In humans, warfare and territoriality seem to be a male "business". Chimpanzees, with whom we share this propensity for out-group hostility and territoriality, are thought to follow the same gender difference. This vision may be too simplistic, as suggested by an international team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. They extensively studied several neighboring groups of western chimpanzees and their findings reveal that females and even the entire group may play a more important role in between-group competition than previously thought. They found that even though adult males seem important in territory increase, territory maintenance and competitive advantage over neighbors act through the entire group in this population of chimpanzees in the Taï National Park.