Deformed skulls in an ancient cemetery reveal a multicultural community in transition

IMAGE: UPPER PART OF THE BODY OF GRAVE 43 DURING EXCAVATION. THE GIRL HAD AN ARTIFICIALLY DEFORMED SKULL, WAS PLACE IN A GRAVE WITH A SIDE NICHE AND RICHLY EQUIPPED WITH... view more 

CREDIT: WOSINSKY MÓR MUSEUM, SZEKSZÁRD, HUNGARY.

The ancient cemetery of Mözs-Icsei d?l? in present-day Hungary holds clues to a unique community formation during the beginnings of Europe's Migration Period, according to a study published April 29, 2020 in the open-access journal PLOS ONE by Corina Knipper from the Curt-Engelhorn-Center for Archaeometry, Germany, István Koncz, Tivadar Vida from the Eötvös Loránd University, Budapest, Hungary and colleagues.

As the Huns invaded Central Europe during the 5th century, the Romans abandoned their Pannonian provinces in the area of modern-day Western Hungary. Pannonia's population entered a period of continuous cultural transformation as new foreign groups arrived seeking refuge from the Huns, joining settlements already populated by remaining local Romanized population groups and other original inhabitants. (Later, the Huns themselves would fall to an alliance of Germanic groups.) To better understand this population changing rapidly under chaotic circumstances, Knipper and colleagues turned to the cemetery of Mözs-Icsei d?l? in the Pannonian settlement of Mözs, established around 430 AD.

The authors conducted an archaeological survey of the cemetery and used a combination of isotope analysis and biological anthropology to investigate the site's previously-excavated burials.

They found that Mözs-Icsei d?l? was a remarkably diverse community and were able to identify three distinct groups across two or three generations (96 burials total) until the abandonment of Mözs cemetery around 470 AD: a small local founder group, with graves built in a brick-lined Roman style; a foreign group of twelve individuals of similar isotopic and cultural background, who appear to have arrived around a decade after the founders and may have helped establish the traditions of grave goods and skull deformation seen in later burials; and a group of later burials featuring mingled Roman and various foreign traditions.

51 individuals total, including adult males, females, and children, had artificially deformed skulls with depressions shaped by bandage wrappings, making Mözs-Icsei d?l? one of the largest concentrations of this cultural phenomenon in the region. The strontium isotope ratios at Mözs-Icsei d?l? were also significantly more variable than those of animal remains and prehistoric burials uncovered in the same geographic region of the Carpathian Basin, and indicate that most of Mözs' adult population lived elsewhere during their childhood. Moreover, carbon and nitrogen isotope data attest to remarkable contributions of millet to the human diet.

Though further investigation is still needed, Mözs-Icsei d?l? appears to suggest that in at least one community in Pannonia during and after the decline of the Roman Empire, a culture briefly emerged where local Roman and foreign migrant groups shared traditions as well as geographical space.

Evidence of Late Pleistocene human colonization of isolated islands beyond Wallace's Line

IMAGE: THE SITE OF MAKPAN, ALOR. view more 

CREDIT: SUE O'CONNOR

A new article published in Nature Communications applies stable isotope analysis to a collection of fossil human teeth from the islands of Timor and Alor in Wallacea to study the ecological adaptations of the earliest members of our species to reach this isolated part of the world. Because the Wallacean islands are considered extreme, resource poor settings, archaeologists believed that early seafaring populations would have moved rapidly through this region without establishing permanent communities. Nevertheless, this has so far been difficult to test.

This study, led by scientists from the Department of Archaeology, Max Planck Institute for the Science of Human History (MPI SHH), alongside colleagues from the Australian National University and Universitas Gadjah Mada, used an isotopic methodology that reveals the resources consumed by humans during the period of tooth formation. They demonstrate that the earliest human fossil so far found in the region, dating to around 42,000-39,000 years ago, relied upon coastal resources. Yet, from 20,000 years ago, humans show an increasing reliance on tropical forest environments, away from the island coasts. The results support the idea that one distinguishing characteristic of Homo sapiens is high ecological flexibility, especially when compared to other hominins known from the same region.

