Evidence from archaeological sites in the medieval English city of Winchester shows that English red squirrels once served as an important host for Mycobacterium leprae strains that caused leprosy in people, researchers report May 3 in the journal Current Biology.
“With our genetic analysis we were able to identify red squirrels as the first ancient animal host of leprosy,” says senior author Verena Schuenemann of the University of Basel in Switzerland. “The medieval red squirrel strain we recovered is more closely related to medieval human strains from the same city than to strains isolated from infected modern red squirrels. Overall, our results point to an independent circulation of M. leprae strains between humans and red squirrels during the Medieval Period.”
“Our findings highlight the importance of involving archaeological material, in particular animal remains, into studying the long-term zoonotic potential of this disease, as only a direct comparison of ancient human and animal strains allows reconstructions of potential transmission events across time,” says Sarah Inskip of the University of Leicester, UK, a co-author on the study.
Leprosy is one of the oldest recorded diseases in human history and is still prevalent to this day in Asia, Africa, and South America. While scientists have traced the evolutionary history of the mycobacterium that causes it, they didn’t know how it may have spread to people from animals in the past beyond some hints that red squirrels in England may have served as a host.
In the new study, the researchers studied 25 human and 12 squirrel samples to look for M. leprae at two archaeological sites in Winchester. The city was well known for its leprosarium (a hospital for people with leprosy) and connections to the fur trade. In the Middle Ages, squirrel fur was widely used to trim and line garments. Many people also kept squirrels trapped wild squirrels as kits in the wild and raised them as pets.
The researchers sequenced and reconstructed four genomes representing medieval strains of M. leprae, including one from a red squirrel. An analysis to understand their relationships found that all of them belonged to a single branch on the M. leprae family tree. They also showed a close relationship between the squirrel strain and a newly constructed one isolated from the remains of a medieval person. They report that the medieval squirrel strain is more closely related to human strains from medieval Winchester than to modern squirrel strains from England, indicating that the infection was circulating between people and animals in the Middle Ages in a way that hadn’t been detected before.
“The history of leprosy is far more complex than previously thought,” Schuenemann said. “There has been no consideration of the role that animals might have played in the transmission and spread of the disease in the past, and as such, our understanding of leprosy’s history is incomplete until these hosts are considered. This finding is relevant to today as animal hosts are still not considered, even though they may be significant in terms of understanding the disease’s contemporary persistence despite attempts at eradication.”
“In the wake of COVID-19, animal hosts are now becoming a focus of attention for understanding disease appearance and persistence,” Inskip said. “Our research shows that there is a long history of zoonotic diseases, and they have had and continue to have a big impact on us.”
A new Netflix documentary has recreated the face of a 75,000-year-old female Neanderthal whose flattened skull was discovered and rebuilt from hundreds of bone fragments by a team of archaeologists and conservators led by the University of Cambridge.
The team excavated the female Neanderthal in 2018 from inside a cave in Iraqi Kurdistan where the species had repeatedly returned to lay their dead to rest. The cave was made famous by work in the late 1950s that unearthed several Neanderthals which appeared to have been buried in succession.
‘Secrets of the Neanderthals’, produced by BBC Studios Science Unit, is released on Netflix worldwide. The documentary follows the team led by the universities of Cambridge and Liverpool John Moores as they return to Shanidar Cave to continue excavations.
“The skulls of Neanderthals and humans look very different,” said Dr Emma Pomeroy, a palaeo-anthropologist from Cambridge’s Department of Archaeology, who features in the new film.
“Neanderthal skulls have huge brow ridges and lack chins, with a projecting midface that results in more prominent noses. But the recreated face suggests those differences were not so stark in life.
“It’s perhaps easier to see how interbreeding occurred between our species, to the extent that almost everyone alive today still has Neanderthal DNA.”
Neanderthals are thought to have died out around 40,000 years ago, and the discoveries of new remains are few and far between. The Neanderthal featured in the documentary is the first from the cave for over fifty years, and perhaps the best preserved individual to be found this century.
While earlier finds were numbered, this one is called Shanidar Z, although researchers think it may be the top half of an individual excavated in 1960.
The head had been crushed, possibly by rockfall, relatively soon after death – after the brain decomposed but before the cranium filled with dirt – and then compacted further by tens of thousands of years of sediment.
When archaeologists found it, the skull was flattened to around two centimetres thick.
The team carefully exposed the remains, including an articulated skeleton almost to the waist, and used a glue-like consolidant to strengthen the bones and surrounding sediment. They removed Shanidar Z in dozens of small foil-wrapped blocks from under seven and a half metres of soil and rock within the heart of the cave.
In the Cambridge lab, researchers took micro-CT scans of each block before gradually diluting the glue and using the scans to guide extraction of bone fragments. Lead conservator Dr Lucía López-Polín pieced over 200 bits of skull together freehand to return it to its original shape, including upper and lower jaws.
