Chimps aren't exactly the soft and cuddly animals that Curious George would have you believe.
Scientists have documented aggression in territorial chimps on numerous occasions, with separate bands of chimps attacking, killing and even cannibalizing one another to gain access to more resources.
But a new study details a far more rare case of chimp murder: One aggressive male chimp appears to have been attacked and killed by members of the group he once led.
The chimp -- named Foudouko by the scientists studying the Fongoli community of chimps in Senegal -- seemed to have been killed in 2013 after he attempted to rejoin the community he once led after five years in exile, the study published in the International Journal of Primatology said.
While scientists didn't see the killing, they did witness the aftermath.
Members of the community attacked and cannibalized Foudouko's body after his death.
"It was very difficult and quite gruesome to watch," Jill Pruetz, a co-author of the new study, said in a statement. "I couldn't initially make sense of what was happening, and I didn't expect them to be so aggressive with the body."
"It was very difficult and quite gruesome to watch"
After being exiled from the group for five years, Foudouko attempted to rejoin as a high-ranking male, but that could have led to his downfall.
Younger males may not have liked the fact that Foudouko wanted to get back into the group, viewing him as additional competition.
However, it's not really a surprise that the exiled chimp wanted to rejoin his band.
"It really struck us that Foudouko lived on the outskirts for so long," Pruetz, a professor of anthropology at Iowa State University, said. "Chimps are very social, so this type of isolation would be a huge stress, and it seemed Foudouko wanted to get back into the social group."
Before Foudouko's exile, he led with fear, according to Pruetz.
"Qualitatively he was probably more aggressive, and I think he did instill a lot of fear in the other individuals," she said in a video.
Even after Foudouko died, it still seemed as though members of the chimpanzee community were frightened of him, according to Pruetz.
They screamed and bared their teeth during the three hours in which the researchers watched the group after the killing.
It's important for scientists and conservationists to learn more about why these chimp killings occur, in part because they hope to protect the endangered species in the future.
Environmental changes in the chimps' habitat may change behavior in the animals, making them more aggressive, and the lopsided gender balance of Fongoli -- there are more males than females -- may have also contributed to Foudouko's death, Pruetz said.
That difference in males and females may actually be human-caused.
Hunters in the area catch female chimps in order to collect infants for sale as pets. According to Pruetz, even if hunters bag one female chimp every couple years, it would change the gender balance of the community.