Pleistocene hominin adaptations in Southeast Asia

Over the last two decades, archaeological evidence from deserts, high-altitude settings, tropical rainforests, and maritime habitats seem to increasingly suggest that Late Pleistocene humans rapidly adapted to a number of extreme environments. By contrast, our closest hominin relatives, such as Homo erectus and Neanderthals, apparently used various mixtures of forests and grasslands, albeit from as far apart as the Levant, Siberia, and Java. However, this apparent distinction needs testing, especially as finds of another closely related hominin, the Denisovans, have been found on the high-altitude Tibetan Plateau.

As one of the corresponding authors on the new paper, Sue O'Connor of Australian National University says, "The islands beyond Wallace's Line are ideal places to test the adaptive differences between our species and other hominins. These islands were never connected to mainland Southeast Asia during the Pleistocene, and would have ensured that hominins had to make water crossings to reach it." Tropical forest settings like those in Wallacea are often considered barriers to human expansion and are a far cry from the sweeping 'savannahs' with an abundance of medium to large mammals that hominins are believed to have relied on.

Fossils and stone tools show that hominins made it to Wallacean islands at least one million years ago, including the famous 'Hobbit,' or Homo floresiensis, on the island of Flores. When our own species arrived 45,000 years ago (or perhaps earlier), it is thought to have quickly developed the specialized use of marine habitats, as evidenced by one of the world's earliest fish hooks found in the region. Nevertheless, as co-author Ceri Shipton puts it "the extent of this maritime adaptation has remained hotly debated and difficult to test using snapshots based on, often poorly preserved, animal remains."

Stable isotope analysis and Late Pleistocene humans

This new paper uses stable carbon isotopes measured from fossil human teeth to directly reconstruct the long-term diets of past populations. Although this method has been used to study the diets and environments of African hominins for nearly half a century, it has thus far been scarcely applied to the earliest members of our own species expanding within and beyond Africa. Using the principle 'you are what you eat,' researchers analyzed powdered hominin tooth enamel from 26 individuals dated between 42,000 and 1,000 years ago to explore the types of resources they consumed during tooth formation.

The new paper shows that the earliest human fossil available from the region, excavated from the site of Asitau Kuru on Timor, was indeed reliant on maritime resources, suggesting a well-tuned adaptation to the colonization of coastal areas. "This fits with our existing models of rapid human movement through Wallacea on the way to Australia," says co-author Shimona Kealy of the Australian National University.

From around 20,000 years ago, however, human diets seem to have switched inland, towards the supposedly impoverished resources of the island forests. Although some individuals maintained the use of coastal habitats, the majority seemingly began to adapt to the populations of small mammals and tropical forest plants in the region. As co-author Mahirta at Universitas Gadjah Mada puts it, "Coastal resources such as shellfish and reef fish are easy to exploit and available year-round, however growing populations likely forced early island occupants to look inland to other resources."

A species defined by flexibility

This study provides the first direct insights into the adaptations of our own species as it settled in a series of challenging island environments in Wallacea. "Early human populations here, and elsewhere, could not only successfully use the enormous variety of often-extreme Pleistocene environments," suggests Patrick Roberts, lead author of the study and Group Leader at MPI SHH, "they could also specialize in them over substantial periods of time. As a result, even if some local populations did fail, the species as a whole would go on to become tremendously prolific."

As dense tropical rainforests replaced mixed grass and woodlands, other hominins in Southeast Asia went extinct. Ecological flexibility, supported by unique technologies and the capacity for social relationships and symbolism, seem to have carried Homo sapiens through the climactic fluctuations of the Late Pleistocene, however. The authors concede that more work is needed to conclusively test the ecological distinction between hominin species. The discovery of Denisovan populations in the tropical environments of Asia or application of this isotopic approach to other hominins in the tropics could yet show Homo sapiens to be less exceptional. Nonetheless, for the time being it seems that it was our species that could best adapt to the variety of environments across the face of the planet, leaving it, by the end of the Pleistocene, the last hominin standing.

