Scientists from Griffith’s Australian Research Centre for Human Evolution(ARCHE) have helped discoverHomo naledi’s surprisingly young age,opening up more questions on where we come from.

Findings published this week injournal eLifeshow thatHomo naledi, the hominin that was discovered by a large team of international researchers in 2013, was alive sometime between 335 and 236 thousand years ago.

ARCHE was among a large team of international researchers led by James Cook University who have presented the long-awaited age of the naledi fossils from the Dinaledi Chamber and announced the new discovery of a second chamber in the Rising Star cave system, containing additional specimens of Homo naledi, including a child and a partial skeleton of an adult male with a remarkably well-preserved skull.

Part of this work was performed by ARCHE director Professor Rainer Grün and Dr Mathieu Duval under hisAustralian Research Council Future Fellowship Grant (FT150100215), using the most advanced analytical procedures to ensure a minimal destruction of the remains.

Dr Duval in the lab.

The core of the work is the direct dating of several human teeth with the Electron Spin Resonance method, which Dr Duval said wasone of the very few methods, if not the only, that could be used for fossil remains older than 50,000 years – the maximum time range covered by the Radiocarbon dating method.

“The obtained data allow locating Homo naledi in a position much more advanced than initially expected in the human evolutionary tree, whereas it seems to be a primitive species within the genus Homo (and in spite of sharing derived features with archaic and modern humans),” Dr Duval said.

“By providing ages that fall in the late Middle Pleistocene, this new dating study shows that Homo naledilived at the same time, and in the same place, as modern humans. These new results combined with those recently obtained for the ‘Hobbits’ in Flores or the Denisovans in Russia, demonstrate that the human lineage is much more complex than thought only a few years ago.”

Professor Grun said the discovery was exciting because these were humans that were not supposed to exist.

“Thenaledi itself is very peculiar. They have a human body but their extremities – their arms and hands – are more like chimpanzees. They have a very strange morphology that draws parallels with the hobbits,” he said.

The work is the latest in a series of important scientific papers recently published by members of ARCHE, in which the role of dating studies were crucial. These include the fossilised bones of the Stone Age victims unearthed at Nataruk (Kenya), the discovery of prehistoric art and ornaments from the Indonesian ‘Ice Age’andthe origin of ‘hobbits’ found in Flores Island.

Professor Grun said these works highlighted the increasing role ARCHE playedin understanding human origins and added to Griffith’s reputation as one of the world’s leading institutions in Quaternary Geochronology. ARCHE sits within the Environmental Futures Research Institute.