Thursday, October 29, 2020

Denisovan DNA in the genome of early East Asians

Scientists identify 34,000-year-old Early East Asian of mixed Eurasian descent




In 2006, miners discovered a hominin skullcap with peculiar morphological features in the Salkhit Valley of the Norovlin county in eastern Mongolia. It was initially referred to as Mongolanthropus and thought to be a Neandertal or even a Homo erectus. The remains of the "Salkhit" individual represent the only Pleistocene hominin fossil found in the country.

Ancient DNA extracted from the skullcap shows that it belonged to a female modern human who lived 34,000 ago and was more related to Asians than to Europeans. Comparisons to the only other early East Asian individual genetically studied to date, a 40,000-year-old male from Tianyuan Cave outside Beijing (China), show that the two individuals are related to each other. However, they differ insofar that a quarter of the ancestry of the Salkhit individual derived from western Eurasians, probably via admixture with ancient Siberians.

Migration and interaction

"This is direct evidence that modern human communities in East Asia were already quite cosmopolitan earlier than 34,000 years ago", says Diyendo Massilani, lead author of the study and researcher at the Max-Planck Institute for Evolutionary Anthropology. "This rare specimen shows that migration and interactions among populations across Eurasia happened frequently already some 35,000 years ago".

The researchers used a new method developed at the Max-Planck Institute for Evolutionary Anthropology to find segments of DNA from extinct hominins in the Salkhit and Tianyuan genomes. They found that the two genomes contain not only Neandertal DNA but also DNA from Denisovans, an elusive Asian relative of Neandertals. "It is fascinating to see that the ancestors of the oldest humans in East Asia from whom we have been able to obtain genetic data had already mixed with Denisovans, an extinct form of hominins that has contributed ancestry to present-day populations in Asia and Oceania", says Byambaa Gunchinsuren, a researcher at the Institute of Archaeology of the Mongolian Academy of Sciences. "This is direct evidence that Denisovans and modern humans had met and mixed more than 40,000 years ago".

"Interestingly, the Denisovan DNA fragments in these very old East Asians overlap with Denisovan DNA fragments in the genomes of present-day populations in East Asia but not with Denisovan DNA fragments in Oceanians. This supports a model of multiple independent mixture events between Denisovans and modern humans", says Massilani.

New ancient genomes reveal a complex common history of dogs and humans

Newly sequenced whole genomes of ancient dogs reveal a complicated genetic legacy that reflects a long, shared history with humans spanning more than 11,000 years into the past. "The dog is the oldest domesticated animal and has a very long relationship with humans. Therefore, understanding the history of dogs teaches us not just about their history, but also about our history," says lead author, Anders Bergström, in an accompanying video. 

While the antiquity of the inextricable bond between dogs and humans is well recognized, its origin - where and when it began - remains shrouded in history. To date, few whole dog and whole wolf genomes have been available for analysis. As a result, very little is known about the population history of prehistoric dogs and how it relates to humans. Here, Bergström and colleagues greatly expand upon the number of ancient dog genomes and present 27 new whole-genome sequences up to 11,000 years old, from across Eurasia. Analyzing these new data alongside other ancient and modern dog genomes, the authors found that all dogs share a common ancestry distinct from present-day wolves, with limited gene flow from wolves since domestication but substantial dog-to-wolf gene flow. 

While the precise timing and location of domestication remain elusive, the results indicate that at least five major dog lineages had already diversified and spread worldwide by 11,000 years ago, suggesting a considerable genetic history during the Paleolithic. Bergström et al. also compared the ancient dog genomes with commensurable ancient human genome-wide data, revealing aspects of dog population history that likely reflect their migration alongside human groups, as well as instances where population histories do not align. 

Together, the findings underscore dogs' complex common history with humans. Pavios Pavlidis and Mehmet Somel discuss the study further in a related Perspective. Of note to reporters focused on trends, this study builds on recent related work published at Science. In 2016, for example, a study by L.A. Frantz and colleagues revealed a deep split between dogs from Western Eurasia and East Asia. In 2018, a study by M. Ni Leathhlobhair showed the first dogs of North America arrived alongside humans and were not domesticated from North American wolves, but rather, from an ancient breed of Siberian sled dog.

