Tarim Basin mummies genomic study genetics

The surprising origins of the Tarim Basin mummies

The surprising origins of the Tarim Basin mummies

Genomic study of the Tarim Basin mummies in western China reveals an indigenous Bronze Age population that was genetically isolated but culturally cosmopolitan

In a new study, an international team of researchers has determined the genetic origins of Asia’s most enigmatic mummies - the Tarim Basin mummies in western China. Once thought to be Indo-European speaking migrants from the West, the Bronze Age Tarim Basin mummies are revealed to be a local indigenous population with deep Asian roots and taste for far-flung cuisine.

Tarim Basin mummies genomic study genetics
Aerial view of the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

As part of the Silk Road and located at the geographical intersection of Eastern and Western cultures, the Xinjiang Uyghur Autonomous Region has long served as a major crossroads for trans-Eurasian exchanges of people, cultures, agriculture, and languages. Since the late 1990s, the discovery of hundreds of naturally mummified human remains dating to circa 2,000 BCE to 200 CE in the region’s Tarim Basin has attracted international attention due to their so-called ‘Western’ physical appearance, their felted and woven woolen clothing, and their agropastoral economy that included cattle, sheep and goat, wheat, barley, millet, and even kefir cheese. Buried in boat coffins in an otherwise barren desert, the Tarim Basin mummies have long puzzled scientists and inspired numerous theories as to their enigmatic origins.

Excavation of burial M75 at the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

The Tarim Basin mummies’ cattle-focused economy and unusual physical appearance had led some scholars to speculate that they were the descendants of migrating Yamnaya herders, a highly mobile Bronze Age society from the steppes of the Black Sea region of southern Russia. Others have placed their origins among the Central Asian desert oasis cultures of the Bactria-Margiana Archaeological Complex (BMAC), a group with strong genetic ties to early farmers on the Iranian Plateau.

To better understand the origin of the Tarim Basin mummies’ founding population, who first settled the region at sites such as Xiaohe and Gumugou circa 2,000 BCE, a team of international researchers from Jilin University, the Institute of Vertebrate Paleontology and Paleoanthropology, the Max Planck Institute for Evolutionary Anthropology, Seoul National University of Korea, and Harvard University generated and analyzed genome-wide data from thirteen of the earliest known Tarim Basin mummies, dating to circa 2,100 to 1,700 BCE, together with five individuals dating to circa 3,000 to 2,800 BCE in the neighboring Dzungarian Basin. This is the first genomic-scale study of prehistoric populations in the Xinjiang Uyghur Autonomous Region, and it includes the earliest yet discovered human remains from the region.

The Tarim Basin mummies were not newcomers to the region

Typical Xiaohe boat coffin with oar. The coffin is covered with a cattle hide. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

To their great surprise, the researchers found that the Tarim Basin mummies were not newcomers to the region at all, but rather appear to be direct descendants of a once widespread Pleistocene population that had largely disappeared by the end of the last Ice Age. This population, known as the Ancient North Eurasians (ANE), survives only fractionally in the genomes of present-day populations, with Indigenous populations in Siberia and the Americas having the highest known proportions, at about 40 percent. In contrast to populations today, the Tarim Basin mummies show no evidence of admixture with any other Holocene groups, forming instead a previously unknown genetic isolate that likely underwent an extreme and prolonged genetic bottleneck prior to settling the Tarim Basin.

“Archaeogeneticists have long searched for Holocene ANE populations in order to better understand the genetic history of Inner Eurasia. We have found one in the most unexpected place,” says Choongwon Jeong, a senior author of the study and a professor of Biological Sciences at Seoul National University.

In contrast to the Tarim Basin, the earliest inhabitants of the neighboring Dzungarian Basin descended not only from local populations but also from Western steppe herders, namely the Afanasievo, a pastoralist group with strong genetic links to the Early Bronze Age Yamanya. The genetic characterization of the Early Bronze Age Dzungarians also helped to clarify the ancestry of other pastoralist groups known as the Chemurchek, who later spread northwards to the Altai mountains and into Mongolia. Chemurchek groups appear to be the descendants of Early Bronze Age Dzungarians and Central Asian groups the from Inner Asian Mountain Corridor (IAMC), who derive their ancestry from both local populations and BMAC agropastoralists.

“These findings add to our understanding of the eastward dispersal of Yamnaya ancestry and the scenarios under which admixture occurred when they first met the populations of Inner Asia,” says Chao Ning, co-lead author the study and a professor of School of Archaeology and Museology at Peking University.

The Tarim Basin groups were genetically but not culturally isolated

Tarim Basin mummies genomic study genetics
A naturally mummified woman from burial M11 of the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

These findings of extensive genetic mixing all around the Tarim Basin throughout the Bronze Age make it all the more remarkable that the Tarim Basin mummies exhibited no evidence of genetic admixture at all. Nevertheless, while the Tarim Basin groups were genetically isolated, they were not culturally isolated. Proteomic analysis of their dental calculus confirmed that cattle, sheep, and goat dairying was already practiced by the founding population, and that they were well aware of the different cultures, cuisines, and technologies all around them.

