PEmbroke Castle has been a seat of power for centuries. It was the birthplace of Henry Tudor, father of Henry VIII, and is one of the country’s best-preserved medieval fortresses, with a maze of passages, tunnels and staircases, as well as a large gatehouse tower. Scientists have discovered that the fortress also hides a surprising secret. A cave known as Wogan Cavern, which lies directly below Pembroke Castle, has been found to contain a treasure trove of prehistoric material, including ancient bones and stone tools left behind by early Homo sapiens and possibly by Neanderthals.
These remains will provide key information about the settlement of Britain in prehistoric times, say scientists, who began their first major excavation of the year at Wogan last week. Work at the site over the coming years should provide answers to major mysteries about prehistoric Britain, including the end of Neanderthal occupation around 40,000 years ago.
Early finds at Wogan include a wide range of fossils, including mammoth, reindeer and woolly rhinoceros, as well as the remains of a manatee, a species that last roamed British waters 125,000 years ago. Archaeologists also found that much of the cave’s floor was covered with a layer of stalagmite that preserved the soil, bones, proteins and DNA that lay beneath.
“The site has fantastic potential,” said Prof Chris Stringer of the Natural History Museum, London. “This is the best prospect we have of providing fresh material that can help us find out how Neanderthals lived in Britain and find out how they were replaced by Homo sapiens.”
One of the issues scientists are trying to resolve is whether or not Neanderthals interbred with Homo sapiens in Britain, as they did in other parts of the world. For good measure, they also want to know if the two species lived side by side or if they replaced each other in successive waves. “Wogan Cavern offers us the prospect of finding material that will give us clear answers to these questions,” Stringer added.
The leader of the excavation, Dr Rob Dinnis from Aberdeen University, said: “We have already shown that preserved layers of bone, stone tools, DNA and other material dating back at least 40,000 years lie beneath Pembroke Castle, while the hippopotamus remains we found suggest. we might push it back to 125,000 years. If so, it is the perfect source to study the transition between Neanderthals and modern humans which probably took place in Britain around 45,000 years ago.”
Over the past few decades, scientists have struggled to explore this interesting aspect of the settlement of Britain because they have faced a critical problem affecting many large prehistoric sites in the UK. In many cases, they have been stripped of all their sediment, rocks and other materials and therefore cannot be studied using the armory of modern technologies that scientists developed in the 20th century.
“In the past, when Victorian or Edwardian archaeologists found remains of Neanderthal or early Homo sapiens at a site, it was usually cleaned of all the sediment and bones it contained,” Dinnis said. “Every last piece of archaeological material was either collected or, even worse, thrown away. This has made modern research at these sites very difficult.”
A classic example of this fossil scavenging is provided by Gough’s Cave, in Cheddar Gorge, where the remains of several ancient people were excavated in Victorian times before the cave was stripped of all its sediment. “More than 500 tons were cleared in a few weeks at the end of the 19th century because the owners of the cave were interested in exposing the stalagmite formations there and therefore turning it into a tourist attraction,” said Stringer.
“They just walked out with wheelbarrows full of stuff and no one knows where they threw it. It was a tragic waste of critically important material that we could still exploit today – if only we knew where it was thrown away.”
Other sites that yielded evidence of ancient occupation but were subsequently emptied include Kents Cavern, in Devon, and Paviland Cave Wales. However, such a fate did not befall Wogan Cavern, archaeologists say. In the Middle Ages it was walled off and used as a storeroom for Pembroke Castle. Much of its floor has remained intact since then, and many of the wonders that lie beneath are believed to have been left undisturbed.
Such pristine preservation would leave any finds made in Wogan Cavern ripe for exploitation using the tools of modern archeology and palaeontology. The technology of sediment DNA analysis looks particularly promising. This can be used to determine whether an individual once lived or worked at a site simply from the genetic material they left behind in the sediment there.
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The technique was developed several years ago by scientists based at Germany’s Max Planck Institute for Evolutionary Anthropology and has already demonstrated his striking sensitivity in a cave system known as Galería de las Estatuas, in northern Spain. Each layer of sediment in the cave system was previously analyzed and precisely dated. Then, using sediment DNA analysis, researchers found that, about 100,000 years ago, the population of Neanderthals that had been living in the cave for thousands of years was displaced by an entirely different group of Neanderthals.
It is unclear why this replacement occurred, but the discovery clearly demonstrates the power of modern genetic analysis which, using DNA from blood and faeces left behind by cave dwellers, has made it possible to trace population movements 100,000 years later to disclose. The hope for Wogan Cavern is that similar analysis will shed light on the interaction of modern humans and Neanderthals in our prehistoric past – simply from the sediments in which they left their DNA.
“This technology means you don’t even have to find bones,” Dinnis added. “If you can only find DNA in samples you take from an archaeological layer that is accurately dated, then you will find out who lived there and get a picture of when the cave was occupied and, more importantly, by whom it was occupied. is .
“We want to know the process of Neanderthal replacement that took place in Britain much better than we do now. Our understanding of it in this corner of Europe is much worse than elsewhere. This is partly due to the fact that we weeded out our best sites over a century ago. The crucial point is that Wogan Cavern should give us the chance to put it right.”
Stringer agrees. “Britain at this time was right on the western edge of the inhabited world. So you’re really looking at individuals struggling to survive on the edge of existence, both Neanderthals and Homo sapiens. It’s a fascinating period and we want to learn a lot more about it.”
