[1/3] A group of chimpanzees listen to other chimpanzees heard at a distance in the West African forests of Cote d'Ivoire, studied as part of research by the Tai Chimpanzee Project, in this undated handout photograph.
But in this case, it involved not people but chimpanzees in Tai National Park in southwestern Ivory Coast, West Africa's largest protected area of rainforest.
Inter-group violence is ubiquitous in chimpanzees, Lemoine said.
They were more likely to advance into dangerous territory after descending a hill if the rival chimpanzees were further away.
Chimpanzees and the closely related bonobos are the species nearest genetically to humans, sharing about 98.8% of our DNA.
Persons:
Wittig, Sylvain Lemoine, Lemoine, " Lemoine, Will Dunham, Rosalba O'Brien
Organizations:
REUTERS Acquire, University of Cambridge, Biology, Inter, Thomson
Locations:
West, Cote d'Ivoire, Tai, Ivory Coast, Washington