“Despite being genetically isolated, the Bronze Age peoples of the Tarim Basin were remarkably culturally cosmopolitan – they built their cuisine around wheat and dairy from the West Asia, millet from East Asia, and medicinal plants like Ephedra from Central Asia,” says Christina Warinner, a senior author of the study, a professor of Anthropology at Harvard University, and a research group leader at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

“Reconstructing the origins of the Tarim Basin mummies has had a transformative effect on our understanding of the region, and we will continue the study of ancient human genomes in other eras to gain a deeper understanding of the human migration history in the Eurasian steppes,” adds Yinquiu Cui, a senior author of the study and professor in the School of Life Sciences at Jilin University.

Tarim Basin mummies genomic study genetics
A profile view of the burial M13 from the Xiaohe cemetery. Credits: Wenying Li, Xinjiang Institute of Cultural Relics and Archaeology

References:

The genomic origins of the Bronze Age Tarim Basin mummies, Nature, DOI: 10.1038/s41586-021-04052-7

 

Press release from the Max Planck Institute for Evolutionary Anthropology.


hepatitis B

New research analyses the evolution of the last ten thousand years of the hepatitis B virus

The University of Valencia participates in a research on the evolution of the last ten thousand years of the hepatitis B virus

A study published in the journal Science traces the evolution of the hepatitis B virus from prehistory to the present, revealing dissemination routes and changes in viral diversity. Domingo Carlos Salazar García, researcher from the Prehistory, Archeology and Ancient History Department of the University of Valencia, has participated in this study led by the Max Planck Institute for the Science of Human History (Germany). The research uncovers the evolution of the hepatitis B virus since the Early Holocene by analyzing the largest dataset of ancient viral genomes produced to date.

hepatitis B
Domingo Carlos Salazar García, researcher from the Prehistory, Archeology and Ancient History Department of the University of Valencia

“This research puts upfront a reality many times ignored but obvious, that viruses have been linked to humans since prehistoric times”, highlighted Salazar, graduated in Medicine and in History, researcher of excellence of the Valencian Community at the University of Valencia. “If SARS-COV-2 has been able to put human societies in check worldwide during the twenty-first century, we can only begin to imagine how viral diseases influenced life in prehistoric times”, he explains. “Historians and archaeologists must start considering more the influence of viruses and other agents that until now have been invisible on the archaeological record when reconstructing past lifestyles”, he says.

The hepatitis B virus (HBV) is a major health problem worldwide, causing close to one million deaths each year. Recent ancient DNA studies have shown that HBV has been infecting humans for millennia, but its past diversity and dispersal routes remain largely unknown. A new study conducted by a large team of researchers from all around the world provides major insights into the evolutionary history of HBV by examining the virus’ genomes from 137 ancient Eurasians and Native Americans dated between ~10,500 and ~400 years ago. Their results highlight dissemination routes and shifts in viral diversity that mirror well-known human migrations and demographic events, as well as unexpected patterns and connections to the present.

Present-day HBV strains are classified into nine genotypes, two of which are found predominantly in populations of Native American ancestry. The study provides strong evidence that these strains descend from an HBV lineage that diverged around the end of the Pleistocene and was carried by some of the first inhabitants of the Americas.

“Our data suggest that all known HBV genotypes descend from a strain that was infecting the ancestors of the First Americans and their closest Eurasian relatives around the time these populations diverged”, says Denise Kühnert, leader of the research group.

 

HBV in prehistoric Europe

The study also shows that the virus was present in large parts of Europe as early as 10,000 years ago, before the spread of agriculture to the continent. “Many human pathogens are thought to have emerged after the introduction of agriculture, but HBV was clearly already affecting prehistoric hunter-gatherer populations”, says Johannes Krause, director of the Department of Archaeogenetics at the Max Planck Institute for Evolutionary Anthropology and co-supervisor of the study.

After the Neolithic transition in Europe, the HBV strains carried by hunter-gatherers were replaced by new strains that were likely spread by the continent’s first farmers, mirroring the large genetic influx associated with the expansion of farming groups across the region. These new viral lineages continued to prevail throughout western Eurasia for around 4,000 years. The dominance of these strains lasted through the expansion of Western Steppe Herders around 5,000 years ago, which dramatically altered the genetic profile of Europeans but remarkably was not associated with the spread of new HBV variants.

 

The collapse and re-emergence of pre-historic HBV

One of the most surprising findings of the study is a sudden decline of HBV diversity in western Eurasia during the second half of the 2nd millennium BCE, a time of major cultural shifts, including the collapse of large Bronze Age state societies in the eastern Mediterranean region.

