The hidden costs of human cooperation.

Cooperation enables humans to reshape entire environments and build complex societies. Although often celebrated, cooperation also has hidden costs. By presenting core mechanisms behind its emergence, we demonstrate that maintaining cooperation frequently relies on social control and coercion, which can lead to extortion and discrimination. Group cooperation further necessitates defining who belongs to the group, fostering exclusion and intergroup conflict. Free-rider concerns fuel scapegoating and polarization. These downsides challenge the notion of cooperation as a simple success story. The resulting conundrum for scientists is not just to explain cooperation but to identify institutions that harness its benefits while limiting its risks. Understanding these complexities is crucial to ensuring that human cooperation serves the common good rather than deepening social divides.