Chimpanzees can be aggressive and lethal toward one another whether or not human activities are affecting their habitat, a new study has found.

Publishing their findings in Nature, a research team studied 152 chimp killings in 15 communities, discovering that even chimpanzee groups with plenty of food and no nearby deforestation exhibited high aggression rates, the CBC reported.

Anthropologists had earlier hypothesized that chimps are more likely to kill one another when people encroach on their territory.

While even chimps with plenty of resources can show aggression, human settlements do affect chimpanzee communities.

"In one village near a research site, the population went from 100 people to 10,000," researcher Jill Pruetz, a professor of anthropology at Iowa State University, said in the study, as quoted by the CBC.  "When you have a human influx like that the chimps don't have much choice but to move. If they move into another chimp community's home range, something is going to happen."

The researchers found that three factors can predict chimp victims: their species, age and sex. Violence is also influenced by community membership and demography.

Human settlements did not significantly influence chimps to be more aggressive, the study found. The likely scenario is that chimps kill one another to increase their chances to reproduce.

"For example, Ngogo is a huge chimp community in Uganda and they have a huge number of males. What they've seen there is more lethal events than any other sites," said Pruetz, according to the CBC.

Chimp killings are still rare, but chimpanzee populations have greatly decreased in the last 50 years due to various factors. Researchers hope that understanding chimp aggression will help scientists figure out how best to protect endangered species.

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