“This could point to important changes in epidemiological dynamics over a very large region during this period, but we will need more research to understand what happened”, says Arthur Kocher, lead author and researcher in the group.

All ancient HBV strains recovered in western Eurasia after this period belonged to new viral lineages that still prevail in the region today. However, it appears that one variant related to the previous prehistoric diversity of the region has persisted to the present. This prehistoric variant has evolved into a rare genotype that seems to have emerged recently during the HIV pandemic, for reasons that remain to be understood.

 

Article: Kocher et al. “Ten millennia of hepatitis B virus evolution”, Science, 2021. DOI: https://www.science.org/doi/10.1126/science.abi5658

Press release from the University of Valencia and Asociación RUVID.


The settlement of Europe could be the result of several immigration waves by a single population

The settlement of Europe could be the result of several immigration waves by a single population

The CENIEH conducts the morphological and metric analysis of the lower molars in the mandible from Montmaurin-La Niche (France) using micro-computed tomography, to study the origin of the Neanderthals.
settlement Europe immigration population
Montmaurin-La Niche mandible/M. Martínez de Pinillos

The Dental Anthropology Group of the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), in collaboration with the paleoanthropologist Amélie Vialet of the Muséum National d’Histoire Naturelle (MNHN) in Paris, has just published a detailed external and internal study of the molars in the mandible from the French site of Montmaurin-La Niche in the Journal of Human Evolution, whose results strengthen the hypothesis that the settlement of Europe could have been the result of several waves of migration at different times by a common source population.

The aim in this paper, led by the researchers Marina Martínez de Pinillos (CENIEH) and Laura Martín-Francés (CENIEH and PACEA-University of Bordeaux), is to shed light on the origin of the Neanderthals. The latest data obtained from paleontological and geomorphological studies place the Montmaurin-La Niche mandible in a chronologically intermediate position between the fossils of the Middle Pleistocene and the Neanderthals.

The micro-computed axial tomography (microCT) technique has enabled the molars in this mandible to be compared with the external and internal structures of over 400 other molars from the European, Asian and African Pleistocene and Holocene.

This exhaustive metric and morphological analysis has revealed that, while the mandible is more closely related to African and Eurasian populations from the Early and Middle Pleistocene, the enamel and dentine morphology and pulp cavity proportions are similar to those in Neanderthals. “Nevertheless, the absolute and relative enamel thickness values (2D and 3D) show greater affinity with those exhibited by certain Early Pleistocene hominins”, says Martínez de Pinillos.

Possible hybridization

Over recent decades, finds of human fossil remains from the European Middle Pleistocene have prompted the debate on the evolutionary scenario of the genus Homo on that continent to be reopened. “The great variability we find among the European Middle Pleistocene fossils cannot be ignored in studying human evolution on our continent”, states Martín-Francés.

This variability in European Middle Pleistocene populations could indicate different migrations at different times and/or fragmentation of the population, thought it might also be due to possible hybridization between residents and new settlers.

Montmaurin-La Niche mandible/M. Martínez de Pinillos

Full bibliographic information

Martínez de Pinillos, M., Martín-Francés, L., Bermúdez de Castro, J. M., García-Campos, C., Modesto-Mata, M., Martinón-Torres, M., & Vialet, A. (2020). Inner morphological and metric characterization of the molar remains from the Montmaurin-La Niche mandible: the Neanderthal signal. Journal of Human Evolution, 145, 102739. doi: 10.1016/j.jhevol.2019.102739.
Press release on the settlement of Europe due to immigration waves from a common source population from CENIEH

The economy of hunter gatherers in the Mediterranean coasts between the Pleistocene and Holocene included exploitation of marine environment

The economy of hunter gatherers in the Mediterranean coasts between the Pleistocene and Holocene included exploitation of marine environment

The study carried out by the Universitat Jaume I, the Municipal Archaeological Museum of Cartagena, the Provincial Council of Castellón and the University of Barcelona confirms that its use during the Mesolithic period was greater than previously thought.
Pleistocene Holocene marine
The map with the sites

New discoveries and material reviews by an inter-institutional research team have confirmed that the economic context at the end of the transition between the Pleistocene and the Holocene on the Mediterranean coast were richer, more complex and more varied than was previously thought. The exploitation of marine resources was not limited to the harvesting of molluscs, but also included fishing, although not many remains have been preserved, probably because the preservation of these types of materials is more delicate or because of the eating habits of ancient human populations.

Until a few years ago, little was known about the characteristics of the economy of hunter-gatherer groups in the Mediterranean during the transition from the Pleistocene (the glacial era, the Palaeolithic) to the Holocene (post-glacial, the time we live in today). Most of the studies carried out in the Iberian Peninsula suggested that the sites of marine exploitation were located particularly in the Cantabrian and Atlantic area, but the new data and studies provided by the research team can change this paradigm.

