Overview
- The Ngogo community expanded its range by 22% after coordinated attacks that killed at least 21 neighboring chimpanzees.
- In the three years after the takeover, females produced 37 infants compared with 15 in the prior three-year period.
- Infant mortality before age three dropped from 41% to 8% following the expansion.
- Long-term ecological and demographic data ruled out alternatives such as increased fruit in the original core range, indicating benefits flowed from access to new resources.
- The study, led by UCLA’s Brian Wood with collaborators from Michigan, Yale, and Arizona State, argues the fitness gains illuminate the evolutionary payoff of coordinated intergroup violence and urges monitoring of other groups and displaced neighbors.