Homo naledi lived more recently than expected

Skull of the Homo naledi nicknamed Neo (Image courtesy John Hawks/University of Wisconsin-Madison/Wits University)
Skull of the Homo naledi nicknamed Neo (Image courtesy John Hawks/University of Wisconsin-Madison/Wits University)

Three articles published in the journal “eLife” describe as many aspects of the research about Homo nalidi, the hominids discovered in the cave system called Rising Star in South Africa. The announcement of their discovery in September 2015 was accompanied by many questions. New fossils were discovered while the original individuals were dated between 236,000 and 335,000 years, relatively young considering their various primitive features.

The discovery of Homo naledi’s bones buried in the Rising Star system was amazing and raised arguments about these hominids’ characteristics, in many ways primitive but with some more similar to those of modern humans. According to some scientists they were primitive Homo erectus but in the end it was accepted that it’s another hominid species. Despite a small brain, Homo naledi perhaps had complex behaviors such as the burial of their dead shown by the fossils uncovered, bodies that seem to have been voluntarily carried into those caves.

The first bones were discovered in what is called Dinaledi Chamber, which has such a narrow access that the researchers had to look for petite women to fully explore it. Professor Lee Berger, who directed the team that made the first discovery, continued his research and in what was called Lesedi Chamber, about one hundred meters away from the other, the fossils of three more individuals were found: two adults and one child with an estimated age of less than five years.

Of the baby and one of the adults so far only some bones have been found but the other adult is almost complete and for this reason was nicknamed Neo, a word that means gift in Sesotho language. In particular, they have found enough pieces of his skull to try to figure out what he actually looked like. His other bones are also interesting because they add some details to the knowledge of his species obtained thanks to the first individuals discovered.

The access to the Lesedi Chamber is almost as difficult as that of the Dinaledi Chamber. The hypothesis that Homo naledi practiced the burial of the dead is one of the controversial ones but it really seems impossible that the bones of the 18 individuals discovered so far ended up in two barely accessible caves unless their bodies were carried down there.

Such behavior has a parallel in the Neanderthals, who certainly buried their dead. In particular, burial evidence were discovered in Spain, in the Sima de los Huesos cave, a similarity with Homo naledi who, however, had a brain with a size a third of that of Neanderthals.

Because of the various primitive characteristics of Homo naledi, many paleoanthropologists thought they were more than a million years old, if not two. The fact that their bones were laid on the ground prevented a quick dating, so the researchers used other methods that provided a dating range not very precise but surprising. These fossils are in fact relatively young, between 236,000 and 335,000 years old.

This dating makes the interpretation of the presence of Homo naledi in today’s South Africa at that time more complex but also more intriguing. This species lived with other hominids with much bigger brains, perhaps even with the first Homo sapiens. It’s also a situation in which defining the various relationships among the various species is difficult.

John Hawks, one of the researchers who participated in this study, stated that attempts were made to retrieve DNA from some bones of the first Homo naledi discovered but with no success. DNA was recovered from older hominid bones but a lot depends on their state of conservation and the need to destroy the part of the bone in which it’s being sought discourages from continuing. Further advances in genetic techniques could lead to new attempts.

For the time being, the studies of Homo naled will continue together with the search for more bones in the Rising Star cave characteristics and that there’s still a lot to be understood in general about the genus Homo’s history.

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