Violence of chimpanzee

Yesterday, I watched a surprising program on TV. This was a documentary about wild animals. In general, people think Chimps are similar to human, but they have tender and good characters. However, can you imagine? They share a lot of aspects with us, human being, especially in violence. I saw a group of male chimps that attacked another group’s male chimps. They broke into other group’s territory. It seems to be a war of humans. They hit and kicked a male chimp cruelly. The chimp would be hard to live. Until now, I think the human is only one creature that kills each other regardless of their existence. Violence is a result of the brain’s excessive develops? Then our intelligence is what for?