Biological messiness relates to infidelity, heterogeneity, stochastic noise and variation—both genetic and phenotypic—at all levels, from single proteins to organisms. Messiness comes from the complexity and evolutionary history of biological systems and from the high cost of accuracy. For better or for worse, messiness is inherent to biology. It also provides the raw material for physiological and evolutionary adaptations to new challenges.
Messy biology and the origins of evolutionary innovations - Nature Chemical Biology
