Qualification: Endogenous Group Formation
Ahn, Isaac, and Salmon provide independent experimental evidence for the design transition in Kaal's evolution-stage claim. Most prior public-goods experiments fixed groups exogenously. Their experiment instead allows participants to change groups under three entry and exit institutions. The formation rules significantly affect group size, contribution dynamics, and earnings. This supports introducing endogenous formation when testing an institutional arc because fixed membership can suppress behavior generated by formation rules. The comparison is bounded. The source studies human membership in public-goods groups, not autonomous agents forming work, and does not test Kaal's reputation, validation, staking, or three-stage substrate. It therefore qualifies the necessity and implementation level of Kaal's evolution stage rather than validating the architecture.
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