Hannah Hilbert-Wolf (centre) from the JCU team finds a new naledi fossil.
Hannah Hilbert-Wolf (centre) from the JCU team finds a new naledi fossil. News Corp Australia

JCU scientists make exciting discovery about humanity's past

A TEAM of James Cook University scientists have made the groundbreaking discovery that primitive hominids lived in Africa about the same time as humans.

The team has spent years dating the Homo naledi fossils discovered in 2013 in South African caves and can now confidently say the hominids are between 236,000 and 335,000 years old.

Homo naledi's teeth and skull are similar to those of humans, and they are thought to have stood about 1.5m tall with a tiny orange-sized brain. JCU Geologist Associate Professor Carl Spandler said when palaeoanthropologists first examined the hominid fossils' anatomy, they estimated them to between one and two million years old.

"The amazing story is that the Homo naledi is so young. It's much, much younger than everyone expected it to be," he said.

"Why it's surprising is this species stands upright and some aspects of it are very similar to our direct ancestors Homo sapiens, except it has a very small brain, a very small skull and very narrow shoulders." Assoc. Professor Spandler said as the oldest dated fossils of Homo sapiens were 200,000 years old, it meant the two species potentially coexisted on the African landscape.

"Essentially it means we have to rethink how we think about hominid evolution," he said.

"From our long lost ancestors all the way to us it was assumed that Homo erectus, which led to Homo sapiens, which led to us, knocked out all its competitors on the way. That's clearly not the case."

The fossils were discovered in two different cave chambers at the Cradle of Humankind World Heritage Site north of Johannesburg.

Some of the research team, including leaders Professor Paul Dirks and Associate Professor Eric Roberts are in South Africa for the announcement. Assoc. Professor Roberts said JCU scientists were confident of the dates.

"Much of the initial work on the age range was done here at JCU in our advanced analytic centre. But to get the final date range we used 10 different labs and six different techniques which also involved double-blind testing," he said.

Professor Dirks said it was unknown why the hominids were in the cave system.

"There's a big debate on whether it's a burial ground or they were trapped there," he said.

"They could have been chased by lions or other humans, they could have got stuck in the cave ... You can speculate all you like, but at the moment the original hypothesis that they were placed there on purpose still holds."

Assoc. Professor Spandler said much of the cave chambers was yet to be excavated and the team may continue its work in the area for years or even decades.