|Cramped conditions inside the Dinaledi chamber|
The Dinaledi chamber and the first specimens, were discovered in 2013 when two cavers encountered a 20 centimetre wide, 12 metre long shaft branching off the preceding chamber.
Out of gruelling work conditions in 99% humidity came one of the richest collections of early hominin bones yet discovered. 15 individuals offered plenty of material to classify. The specimens lay within the genus Homo, but constituted a new species which researchers dubbed Homo naledi.
'It's got a tiny head and ape-like body, but arms and legs that are very human-like, something completely unexpected and we found it in incredible abundance,' said Lee Berger from the University of Witwatersrand. Berger's interpretations are controversial, in particular his proposition that the specimen's location in a cave represented an act of burial.
|The impressive collection of specimens of Homo nadeli|
Additionally, its age makes it difficult to place precisely within the hominin family tree, although current figures suggest that the fossils are no more than three million years old.
Determining its precise age will be important in determining whether it was ancestral to a contemporary, or descendant, of Homo habilis its closest relative both temporally and phylogenetically.
'I'm respectful of the material they found and I'm respectful of the efforts they made to recover it, but I'm extremely sceptical about the interpretation of them,' said palaeoanthropologist Bernard Wood. Further study, particularly of the age of Homo nadeli, is needed before its precise place in hominin history can be established. Only then can theories regarding mental capacity be accurately assessed. Nevertheless, Homo nadeli represents an intriguing addition to the family tree.