African skeletons from early colonial Mexico tell the story of first-generation slaves

An interdisciplinary study into the origins and health status of three African skeletons unearthed in Mexico shows evidence of forced migration, physical trauma, and the introduction of infectious diseases from Africa

MAX PLANCK INSTITUTE FOR THE SCIENCE OF HUMAN HISTORY

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IMAGE: SKULLS AND DENTAL DECORATION PATTERNS FOR THE THREE AFRICAN INDIVIDUALS FROM THE SAN JOSÉ DE LOS NATURALES ROYAL HOSPITAL. A. SKULL FROM INDIVIDUAL 150 (SJN001). B. SKULL FROM INDIVIDUAL 214... view more 

CREDIT: COLLECTION OF SAN JOSÉ DE LOS NATURALES, OSTEOLOGY LABORATORY, (ENAH), MEXICO CITY, MEXICO. PHOTO: R. BARQUERA & N. BERNAL.

Five centuries after Charles I of Spain authorized the transport of the first African slaves to the Viceroyalty of New Spain, the ancestry of the hundreds of thousands of abducted and enslaved people forms an integral part of the genetic and cultural heritage of the Americas. The origins and experiences of those enslaved individuals, however, remains largely unknown.

This study, published in Current Biology, applies an interdisciplinary approach to explore the backgrounds and living conditions of three African individuals recovered from a mass grave on the grounds of Hospital Real de San José de los Naturales, an early colonial period hospital in Mexico City officially devoted to the indigenous population. Dated to the 16th century, these individuals tell the stories of some of the earliest people forcefully relocated to the Americas in the early years of European colonialism.

Multidisciplinary study reconstructs the lives of early enslaved Africans

The three individuals in the study first caught the attention of the team with their distinct dental modifications, a filing of the upper front teeth consistent with cultural practices recorded for African slaves which can still be observed in some groups living in western Africa today.

"Combining molecular biology, isotopic data and bioinformatic tools with classical historical, anthropological and archaeological evidence allowed us to gain insights into the life history of some of the earliest African slaves in the Americas," says Johannes Krause, director of the Department of Archaeogenetics at the Max Planck Institute for the Science of Human History (MPI SHH).

Genetic analysis showed that all three individuals shared a Y-chromosome lineage that is highly prevalent in Sub-Saharan Africa, and which is now the most common lineage among African Americans. Combined with isotopic data showing that all three individuals were born outside of Mexico and osteobiographies showing years of physical abuse before premature death, the findings suggest that these individuals may be among the first Africans to reach the Americas after being abducted in their homelands in Sub-Saharan Africa.

"Modern lab techniques allow us to gather incredible amounts of data from very little biological material. The amount of information we can give back to archaeologists, anthropologists and society today using only one tooth from each individual is something we could only dream about just ten years ago," says Rodrigo Barquera, the study's lead author.

The spread of pathogens across the Atlantic

Researchers from all three departments and one independent group of the MPI SHH and two laboratories from the ENAH combined their expertise to tell the story of these individuals, examining not only their ancestry and origins, but also their health status and life experiences. The team was able to reconstruct two full pathogen genomes from tooth samples. One individual was infected with a strain of the Hepatitis B virus (HBV) typically found in western Africa today.

"Although we have no indication that the HBV lineage we found established itself in Mexico, this is the first direct evidence of HBV introduction as the result of the transatlantic slave trade," says Denise Kühnert, leader of the tide research group at MPI SHH. "This provides novel insight into the phylogeographic history of the pathogen."

Another individual was infected with Treponema pallidum pertenue which causes yaws, a painful infection of the bones similar to syphilis that affects joints and skin. The same strain of yaws has been previously identified in a 17th century colonist of European descent, suggesting the establishment of this disease lineage of African origin in the early colonial population of Mexico.

"This study sheds light into early cases of yaws after the European colonization of the Americas," says Aditya Kumar Lankapalli of MPI SHH. "Future studies should focus on understanding the transmission and introduction of this pathogen to the Americas. More high-coverage ancient Treponema genomes will allow us to get a better understanding of the coevolution and adaptation of this pathogen to humans."

"Interdisciplinary studies like this will make the study of the past a much more personal matter in the future," adds Thiseas C. Lamnidis. The authors hope that future interdisciplinary endeavors will continue to provide insights into the lives, deaths and legacies of historically oppressed groups whose stories have been buried, often in mass graves.

