For the first time ever, a troop of wild chimpanzees were caught warding off a leopard and eating its freshly killed prey, lending more insight into how humans may have evolved to eat meat and develop the skills to communicate and coordinate together.

The event was captured by researchers working in the Mahale Mountains of Tanzania in November 2016. They had been watching the group for several hours before spotting a leopard sitting in a nearby tree. A female chimp started giving off aggressive “waa barks” and was joined by another after some time. Within an hour, the group and its alpha male, naturally named Primus, joined the other two chimps at what appeared to be the leopard’s kill site. The troop was seen carrying the carcass of a blue duiker with fresh blood oozing from wounds on its throat likely caused by the leopard.

“Because they frequently emitted waa barks, they probably recognized the continued presence of the leopard. They did not show excessive fear or panic, nor did they attempt to flee,” wrote the researchers in the Journal of Human Evolution. “Multiple chimpanzees shouting loudly may be enough to chase away a leopard or at least deter it from approaching.”

Together, the chimps ate the duiker carcass for nearly five hours, during which time the leopard was seen returning to the site – each time met with barking chimps.

The interaction has potential implications for how early humans evolved into what we are today. Many scholars believe that eating meat was important during human evolution and that hominins probably first began eating meat by scavenging for it. However, the debate lies in whether the method of scavenging was passive (hominins getting ahold of the carcass after the original predator had already finished eating and left) or confrontational (chasing away original predator to get ahold of its still-meaty carcass). The latter would have been safer for meat consumption but more dangerous due to conflict with the predator.

Looking to one of our closest relatives today helps shed a light into our past. Chimps have been observed scavenging meat, but it is rare and was always passive – until now. Researchers compiled and reviewed 49 cases of chimpanzee encounters with animal carcasses in the Mahale Mountains between 1980 and 2017. If chimps fend off a leopard today, it means that chimp-sized humans may have once chased off leopard-sized predators hundreds of thousands of years ago.

Theories hold that early humans started scavenging and eating meat during the transition from the Pliocene to the Pleistocene, possibly using stone tools or scavenging from predators, or perhaps a combination of the two. Modern-day hunter-gatherer societies also exhibit confrontational hunting. The Hadza people in Tanzania are known for obtaining as much as 20 percent of their food by doing so, while the San people in southern Africa often snatch kills from large carnivores after following flying vultures. Ugandan farmers are also known to opportunistically chase away large predators in order to get their meat.

But the researchers are quick to note that this is a one-off occurrence. Alexander Piel of Liverpool John Moores University, who was not involved in the study, told New Scientist that it’s not certain the leopard killed the duiker or if it was sick.

[H/T: New Scientis]