Two studies expand insights into Denisovan ancestry and population history in East Asia

In a pair of studies, researchers provide evidence that expands our understanding of modern humans in eastern Asia and their interactions with their most elusive cousins, the Denisovans. While admixture between humans and Denisovans is widely recognized, physical remains of the archaic hominin species are exceedingly rare. What's more, ancient genomic evidence from early modern humans in eastern Asia, which would capture the nature of admixture events between the two species and inform on humans' timing and movement into and across Asia, is lacking. Recently, the fragment of a jawbone, which is suspected to be of Denisovan origin, was recovered from the Baishiya Karst Cave (BKC) located high on the Tibetan Plateau. However, the bone is poorly dated and its Denisovan origin is tenuous. Here, Dongju Zhang and colleagues describe the stratigraphy and chronology of BKC and report on sedimentary DNA analyses, which reveal long-term Denisovan occupation of the cave. Zhang et al. extracted genetic material from cave sediments and identified Denisovan mitochondrial DNA (mtDNA) within them. 

The findings indicate that Denisovans occupied the high-altitude cave as early as 100,000 years ago, and possibly as recently as 45,000 years ago, as well as at a point in-between. Such long-term occupation of high-altitude regions suggests that Denisovan admixture could have contributed to the high-altitude adaptations that allowed modern humans to colonize the Tibetan Plateau. 

In another study, Diyendo Massilani and colleagues present the genome recovered from a 34,000-year-old skullcap discovered in the Salkhit Valley in eastern Mongolia. Ancestry modeling of the new genome with regards to other Pleistocene individuals suggests relatively recent Denisovan admixture, perhaps within 1,000 years before the Salkhit individual lived. According to Massilani et al., the Denisovan ancestry identified here, as well as that identified in another 40,000-year-old individual found near Beijing, likely derived from the same admixture events that contributed to present-day mainland Asians. They are, however, distinct from the Denisovan DNA contributions to present-day Australasians. These findings provide a reference point in the early history of modern humans in eastern Eurasia - a region that has lacked genomic evidence.

New Denisovan DNA expands diversity, history of specie





While the continents of Africa and Europe have been obvious and fruitful treasure troves for exploration and discovery of our modern human origins, Asia has been somewhat overlooked. Scientists have thought that modern humans left Africa about 60,000 years ago and, as they colonized Western Eurasia, found a world empty of any other archaic hominin species. This assumption stemmed in part from the fact that the prehistory of Asia is poorly known compared to that of Africa and Europe.

But research published this week in the journal Science adds more evidence to the record that Denisovans, a group of extinct hominins that diverged from Neanderthals about 400,000 years ago, may have more widely inhabited northeast central Asia. Ancient Denisovan mitochondrial DNA has been recovered in sediments from Baishiya Karst Cave, a limestone cave at the northeast margin of the Tibetan Plateau, 3280 meters above sea level. Samples of sediments were analyzed by an international team including ASU researcher Charles Perreault. Denisovan mitochondrial DNA was recovered that have been dated from around 100,000 to 60,000 years ago, and also possibly as recently as 45,000. If true, this last date may overlap with the presence of modern humans in northeast central Asia.

Perreault is a research affiliate with the Arizona State University Institute of Human Origins and an associate professor with the School of Human Evolution and Social Change.

"When we started developing this project about 10 years ago," said Perreault, "none of us expected Baishya Cave to be such a rich site. We've barely scratched the surface -- three small excavation units have yielded hundreds of stone tools, fauna and ancient DNA. There's a lot that remains to be done."

A mandible fossil (the "Xiahe mandible") from the same cave and dated to 160,000, had been previously identified, tenuously, as Denisovan, based on a single amino acid position. This current study dispels any doubt left that the Denisovans occupied the cave.

