Chimpanzees kill neighbors to acquire more territory--study

Research study leader Dr. John Mitani, an anthropologist at the University of Michigan said in an e-mailed statement that chimps only uses “fists and feet" for attacking their victims.

"Multiple chimps pummel the victims with both [appendages]. I think the victims die from internal injuries. Victims are usually totally immobilized and don't really stand a chance of getting away," added Mitani.

Even before the publication of this new study, chimpanzees were known to kill each other or their neighbors, however, the reason behind this was not known back then.

So this new research study “indicate that they do so to expand their territories at the expense of their victims," explained Mitani.

For this study researchers observed a primate colony predominately male patrol groups in Ngogo, Kibale National Park in Uganda for close to ten years (from 1999 to 2008). As per Mitani, within this time period chimp gang killed 21 of their neighbors.

Motivation behind attacking neighbors
Even after establishing, chimpanzees kill their neighbor to acquire more territory, researchers admitted that they are still clueless about attacking party’s ultimate motive behind killings.

For this study researchers observed a primate colony predominately male patrol groups in Ngogo, Kibale National Park in Uganda for close to ten years (from 1999 to 2008).

However, researchers believe that access to more food resources and females (from defeated gang) could very well be the motivation.

Mitani revealed that killing usually took place during “patrols” during which packs of chimps creeps into neighbors jurisdiction to have rough estimation of their enemy’s strength.

"Patrollers are quiet and move with stealth. They pause frequently to scan the environment as they search for other chimpanzees. Attacks are typically made only when patrolling chimpanzees have overwhelming numerical superiority over their adversaries,” said Mitani.

No conclusions about humans warfare attitude
Some believe that studying chimpanzee warfare could provide some insight into humans’ aggressive behavior too as both might have inherited their territorial aggression from their shared ancestors, who lived some five-million-years ago.

However, lead researcher of the new study Mitani cautioned against drawing any conclusions about humans warfare attitude based on his study as it only gives useful insight into primate teamwork.

"Warfare in the human sense occurs for lots of different reasons. I'm just not convinced we're talking about the same thing," said Mitani.

He added, "What we've done at the end of our paper is to turn the issue on its head by suggesting our results might provide some insight into why we as a species are so unusually cooperative.”