The research and analysis work, whose conclusions have been published in The Journal of Island and Coastal Archaeology, has involved Dídac Román, doctoral researcher of excellence of the GenT Plan of the Valencian Regional Government in the Department of History, Geography and Art at the Universitat Jaume I and the Pre-EINA research group; Miguel Martínez Andreu from the Municipal Archaeological Museum of Cartagena; Gustau Aguilella from the Archaeological and Prehistoric Research Service of the Castellón Provincial Council and Josep Maria Fullola and Jordi Nadal from the Prehistoric Studies and Research Seminar (SERP) of the University of Barcelona.

Data collected during the research confirm that the use of marine resources during the late Palaeolithic and Mesolithic on the Iberian Mediterranean coast was clearly more common than was previously thought with the data available at the time. The difference regarding the presence of less evidence than in the case of the Cantabrian and Atlantic coasts, where there are more hunter-gatherer-fisherman sites catalogued, could be due to different reasons: greater richness and diversity of life due to the cold marine currents, more abundant in nutrients; presence of tides and other environmental factors and better preservation of the sites over time thanks to a coastal platform and a steeper coastline that protected them from the progressive flooding of the environment with the melting of the poles during the Holocene.

Dídac Román, Miguel Martínez-Andreu, Gustau Aguilella, Josep Maria Fullola & Jordi Nadal (2020): “Shellfish collectors on the seashore: the exploitation of the marine environment between the end of the Paleolithic and the Mesolithic in the Mediterranean Iberia”, The Journal of Island and Coastal Archaeology.

Press release from Asociación RUVID

 

The new findings and examinations of material carried out by a multi-institutional research proved the economic context at the end of the transition between the Plesitocene and the Holocene in the Mediterranean coasts to be richer, more complex and varied than what we thought. Exploitation of marine resources was not limited to a recollection of molluscs, but it also included fishing, although not many remains were preserved, probably because the preservation of such materials is more delicate or due to the eating habits of ancient human populations.

The conclusions of this research and analytical study have been published in The Journal of Island and Coastal Archaeology. Among the participants in the study are Dídac Román, researcher at Plan Gent of the Valencian Government in the Department of History, Geography and Arts of the University Jaume I and the research group Pre-EINA; Miguel Martínez Andreu, from the Archaeological Museum of Cartagena; Gustay Aguilella, from the Service of Archaeological and Prehistoric Research of Diputación de Castellón, and Josep Maria Fullola and Jordi Nadal, from the Prehistoric Studies and Research Seminar (SERP) of the University of Barcelona, in which the first signer of the study participates as well.

Until some years ago, we did not know much about the economic features of hunter-gatherer groups in the Mediterranean during the transition from the Pleistocene (ice age, Palaeolithic), to the Holocene (post-glaciation, current moment we live in). Most of the studies carried out in the Iberian Peninsula suggested that the areas of marine exploitation were specifically in the Cantabrian and Atlantic areas, but new data and studies conducted by the research team change this paradigm now.

The collected data during the research study states that the use of marine resources at the end of the Palaeolithic and Mesolithic in the Iberian Mediterranean coasts was more common than what people thought with the existing data. The difference regarding the presence of less evidence in the Cantabrian and Atlantic coasts, where there are more areas of hunter-gatherer-fishers, could be due to several reasons: more richness and life diversity due to cold marine currents, more nutrients; presence of tides and other environmental factors, and a better preservation of the areas over time (thanks to a littoral platform and an abrupt coast that protected these from a progressive flood of the environment with the melting of the poles during the Holocene).

SERP studies and Catalan records

Although the results of the article resulted from an interdisciplinary study, in which members of different research centres collaborated to obtain data from all regions, SERP-UB has led two essential aspects in this study. On the one hand, the analysis of the bioarchaeological elements –mainly faunistic remains–, on which the conclusions are based in order to show the importance of the utility of the marine resources by the communities of hunter-gatherers in the study area. On the other hand, obtaining radiocarbon dating in different sites, some excavations from years ago and others which are currently active. These datings are the ones to enable researchers to date the exploitation marine events between 13,000 and 7,000 years ago approximately. Moreover, the SERP studies carried out the interpretation of data in the Catalan area, with the examination of material from old excavations that are now in different museums.

Among these are the collections in the Archaeology Museum Salvador Vilaseca in Reus, which features material from key sites for the current study, such as Camping Salou (Salou) or the cave Cova del Solà d’en Pep (Hospitalet de l’Infant), excavated by Salvador Vilaseca. Although they are not mentioned in the article, other synchronic archaeological excavations are now a target excavation for SERP in Catalonia. The objective is to go beyond the evaluation of the importance of the subsistence of marine origins in the coastal areas but also to value the type of resources among the last populations of hunter-gatherers in the area. Thus, shells used as ornaments have been found in Priorat (El Filador and Hort de la Boquera), Moianès (Balma del Gai), La Noguera (Cova del Parco) and even in Cerdanya (Montlleó).