This discovery in Baishiya Karst Cave is the first time Denisovan DNA has been recovered from a location that is outside Denisova Cave in Siberia, Russia -- previously the single location in the world where a handful of DNA-bearing Denisovan fossil bones have been discovered. In 2010, a fingerbone belonging to a previously unknown hominin species was found buried in Denisova Cave in the Russian Altai Mountains. Evidence of this new species forced anthropologists to revise their model of human evolution outside of Africa.

Finding Denisovan DNA on the Tibetan Plateau itself is surprising. Evidence of archaic hominins 2000 meters above sea level is unusual. Life this high on the plateau is harsh for many reasons, including its thin air, and humans can develop altitude sickness anywhere above 2500 meters above sea level. This suggests that the Denisovans may have evolved adaptations to high altitude, much like modern Tibetans. The dates of the sediments with mitochondrial DNA, along with the older 160,000-year-old Xiahe mandible, suggest that the Denisovans have been on the Plateau perhaps continuously for tens of thousands of years -- more than enough for genetic adaptations to emerge.

Getting DNA samples from geographic locations outside of Siberia is also important to understand the genetic diversity and the population structure and history of the Denisovan group as a whole. Researchers suspected that Denisovans were widespread in Asia, based on the widespread Denisovan genomic signal among present-day Asians.

The Denisovan fossil and the DNA it contained, indicate that early modern humans coexisted in Asia with other archaic hominin species, but, unexpectedly, that they interbred with them. Like Neanderthals, Denisovan population intermixed with modern humans as they dispersed into Asia. In fact, there's evidence that the genetic adaptations to high altitude in present-day Tibetans come from Denisovans. If confirmed, this is a great example of how intermixing with local archaic populations has shaped, and helped, the spread of modern humans around the world. In this case, it allowed humans to colonize the Tibetan Plateau perhaps faster than they would otherwise have been able to.

"Baishiya Cave is an extraordinary site that hold tremendous potential to understand human origins in Asia," said Charles Perreault. "Future work in Baishiya Cave may give us a truly unique access to Denisovan behavior and solidifies the picture that is emerging, which is that Denisovans, like Neanderthals, were not mere offshoots of the human family tree -- they were part of a web of now-extinct populations that contributed to the current human gene pool and shaped the evolution of our species in ways that we are only beginning to understand."

Archaeologists reveal human resilience in the face of climate change in ancient Turkey

New study fills gaps in chronological timelines of Bronze and Iron Age societies


Research News




TORONTO, ON - An examination of two documented periods of climate change in the greater Middle East, between approximately 4,500 and 3,000 years ago, reveals local evidence of resilience and even of a flourishing ancient society despite the changes in climate seen in the larger region.

A new study led by University of Toronto and Cornell University archaeologists working at Tell Tayinat in southeastern Turkey, demonstrates that human responses to climate change are variable and must be examined using extensive and precise data gathered at the local level. The study highlights how challenge and collapse in some areas were matched by resilience and opportunities elsewhere.

The findings published today in PLoS ONE are welcome contributions to discussions about human responses to climate change that broaden an otherwise sparse chronological framework for the northern part of the region known historically as the Levant, which stretches the length of the eastern edge of the Mediterranean Sea.

"The study shows the end of the Early Bronze Age occupation at Tayinat was a long and drawn out affair that, while it appears to coincide with the onset of a megadrought 4,200 years ago, was actually the culmination of processes that began much earlier," says Tim Harrison, professor and chair of the Department of Near & Middle Eastern Civilizations in the Faculty of Arts & Science at the University of Toronto (U of T), and director of the Tayinat Archaeological Project. "The archaeological evidence does not point towards significant local effects of the climate episode, as there is no evidence of drought stress in crops."

"Instead, these changes were more likely the result of local political and spatial reconfiguration."

The mid-to late Early Bronze Age (3000-2000 BCE) and the Late Bronze Age (1600-1200 BCE) in the ancient Middle East are pivotal periods of early inter-connectedness among settlements across the region, with the development of some of the earliest cities and state-level societies. But these systems were not always sustainable, and both periods ended in collapse of civilisations/settlements, the reasons for which are highly debated.

