strategy—neither overuse nor underuse—that is continuously stable, like a well-designed thermostat.
Convex: a polarized world
If benefits increase as a convex function (increasing marginal returns), evolution can diverge toward:
1. Overuse: resources depleted. 2. Underuse: resources abandoned, ecosystem services lost. 3. Bistability: the system stabilizes at either extreme, depending on initial conditions. 4. Evolutionary branching: the population splits into overusing and underusing subgroups.
Most surprisingly, overuse and underuse are fully symmetric in this framework—different attractors of the same mathematical structure, not moral failures or institutional defects.
Why Is Not Using Also a Tragedy?
Consider a grassland: provisioning (forage) works best with moderate grazing—too few cattle and grass becomes old and less nutritious. Non-provisioning services (carbon, water, habitat) peak when the grassland is healthy and decline under both overgrazing and shrub encroachment. Many ecosystems have an optimal use intensity—below it, non-provisioning services decline. In Europe, moderate grazing prevents shrub invasion, disperses seeds, creates microhabitats, and maintains grazing-dependent symbioses. When grazing stops entirely, these services disappear.
The Global Picture of Underuse
Policy Implications: Finding the Goldilocks Zone
The Bigger Philosophy
The underuse side of the commons tragedy reveals a deeper truth: nature and humanity are not opposites. From Amazonian terra preta to European semi-natural grasslands, from Aboriginal fire-stick farming to rice-fish systems in Southeast Asia—humanity's imprint on Earth is indelible, and much of it is positive. Conservation is not isolation; sustainability is not abandonment. True wisdom lies in the "Goldilocks zone"—not too much, not too little, but just right—and that state is dynamic, evolving, and requires continuous attention.
Conclusion
A revised parable:
> Imagine a pasture open to all herders. Each rational herder calculates—but the result may be "one more cow" or "just leave for a city job." The former leads to overgrazing; the latter lets shrubs swallow the grassland. Both endings are tragedies.
The tragedy of the commons has never been one-dimensional. It can be the price of greed—or the price of forgetting. Understanding this is the first step toward a genuinely sustainable future.