Chimpanzees in the wild have been carrying out lethal attacks against gorillas for the first time, according to scientists.

The attacks between the two species were observed at the Loango National Park in Gabon. On Monday, researchers from the Osnabrück University and the Max Planck Institute for Evolutionary Anthropology in Germany published the study in the journal Nature.

The team initially assumed the chimpanzees would be relaxed and playful around the gorillas. 

“Interactions between chimpanzees and gorillas have so far been considered as relatively relaxed,” Simone Pika, a cognitive biologist at Osnabrück University, wrote in the study.

“We have regularly observed both species interacting peacefully in foraging trees. Our colleagues from Congo even witnessed playful interactions between the two great ape species.”

However, in December 2019, the researchers witnessed the chimps carry out the first attack against gorillas and their offsprings.

“At first, we only noticed screams of chimpanzees and thought we were observing a typical encounter between individuals of neighboring chimpanzee communities,” Lara M. Southern, the lead author of the study, said in a statement.

“But then, we heard chest beats, a display characteristic for gorillas, and realized that the chimpanzees had encountered a group of five gorillas.”

While the adult apes were able to get away, scientists saw some of the infants were separated from their mothers and killed. The researchers also witnessed a similar attack which resulted in the death of another gorilla infant.

One attack lasted 52 minutes, and the other went on for 79 minutes. Although both chimps and apes are known to be territorial, scientists are still trying to determine what is causing the chimpanzees to carry out unprovoked attacks. 

“Our observations provide the first evidence that the presence of chimpanzees can have a lethal impact on gorillas,” Tobias Deschner, a primatologist at the Max Planck Institute for Evolutionary Anthropology, stated in the study.

“We now want to investigate the factors triggering these surprisingly aggressive interactions.” 

chimpanzees-learn-call Chimps know when they are right, and can adjust their behavior based on their thinking, researchers claim. Photo: Reuters