Ten Mediterranean sites

Researchers analysed remains from ten archaeological sites, located over the 800 kilometers of the Mediterranean coast, from Tarragona to Málaga, specifically La Cativera, Camping Salou and Solà d’en Pep (Tarragona); L’Assut and La Cova (Castellón); El Collado (Valencia); Algarrobo, Caballo and La Higuera (Murcia)and Nerja (Málaga). Contrary to what people thought, places in the south show a larger diversity of resources (the most paradigmatic is in the cave in Nerja). This would happen due to the entrance of waters from the Atlantic Ocean, its proximity, and it can be proved because there is presence of species such as L. Obtusata and species from colder climates such as cod species M. Aeglefinus and O. Pollachius. The Mediterranean is poorer regarding its biology due to salinity, temperature, lack of nutrients and unpredictable tides.

In general, the exploitation of marine resources (mainly molluscs) is related to the exploitation of terrestrial invertebrates and the presence of mammal remains (deer, Iberian ibex, rabbits, among others). However, researchers confirmed there is a decrease in terrestrial invertebrates in favour of marine resources over time. This feature has been observed in those places that conserved remains over long periods of time such as the cave in Nerja, or studied areas that show an older chronology such as Càmping Salou, La Cova, Caballo, Algarrobo and La Higuera. Among the studied molluscs are sea urchins (Solà d’en Pep and Nerja), crustaceans (Caballo), and cephalopods (Nerja), and among fish, the red sea bream is the most found in places with seasonal marsh (El Collado, Caballo and La Higuera), varieties of cod in Nerja and marine birds and mammals (Monachus and Deplhinus).

Another important aspect of the study was to evaluate whether the location and exploitation could be linked to the proximity to the sea, but according to the obtained data, at the time of occupation, these places were not exactly coastal areas (La Cova and El Collado, for instance); their inhabitants had to move about thirty kilometres to get supplies.

The research team used data on the fluctuations of the sea level during its activity in the late Palaeolithic and Mesolithic to calculate the distance to the coast. To estimate the distance, they combined different digital models of the area with bathymetry, which enabled a simulation of different positions of the coast in ranks, and researchers could specify whether it was within the two-hour isochrone of the sites, a distance considered the common area where hunter-gatherers carried out their activities.

The extension of the continental platform and the shape of the coast has been important for this research. The south east area of the peninsula is a relatively sheer area with a continental platform that has deep cliffs, but these features have protected it from important orographic changes. The central area (Tarragona, Castellón and Valencia) is completely different. The sedimentation of the Ebro Riber conditions the existence of a smooth and low altitude in the coast with a big continental platform that has changed its orography due to marine regression and transgression.

Reference article:

Dídac Román, Miguel Martínez-Andreu, Gustau Aguilella, Josep Maria Fullola & Jordi Nadal (2020): “Shellfish collectors donde the seashore: The exploitation of the marino environment between the end of the Paleolithic and the Mesolithic in the Mediterranean Iberia”The Journal of Island and Coastal Archaeology. tandfonline.com/doi/full/10.1080/15564894.2020.1755395

 

Press release from the University of Barcelona.


South American population decline populations Patagonia

Abrupt climate change drove early South American population decline

Abrupt climate change drove early South American population decline

Abrupt climate change some 8,000 years ago led to a dramatic decline in early South American populations, suggests new UCL research.

South American population decline populations Patagonia
Patagonia. Photo by Céline Harrand, Public Domain

The study, published in Scientific Reports, is the first to demonstrate how widespread the decline was and the scale at which population decline took place 8,000 to 6,000 years ago.

"Archaeologists working in South America have broadly known that some 8,200 years ago, inhabited sites in various places across the continent were suddenly abandoned. In our study we wanted to connect the dots between disparate records that span the Northern Andes, through the Amazon, to the southern tip of Patagonia and all areas in between," said lead author, Dr Philip Riris (UCL Institute of Archaeology).

"Unpredictable levels of rainfall, particularly in the tropics, appear to have had a negative impact on pre-Columbian populations until 6,000 years ago, after which recovery is evident. This recovery appears to correlate with cultural practices surrounding tropical plant management and early crop cultivation, possibly acting as buffers when wild resources were less predictable," added Dr Riris.

The study focused on the transition to the Middle Holocene (itself spanning 8,200 and 4,200 years ago), a period of particularly profound change when hunter-gatherer populations were already experimenting with different domestic plants, and forming new cultural habits to suit both landscape and climate change.

While the research shows that there was a significant disruption to population, the study highlights that indigenous people of South America were thriving before and after the middle Holocene.

