[PART 2] Homo naledi – how old is it really?
One of the original “underground astronauts” on the expedition said she had always felt that the Homo naledi fossils were ‘young’.
The News’ previous article about the fossil discoveries at the Cradle of Humankind announced that the Homo naledi remains from the Dinaledi Chamber have been found to be much younger than previously believed. But how did the scientists on the project figure out how old the fossils are, and what impact does this discovery have on the theories about where human beings come from?
Refresh your knowledge by reading the original article here
In a highly complex scientific process, the team used several methods to determine the age of the fossils. Firstly, they used a process of optically stimulated luminescence to date the deposits in the cave. Then they used Uranium-Thorium dating, and to that they added a palaeomagnetic analysis of the flowstones in the cave to establish how the sediments relate to the geological timescale in the Dinaledi Chamber.
Finally, they used Uranium series dating (U-series) and electron spin resonance dating (ESR) on the teeth of Homo naledi, and together, these results provided the final age range.
“We used double blinds wherever possible,” said Professor Jan Kramers, a uranium dating specialist at the University of Johannesburg.
Dr Hannah Hilbert-Wolf, a geologist from James Cook University in Australia who also worked on the Dinaledi Chamber, noted that it was crucial to figure out how the sediments within the Dinaledi Chamber are layered, in order to build a framework for understanding all of the dates obtained.
“Of course we were surprised at the young age, but as we realised that all the geological formations in the chamber were young, the U-series and ESR results were perhaps less of a surprise in the end,” added Professor Eric Roberts, who works at both the James Cook and Wits Universities, and is one of the few geologists to have actually entered the Dinaledi Chamber, because the entrance to it is only 18cm wide.
Dr Marina Elliott, Exploration Scientist at Wits and one of the original “underground astronauts” on the 2013 Rising Star Expedition, said she had always felt that the Homo naledi fossils were quite young. “I’ve excavated hundreds of the bones of Homo naledi, and as soon as I touched the first one, I realised that there was something different about them – they appeared hardly fossilised.”
To view more photos of the find, click here.
Read more about the impact of this discovery on the theories about where human beings come from in our next article, which will appear tomorrow.
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