Physician-scientist Jonas Salk comments on the concerns about humanity's future and the values he shared with Jacob Bronowski. The author outlines his own view of evolution and acknowledges Bronowski's contributions to our further understanding of this process in which humans are participants as well as products. Like Bronowski, the author believes the human race has the power to influence its future, whether by creating disaster or by saving itself through conscious choice. He envisions as the next evolutionary step the creative interaction and convergence of the various cultures, including the ‘two cultures’ of science and humanism examined by Bronowski. The author suggest that our ‘evolutionary instinct’ will guide us in this direction, and he challenges us to prepare for a future without catastrophe.