Cooperation Emerges When Groups Are Small and Memories Are Long

In a new paper published in the journal Scientific Reports, Penn researchers use game theory to demonstrate the complex set of traits that can promote the evolution of cooperation. Their analysis showed that smaller groups in which actors had longer memories of their fellow group members’ actions were more likely to evolve cooperative strategies. The work suggests one possible advantage of the human’s powerful memory capacity: It has fed our ability as a society to cooperate.

“In the past we’ve looked at the interactions of two players to determine the most robust evolutionary strategies,” said Joshua Plotkin, a professor of biology. “Our new analysis allows for scenarios in which players can react to the behaviors and strategies of multiple other players at once. It gives us a picture of a much richer set of social interactions, a picture that is likely more representative of the complexities of human behavior.”

Plotkin collaborated with Alexander J. Stewart, then his postdoctoral researcher and now a Royal Society research fellow at University College London, on the work, which builds on years of game theory examinations by the pair.

Click here to read the full article.

Arts & Sciences News

Mark Devlin Elected to National Academy of Sciences

He joins three others from Penn to receive the honor this year, all recognized for “distinguished and continuing achievements in original research.”

View Article >
Michael Jones-Correa and Sophia Rosenfeld Elected to American Academy of Arts & Sciences

They join three others from the University of Pennsylvania, selected as part of the Academy’s mission to convene leaders from “every field of human endeavor to examine new ideas, address issues of importance to the nation and the world, and work together.”

View Article >
Eva Del Soldato Awarded 2025-26 Rome Prize

She joins Sean Burkholder, of the Weitzman School of Design, and just 33 others in receiving the prestigious honor from the American Academy in Rome.

View Article >
Mark Trodden named Dean of Penn’s School of Arts & Sciences

A distinguished physicist and accomplished academic leader, Trodden will assume the role on June 1.

View Article >
Two Penn Arts & Sciences Faculty Named Guggenheim Fellows

Marcia Chatelain, Presidential Penn Compact Professor of Africana Studies, and Matthew Levendusky, Professor of Political Science, are among 198 in the U.S. and Canada selected for this 100th class of fellows.

View Article >
Penn ATLAS Shares 2025 Breakthrough Prize in Fundamental Physics

The team, which includes Joseph Kroll, Evelyn Thomson, Elliot Lipeles, Dylan Rankin, and Brig Williams from the Department of Physics and Astronomy, is part of an expansive collaboration studying high-energy collisions from the Large Hadron Collider.

View Article >