Second-Order Thinking

Biological Parallel

When sea otters were hunted to near-extinction, kelp forests collapsed—not because otters eat kelp, but because they eat sea urchins that devour kelp. Trophic cascades reveal how removing one species triggers chain reactions across ecosystems. In Yellowstone, wolf reintroduction changed river courses because wolves hunted elk, which stopped overgrazing willows, which stabilized riverbanks. Second-order effects dominate ecology; the direct impact is rarely the final impact.