Northern Illinois University
Department of Biological Sciences
College of Liberal Arts and Sciences

Professor Neil W. Blackstone

The history of life is a history of the elaboration of levels or units of evolution—molecules within cells, cells within cells, cells within organisms. At each transition, conflicts between the lower level units had to be mediated in order for the higher level unit to emerge. These mechanisms of conflict mediation may themselves have been innovations that subsequently provided the raw material for further evolution. For instance, mechanisms for mediating conflicts between mitochondria and host cells (e.g., within-cell signaling with calcium, redox state, and reactive oxygen species) were likely co-opted into mechanisms of development and conflict resolution in multicellular organisms (e.g., "second messenger" systems, between-cell redox signaling, and programmed cell death).