The structure and dynamics of knowledge are central to modern evolutionary economics. In the canonical evolutionary model, knowledge exists in the routines and competencies of firms, an approach optimized to study industrial dynamics. In mainstream economics however, knowledge is represented as human capital, an investment by workers in education and skills, an approach suited to the study of labor markets, education, jobs and careers. Evolutionary economics has little to say about this. We propose a new research program for evolutionary economics that develops an evolutionary theory of human capital by developing a meso perspective that represents human capital as a position on a network of knowledge, and economic evolution as a change in that network. Our new approach proposes an evolutionary model of the evolution of jobs and occupations as the evolving structure of that network and of a career as a path through that network.