The absence of detailed timelines for societal activity throughout the region leaves a significant gap in understanding the associations between climate change and social responses. While the disintegration of political or economic systems are indeed components of a societal response, collapse is rarely total.

Using radiocarbon dating and analysis of archaeological samples recovered from Tell Tayinat, a location occupied following two particularly notable climate change episodes 4,200 and again 3,200 years ago, the Toronto-Cornell team established a robust chronological timeframe for Tayinat for these two pivotal periods in the history of the ancient Middle East.

"The absolute dating of these periods has been a subject of considerable debate for many years, and this study contributes a significant new dataset that helps address many of the questions," says Sturt Manning, Goldwin Smith Professor of Classical Archaeology in the Department of Classics at Cornell University's College of Arts & Sciences, and lead author of the study.

"The detailed chronological resolution achieved in this study allows for a more substantive interpretation of the archaeological evidence in terms of local and regional responses to proposed climate change, shedding light on how humans respond to environmental stress and variability."

The researchers say the chronological framework for the Early Iron Age demonstrates the thriving re-settlement of Tayinat following the 3,200 years ago event during a reconstructed period of heightened aridity.

"The settlement of Tayinat may have been undertaken to maximize access to arable land, and crop evidence reveals the continued cultivation of numerous water-demanding crops, revealing a response that counters the picture of a drought-stricken region," says Harrison. "The Iron Age at Tayinat represents a significant degree of societal resilience during a period of climatic stress."

Wednesday, October 28, 2020

Bison engravings in Spanish caves reveal a common art culture across ancient Europe

Study finds ancient Gravettian art culture much more widespread than thought




Recently discovered rock art from caves in Northern Spain represents an artistic cultural style common across ancient Europe, but previously unknown from the Iberian Peninsula, according to a study published October 28, 2020 in the open-access journal PLOS ONE by Diego Garate of the Instituto Internacional de Investigaciones Prehistóricas de Cantabria, Spain, and colleagues.

The history of ancient human art includes various cultural complexes characterized by different artistic styles and conventions. In 2015, new instances of rock art were discovered in three caves in Aitzbitarte Hill in northern Spain, representing an artistic style previously unknown from the Iberian Peninsula. In this study, Garate and colleagues compare this artistic style to others from across Europe.

The artwork in the Aitzbitarte caves consists mostly of engravings of bison, complete with the animals' characteristic horns and humps. The authors note the particular style in which the animals' horns and legs are drawn, typically without proper perspective. Pairs of limbs are consistently depicted as a "double Y" with both legs visible, and the horns are similarly draw side-by-side with a series of lines in between.

This is consistent with the artistic style of the Gravettian cultural complex, characterized by specific customs in art, tools, and burial practices between about 34,000 and 24,000 years ago. This culture is known from across Europe but has not been seen before on the Iberian Peninsula. The authors combine this new discovery with data from around Europe to show that the Gravettian culture was more widespread and varied than previously appreciated.

The authors add: "The study analyses the particularities of Palaeolithic animal engravings found in the Aitzbitarte Caves (Basque Country, Spain) in 2016. These prehistoric images, mainly depicting bison, were drawn in a way that has never before been seen in northern Spain; in a kind of fashion in the way of drawing the engravings that is more characteristic of southern France and some parts of the Mediterranean. The study has shown the close regional relationships in Western Europe cave art since very early times, at least, 25,000 years ago."

Major new African genome study finds varieties that inform African history, migration and immunity

 The study, in which six Wits researchers were involved, show that these newly discovered variants were found mostly among newly sampled ethnolinguistic groups.

Researchers identified new evidence for natural selection in and around 62 previously unreported genes associated with viral immunity, DNA repair and metabolism.

They observed complex patterns of ancestral mixing within and between populations, alongside evidence that populations from Zambia was a likely intermediate site along the routes of expansion of Bantu-speaking populations.

These findings improve the current understanding of migration across the continent, and identify responses to human disease and gene flow as strong determinants of population variation.

The study contributes a new major source of African genomic data, which showcases the complex and vast diversity of African genetic variation and which will support research for decades to come.

