Broken Hill mine, Kabwe, Zambia
The Kabwe skull
About 299,000 years (a best estimate on a skull from a mine that is gone)
In 1921, during lead and zinc mining at Broken Hill, now Kabwe, miners recovered a skull that was named as its own species and later folded, often, into Homo heidelbergensis. For decades it was estimated at about 500,000 years by comparison with other sites, because the cave was dug away. Direct dating on the bone itself gives a best age of 299,000 years, plus or minus 25,000. That puts it in Africa at the same time as early members of our species, and the ancestor story gets harder.
Why this is extraordinary
In 1921, miners taking lead and zinc out of a cave at Broken Hill, the place now called Kabwe, brought up a skull. It was the first fossil of an extinct human species to be found in Africa, and it was given its own name, Homo rhodesiensis. Look at the cast and the brows are a shelf, the nose is broad, the vault is long and not the high rounded shape of a modern head. The brain inside a reconstruction of this skull is about 1,300 cubic centimetres, inside the living human range, on a face that is not ours. Ten of the upper teeth had cavities. The face is flatter than the older erectus face. That mix is why many researchers stopped using the 1921 name and put the skull with Homo heidelbergensis, a species also known from Europe. Others keep rhodesiensis, because this skull is the specimen the name is tied to. Both names are in print.
The year was the harder problem. The cave was quarried away, so nobody can go back to the layer. Comparison with other fossils suggested about 500,000 years, and that figure lasted for decades. In 2020 a direct analysis of the bone, using uranium that seeps into a buried skull, produced a best estimate of 299,000 years, plus or minus 25,000, which is to say about 274,000 to 324,000. The catch is in the words “best estimate.” Uranium does not enter every bone on a schedule the lab can see, and an unsystematic find in a mine is not a skeleton drawn on a section. The paper says so. The older half-million was a comparison precisely because the section was already gone.
Set 299,000 beside the early Homo sapiens fossils, including the ones at Jebel Irhoud, and this heavy-browed person is not a grandparent who had left the stage. He, or a close relative, is still in Africa while people with our kind of face are already here. Homo naledi is in that same crowded picture. A neighbour can still be an ancestor. What the young date removes is the tidy version in which one species ends and the next begins. There is no sky in this room. A skull in a lead mine has no star lore attached to it.
A third name is now in print beside the 1921 name and Homo heidelbergensis. A proposal first published in 2021 argues for Homo bodoensis, framed on a different skull, the Bodo skull, which it names as the type. It places the Kabwe skull in that group and suggests it could be a late survivor, and it asks that both older names be set aside. This skull is not the type of that proposed species. A reply argues that the 1921 name is the one tied to this skull and that the naming rules do not drop it. A further reply from the proposal argues that the new name should still stand. A visitor choosing a label has three published choices, and the uranium catch already in this room is untouched by the name.
The photograph is a cast, and the pale area on the top of the head is the cast’s surface, not a patch to be read as anatomy of the original. What this changes: if 299,000 years holds, Kabwe is late, and the human story in Africa at that time is several lineages at once. If the uranium model has made the skull too young, the older comparative age comes back into the argument, and an ancestral place with it. The wooden joint at Kalambo Falls is a different river and a different question, and no bone there names a species.
Why it matters
A 500,000-year-old heidelbergensis can sit on the line that leads to us. A 300,000-year-old skull with a heavy brow, alive beside early Homo sapiens, is a neighbour, and maybe not a parent. The mine is gone, so the layer that would settle the company it kept is gone too.
The skull is one of the best preserved of any fossil hominin from Africa. It was given the name Homo rhodesiensis. Many researchers now place it in Homo heidelbergensis. The braincase is low, the brows are large, and there is a torus at the back of the skull, traits shared with Homo erectus. The face is flatter than an erectus face, and the brain is given as about 1,300 cubic centimetres. Ten of the upper teeth have cavities. The 2020 study dated the skull directly and reports a best estimate of 299,000 years, mean plus or minus 25,000 at two standard deviations, so about 274,000 to 324,000. The paper is plain that recovery was unsystematic and that the quarry has destroyed the site, which is why a sealed-layer date was never possible. The older figure of about 500,000 years was a comparison, not a measurement on this bone. The young date is used to argue that late Middle Pleistocene Africa held more than one kind of human at once, including early Homo sapiens and Homo naledi, and to ask whether heidelbergensis, or rhodesiensis, was a direct ancestor. No sky lore attaches to a skull from a mine.
