A Controversial Ancient Burial Site Gets More Mysterious
Homo naledi tooth enamel from Rising Star yielded no Y marker, raising new questions about sex, burial, and ancient social behavior.
RISING STAR, SOUTH AFRICA — A Controversial Ancient Human Burial Site Just Got More Mysterious after protein analysis of Homo naledi fossils from the Rising Star cave system found no marker linked to the Y chromosome. The result raises a strong possibility that the individuals studied were female, or at least that the usual male signal was absent from the samples.
The finding does not settle the long-running argument over whether Rising Star was a deliberate burial site. It does, however, sharpen the question. If most of the people placed there were female, where are the male Homo naledi remains — and what does that say about how the species treated its dead?
Tooth enamel opened the new clue
Homo naledi was first identified from discoveries in South Africa in 2013. Researchers later linked at least 20 individuals to the species, with the fossils dating to between 236,000 and 335,000 years ago. The Rising Star cave system quickly became one of paleoanthropology’s most argued-over sites.
The new study focused on peptides from amelogenin, a protein that helps form tooth enamel. Amelogenin X shows up in both sexes, since all humans carry an X chromosome. Amelogenin Y is different. It points to the Y chromosome and usually signals a biologically male individual.
In the enamel samples examined, the researchers found no sign of amelogenin Y. That is the critical detail. It does not prove the fossils were all XX. It does mean the biomolecular marker most often used to identify male sex was not detected in the material available to the team.
That result matters. A lot. If the pattern reflects the population itself, Rising Star may preserve an unusual biological or social signal in ancient hominins.
Why scientists are staying cautious
The research team did not claim certainty, and for good reason. Ancient protein analysis can reveal useful clues, but it works with a limited window. The absence of a Y-linked marker could mean the group was dominated by females. It could also mean a mutation or gene deletion altered the signal in a specific Homo naledi population.
Statistical tests pointed toward a high probability that most specimens at the site were female. High probability is not proof. So the study leaves room for another explanation: the Y marker may have disappeared in that population even if some of the individuals were male.
Palesa Madupe, an evolutionary anthropologist at the University of Copenhagen, said enamel is especially useful because it protects proteins so well. “Unlike bone remains, proteins in tooth enamel are preserved because enamel, the hardest tissue in the human body, protects proteins from environmental contamination even for millions of years,” she said.
That is why the sample matters. Warm climates and long time spans usually destroy easier evidence. Tooth enamel can still hold onto a few biochemical traces.
The burial debate gets sharper
Rising Star has long sat at the center of a bigger fight: did Homo naledi intentionally place bodies inside the cave? If that claim holds, the site could represent some of the earliest evidence for deliberate burial in human history.
Many experts have not accepted that idea. They question whether the cave’s hard-to-reach chambers could really have been used for ritual burial, or whether natural forces moved the bodies there instead. Lee Berger, the paleoanthropologist involved in the latest study, has argued before that Homo naledi did bury its dead deliberately. Other researchers have pushed back hard.
The new paper takes a more careful line. No triumphal language. Just a stronger, stranger data point.
If the cave really is a burial place, the sex pattern becomes even more interesting. One possibility is that the site was used mainly for females. Another is that a separate burial cave for males still has not been found.
A small population could explain it too
The study also found very low genetic diversity in the protein sequences. That kind of pattern often appears in isolated populations or groups that lived through inbreeding over long periods. A small gene pool can do odd things fast.
One possibility is that a mutation or deletion removed the amelogenin Y signal from the population and that change spread after a bottleneck. In that case, some individuals could still have been male, even though the usual biomolecular marker no longer appeared in the enamel.
Marc Dickinson, a fossil chemist at the University of York, called the absence of male markers “very interesting.” He said advances in ancient protein analysis are opening “the door to a much richer and more nuanced understanding of ancient hominins.”
That matters beyond one cave in South Africa. Fossils are not just old bones locked in stone. Sometimes a protein fragment in tooth enamel can shift how scientists read sex, social structure, and burial behavior in a species that lived hundreds of thousands of years ago.
For now, the Rising Star case stays open. The next sample may bring a clearer answer. Or it may deepen the mystery even further, especially if new enamel analyses keep turning up the same missing Y marker.
