30. Why do many interventions have modest effects in mammals?

Mammals are long-lived relative to many model organisms, and their maintenance systems are already substantially optimized; further improvements may have diminishing returns. In addition, the deleteriome is widely distributed due to complexity of these species: improving one pathway can shift failure to another, producing only modest net gains. Finally, laboratory conditions compress variability and remove many real-world stresses, which can limit observable benefits. This suggests that large, reliable effects will likely require combined interventions that address multiple components or that are tailored to the dominant weak links.