Photo tour
1 photograph, unedited. On a phone, swipe the row. Choose one to look closely.
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- The original skull is not the photograph. The cast shows the heavy brow and the worn teeth. It does not show the quarry.
What is still unexplained
These sit beside the consensus account, with the same visual weight. None of them is marked solved.
Location and dating
- Location
- The Broken Hill lead and zinc mine at Kabwe, Central Province, Zambia. The pin is the town, 14.443 south, 28.447 east. The cave inside the mine has been quarried away. The photograph is a cast.
- Period label
- Current consensus — open to revision Best estimate 299,000 years, plus or minus 25,000, from direct dating. The older estimate of about 500,000 years is the comparative age. Middle Pleistocene either way.
- How this dating was done
- Uranium-series isotopes in the skull, cross-checked with other materials from the old collections. Not radiocarbon. The 500,000-year figure was anatomical and faunal comparison, which the destruction of the site had forced.
- What could change it
- The 2020 measurement is already the change, from about 500,000 to about 299,000. A further change would be a different uranium-uptake model that moves the same measurements, or a fossil from an intact Zambian cave of one of the two ages.
What is actually there
- The skull was found in 1921 in a mine and named Homo rhodesiensis.
- It is often placed in Homo heidelbergensis.
- A 2021 proposal adds Homo bodoensis, typed on the Bodo skull, with this skull as a possible late member, and a reply keeps the 1921 name under the naming rules.
- Brain size is about 1,300 cubic centimetres. Ten upper teeth are cavitied.
- Direct dating gives 299,000 ± 25,000 years. The older estimate was about 500,000.
- The cave no longer exists.
- The photograph is a cast. No sky reading belongs to the skull.
Open questions
| Question | Status |
|---|---|
| Is 299,000 years the age of the person? | Open. It is the best direct estimate. The destroyed site and the uranium model are the catches. |
| Is this a parent of Homo sapiens or a contemporary? | Open. The young date puts the skull beside early members of our species. Ancestry is not ruled out. A single line is. The label is also open, the 1921 name, Homo heidelbergensis, or Homo bodoensis. |
The current narrative
Where publication stands today. It is the best-supported reading, and it is open to revision. It is not a verdict.
The current narrative — open to revision
A late contemporary, not a simple ancestor
Kabwe 1 died about 299,000 years ago and belongs with Homo heidelbergensis or Homo rhodesiensis, a kind of human still present while early Homo sapiens were already in Africa.
What supports this
- The 2020 direct date is a measurement on the skull, 299,000 ± 25,000 years.
- That window overlaps the ages published for early Homo sapiens and for Homo naledi.
- The brow, the low vault, and the 1,300-cubic-centimetre brain are the mix the species names were built to hold.
What pushes back
- The site is destroyed, so the skull’s companions are not a recorded layer.
- Uranium uptake can move a bone date. The paper calls its result a best estimate for that reason.
- A comparative age near 500,000 years is still in the older literature and would restore a simpler ancestral place.
- A 2021 proposal asks that both Homo heidelbergensis and the 1921 name be set aside, in favour of Homo bodoensis, typed on the Bodo skull.
What would settle it
The 2020 study’s direct estimate and the older comparative age are both published. The overlap with early Homo sapiens is what that direct estimate does, on the uptake model the study uses. The name is a separate choice, and this room does not make it.
Emerging narratives
Other published readings. Each may be right. None is adopted here unless the evidence carries it.
An emerging narrative
An older ancestor near 500,000 years
The skull is closer to half a million years old, and under the name heidelbergensis it remains a plausible ancestor of later humans.
What supports this
- For decades the comparative age, about 500,000 years, was the working figure, tied to similar fossils.
