This chapter examines the deep connections between biological organization, agency, and evolution by natural selection. Using Griesemer’s account of the reproducer, I argue that the basic unit of evolution is not a genetic replicator, but a complex hierarchical life cycle. Understanding the self-maintaining and self-proliferating properties of evolvable reproducers requires an organizational account of ontogenesis and reproduction.

This leads us to an extended and disambiguated set of minimal conditions for evolution by natural selection—including revised or new principles of heredity, variation, and ontogenesis. More importantly, the continuous maintenance of biological organization within and across generations implies that all evolvable systems are agents or contain agents among their parts. This means that we ought to take agency seriously—to better understand the concept and its role in explaining biological phenomena—if we aim to obtain an organismic theory of evolution in the original spirit of Darwin’s struggle for existence.

This kind of understanding must rely on an agential perspective on evolution, complementing and succeeding existing structural, functional, and processual approaches. I sketch a tentative outline of such an agential perspective and present a survey of methodological and conceptual challenges that will have to be overcome if we are to properly implement it.

J. Jaeger, The Fourth Perspective: Evolution and Organismal Agency, in: Mossio, M. (eds), Organization in Biology. History, Philosophy and Theory of the Life Sciences 33 (2024), Springer, Cham.