All 23 Homo naledi Skeletons Are Female — and That Changes Everything

TL;DR

• The finding: Proteomic analysis of 23 Homo naledi teeth from South Africa's Rising Star Cave found zero male markers. Every individual — from infants to elders — is female.
• The technique: First-ever paleoproteomic sex determination of this species, using amelogenin proteins preserved in tooth enamel. Ancient DNA had degraded beyond recovery in the African heat; proteins survived.
• The odds: The probability of 20+ individuals all being female by chance is roughly 0.000095% — the equivalent of flipping a coin and getting the same side 20 times in a row.
• The implication: The most parsimonious explanation is deliberate, sex-segregated mortuary practice — burial — by a hominin with a brain the size of a chimpanzee's.
• The paper: Madupe, Cappellini, Hawks, Berger et al., Cell, 24 June 2026. DOI: 10.1016/j.cell.2026.05.044.

What Happened

In 2013, a team led by paleoanthropologist Lee Berger pulled more than 1,500 fossil bones from a narrow, twisting chamber deep inside South Africa's Rising Star Cave system. The bones belonged to a species nobody had seen before: Homo naledi, a small-bodied hominin with a puzzling mosaic of features — human-like hands and feet, an ape-like torso, and a brain no bigger than a chimpanzee's. The fossils dated to between 335,000 and 236,000 years ago, meaning Homo naledi walked the Earth at the same time as early Homo sapiens.

From the beginning, the site was strange. The Dinaledi Chamber was nearly inaccessible — a vertical shaft so tight that Berger had to recruit a team of slender cavers to squeeze through. There were almost no other animal bones in the chamber. No signs of predation. No evidence of water transport. Just Homo naledi, in extraordinary numbers: at least 20 individuals, from newborns to the elderly.

Berger proposed something radical: Homo naledi had deliberately placed its dead there. A burial chamber, built by a creature with a brain a third the size of ours.

The field pushed back. Hard. Critics argued the bones could have washed in, or that the hominins could have been dragged there by carnivores, or that they simply got lost and died. The debate has been running for over a decade.

Now a team led by Palesa Madupe — a South African-born molecular scientist at the Max Planck Institute for Evolutionary Anthropology — has produced a finding that reshapes the argument entirely.

They extracted ancient proteins from the tooth enamel of 23 Homo naledi teeth, representing at least 20 different individuals across four separate chambers in the cave system. They searched for amelogenin-Y (AMELY), a protein encoded exclusively on the male Y chromosome. In a mixed-sex population, you would expect to find it in roughly half the samples.

They found it in none of them.

Every individual — every infant, every juvenile, every adult — carried only AMELX, the X-chromosome variant. All of them were female.

What It Actually Means

The statistical case is overwhelming. The probability of sampling 20 individuals from a 50/50 population and getting all females is 0.000095% — one in roughly a million. As University of Wisconsin paleoanthropologist John Hawks, a co-author of the study, told Ars Technica: "It's like, there is no other process that can make this happen."

There are only two plausible explanations, and both are extraordinary.

Explanation one: deliberate sex-segregated burial. Homo naledi placed its female dead in the Rising Star chambers as part of a cultural practice. The males are somewhere else — perhaps in another chamber not yet discovered, or at another site entirely. This would make Rising Star the first known sex-specific mortuary site created by a non-human species.

Explanation two: a population-wide deletion of the AMELY gene. In rare cases, the gene that codes for AMELY can be deleted from the Y chromosome. This has been documented in modern humans and in at least one Neanderthal male. But for it to affect every male in a population — or even half the 20 individuals tested — would be, as co-author Enrico Cappellini put it, "very unlikely."

The team ran the numbers. The AMELY-deletion scenario doesn't hold statistically. The burial scenario does.

"This was no longer chance, at this point," Berger told Ars Technica.

The Collateral Damage to Existing Theory

The finding doesn't just strengthen the burial hypothesis. It quietly demolishes something else: the assumption that Homo naledi was the least sexually dimorphic hominin ever discovered.

When Berger's team first described the species, they noted that all the skeletons looked remarkably similar in size and build. In most apes — gorillas, for instance — males and females are dramatically different in size. The researchers assumed Homo naledi simply had unusually low sexual dimorphism.

Now we know the real reason: they were all the same sex. We have never seen a male Homo naledi. Everything we think we know about the species' body proportions, its brain size, its skeletal variation — all of it is drawn exclusively from females.

As Hawks noted, it's possible that male Homo naledi fossils already exist in museum collections, misclassified because they don't match the small-bodied female template. "If the males are much larger, differently developed, we don't know that we don't already have a male that we haven't recognized as Homo naledi," he said.

The Deeper Question

The burial debate isn't really about bones. It's about what we're willing to grant to minds that aren't ours.

Homo naledi had a brain volume of roughly 460–560 cubic centimetres — about the size of a chimpanzee's, and roughly a third of the modern human average. For decades, the dominant assumption in paleoanthropology has been that complex cultural behaviours — burial, art, symbolic thought — require large, human-like brains. Homo naledi keeps breaking that assumption.

