Britain's earliest Homo sapiens fossil may have been misdated by preservation adhesive
This jaw bone excavated in 1927 was dated to 35,000 years ago, but preservation adhesive can distort radiocarbon dating, and researchers believe the actual age should be earlier.
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One cavern stacks half a million years of three human species
In the deepest stratigraphic layer (breccia layer) of Kent's Cavern are fossils of extinct cave bears and hand axes thought to have been made by Homo heidelbergensis—an extinct human species—dating back roughly 500,000 years ago. Neanderthals later used this cavern, and then Homo sapiens after them, which is why it's called ‘Britain's First Home’: few sites simultaneously record the activity of three different human species at a single location.
— Helen FulasA 150-year-old indexing system still points the way today
Nineteenth-century archaeologists typically excavated caves by taking only the fossils they wanted without recording provenance, and much material was simply discarded. William Pengelly was an exception: he spent 15 years systematically excavating the entire cavern and invented the ‘prism system’—dividing the excavation area into small blocks one yard long, one foot wide, and one foot deep, recording finds from each block by number. 150 years later, the team used his numbering to locate in the Torquay Museum the precise position of the stone tools originally excavated, and this determined where they placed their current excavation squares.
— Helen FulasPreservation adhesive on the fossil surface may have misdated it
The KC4 jaw bone fossil was directly radiocarbon dated in the 1980s, yielding a date of roughly 35,000 years ago, which temporarily made it the oldest known Homo sapiens fossil in Britain. But it was later discovered that the fossil's surface was covered with adhesive used for preservation, and radiocarbon dating distorts if it encounters contamination. Helen believes the true age should be earlier than 35,000 years; a team once dated the stone tools from the layers above and below, calculating roughly 42,000 years, but whether this method applies to this site remains contested in the field.
— Helen FulasA German site reassigned these stone tools from Neanderthals to humans
LRJ is a class of leaf-shaped stone points (leaf points) spanning 1500 kilometers from Britain to Poland, long regarded as the signature tool of Europe's last Neanderthals. But when the team re-excavated the Ranis site in Germany, they found that the remains found in layers with similar LRJ stone points were Homo sapiens, not Neanderthals, and dating showed Homo sapiens was already present north of the Alps in Europe as early as 45,000 years ago. Kent's Cavern is precisely the type site for British LRJ stone points, where about 10 specimens have been found, and this new excavation aims to test whether the same conclusion applies here.
— Helen FulasWhen Homo sapiens arrived, you could walk from Britain to France
Helen points out that when Homo sapiens arrived in Britain, the English Channel was still dry land—Britain was connected to the European continent, and people could walk directly from Britain to France. This meant Britain was not peripheral but part of the European continent extending northwest, which explains why the same LRJ stone points appear simultaneously in Britain and Poland 1500 kilometers away—these people were likely hunters migrating along this landmass, following game.
— Helen FulasBone fragments invisible to the naked eye can now be identified in the lab
Bone in the archaeological record readily weathers and fractures, which is why only a handful of sites have preserved human remains from this transitional period. Helen explains that the team now has biomolecular techniques that can identify whether even bone fragments too small for naked-eye species identification came from humans, and can perform DNA analysis and dating. This means there may have been more early Homo sapiens bone fragments in the past that were overlooked because they were too small and inconspicuous, mistaken for ordinary bone fragments.
— Helen FulasA newly discovered cave opening may be the true source of this fossil
The KC4 fossil and the surrounding Neanderthal and Homo sapiens stone tools were all excavated in the vestibule area near the cavern entrance, but it was previously unclear where exactly these materials washed in from. About ten years ago, John and Rob discovered a previously unknown and undisturbed cave opening near the vestibule. Helen plans to return to this ‘Northeast Gallery’in future seasons and screen-wash the spoil heaps piled aside after the Torquay Natural History Society's original excavation, hoping to find unrecovered remains in this new entrance's deposit—quite possibly the true source of the KC4 materials.
— Helen FulasIn their own words · checked verbatim
So he called it the most fossiliferous place in the cave.
Helen Fulas5:09
The fossil was directly radiocarbon dated in the 1980s to about 35,000 years old, which made it the oldest Homo sapiens we have. But now we know that with radiocarbon dating, if you have any contamination on the fossil, it can make your dates incorrect.
Helen Fulas15:21
So it's quite common that curators or excavators would try to preserve fossils, important fossils, by gluing them or adding consolidants to them to try to preserve them. But it means that with a lot of the modern methods that we use today, it introduces contamination.
Helen Fulas16:22
So they are very long, beautiful glades. And it's thought that they were used on the ends of spears and that the LRJ sites that we found are kind of short term hunting camps
Helen Fulas20:34
So we actually had evidence of Homo sapiens in Europe, north of the Alps, before 45,000 years ago.
Helen Fulas21:37
the UK would have actually been attached to the continent and you would have been able to walk from Britain over to France.
Helen Fulas26:48
We have recently found evidence for a previously undiscovered entrance, which is very close to the vestibule, which is potentially the source of all of the artifacts and fossils which were found in the vestibule.
Helen Fulas50:54
Figures
| Pengelly's systematic excavation duration | 15 years | 11:13 |
| LRJ stone tool distribution range | 1500 kilometers (Britain to Poland) | 19:28 |
| KC4 fossil discovery date | March 14, 1927 | 13:16 |
Glossary
- LRJ (Lincombeian-Ranisian-Jerzmanowician)
- A class of leaf-shaped stone point assemblages distributed from Britain to Poland.
- Leaf points
- Long leaf-shaped stone hunting tools fitted to spearheads.
- Marine isotope stage 3 (MIS3)
- A glacial period climate phase roughly 60,000 to 27,000 years ago.
- Prism system
- Pengelly's excavation method of recording finds by number from fixed-size small excavation blocks.
- Aurignacian
- A stone and bone tool culture long regarded as the marker of early Homo sapiens' entry into Europe.
How to listen
Listeners interested in British Paleolithic archaeology and the replacement of Neanderthals by Homo sapiens, especially those concerned with excavation details and dating method controversies.
The segment between 32:02 and 35:10 about subscription services and gossip over Alexander's successors is unrelated to this episode's subject and can be skipped.