Co-author, Dr Manuel Arroyo-Kalin (UCL Institute of Archaeology), said: "In the years leading up to population decline, we can see that population sizes were unharmed. This would suggest that early Holocene populations, probably with a social memory of abrupt climate change during the Pleistocene-Holocene transition, developed successful strategies to deal with climate change.

"Abandonment of certain regions and the need to adapt quickly to new circumstances may have promoted the exploration of alternative strategies and new forms of subsistence, including the early adoption of low scale cultivation of domestic plants. Viewed in the context of at least 14,000 years of human presence in South America, the events of the Middle Holocene are a key part of indigenous South Americans' cultural resilience to abrupt and unexpected change."

In this new study, archaeologists examined data from nearly 1,400 sites consisting of more than 5,000 radiocarbon dates to understand how population changed over time, and cross-referenced this information with climate data.

Dr Riris explained: "We studied ancient records of rainfall such as marine sediments for evidence of exceptional climate events. Within windows of 100 years, we compared the Middle Holocene to the prevalent patterns before and after 8,200 years ago. Normal patterns of rainfall suggest on average an unusually dry or wet year every 16-20 years, while under highly variable conditions this increases to every 5 years or so. This puts in perspective the challenge that indigenous communities would have faced."

The authors believe that the research offers crucial historical context on how ancient indigenous South American populations dealt with climate change.

Dr Arroyo-Kalin concluded: "Our study brings a demographic dimension to bear on understandings of the effects of past climate change, and the challenges that were faced by indigenous South Americans in different places. This understanding gauges the resilience of past small-scale productive systems and can potentially help shape future strategies for communities in the present."

###

The research was funded by a UCL CREDOC grant, the Sainsbury Research Unit at University of East Anglia and a British Academy Postdoctoral Fellowship at UCL.

 

 

 

Press release from University College London


Amazonia Llanos de Moxos Bolivia agriculture

Human settlements in Amazonia much older than previously thought

Human settlements in Amazonia much older than previously thought

Amazonia Llanos de Moxos Bolivia agriculture
An endless watery plain characterizes the Llanos. Picture by Sam Beebe, CC BY-SA 2.0

UNIVERSITY PARK, Pa. -- Humans settled in southwestern Amazonia and even experimented with agriculture much earlier than previously thought, according to an international team of researchers.

"We have long been aware that complex societies emerged in Llanos de Moxos in southwestern Amazonia, Bolivia, around 2,500 years ago, but our new evidence suggests that humans first settled in the region up to 10,000 years ago during the early Holocene period," said Jose Capriles, assistant professor of anthropology. "These groups of people were hunter gatherers; however, our data show that they were beginning to deplete their local resources and establish territorial behaviors, perhaps driving them to begin domesticating plants such as sweet potatoes, cassava, peanuts and chili peppers as a way to acquire food."

The archaeological team conducted its study on three forest islands -- Isla del Tesoro, La Chacra and San Pablo -- within the seasonally flooded savanna of the Llanos de Moxos in northern Bolivia.

"These islands are elevated above the surrounding savanna, so they do not flood during the rainy season," said Capriles. "We believe people were using these sites recurrently as seasonal camps, particularly during the long rainy seasons when most of the Llanos de Moxos become flooded."

The team's excavations of the forest islands revealed human skeletons that had been intentionally buried in a manner unlike that of typical hunter gatherers and instead were more akin to the behaviors of complex societies -- characterized by political hierarchy and the production of food. Their results appear today in Science Advances.

"If these were highly mobile hunter gatherers you would not expect for them to bury their dead in specific places; instead, they would leave their dead wherever they died," said Capriles.

Capriles noted that it is rare to find human or even archaeological remains that predate the use of fired pottery in the region.

"The soils tend to be very acidic, which often makes the preservation of organic remains very poor," he said. "Also, organic matter deteriorates quickly in tropical environments and this region completely lacks any type of rock for making stone tools, so even those are not available to study."

According to Umberto Lombardo, earth scientist at the University of Bern, when the researchers first published their discovery of these archaeological sites in 2013, they had to base their conclusions on indirect evidence -- mostly geochemical analyses -- rather than direct evidence such as artifacts.

"Because of the lack of direct evidence many archaeologists were skeptical about our findings," said Lombardo. "They did not really believe that those forest islands were early Holocene archaeological sites. The current study provides strong and definitive evidence of the anthropocentric origin of these sites, because the archaeological excavations uncovered early Holocene human burials. These are the definitive proof of the antiquity and origin of these sites."

Capriles noted that the human bones on these forest islands were preserved despite the poor conditions because they were encased within middens -- or trash heaps -- containing abundant fragments of shell, animal bones and other organic remains.

"These people were foraging apple snails during the wet season and disposing of the shells in large heaps, called middens," said Capriles. "Over time, water dissolved the calcium carbonate from the shells and those carbonates precipitated over the bones, effectively fossilizing them."