“Each skull fragment is gently cleaned while glue and consolidant are re-added to stabilise the bone, which can be very soft, similar in consistency to a biscuit dunked in tea,” said Pomeroy. “It’s like a high stakes 3D jigsaw puzzle. A single block can take over a fortnight to process.”
The team even referred to forensic science – studies on how bones shift after blunt force trauma and during decomposition – to help them understand if remains had been buried, and the ways in which teeth had pinged from jawbones.
The rebuilt skull was surface scanned and 3D-printed, forming the basis of a reconstructed head created by world-leading palaeoartists and identical twins Adrie and Alfons Kennis, who built up layers of fabricated muscle and skin to reveal a face.
New analysis strongly suggests that Shanidar Z was an older female, perhaps in her mid-forties according to researchers – a significant age to reach so deep in prehistory.
Without pelvic bones, the team relied on sequencing tooth enamel proteins to determine her sex. Teeth were also used to gauge her age through levels of wear and tear – with some front teeth worn down to the root. At around five feet tall, and with some of the smallest adult arm bones in the Neanderthal fossil record, her physique also implies a female.
While remnants of at least ten separate Neanderthals have now come from the cave, Shanidar Z is the fifth to be found in a cluster of bodies buried at a similar time in the same location: right behind a huge vertical rock, over two metres tall at the time, which sits in the centre of the cave.
The rock had come down from the ceiling long before the bodies were interred. Researchers say it may have served as a landmark for Neanderthals to identify a particular site for repeated burials.
“Neanderthals have had a bad press ever since the first ones were found over 150 years ago,” said Professor Graeme Barker from Cambridge’s McDonald Institute for Archaeological Research, who leads the excavations at the cave.
“Our discoveries show that the Shanidar Neanderthals may have been thinking about death and its aftermath in ways not so very different from their closest evolutionary cousins – ourselves.”
The other four bodies in the cluster were discovered by archaeologist Ralph Solecki in 1960. One was surrounded by clumps of ancient pollen. Solecki and pollen specialist Arlette Leroi-Gourhan argued the finds were evidence of funerary rituals where the deceased was laid to rest on a bed of flowers.
This archaeological work was among the first to suggest Neanderthals were far more sophisticated than the primitive creatures many had assumed, based on their stocky frames and ape-like brows.
Decades later, the Cambridge-led team retraced Solecki’s dig, aiming to use the latest techniques to retrieve more evidence for his contentious claims, as well as the environment and activities of the Neanderthals and later modern humans who lived there, when they uncovered Shanidar Z.
“Shanidar Cave was used first by Neanderthals and then by our own species, so it provides an ideal laboratory to tackle one of the biggest questions of human evolution,” said Barker.
“Why did Neanderthals disappear from the stage around the same time as Homo sapiens spread over regions where Neanderthals had lived successfully for almost half a million years?”
A study led by Professor Chris Hunt of Liverpool John Moores University now suggests the pollen was left by bees burrowing into the cave floor. However, remains from Shanidar Cave still show signs of an empathetic species. For example, one male had a paralysed arm, deafness and head trauma that likely rendered him partially blind, yet had lived a long time, so must have been cared for.
Site analysis suggests that Shanidar Z was laid to rest in a gully formed by running water that had been further hollowed out by hand to accommodate the body. Posture indicates she had been leant against the side, with her left hand curled under her head, and a rock behind the head like a small cushion, which may have been placed there.
While Shanidar Z was buried within a similar timeframe as other bodies in the cluster, researchers cannot say how contemporaneous they are, only that they all date to around 75,000 years ago.
In fact, while filming onsite for the new documentary in 2022, the team found remains of yet another individual in the same burial cluster, uncovering the left shoulder blade, some ribs and a fairly complete right hand.
Further research since Shanidar Z was found has detected microscopic traces of charred food in the soil around the older body cluster. These carbonised bits of wild seeds, nuts and grasses, suggest not only that Neanderthals prepared food – soaking and pounding pulses – and then cooked it, but did so in the presence of their dead.
“The body of Shanidar Z was within arm’s reach of living individuals cooking with fire and eating,” said Pomeroy. “For these Neanderthals, there does not appear to be that clear separation between life and death.”
“We can see that Neanderthals are coming back to one particular spot to bury their dead. This could be decades or even thousands of years apart. Is it just a coincidence, or is it intentional, and if so what brings them back?”
“As an older female, Shanidar Z would have been a repository of knowledge for her group, and here we are seventy-five thousand years later, learning from her still,” Pomeroy said.
New research led by the University of Sydney offers fresh understanding of the migration patterns of Australia and New Guinea’s First Peoples, and where they lived in the 40,000 years following humanity’s arrival on the then combined continent.
