Researchers recently unearthed a rhino skeleton on Kalinga, a province within the Philippine island of Luzon. The skeleton showed signs of deliberate butchering by stone tools. But when these cuts were made more than 700,000 years ago, there shouldn’t have been any tool-users around to butcher the animal—at least according to our old understanding.

…The most likely candidate to have made these rhino cuts is Homo erectus, an ancient Asian species of human that went extinct around 140,000 years ago. The tools used on the carcass seem to corroborate this theory.

But the study authors concede there is a problem with this hypothesis. The Philippines are a fairly isolated chain of islands in the Pacific that, at the time, would have been accessible only by boat. According to the paper, “it still seems too farfetched to suggest” that any early human relative could have made the journey. And yet, the butchered rhino is there.

…It also seems to predate all known watercraft, and Pobiner says, “the evidence from Kalinga also adds to the growing indication that whether intentionally or not, at least one pre-modern human species of hominin was able to cross sea barriers in the Middle Pleistocene.”