Because the human bones were fossilized, the team was unable to date them directly using radiocarbon dating. Instead, they used radiocarbon dating of associated charcoal and shell as a proxy for estimating the time range that the sites were occupied.

"The abundant remains of burned earth and wood suggests that the people were using fire, likely to clear land, cook food and keep warm during long rainy days," said Capriles.

According to Capriles, a gap exists between the people his team studied who lived on the forest islands between 10,000 and 4,000 years ago and the rise of complex societies, which began around 2,500 years ago.

"This paper represents the first step in the effort to learn more about the people who inhabited southwestern Amazonia for thousands of years but we know nothing about," said Lombardo.

Capriles added, "Are the people we found direct predecessors of those later, more complex societies? There are still questions to be answered and we hope to do so in future research."

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genetics history prehistory Spain Iberia Iberian populations genetic history

Unique diversity of the genetic history of the Iberian Peninsula revealed by dual studies

Unique diversity of the genetic history of the Iberian Peninsula revealed by dual studies

Two studies, one looking at Iberian hunter-gatherers between 13,000 and 6,000 years ago and another looking at Iberian populations over the last 8000 years, add new resolution to our understanding of the history and prehistory of the region

Vanessa Villalba-Mouco performing aDNA labwork. Credit: Marieke S. van der Loosdrecht

An international team of researchers have analyzed ancient DNA from almost 300 individuals from the Iberian Peninsula, spanning more than 12,000 years, in two studies published today (14/03/2019) in Current Biology and Science. The first study looked at hunter-gatherers and early farmers living in Iberia between 13,000 and 6000 years ago. The second looked at individuals from the region during all time periods over the last 8000 years. Together, the two papers greatly increase our knowledge about the population history of this unique region.

The Iberian Peninsula has long been thought of as an outlier in the population history of Europe, due to its unique climate and position on the far western edge of the continent. During the last Ice Age, Iberia remained relatively warm, allowing plants and animals - and possibly people - who were forced to retreat from much of the rest of Europe to continue living there. Similarly, over the last 8000 years, Iberia's geographic location, rugged terrain, position on the Mediterranean coast and proximity to North Africa made it unique in comparison to other parts of Europe in its interactions with other regions. Two new studies, published concurrently in Current Biology and Science, analyze a total of almost 300 individuals who lived from about 13,000 to 400 years ago to give unprecedented clarity on the unique population history of the Iberian Peninsula.

Iberian hunter-gatherers show two ancient Paleolithic lineages

For the paper in Current Biology, led by researchers at the Max Planck Institute for the Science of Human History, researchers analyzed 11 hunter-gatherers and Neolithic individuals from Iberia. The oldest newly analyzed individuals are approximately 12,000 years old and were recovered from Balma Guilanyà in Spain.

Excavation work in progress at the site of Balma Guilanyà. Credit: CEPAB-UAB

Earlier evidence had shown that, after the end of the last Ice Age, western and central Europe were dominated by hunter-gatherers with ancestry associated with an approximately 14,000-year-old individual from Villabruna, Italy. Italy is thought to have been a potential refuge for humans during the last Ice Age, like Iberia. The Villabruna-related ancestry largely replaced earlier ancestry in western and central Europe related to 19,000-15,000-year-old individuals associated with what is known as the Magdalenian cultural complex.

Interestingly, the findings of the current study show that both lineages were present in Iberian individuals dating back as far as 19,000 years ago. "We can confirm the survival of an additional Paleolithic lineage that dates back to the Late Ice Age in Iberia," says Wolfgang Haak of the Max Planck Institute for the Science of Human History, senior author of the study. "This confirms the role of the Iberian Peninsula as a refuge during the Last Glacial Maximum, not only for fauna and flora but also for human populations."

This suggests that, far from being replaced by Villabruna-related individuals after the last Ice Age, hunter-gatherers in Iberia in fact already had ancestry from Magdalenian- and Villabruna-related sources. The discovery suggests an early connection between two potential refugia, resulting in a genetic ancestry that survived in later Iberian hunter-gatherers.

"The hunter-gatherers from the Iberian Peninsula carry a mix of two older types of genetic ancestry: one that dates back to the Last Glacial Maximum and was once maximized in individuals attributed to Magdalenian culture and another one that is found everywhere in western and central Europe and had replaced the Magdalenian lineage during the Early Holocene everywhere except the Iberian Peninsula," explains Vanessa Villalba-Mouco of the Max Planck Institute for the Science of Human History, first author of the study.

The researchers hope that ongoing efforts to decipher the genetic structure of late hunter-gatherer groups across Europe will help to even better understand Europe's past and, in particular, the assimilation of a Neolithic way of life brought about by expanding farmers from the Near East during the Holocene.