"Africa is the continent with greatest genetic diversity and this study shows the importance of African genomic data for taking science and health research forward. It is an important step in redressing existing biases in available data for research, which hamper the study of African health problems and narrows global research," says Zané Lombard, a senior author of the study and an Associate Professor in the Division of Human Genetics in the Faculty of Health Sciences at Wits and at the National Health Laboratory Service.

Lombard led the study under the auspices of the Human Heredity and Health in Africa (H3Africa) Consortium in association with Dr Neil Hanchard, Baylor College of Medicine, Texas, U.S.A, and Dr Adebowale Adeyemo, National Human Genome Research Institute, Maryland, U.S.A.

Members of the H3Africa Consortium who contributed to this work comprise people from 24 institutions across Africa, including the Sydney Brenner Institute for Molecular Bioscience (SBIMB) in the Faculty of Health Sciences at Wits University.

The SBIMB's Dr Ananyo Choudhury, Dr Dhriti Sengupta, Professor Scott Hazelhurst and Mr Shaun Aron led analyses and writing the paper, while Professor Michèle Ramsay, director of the SBIMB, participated in developing the study design and was a principal investigator who contributed samples towards this large-scale sequencing effort.


The study found a vast breadth of genomic diversity among these genomes, with each ethnolinguistic group harbouring thousands of unique genetic variants.

Not only populations from the same geographic region but even those from the same country showed a great deal of variation among themselves, reflecting the deep history and rich genomic diversity across Africa.

"We used a wide variety of computational techniques to gain insights into population history, environmental adaptation, and susceptibility to diseases from these genomes", says Choudhury, first author of the study and a senior scientist at the SBIMB.

"We were able to discover over 3 million novel variants within these genomes. This was after comparison with more than 1000 African genomes in public repositories, suggesting that the potential for discovering novel genetic variants by sequencing African populations is still far from saturation."

First evidence of East Africa to Nigeria migration 50+ generations ago

In addition to contributing to the vast amount of novel variation observed in African populations, the inclusion of previously unstudied population groups in the study enabled scientists to add puzzle pieces to the jigsaw of established historical interactions and migration events on the continent.

"Inclusion of novel African genomes in our study strongly supported Zambia as an intermediate site in the Bantu-migration route to the South and East of the continent," said Mr Shaun Aron, lead analyst on the population genetics component of the study and a lecturer in the SBIMB.

Evidence supporting movement from East Africa to central Nigeria between 1500 and 2000 years ago was revealed through the identification of a substantial amount of East African ancestry, particularly Nilo-Saharan from Chad, in a central Nigerian ethnolinguistic group, the Berom.

"This highlights the complex historical movement of people on the continent and diversity of even proximally close African groups," says Aron.


The researchers found more than 100 areas of the genome that had probably been under natural selection; a sizable proportion of which were associated with immunity related genes.

Natural selection - "selected by nature" - comes from Charles Darwin's work into survival of the fittest. It means that when individuals are exposed to certain environmental factors (diet, viral infection, etc.) some gene variants may give the humans that bear them in their genome an added advantage to survive.

"While genes involved in resistance to insect-transmitted diseases like malaria and sleeping sickness have long been known to be positively selected, our study shows that other viral infections could have also helped to shape genomic differences between people and groups by altering the frequency of genes that affect individuals' disease susceptibility," says Dr Dhriti Sengupta of the SBIMB and one of the lead analysts.

Also, the selection signals were not homogenous across the continent. Sengupta says, "There were noticeable variations in selection signals between different parts of the continent, indicating that large-scale local-adaptations might have accompanied the migration of populations to new geographies, and consequent exposure to new diets and pathogens."

Selection signals are parts of the genome that give us a signature (signal) that the specific part of the genome was under selection pressure at some point.


Lombard, a senior author on the paper and an Associate Professor in the Division of Human Genetics at Wits, says: "The findings have broad relevance, from population genetics research into human history and migration, to clinical research into the impact of specific variants on health outcomes".

Immediate next steps include further examination of the initial findings and leveraging the data to represent more African populations.