Study traces spread of early dairy farming across Western Europe

UNIVERSITY OF YORK

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A study has tracked the shift from hunter-gatherer lifestyles to early farming that occurred in prehistoric Europe over a period of around 1,500 years.

An international team of scientists, led by researchers at the University of York, analysed the molecular remains of food left in pottery used by the first farmers who settled along the Atlantic Coast of Europe from 7,000 to 6,000 years ago.

The researchers report evidence of dairy products in 80% of the pottery fragments from the Atlantic coast of what is now Britain and Ireland. In comparison, dairy farming on the Southern Atlantic coast of what is now Portugal and Spain seems to have been much less intensive, and with a greater use of sheep and goats rather than cows.

The study confirms that the earliest farmers to arrive on the Southern Atlantic coast exploited animals for their milk but suggests that dairying only really took off when it spread to northern latitudes, with progressively more dairy products processed in ceramic vessels.

Prehistoric farmers colonising Northern areas with harsher climates may have had a greater need for the nutritional benefits of milk, including vitamin D and fat, the authors of the study suggest.

Senior author of the paper, Professor Oliver Craig from the Department of Archaeology at the University of York, said: "Latitudinal differences in the scale of dairy production might also be important for understanding the evolution of adult lactase persistence across Europe. Today, the genetic change that allows adults to digest the lactose in milk is at much higher frequency in Northwestern Europeans than their southern counterparts".

The research team examined organic residues preserved in Early Neolithic pottery from 24 archaeological sites situated between Portugal and Normandy as well as in the Western Baltic.

They found surprisingly little evidence for marine foods in pottery even from sites located close to the Atlantic shoreline, with plenty of opportunities for fishing and shellfish gathering. An exception was in the Western Baltic where dairy foods and marine foods were both prepared in pottery.

Lead author of the paper, Dr Miriam Cubas, said: "This surprising discovery could mean that many prehistoric farmers shunned marine foods in favour of dairy, but perhaps fish and shellfish were simply processed in other ways.

"Our study is one of the largest regional comparisons of early pottery use. It has shed new light on the spread of early farming across Atlantic Europe and showed that there was huge variety in the way early farmers lived. These results help us to gain more of an insight into the lives of people living during this process of momentous change in culture and lifestyle - from hunter-gatherer to farming."

'Latitudinal gradient in dairy production with the introduction of farming in Atlantic Europe' is published in Nature Communications.

Diverse livelihoods helped resilient Levänluhta people survive a climate disaster

UNIVERSITY OF HELSINKI

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IMAGE: LEVÄNLUHTA IS AMONG THE MOST UNIQUE ARCHAEOLOGICAL SITES, EVEN ON A GLOBAL SCALE. BONES BELONGING TO NEARLY A HUNDRED INDIVIDUALS WHO DIED IN THE IRON AGE HAVE BEEN DISCOVERED IN... view more 

CREDIT: ANNA WESSMAN

A multidisciplinary research group coordinated by the University of Helsinki dated the bones of dozens of Iron Age residents of the Levänluhta site in Finland, and studied the carbon and nitrogen stable isotope ratios. The results provide an overview of the dietary habits based on terrestrial, marine and freshwater ecosystems, as well as of sources of livelihoods throughout the Levänluhta era.

Ever since the 17th century, human bones have been emerging from the spring-containing lake burial site at Levänluhta in Southern Ostrobothnia, western Finland. The secrets of these Iron Age remains are now beginning to be revealed through measuring isotopes of atomic nuclei. A recently published study offers an overview of a diverse community that relied on an extremely broad range of livelihoods, which matches well with the understanding provided by archaeological discoveries.

The carbon and nitrogen in human food end up in the skeletal system and soft tissues as building blocks for the human body. There are three isotopes of carbon and two of nitrogen, and information pertaining to past events is recorded in the contents and ratios of these isotopes.

"The isotope data of the human remains at Levänluhta is divided into three clearly distinct groups, a unique occurrence around the Baltic Sea area," says Docent Markku Oinonen, director of the Laboratory of Chronology at the University of Helsinki.

