New research details two fatal encounters in which wild chimpanzees attacked and killed gorillas. It's a rare example of one great ape species attacking another—and scientists are worried that climate change might have something to do with it.

Chimps and gorillas can be violent and territorial, but their squabbles—which can be fatal at times—happen almost exclusively within their own species. As for lethal conflicts involving two different great ape species (at least those not involving humans), that's virtually unheard of. Hence the importance of new research published in Scientific Reports, in which scientists document two fatal clashes involving chimps and gorillas at Loango National Park in Gabon.

The reason for these seemingly unprovoked attacks is unknown, but the fatal encounters may be linked to diminished access to food.