Robustness, the insensitivity of some of a biological system's functionalities to a set of
distinct conditions, is intimately linked to fitness. Recent studies suggest that it may also play
a vital role in enabling the evolution of species. Increasing robustness, so is proposed, can
lead to the emergence of evolvability if evolution proceeds over a neutral network that
extends far throughout the fitness landscape. Here, we show that the design principles used
to achieve robustness dramatically influence whether robustness leads to evolvability. In …