Dietary modelling speaks of diverse livelihoods

There is variation between the isotope ratios of terrestrial, marine (the Baltic Sea) and freshwater food sources included in the background data used in the study. Thanks to this variation, dietary modelling based on isotopic analyses generates information on the relative shares of these different food groups. It appears that most of the people found buried in Levänluhta exploited all three food sources available to them: the Gulf of Bothnia, the plains and wilderness surrounding them and the Kyrönjoki river flowing close by. In most of the remains, the share of terrestrial food sources was roughly 85%, with an emphasis on protein-rich foodstuffs. This is a trend that prevails in the basic population throughout the entire period.

However, in certain remains approximately half of the food had been caught at sea, indicating seal hunting or fishing in the Gulf of Bothnia. Furthermore, the dataset includes a group that used no freshwater food resources at all. The researchers posit that there might be a possible connection to archaeologically observed links with locations further away in the Baltic Sea area.

Resilience generated by livelihoods helped survive a climate disaster

In the middle of the Levänluhta era, the most severe climate disaster in 2,000 years took place. In the 540s volcanic eruptions initiated a cold and dark period lasting several years, possibly reflected in folktales across the northern hemisphere. Recently the researchers working in the project headed by Oinonen have found a link between the disaster and a reduction in the quantity of light observed in the carbon isotopes found in the annual growth rings of trees in Lapland between 541 and 544.

"If you want to date Fimbulwinter, the three successive winters mentioned in Scandinavian sagas, this is the best candidate," Oinonen considers.

Fimbulwinter has been said to have caused a collapse in farming in the areas surrounding Sweden and Estonia. However, the ratio of food from terrestrial sources consumed by the Levänluhta population does not decrease after this period. Instead, the group relying heavily on marine food starts to fade out. The largest group of people continued to supplement their diet with marine food, actually increasing its presence in the human remains buried in the middle of the 7th century. Protein-rich food indicates produce derived from animals, and it appears that, instead of farming, most of the population probably based their sustenance on animal husbandry and hunting. In fact, fur trade has traditionally been thought as the source of wealth during the Iron Age in these southern roots of the Suomenselkä water divide.

Prior genetic research and place name data indicate a connection between the Levänluhta population and the Sámi. Signs of the diverse livelihoods of Iron Age Sámi have also been previously observed in Sweden on the same latitudes. Indeed, the researchers are considering whether the lake burial site of Levänluhta could be a manifestation of sáivas, the sacred spring-containing lakes in the Sámi mythology.

How is the research conducted?

The amount of radiocarbon, the radioactive isotope of carbon, serves as evidence of time periods, while the ratios of stable isotopes relate to the food sources used. By combining methods, researchers can build time series on changes in human diets and livelihoods over time.

Researchers at the University of Helsinki have carried out almost 40 radiocarbon and carbon and nitrogen isotope analyses with the bone material excavated from Levänluhta. Combining these findings with an extensive background dataset on the isotope values of nutrients and their relative quantities has enabled the conduct of dietary modelling and time series analyses throughout the Levänluhta period.

About Leväluhta

Levänluhta is among the most unique archaeological sites, even on a global scale. Bones belonging to nearly a hundred individuals who died in the Iron Age have been discovered in the middle of the Southern Ostrobothnia plains in western Finland since the 17th century. The deceased were buried during the Iron Age, roughly between the 4th and 9th centuries, probably in a lake located at the site at the time, subsequently transformed into wetland due to the post-glacial rebound as well as, later on, to arable land due to human activity. Today, three springs and their ferrous red water serve as reminders of this ancient burial site.

The published study was carried out as a multidisciplinary cooperation coordinated by the University of Helsinki, with contributions by researchers from the Laboratory of Chronology and the disciplines of archaeology, genetics and forensics from the University, as well as researchers from Natural Resources Institute Finland, the University of Tübingen and the University of Bern. Funding for the study was provided by the Emil Aaltonen Foundation through a project headed by Docent Anna Wessman.