Using a dynamic model charting the changing landscape, researchers have provided a more realistic description of the of the areas inhabited by the first humans to traverse Sahul: the landmass combining what is now Australia, Tasmania and New Guinea.
Led by Associate Professor Tristan Salles from the School of Geosciences at the University of Sydney, the research model factors-in evolution of the landscape, driven by climate, during the time of human dispersal. This is a novel approach; previous studies of migration patterns have relied heavily on archaeological findings.
“One aspect overlooked when evaluating how people spread across the continent is the evolution of the Earth’s surface which took place as people migrated,” Associate Professor Salles said.
“Yet landscapes and landform are deeply engraved in Aboriginal culture.”
Humans first set foot on Sahul around 75,000 years ago. The research team used an established landscape evolution model detailing climatic evolution from 75,000 to 35,000 years ago. The model offers a fresh perspective on terrains and environments inhabited by the first hunter-gatherer communities as they traversed Sahul.
Researchers ran thousands of simulations to describe possible migration routes originating from two entry points into Sahul: a northern route through Western Papua and a southern route from the Timor Sea shelf.
Their results were consistent with previous findings, predicting a high likelihood of human occupation at already iconic archaeological sites such as: Ngarrabullgan Cave (in North Queensland), the Puritjarra rock shelter (Central Australia), and the Riwi Cave and Carpenter’s Gap 1 rock shelter in the Kimberley (Western Australia).
Results indicated migration speeds of between 360 metres and 1.15 kilometres a year, depending on entry points and arrival times. They also show that human settlers would have dispersed across the continental interior along river corridors on both sides of Lake Carpenteria.
“Our palaeoecological reconstructions show evidence of diverse interior habitats varying from high altitude tropical forest, subtropical savannah to semiarid woodland and grassland,” Associate Professor Salles said.
Instead of finding well-defined migration routes (indicated by the grey lines on the below map), the research suggests a radiating wave of migration following rivers and coastlines. This correlates with known migration corridors: east of Lake Carpentaria following the Great Dividing Range; southern corridors connecting Lake Eyre to the eastern corridors; and the central super-highways transecting Australia’s arid interior.
Used in conjunction with mechanistic simulations, the findings could help evaluate how often a specific location is likely to have been visited.
“This could help identify new areas of archaeological interest as a precursor to more costly and time-consuming archaeological surveys,” Associate Professor Salles said.
RESEARCH
Salles, T. et al. ‘Physiography, foraging mobility and the first peopling of Sahul’. Nature Communications (Vol 15, 2024). DOI: 10.1038/s41467-024-47662-1
LOCATION OF TONGTIANYAN CAVE (LIUJIANG) IN GUANGXI PROVINCE, SOUTHERN CHINA, TOGETHER WITH THE LOCATION OF OTHER KEY FOSSILS OF HOMO SAPIENS IN CHINA. FRONTAL VIEW OF THE LIUJIANG CRANIAL AND POSTCRANIAL ELEMENTS.
The emergence of Homo sapiens in Eastern Asia has long been a subject of intense research interest, with the scarcity of well-preserved and dated human fossils posing significant challenges.
Tongtianyan cave, located in the Liujiang District of Liuzhou City, Southern China, has been a focal point of this research, housing one of the most significant fossil finds of Homo sapiens. However, the age of the fossils found within has been a matter of debate – until now.
In a new international study in Nature Communications, with contributions by Griffith University, researchers have provided new age estimates and revised provenance information for the Liujiang human fossils, shedding light on the presence of Homo sapiens in the region.
Using advanced dating techniques including U-series dating on human fossils, and radiocarbon and optically stimulated luminescence dating on fossil-bearing sediments, the study revealed new ages ranging from approximately 33,000 to 23,000 years ago. Previously, studies had reported ages of up to 227,000 years of age for the skeleton.
“These revised age estimates align with dates from other human fossils in northern China, suggesting a geographically widespread presence of H. sapiens across Eastern Asia after 40,000 years ago,” said Professor Michael Petraglia, study co-author and Director of Griffith’s Australian Research Centre for Human Evolution.
Dr Junyi Ge, of the Chinese Academy of Sciences, and lead author of the study, said: “This finding holds significant implications for understanding human dispersals and adaptations in the region. It challenges previous interpretations and provides insights into the occupation history of China.”
The Liujiang skeletal remains, discovered in 1958, have long been considered among the most significant human fossils from Eastern Asia.
With their excellent preservation, the cranial, dental, and postcranial remains have been the subjects of extensive biological and morphological comparisons across Eurasia.
Dr Qingfeng Shao, of the Nanjing Normal University added: “The findings of this study overturn earlier age estimates and palaeoanthropological interpretations, emphasising the need for robust dating methods and proper provenance documentation in the study of human evolution.”
The study’s comprehensive dating analyses highlights the importance of accurate age estimates in advancing our understanding of modern human origins and dispersals.
