Organisms by their design are not made to adapt too far.

Kelly’s line points to a constraint in biological (and, by analogy, technological or organizational) systems: adaptation is real, but it is not unlimited. Organisms are shaped by evolutionary trade-offs—specializations that make them highly fit in certain environments while leaving them brittle outside those conditions. “Design” here can be read as evolved structure: anatomy, metabolism, and behavior are optimized within bounds, and pushing beyond those bounds can incur steep costs or failure. The remark also implicitly contrasts living systems with more modular, reconfigurable systems (like some technologies), suggesting that resilience often comes from diversity, redundancy, and flexibility rather than expecting any single organism to stretch indefinitely.