- An ancestral role is easier if the skull dies out before early Homo sapiens are well established.
- Unsystematic mining really did make a layer date impossible, which is why comparison was used.
What pushes back
- The 2020 study dated the bone, not a lookalike.
- 274,000 to 324,000 years does not reach 500,000.
- Even an older skull can be a cousin. Age alone does not draw the family tree.
What would settle it
It stays because half a million years was the published estimate for most of the skull’s career, and the destroyed cave is a real limit. It is not the centre once a direct estimate exists and is centuries younger.
An emerging narrative
A third name, typed on another skull
A proposal first published in 2021 argues for a third name, Homo bodoensis, framed on the Bodo skull. It places the Kabwe skull in that group as a possible late survivor, and it asks that both the 1921 name and Homo heidelbergensis be set aside. This skull is not the type.
What supports this
- The proposal names the Bodo skull as the type, and lists the Kabwe skull among the other specimens, not as the specimen the name is anchored to.
- It argues that both older names fail to hold the variety it wants the new name to cover, and it suggests this skull could be a late survivor of that group.
- A later reply from the same proposal argues that the new name should still stand.
What pushes back
- A reply argues that the 1921 name is the one tied to this skull, and that the naming rules do not drop it.
- That reply treats the new name as another label for a group that already has the 1921 name, because this skull sits inside the group.
- The uranium estimate, 299,000 ± 25,000 years, is a date. It does not choose a Latin name.
What would settle it
Three published names remain, the 1921 name, Homo heidelbergensis, and Homo bodoensis. This room does not choose one.
Should the current view be reevaluated?
Open to revision
The best direct age in the 2020 study is 299,000 ± 25,000 years, and three published names sit beside it: the 1921 name, Homo heidelbergensis, and Homo bodoensis. The missing cave keeps a residue of doubt on the company the skull kept. The older comparative age remains a published reading. None of these closes the others.
What drives this
- A direct date of 299,000 ± 25,000 years against a comparative 500,000.
- A destroyed context.
- Three published names, the 1921 name, Homo heidelbergensis, and Homo bodoensis, and a possible overlap with early Homo sapiens.
This is the museum’s own weighing of the evidence. It is not a visitor vote, and it is separate from the slider.
Weigh it yourself
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If the contested reading is right
What would follow if a reading that is not the consensus turned out to be true, and what could settle it. This explains the stakes. It does not adopt the reading.
A 299,000-year-old contemporary of early Homo sapiens
Late Middle Pleistocene Africa would hold several human lineages at once, and this skull would not be a straightforward parent of people like those at Jebel Irhoud.
Why it is still worth a test
An agreed uranium-uptake model, and any surviving notes that place the skull in a bed with dated animals.
The label is Homo bodoensis, with this skull as a late member
The 1921 name and Homo heidelbergensis would be the names a proposal asks the field to set aside. The type would be the Bodo skull, not this one. The 299,000-year estimate would still be a date, not a name.
Why it is still worth a test
A published ruling on whether the naming rules keep the 1921 name, which is the question the reply already puts.
Sources
- Dating the skull from Broken Hill Nature, 2020, 299,000 ± 25,000 years
- Kabwe 1 Smithsonian Human Origins, brain size and the older species discussion
- The case for Homo bodoensis Evolutionary Anthropology, first published 2021. Proposes a third name, typed on the Bodo skull, and places this skull in the group as a possible late survivor.
- A reply on the naming rules Evolutionary Anthropology, 2022. Argues that the 1921 name is the one tied to this skull and that the naming rules do not drop it.
- Homo bodoensis and why it matters Evolutionary Anthropology, 2022. The proposal’s further reply, arguing that the new name should still stand.
- Nomenclatural note on Homo bodoensis A priority note. Records the Bodo skull as the type, this skull as a member of the group, and the reply that the 1921 name is not dropped by the rules.
Image credits
- A cast of Kabwe 1, the Broken Hill skull. The original is not this object. The pale cap is on the cast. The mine where the skull was found has been quarried away. . Gerbil, CC BY-SA 3.0. Shown unedited.