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Archaeologists verify Florida's Mound Key as location of elusive Spanish fort

FLORIDA MUSEUM OF NATURAL HISTORY

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IMAGE: SPANISH HISTORICAL RECORDS NAMED FLORIDA'S MOUND KEY, THE CAPITAL OF THE CALUSA KINGDOM, AS THE SITE OF FORT SAN ANTÓN DE CARLOS, HOME OF ONE OF THE EARLIEST NORTH AMERICAN... view more 

CREDIT: VICTOR THOMPSON

GAINESVILLE, Fla. --- Florida and Georgia archaeologists have discovered the location of Fort San Antón de Carlos, home of one of the first Jesuit missions in North America. The Spanish fort was built in 1566 in the capital of the Calusa, the most powerful Native American tribe in the region, on present-day Mound Key in the center of Estero Bay on Florida's Gulf Coast.

Archaeologists and historians have long suspected that the fort, named for the Catholic patron saint of lost things, was located on Mound Key. Researchers have been searching for concrete evidence in the area since 2013.

"Before our work, the only information we had was from Spanish documents, which suggested that the Calusa capital was on Mound Key and that Fort San Antón de Carlos was there, too," said William Marquardt, curator emeritus of South Florida archaeology and ethnography at the Florida Museum of Natural History. "Archaeologists and historians had visited the site and collected pottery from the surface, but until we found physical evidence of the Calusa king's house and the fort, we could not be absolutely certain."

The Calusa were one of the most politically complex groups of fisher-gatherer-hunters in the world and resisted European colonization for nearly 200 years, Marquardt said. They are often considered to be the first "shell collectors," using shells as tools, utensils and jewelry and discarding the fragments in enormous mounds. They also constructed massive structures known as watercourts, which acted as fish corrals, providing food to fuel large-scale construction projects and a growing population.

The Calusa kingdom controlled most of South Florida before being devastated by European disease. Researchers believe that by the time the Spanish turned Florida over to the British, any remaining Calusa had already fled to Cuba.

Researchers continue to question how the Spanish survived on Mound Key and met their daily needs despite unreliable shipments of minimal supplies from the Caribbean and strained relations with the Calusa - whose surplus supplies they needed for survival. The only Spanish fort known to be built on a shell mound, Fort San Antón de Carlos was abandoned by 1569 after the Spaniards' brief alliance with the Calusa deteriorated, causing the Calusa to leave the island and the Spanish to follow shortly after.

"Despite being the most powerful society in South Florida, the Calusa were inexorably drawn into the broader world economic system by the Spaniards," Marquardt said. "However, by staying true to their values and way of life, the Calusa showed a resiliency unmatched by most other Native societies in the Southeastern United States."

Researchers from the University of Florida, the University of Georgia and students from UGA's archaeological field school used a combination of remote sensing, coring, ground-penetrating radar and excavations to uncover the walls of the fort and a few artifacts, including ceramic shards and beads.

The fort is also the earliest-known North American example of "tabby" architecture, a rough form of shell concrete.

"Tabby," also called "tabbi" or "tapia," is made by burning shells to create lime, which is then mixed with sand, ash, water and broken shells. At Mound Key, the Spaniards used primitive tabby as a mortar to stabilize the posts in the walls of their wooden structures. Tabby was later used by the English in their American colonies and in Southern plantations.

Marquardt said that while the team uncovered a substantial amount of the walls they found, it is still only a small sample of the entire fort, and there is still much more to learn and excavate.

Discovery of the fort has the potential to reduce archaeologists' dependence on Spanish reports for information about ancient Floridian history, he said.

"Seeing the straight walls of the fort emerge, just inches below the surface, was quite exciting to us," Marquardt said. "Not only was this a confirmation of the location of the fort, but it shows the promise of Mound Key to shed light on a time in Florida's - and America's - history that is very poorly known."

Icelandic DNA jigsaw-puzzle brings new knowledge about Neanderthals

An international team of researchers has put together a new image of Neanderthals based on the genes Neanderthals left in the DNA of modern humans when they had children with them about 50,000 years ago

AARHUS UNIVERSITY

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IMAGE: DNA OF ICELANDERS PROVIDES NEW KNOWLEDGE ABOUT EXTINCT HUMAN SPECIES view more 

CREDIT: ASTRID REITZEL, AAARHUS UNIVERSITY

An international team of researchers has put together a new image of Neanderthals based on the genes Neanderthals left in the DNA of modern humans when they had children with them about 50,000 years ago. The researchers found the new pieces of the puzzle by trawling the genomes of more than 27,000 Icelanders. Among other things, they discovered that Neanderthal women gave birth when they were older than the Homo-Sapien women at that time, and Neanderthal men became fathers when they were younger.

