EFFECT OF SUBORDINANCE, LACK OF SOCIAL HIERARCHY, AND RESTRICTED FEEDING ON MURINE SURVIVAL AND VIRUS LEUKEMIA

When caged in groups of three and fed ad libitum, dominant male mice survived longer than subordinate group members which again lived longer than males caged in groups of nine, among whom no rank order was established. In groups of nine the social structure was not affected when the food supply was reduced to the lowest level not affecting survival, but in groups of three, food reduction made the survival of both dominant and subordinate animals drop to a level matching that of groups of nine. After challenge with a small dose of Moloney virus, leukemia developed among ad libitum fed subordinate mice in groups of three and members of groups of nine, but not among the dominant animals. Food restriction enhanced the leukemia incidence, but dominant animals continued to go free. We conclude that subordinance and also lack of social hierarchy result in a higher incidence of virus induced leukemia, that severe food restriction does the same, and that the effect of social order on leukemia development prevails even under feeding conditions that nearly abolish group-related differences in survival.