Zambia has an incredibly rich archaeological record, that spans a huge amount of human history. There are several sites from the African Iron Age that have been important for understanding the spread of metal working in Africa, but probably most exciting is the globally famous fossil finds from Kabwe mine, once known as ‘Broken Hill’.
What makes the site so important is the discovery, in 1921, of a fossil of what looked like a human skull. It was found by a Swiss miner that was overseeing operations in the area, and whilst it’s likely that he and the other miners didn’t think much of the find at the time, they still had the good sense to report it to the mine manager.
It was thought the skull was probably of significant age, so it was sent to the British Museum in London to be analysed. It was there discovered that the skull was not of a modern human, but probably represented an earlier form, possibly ancestral, of our own species.
However, there are many problems with the physical context of the skull in the ground. Usually archaeologists can infer a lot about the relative age of fossils if they’re found in the ground in a specific layer of earth. For instance if the fossil was discovered in the same layer as extinct animals, we know it can’t be modern. But because the skull was found in an unstratified cave deposit, archaeologists were unable to give it a relative date.
Prior to this, during another mining operation in 1907, miners stumbled across another cave in which they found lots of fossilised bones and stone tools, but no human fossils. This cave was quite close to the one that the Kabwe Cranium was later found in, which has led some people to infer that the humans whose remains were represented by the cranium were making these tools. This can never be proven, however, because the tools were not found in association with the cranium.
The cranium, meanwhile, was originally designated as the species Homo rhodesiensis, but more recent analyses have placed the individual remains within the species Homo heidelbergensis. Homo heidelbergensis is a really interesting species, because it is thought that this species is ancestral to both our own genus Homo sapiens, but also to our closest human (now extinct relatives) Homo neanderthalensis (Neanderthals).
So what we’re seeing at Kabwe is the probable remains of an individual who lived in the area, who was of the species Homo heidelbergensis, and whose relatives eventually evolved into our own species, somewhere in the region of East Africa, not too far away.
It is still one of the most important fossil specimens in the world, because there haven’t been many heidelbergensis finds in Africa, and if they were ancestral to Homo sapiens, we can begin to fill in the gaps in human evolution.
The skull was dated in 1974 to be approximately 110,000 years old, which would place it in the same time range as Homo sapiens, however the shape of the skull suggests it is of an earlier species. Additionally, the stone tools have been compared to similar findings at other sites in Zambia with a better stratigraphic record, such as Mumbwa caves, which would date them considerably earlier.
The cranium is currently in the process of being re-dated by a team based at the Natural History Museum in London. We hope this will shed new light on the age of the fossil, as well as any possible associations with their tool technology.
The Kabwe Cranium is hugely important for bettering our understanding of the evolution of our own species, and of the capabilities of Homo heidelbergensis, which may have been more complex that has been assumed in the past. Whilst archaeologists would have preferred that the skull be discovered in a stratified cave where they could excavate slowly and carefully, the skull may never have been found in the first place had it not been for the mining operations in Kabwe.
Sophie Flynn studies Paleaoanthropology and Palaeolithic Archaeology at University College London.