A headline grabbing claim was made in 2023: Homo naledi may have deliberately buried its dead.
The claims came from a preprint uploaded by some of those working at the Rising Star Cave System in South Africa. According to the original researchers, new evidence they unearthed suggested that despite having tiny brains, Homo naledi may have lit fires and decorated walls around the graves of their dead.
The paper was followed by extensive media coverage and a popular Netflix documentary. Despite the popularity, nearly unanimous publicly available peer reviews argued that the evidence presented did not support what the researchers claimed. The issues raised by these critics have not yet been fully addressed by the authors.
Now, HERI Co-director Dr Robyn Pickering has raised more questions in a new peer reviewed paper published by the journal, PaleoAnthropology. In it, she and co-authors Dr Kimberly Foecke from George Mason University, and Dr Alain Queffelec from Université Bordeaux, present a critical assessment of the geochemical and sedimentological data used as a cornerstone for the preprint claims.
The results, they say, suggest no evidence that Homo naledi deliberately buried its dead.
Having worked on the geology of the Cradle of Humankind caves for the last 20 years, where the Rising Star Cave System is based, Pickering expressed early misgivings about how geochemical and sedimentological data specifically had been used to fit the 'deliberate burial' narrative.
Teaming up with Foecke’s expertise on the application of geochemical techniques in archaeological/palaeo settings, and Queffelec’s skill collecting, reducing and presenting geochemical data, the team worked to re-analyse the pre-print’s geochemical data (available online in their preprint but not yet peer reviewed).
“We found that the raw data reduction in the preprint was inaccurate, revealed structural issues with how the data had been visualised and interpreted, and misapplication of some statistical methods they used,” says Pickering.
The findings also note that the setting of the cave, where the Homo naledi evidence was discovered, is a site of repeated disruption by collapse and water that is not consistent with the type of environment needed to preserve a burial.
As with much of the criticism voiced around the preprint claims, the Rising Star authors have not yet responded to this new paper’s findings. However, Pickering and colleagues hope the work is not viewed as an attack on Berger and colleagues, but as a caution for the academic community at large.
“Our paper encourages those in our field to be more rigorous in the application of these types of geochemical tools to questions about burial and we offer a set of best practices for this approach in archaeological contexts,” says Foecke.
They also emphasise that following publishing norms, like only publicising a paper once it is accepted after peer review, is an important part of academic integrity.
Indeed, there is great public interest in the story of human evolution, Homo naledi, and the Rising Star Cave System which must be respected by academics who may rely on that fascination to drive interest in, funding of, and a future for their research.
“As academics, we owe it to our field and the public to maintain the highest standards of research in publications and in the communication of results,” says Pickering.