Developmental robustness.
Developmental robustness, the capacity to stay "on track" despite the myriad vicissitudes that inevitably plague a developing organism, is, I argue, a prerequisite for natural selection and key to our understanding of the evolution of developmental processes. But how is such robustness achieved? And how can we reconcile this property with the delicate precision that seems to characterize so many developmental mechanisms, with what Michael Behe calls "irreducible complexity"? By looking at context, I argue. Developmental mechanisms must be robust with respect to the kinds of insults they are most likely to face, but with respect to less likely vicissitudes, they can be fragile. More specifically, I examine the relative absence of reaction-diffusion mechanisms in development and suggest that such mechanisms, theoretically attractive though they may be, have been judged by evolution to be ill suited for providing protection against the kinds of vicissitudes developing organisms are most likely to face, and have been supplanted by more intricate mechanisms that are protected from insult by structural design.
Keller
Evelyn Fox
EF
California Institute of Technology, Humanities and Social Sciences, Pasadena, CA 91125-7700, USA. efkeller@mit.edu
D000222:Adaptation, Physiological; D000818:Animals; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008957:Models, Genetic; D015233:Models, Statistical; D009024:Morphogenesis / Q000502:physiology*; D010641:Phenotype; D012641:Selection, Genetic