Fig 4. After male replacement, new males showed two strategies, either aggression or tolerance, which would bring different reproductive success. When males adopted a strategy of aggression, they obtained increased reproductive success from killing infants because they sired the next offspring of victims’ mother sooner. However, they completely lost benefits as lactating females emigrated if the first set of attack did not kill the offspring. Therefore, male would benefit from their strategies because (a) male tenures are longer than inter-birth intervals of female if keeping mothers and their unweaned infant in their social unit, (b) tenures of tolerant male are longer tenures than those of aggressive male if the male tolerate the unweaned infant without attack.