Encouraging people to contribute to a common good can have a surprising drawback: a risk that rewards become concentrated among a smaller group, putting the rest at a disadvantage. Put more simply, "equality and cooperation are often in conflict," says Joshua Plotkin, Walter H. and Leonore C. Annenberg Professor of the Natural Sciences in the School of Arts & Sciences.
Plotkin, an evolutionary biologist and applied mathematician, has spent years studying cooperation. In a study published in Nature, he and colleagues developed a theoretical analysis showing that cooperation tends to benefit the more well-connected. The findings have implications for everything from how scientific papers credit authors to large-scale efforts combating climate change.
Such information, according to Plotkin, could be particularly valuable for lawmakers and other officials who are able to determine resource allocation as they stimulate collective gains—benefits or profits achieved by a group rather than by individuals. "The way a society chooses to divide collective gains can boost cooperation precisely by concentrating wealth," he explains. "So, policymakers must weigh the value of cooperation against inequality that comes with it."
How rewards get divided
As an example, Plotkin points to joint ventures, which could range from a band splitting album royalties to company founders dividing equity and share-farming arrangements that involve running separate agricultural businesses on the same land. Each of those scenarios entails people combining their resources into a single enterprise, likely agreeing in advance how to divide any meaningful gains or benefits. That doesn't always mean the same thing, however: Allocation can be split evenly, for instance, or weighted toward those who have more to contribute.
According to the paper's findings, Plotkin says that the "allocation rule"—a standard term in the field for distributing the rewards from cooperation—can shape how willing people are to cooperate in a venture to begin with and how lopsided the eventual gains become. Those dynamics could play out in many areas.
From author lists to climate deals
Contributing to a scientific paper is an act of cooperation, and the allocation rule concerns the assignment of author credit; authors could be listed according to how much they contributed or in alphabetical order, implying even credit distribution. This could matter greatly in competitive fields where credit is critical to advancement, Plotkin explains.
In scenarios like cutting emissions under climate treaties, the allocation rule can have truly global effects, Plotkin says. Benefits like carbon-offset credits could be divided in proportion to a country's contribution, or uniformly, regardless of its possible impact. "Dividing the benefits equally among nations may draw more of them into the agreement, but tends to concentrate the gains in a few large, centrally positioned players," he says.
Cooperation after the breakthrough
Plotkin's lab uses mathematics to study the spread of behaviors and strategies through populations. To analyze cooperation and grasp the spread of social behavior in a population, his team adapted concepts and calculations originally used for studying the spread of genes. Prior studies from his lab and other researchers have centered on sustaining cooperation in a world where it's tempting to be selfish. Plotkin's team, by contrast, was interested in a different question: How cooperators divide benefits after producing something of value, and what that result means for long-term prosperity and equality.
"What's new here is that we treat cooperation not as the finish line but as a starting point: Once it takes hold, what does this mean for the distribution of welfare?" Plotkin asks. "That connects evolutionary dynamics to questions traditionally studied by economics and the social sciences, such as inequality and the design of institutions."
Testing responses to inequality
He says the team plans to build on the paper's findings, analyzing questions such as how societies adjust benefit-sharing once they notice that inequality has emerged. Adaptive policies that account for the appearance of inequality, Plotkin ponders, might have the potential to remove the conflict his team identified—but it's too soon to tell.
"We've really only scratched the surface of this problem, considering a few standard and simple allocation rules," he says. "There's so much more to do."
Publication details
Anzhi Sheng et al, Cooperation conflicts with equality when allocating public goods, Nature (2026). DOI: 10.1038/s41586-026-10550-3
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Citation: Research cautions that sometimes working together can actually spur inequality (2026, July 27) retrieved 27 July 2026 from https://phys.org/news/2026-07-cautions-spur-inequality.html
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