How do the same mechanisms that faithfully regenerate complex developmental programmes in spite of environmental and genetic perturbations also allow for responsiveness to environmental signals, adaptation, and genetic evolution? In this seminar, I will present work using the nematode Caenorhabditis elegans as a model to explore the phenotypic space of growth and development in various genetic and environmental contexts. Using custom automated microscopes, we have measured the growth curves of ~700 individual C. elegans; the contexts include three C. elegans wild-isolates and four different bacterial foods in all combinations, as well as a few single-gene mutants. I will introduce the concepts of concentration of dimension and of a phenotypic manifold as principles for understanding the origin of robustness and plasticity in complex biological systems. I will also show how phenotypic manifolds may aid in predicting the evolutionary paths of different populations from observations of variations within a single population. Time and interest permitting, I will present some connections between these ideas and the theory of projection operators from statistical physics.