Scientists don’t yet know exactly how old Homo naledi is and so it’s difficult to slot the species into the tree of life. Part of the problem is the soft clay sediments in which most of the bones were found and the fact that there aren’t many flowstones that can be directly linked to the fragments.
The Rising Star Expedition has tried three separate approaches to properly date the fossils and none of them have worked. Scientists are trying other avenues now, but they don’t want to guess at the species’s age without something more solid to go on:
“If it turns out that H. naledi is old, say older than around 2-million-years, it would represent the earliest appearance of Homo that is based on more than just an isolated fragment. On the other hand, if it turns out that H. naledi is young, say less than 1 million years old, it would demonstrate that several different types of ancient humans all existed at the same time in southern Africa, including an especially small-brained form like H. naledi. Given its primitive skeletal adaptations, this might have profound implications for the development of the African archaeological record. It would also have profound implications for our understanding the origins of complex behaviours previously thought to arise only with the origins of hominins not very different from our own species as recently as 350,000 years ago.”
Check out our timeline of major fossil discoveries made in South Africa over the last one hundred years or so:
Our understanding of the human lineage has changed in recent years owing to a large number of new fossil discoveries like sediba and Ardipithecus ramidus. However, given that H. naledi shares some characters with australopiths, and other characters with species of early Homo such as H. habilis and H. erectus, it is possible that this new species may be rooted in the initial origin and diversification of the genus Homo. At the same time, H. naledi shares characters that are otherwise encountered only in H. sapiens. As a result, our team has proposed the testable hypothesis that the common ancestor of H. naledi, H. erectus, and H. sapiens shared humanlike manipulable capabilities and terrestrial bipedality, with hands and feet like H. naledi, an australopith-like pelvis and the H. erectus-like aspects of cranial morphology that are found in H. naledi. Future fossil discoveries in the Dinaledi Chamber and elsewhere will certainly help us to test this hypothesis.