The cave wasn't just a dumping ground—it was a place of choice
In the limestone depths of South Africa's Rising Star cave, ancient teeth are quietly rewriting what we thought we knew about one of humanity's most enigmatic relatives. Protein analysis of twenty Homo naledi fossils suggests every recovered individual may have been female — a finding that, if confirmed, would push the origins of intentional, sex-specific burial practices back further than any known human or Neanderthal site. It is a reminder that the past does not surrender its secrets easily, and that the bones we find may tell us as much about the living culture that placed them as about the individuals themselves.
- A new paleoproteomics study found female-linked proteins but zero male-linked proteins across twenty Homo naledi teeth, upending prior skeletal classifications based on body size.
- The finding throws into question a decade of interpretation — if every skeleton is female, the cave may not be a random accumulation of remains but a deliberate, culturally organized space.
- Researchers are proposing that Homo naledi, a small-brained species already controversial for apparent fire use and intentional burial, may have practiced sex-specific funerary rites predating any known Neanderthal burial site.
- Scientists are urging caution: absence of male proteins is not proof males were never present, and the sample size leaves room for chance or incomplete preservation to distort the picture.
- The study also demonstrates that paleoproteomics can extract meaningful biological data from fragile fossils non-destructively — a methodological breakthrough with implications far beyond this single cave.
Deep in South Africa's Cradle of Humankind, a cave called Rising Star has spent over a decade defying easy explanation. Now, protein analysis of twenty teeth from Homo naledi fossils is adding another layer of mystery: every skeleton recovered from the site may have been female.
The study, published in Cell, used paleoproteomics to examine biological markers preserved in tooth enamel. Researchers detected AMELX proteins, present in both sexes, but found no AMELY proteins, which appear only in males. The absence led them to conclude that all sampled individuals were female — including some previously classified as male based on skeletal size and build.
Homo naledi has always been a strange branch on the human family tree. Small-brained and ancient, yet upright-walking with surprisingly modern hands and feet, the species has already drawn controversy for apparent fire use and deliberate placement of the dead. If the all-female protein finding holds, it suggests the cave may have served a culturally intentional purpose — a sex-specific burial site that would predate any known Neanderthal or modern human equivalent by hundreds of thousands of years. Lead researcher Lee Berger proposed the pattern reflects deliberate, socially organized burial by sex, while co-author John Hawks noted that sex-specific funerary practices appear across many human societies throughout history.
As a secondary finding, the study identified a genetic variant shared between Homo naledi and Paranthropus robustus, hinting at evolutionary connections still poorly understood.
Experts are urging measured interpretation. Elizabeth Sawchuk of the Cleveland Museum of Natural History stressed that the absence of male evidence is not proof of male absence — males could have been buried elsewhere, or the sample may be skewed by chance. Co-author Enrico Cappellini acknowledged that either explanation carries profound implications. The teeth have offered a clue, but the cave's full story remains sealed in stone.
Deep in South Africa's Cradle of Humankind, in a cave system called Rising Star, researchers have been pulling fragments of an ancient human relative from the rock for over a decade. What they've found there has consistently refused to fit neatly into the story we thought we knew about human evolution. Now, a new analysis of proteins preserved in twenty teeth from those fossils is suggesting something unexpected: every skeleton recovered from that cave may have belonged to a female.
The work, published in Cell, used a technique called paleoproteomics to examine biological markers in the tooth enamel. The researchers found AMELX proteins, which appear in both males and females, but detected no AMELY proteins—the kind that only males carry. This absence led them to conclude that all the individuals in their sample were female, even some that had previously been classified as male based on their skeletal size and build. It's a finding that upends earlier interpretations and raises a question that has haunted Homo naledi since its discovery: what was really happening in that cave?
Homo naledi itself remains one of the strangest branches on the human family tree. Since 2013, when Lee Berger, a National Geographic explorer-in-residence leading the Rising Star project, and his team first began systematic excavations, nearly two dozen skeletons have emerged from the limestone. The species is a puzzle—small-brained and ancient, yet capable of walking upright with hands, legs, and feet that look surprisingly modern. Researchers have controversially suggested that these creatures may have used fire and deliberately placed their dead in the cave, practices we typically associate with much later, more cognitively advanced humans.
If the protein analysis holds up, the all-female sample opens a new interpretive door. Rather than random accumulation of bones, the cave could represent something intentional and culturally significant. Berger himself proposed that the pattern points to deliberate burial organized by sex—that Homo naledi may have selected and placed only females in this location as part of a meaningful social practice. John Hawks, a paleoanthropologist at the University of Wisconsin, Madison, and a co-author of the study, noted that many historical human societies practiced sex-specific burial rites. If Homo naledi did the same, these remains would predate any known burial site of Neanderthals or modern humans, pushing back the archaeological record of such behavior by hundreds of thousands of years.
The work also demonstrates something methodologically important: protein analysis can extract biological information from rare and fragile fossils without the destructive damage that older techniques required. As a bonus, the researchers identified a genetic variant shared between Homo naledi and Paranthropus robustus, another ancient human relative from the same region, hinting at evolutionary connections still poorly understood.
But experts are urging restraint. Elizabeth Sawchuk, curator of human evolution at the Cleveland Museum of Natural History, called the result intriguing but cautioned that it comes from an already enigmatic species. She emphasized a crucial logical point: the absence of male-linked proteins is not the same as proof that males were never present. They could have been buried elsewhere, or the sample could be skewed by chance. Homo naledi, she noted, continues to yield more questions than answers. Enrico Cappellini, a paleoproteomics professor at the University of Copenhagen and another study author, acknowledged that either explanation—whether the cave truly held only females or whether the pattern reflects something else entirely—would carry profound implications for understanding how this species lived and evolved. For now, the teeth have spoken, but the cave's full story remains locked away.
Notable Quotes
The fossils surprised us. Homo naledi has always been an enigmatic discovery.— Lee Berger, National Geographic explorer-in-residence leading the Rising Star project
The absence of male-linked evidence is not the same as proof that males were absent. Studies of Homo naledi continue to yield more questions than answers.— Elizabeth Sawchuk, curator of human evolution at the Cleveland Museum of Natural History
The Hearth Conversation Another angle on the story
Why does it matter if all these skeletons are female? What changes if that's true?
It suggests the cave wasn't just a dumping ground for bodies. If only females were placed there deliberately, it means Homo naledi had social practices—they were making choices about death and burial based on who someone was. That's a kind of cultural behavior we didn't think they were capable of.
But couldn't the females just have died there by accident? Why assume intention?
Fair question. That's exactly what the skeptics are saying. But if you find only females across multiple individuals, accident becomes less likely. Intention starts to look plausible. The researchers think it's worth taking seriously.
This protein test—how does it work without destroying the fossils?
They're reading the chemistry locked inside the tooth enamel itself. Instead of breaking the bone apart, they're reading what's already there. It's like reading a book instead of burning it for warmth.
What's the strangest part of Homo naledi to you?
That it exists at all. Small brain, ancient, but hands and feet that look almost modern. And possibly burying its dead. It's like evolution was experimenting with different combinations, and this one doesn't fit our usual story.
So what happens next? Do we just wait for more teeth?
We need more samples, ideally from other sites. And we need to be honest about what we don't know. Right now, this finding is a door opening. Whether it leads somewhere depends on what we find next.