It is well-known that a group of our ancestors left Africa and, about 50,000 years ago, met Neanderthals in Europe, and then had children with them.

Now, a new analysis shows that the Neanderthals may have had children with another extinct species of human (Denisovans), before they met Homo Sapiens, and that these children have been fertile and transferred genes from both species further on to modern people.

The analysis also shows that the Neanderthal women living 100,000 - 500,000 years ago on average became mothers at a later age than the contemporary Homo-Sapien women living in Africa. On the other hand, Neanderthal men fathered at a younger age than their Homo-Sapien cousins in Africa.

How can an analysis show all that?

Neanderthals may well be extinct, but small pieces of their DNA live on in us. All living people outside Africa have up to two per cent Neanderthal genes in their DNA.

However, this two per cent is scattered as small fragments in our genomes, and not all individuals have inherited the same fragments. The fragments are like pieces of a jigsaw puzzle, and if they are put together correctly, they will show a picture of the genome in the Neanderthal population that the modern Homo Sapiens had children with.

New method to find the pieces

First, of course, we have to find these pieces. And this is precisely what the group of researchers from Denmark, Iceland and Germany did to produce their results, published today in the scientific journal Nature.

One of them, Laurits Skov, postdoc from the Bioinformatics Research Centre (BiRC) at Aarhus University, has developed a method for tracing Neanderthal fragments in our DNA. Laurits and PhD student Moisès Coll Macià took the method to Iceland, where the genetics firm deCODE has amassed genetic data and health information for more than half of the Icelandic population.

"We spent several months at deCODE in Reykjavik on what can be called field studies for a computational biologist. By combining my method with deCODE's data and expertise, we have analysed 27,566 genomes, and this makes our study 10-times larger than previous studies of Neanderthal genes in human DNA," says Laurits Skov.

Together, the many fragments account for approximately half of a complete Neanderthal genome.

Denisovan genes gone astray?

However, the researchers also found significant fragments of genetic material from another archaic species of human, Denisovans, in the DNA of the Icelanders, and this was something of a surprise. Up to now, Denisovan genes have primarily been found in Australian Aborigines, East Asians and people in Papua New Guinea. So how did these genes end up in Islanders' DNA? And when?

Based on the distribution of genes and mutations, the researchers came up with two possible explanations.

Either Neanderthals had children with Denisovans before they met the Homo Sapiens. This would mean that the Neanderthals with whom Homo Sapiens had children were already hybrids, who transferred both Neanderthal and Denisovan genes to the children.

"Up to now, we believed that the Neanderthals modern people have had children with were "pure" Neanderthals. It's true that researchers have found the remnants of a hybrid between Denisovans and Neanderthals in a cave in East Asia, but we have not known whether there were more of these hybrids and whether, thousands of years later, they had children with modern humans," explains Professor Mikkel Heide Schierup from BiRC.

Or Homo Sapiens met Denisovans long before they met Neanderthals. So far, it has been thought that modern humans met Neanderthals and had children with them first, and not until tens of thousands of years later did they have children with Denisovans.

"Both explanations are equally likely, and both explanations will be scientific news," says Mikkel Heide Schierup.

Neandertal genes of little importance

The study also shows that the Neanderthal DNA has no great importance for modern humans.

"We have previously thought that many of the Neanderthal variants previously been found in modern human DNA were associated with an increased risk of diseases. However, our study shows that the human gene variants located directly beside the Neanderthal genes are better explanations for the risk. We have also found something that can only be explained by Neanderthal genes, but this doesn't mean that much," says Mikkel Heide Schierup.

The properties and risks of diseases that can be linked to Neanderthal DNA are: slightly lower risk of prostate cancer, lower levels of haemoglobin, lower body length (one millimetre) and slightly faster blood plasma clotting.