Cooperation and conflict in the evolution of individuality. II. Conflict mediation.

Evolutionary transitions in the units of selection require the promotion of cooperation and the regulation of conflict among the lower level units. For multicellular organisms to emerge as a new unit of selection, the selfish tendencies of their component cells had to be controlled. Theoretical results indicate organisms may regulate this internal conflict and competition in several ways: by reducing the somatic mutation rate, by sequestering cells in a germ line and by directly reducing the benefits to cell of defecting.