The definitive dating of the remains of the extinct hominin Homo naledi has been completed, and the results have left researchers’ original assumptions about the age of the creature in the dust: initially thought to be 2.5 million years old, the remains have been found to be only one-tenth of that age, at roughly 250,000 years — meaning that this species co-existed with modern humans.

The remains of Homo naledi were first discovered deep in South Africa’s Rising Star cave system in 2013. The remains showed signs of being the subject of ritual burial, an amazing revelation for a culture that was assumed to be buried that deep in antiquity to be concerned for their dead. Although the new dating, clocking in between 335 and 236 thousand years, would appear to blunt the idea of such a comparatively sophisticated concept being that ancient, this still means that a very primitive form of human that had more in common physiologically with the more primitive Homo habilis than with its contemporary Homo sapiens neighbors, still felt the need to dispose of their dead.

But the major importance of Homo naledi’s young age to the scientific community is that this is the first evidence that the otherwise primitive Naledi co-existed alongside other, more developed species of hominins like Homo sapiens — possibly for as long as two million years — instead of having fallen by the wayside, out-competed by the likes of Humans and Neanderthals.

"The dating of naledi was extremely challenging," explains Professor Paul Dirks of James Cook University and the University of the Witwatersrand. "Eventually, six independent dating methods allowed us to constrain the age of this population of Homo naledi to a period known as the late Middle Pleistocene." According to modern theories, only Homo sapiens was supposed to be present in Africa during the late Middle Pleistocene. And more importantly, this is the era when more complex human behavior began to appear, such as tool use and burial of the dead — meaning that if Homo neledi was also present at that time, which species came up with these concepts first?

"We can no longer assume that we know which species made which tools, or even assume that it was modern humans that were the innovators of some of these critical technological and behavioural breakthroughs in the archaeological record of Africa," explains Professor Lee Berger, of The University of the Witwatersrand. "If there is one other species out there that shared the world with ‘modern humans’ in Africa, it is very likely there are others. We just need to find them."