Ancient DNA from individuals spanning the last 8000 years helps clarify the history and prehistory of the Iberian Peninsula

The paper published in Science focuses on slightly later time periods, and traces the population history of Iberia over the last 8000 years by analyzing ancient DNA from a huge number of individuals. The study, led by Harvard Medical School and the Broad Institute and including Haak and Villalba-Mouco, analyzed 271 ancient Iberians from the Mesolithic, Neolithic, Copper Age, Bronze Age, Iron Age and historical periods. The large number of individuals allowed the team to make more detailed inferences about each time period than previously possible.

The researchers found that during the transition to a sedentary farming life-style, hunter-gatherers in Iberia contributed subtly to the genetic make-up of newly arriving farmers from the Near East. "We can see that there must have been local mixture as the Iberian farmers also carry this dual signature of hunter-gatherer ancestry unique to Iberia," explains Villalba-Mouco.

Between about 2500-2000 BC, the researchers observed the replacement of 40% of Iberia's ancestry and nearly 100% of its Y-chromosomes by people with ancestry from the Pontic Steppe, a region in what is today Ukraine and Russia. Interestingly, the findings show that in the Iron Age, "Steppe ancestry" had spread not only into Indo-European-speaking regions of Iberia but also into non-Indo-European-speaking ones, such as the region inhabited by the Basque. The researchers' analysis suggests that present-day Basques most closely resemble a typical Iberian Iron Age population, including the influx of "Steppe ancestry," but that they were not affected by subsequent genetic contributions that affected the rest of Iberia. This suggests that Basque speakers were equally affected genetically as other groups by the arrival of Steppe populations, but retained their language in any case. It was only after that time that they became relatively isolated genetically from the rest of the Iberian Peninsula.

Additionally, the researchers looked at historical periods, including times when Greek and later Roman settlements existed in Iberia. The researchers found that beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean. They found that Greek and Roman settlements tended to be quite multiethnic, with individuals from the central and eastern Mediterranean and North Africa as well as locals, and that these interactions had lasting demographic as well as cultural impacts.

"Beyond the specific insights about Iberia, this study serves as a model for how a high-resolution ancient DNA transect continuing into historical periods can be used to provide a detailed description of the formation of present-day populations," explains Haak. "We hope that future use of similar strategies will provide equally valuable insights in other regions of the world."

genetics history prehistory Spain Iberia Iberian populations genetic history Iberian Peninsula
Cueva de Chaves site. Credit: Museo de Huesca

Press release from the Max Planck Institute for the Science of Human History/Max-Planck-Institut für Menschheitsgeschichte (MPI-SHH)


Campo Laborde Pampas megafauna extinction giant ground sloth

Evidence for human involvement in extinction of megafauna in the late Pleistocene

Evidence for human involvement in extinction of megafauna in the late Pleistocene

Campo Laborde: A Late Pleistocene giant ground sloth kill and butchering site in the Pampas

Campo Laborde Pampas megafauna extinction giant ground sloth
Lithic tool associated with giant ground sloth bones. Credit: Gustavo Politis and Pablo Messineo

By re-dating giant ground sloth remains found in the Argentinian Pampas region using more advanced technology, scientists say they have provided evidence that humans hunted and butchered this animal near a swamp during the end of the Pleistocene. Based on their radiocarbon dates of this specimen, the authors say that their report challenges the popular hypothesis that megamammals from South America survived well into the Holocene in the Pampas, instead suggesting they took their last breaths in the Pleistocene. Loss of up to 90% of large animal species on ice-free continents occurred during the end of the Pleistocene, and many megafauna went extinct. To date, studies have suggested that humans and/or climate-driven events could be to blame for megafauna loss, but the causes and dynamics of megafauna extinction are hard to determine, and direct evidence of human predation on megafauna is scarce. The Argentinian archeological site Campo Laborde has produced many megafauna fossils, but accurate radiocarbon dating has been difficult on these bones because the fossils have very little collagen, making it hard to extract. Dating is also challenging because the collagen is heavily contaminated with sedimentary organic matter. To overcome this contamination, Gustavo G. Politis and colleagues thought to apply XAD purification chemistry, which can isolate the amino acids in a bone's collagen, resulting in a more accurate radiocarbon date, they say. Only one bone from a giant ground sloth found at Campo Laborde contained collagen. This specimen was first dated in 2007 as being around 9,730 years of age (pegging it to the Holocene, which began around 11,650 years ago). Using accelerator mass spectrometry to radiocarbon date the amino acids of the specimen, Politis determined that the giant ground sloth bone better dated to around 10,570 years of age, plus or minus 170 years. According to the authors, contaminated collagen was the reason for the previous "younger" (Holocene) dates. In addition to the previously discovered lithic artifacts that were found around the giant ground slot and dated to around 11,800 and 10,000 years before present, this study "solidly dates" the killing and exploitation of the giant ground sloth to the late Pleistocene and does not support extinct megamammals surviving into the Holocene at Campo Laborde, the authors say.

Press release by AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE