Pierre Durand (Johannesburg): The changing paradigm of programmed (cell) death (Team Meeting)

Our understanding of programmed death and its many manifestations such as programmed cell death, programmed organismal death, aging, behavioural suicide, etc. is undergoing a fundamental reappraisal—perhaps even a Thomas Kuhn-like paradigm shift. The realisation over the last few decades that heritable, programmed forms of dying are integral to evolutionary concepts and processes (e.g., the immunological organism concept or the evolution of individuality across the scales of life) has reawakened an interest in the philosophy of the biology of death. A synthesis of the different kinds of cell and organismal death has hardly been explored, largely because the concepts and different manifestations are poorly formulated and assumed to be unrelated, neither to each other nor to the evolution and maintenance of new kinds of individuals.

In this seminar, I will discuss four topics that percolate through my research interests. The emphasis is on programmed cell death (PCD) but includes the other forms of programmed death (PD) alluded to above. First, the conceptual underpinnings of PCD specifically and PD in general are discussed. This includes the hypotheses for the origin and maintenance of cell death, its nature, its meaning in biology and medicine, and its unappreciated role in the history of life. Second, the proximate questions and mechanisms concerning the modes and molecular pathways for death in a range of organisms from bacteria and algae to animal cancers are discussed. The conflation of ideas around the measurements of cell and organismal death is highlighted and the range of death states is considered. Third, the ultimate causation and multilevel selection pressures for death is examined. There is a focus on what I consider the ’units’ of death and the levels of selection. Fourth, the unexpected role of PCD as an adaptation in populations of infectious agents and cancer cells is highlighted. The discovery that PCD is related to the infectivity of groups of infectious agents and is important for the survival of cancer cell populations is emphasized. These have practical applications in pathology and subsequent treatment protocols.

I will conclude by introducing fundamental metaphysical explanations for death, ones positioned at the interface of biology, medicine and philosophy.