In 2023, Berger, Hawks, and colleagues published evidence that Homo naledi used fire to navigate the cave system and carved abstract engravings — crosshatch patterns and geometric shapes — into the chamber walls. Those claims were fiercely contested. The all-female finding adds a new layer of evidence that is harder to dismiss: a statistical signal so strong it essentially forces the conclusion that something deliberate was happening in that cave.

As Berger reflected on the engravings: "Those symbols weren't meant for us. Whatever they're meant for, it certainly wasn't for a Homo sapiens. They were meant either for them to come back to, their descendants to come back to, or some other purpose, but they weren't meant for us."

Hype Deconstruction

This is not evidence that Homo naledi was a single-sex species. Males existed — they had to, for the species to persist for hundreds of thousands of years. The question is where they are, and why they were treated differently in death.

This is also not the first claim of non-human burial. Neanderthals buried their dead — that case is now broadly accepted. What makes Homo naledi different is the brain size. If a creature with a chimp-sized brain practised sex-segregated mortuary ritual, then the relationship between brain volume and cultural complexity needs to be rethought from the ground up.

And a note of caution: the AMELY-deletion hypothesis, while statistically unlikely, is not impossible. Elizabeth Sawchuk, curator of human evolution at the Cleveland Museum of Natural History (who was not involved in the study), noted that the absence of AMELY protein does not definitively prove the absence of males. The team acknowledges this. But the weight of probability sits firmly on the side of deliberate burial.

Stakeholder Landscape

Cross-Layer Implications

For paleoproteomics: This study is a proof of concept. Ancient DNA degrades rapidly in warm climates — most African hominin fossils older than ~10,000 years have yielded no usable DNA. But tooth enamel proteins can survive for millions of years. Madupe's team has opened a door to genetic-style analysis of species that were previously molecularly inaccessible, including Australopithecus, Paranthropus, and early Homo.

For the philosophy of mind: If Homo naledi — with its chimp-sized brain — practised burial, used fire, and carved symbols, then what exactly is the relationship between brain volume and cognition? The question is no longer whether non-human hominins had culture. It's how many of them did, and how far back it goes.

For excavation ethics: Berger told Ars Technica that the protein results prompted his team to pause excavations at Rising Star. "It certainly will mean we have to stop digging hominins like dinosaurs," he said. "I think that we have the responsibility to be respectful, but we also have a responsibility to also be real. This is more like a Star Trek episode, you know? I know what we do if it's a human culture, but it isn't one." The ethical framework for excavating a non-human but clearly cultured species does not yet exist.

For the human origins narrative: The story of human evolution has been steadily decentralising Homo sapiens. Neanderthals made art. Denisovans interbred with multiple hominin lineages. Now Homo naledi — a species that wasn't even on the radar until 2013 — appears to have practised ritualised mortuary behaviour hundreds of thousands of years ago. The idea that modern humans invented culture is looking less like a scientific conclusion and more like a story we told ourselves.

What This Means for You

If you're a scientist or student in paleoanthropology, archaeology, or evolutionary biology: Watch the paleoproteomics space. The technique Madupe's team used — minimally destructive acid etching followed by mass spectrometry — is now validated on a large hominin sample. The same approach can be applied to other sites. The protein variants the team found (including one shared with Paranthropus robustus and one apparently unique to Homo naledi) suggest that proteomics may eventually help build a molecular family tree for hominins — something that has been impossible for African fossils until now.

If you're a science-interested reader: This is one of those rare moments where a single study meaningfully shifts a long-running debate. The burial hypothesis for Homo naledi has been controversial for a decade. The all-female finding doesn't settle it — science rarely settles anything in one paper — but it makes the sceptical position considerably harder to maintain. If you've been following the Rising Star story, this is the most significant development since the species was first described in 2015.

If you're simply curious about what it means to be human: The boundary between "us" and "them" keeps getting thinner. A species with a brain the size of a chimpanzee's appears to have treated its dead with intention, perhaps even with something resembling ritual. Whatever Homo naledi was doing in that cave, it wasn't random. And that should make us a little less certain about what makes us special.

Uncertainty Ledger

Bottom Line

Twenty-three teeth. Twenty individuals. Zero males. The numbers don't lie, and they don't leave much room for coincidence. The most likely explanation is that Homo naledi — a small-brained hominin that lived 300,000 years ago in what is now South Africa — deliberately placed its female dead in the deepest chamber of the Rising Star cave system. If that's true, then complex mortuary behaviour is not a Homo sapiens invention. It's older, stranger, and more widely shared across the hominin family tree than we ever imagined. The question is no longer whether other species had culture. It's how many of them did — and what else we've been wrong about.

Sources: Ars Technica (Tier 2), CNN (Tier 2), New Scientist (Tier 2), Live Science (Tier 2), Archaeology News Online Magazine (Tier 2), Daily Maverick (Tier 2), Technology Networks (Tier 2), Times of India (Tier 3), Cell (Madupe et al., 2026, DOI: 10.1016/j.cell.2026.05.044) (Tier 1)