The researchers hope their work will lead to wider recognition of the extent of uncatalogued genomic variation across the African continent and the need for continued inclusion of the many diverse populations in Africa in genomics research.

"Adding genomic data from all global populations - including Africa - is essential to ensure that everyone can benefit from the advances in health that precision medicine offers," says Lombard. Precision medicine - or 'personalised' medicine - refers to disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle for each person.


The study represents a major milestone in advancing African genomics research capacity. Instead of African data being analysed elsewhere - as has been the general trend over the last decade - this research was conducted predominantly by local African researchers using local computational facilities.

Studies like this one highlight the importance of computing infrastructure and storage capacity for large data projects at Wits and in South Africa.

Infrastructure such as the computing cluster at Wits, established and managed by Professor Scott Hazelhurst, director of Wits Bioinformatics, is essential to support genomics research and growing African datasets. He says: "Initiatives such as the H3Africa Consortium have laid the foundation to foster and encourage collaborative research in Africa, which has made studies like these possible."

Professor Michèle Ramsay, director of the SBIMB, says: "This study, in a sense, announces the availability of both infrastructure and analytic skills for large-scale genomics research on the continent."

Monday, October 26, 2020

Inks containing lead were likely used as drier on ancient Egyptian papyri


Research News




Analysing 12 ancient Egyptian papyri fragments with X-ray microscopy, University of Copenhagen researchers were surprised to find previously unknown lead compounds in both red and black inks and suggest they were used for their drying properties rather than as a pigment. A similar lead-based "drying technique" has also been documented in 15th century European painting, and the discovery of it in Egyptian papyri calls for a reassessment of ancient lead-based pigments.

The ancient Egyptians have been using inks for writing since at least 3200 BC, using black inks for the primary body of text and using red inks to highlight headings and keywords. In a new study published today in PNAS, a cross-disciplinary team of researchers from the University of Copenhagen have employed advanced synchrotron radiation based X-ray microscopy equipment to investigate red and black inks preserved on a sample of 12 papyrus fragments from Roman period Egypt (around 100 to 200 AD).

"Our analyses of the inks on the papyri fragments from the unique Tebtunis temple library revealed previously unknown compositions of red and black inks, particularly iron-based and lead-based compounds." says Egyptologist and first author of the study Thomas Christiansen from the University of Copenhagen.

Chemistry Professor and co-author Sine Larsen adds:

"The iron-based compounds in the red inks are most likely ocher - a natural earth pigment - because the iron was found together with aluminium and the mineral hematite, which occur in ocher. The lead compounds appear in both the red and black inks, but since we did not identify any of the typical lead-based pigments used to colour the ink, we suggest that this particular lead compound was used by the scribes to dry the ink rather than as a pigment."

A similar lead-based drying technique was used in 15th century Europe during the development of oil painting, and the researchers believe that the Egyptians must have discovered 1,400 years earlier that they could ensure their papyri did not smear by applying this particular ink. According to the researchers, their discovery calls for a reassessment of lead-based compounds found in ancient Mediterranean inks in that drying techniques may have been widespread much earlier than previously believed.

Ink production was specialized in ancient Egypt

The studied papyri fragments all form part of larger manuscripts belonging to the Papyrus Carlsberg Collection at the University of Copenhagen, more specifically from the Tebtunis temple library, which is the only surviving large-scale institutional library from ancient Egypt. The temple priests, who wrote the analyzed papyri manuscripts, did probably not manufacture the inks themselves as the complexity of particularly the red inks must have required specialist knowledge:

"Judging from the amount of raw materials needed to supply a temple library as the one in Tebtunis, we propose that the priests must have acquired them or overseen their production at specialized workshops much like the Master Painters from the Renaissance," Thomas Christiansen explains. He concludes:

"The advanced synchrotron-based microanalyses have provided us with invaluable knowledge of the preparation and composition of red and black inks in ancient Egypt and Rome 2,000 years ago. And our results are supported by contemporary evidence of ink production facilities in ancient Egypt from a magical spell inscribed on a Greek alchemical papyrus, which dates to the third century AD. It refers to a red ink that was prepared inside a workshop. This papyrus was found in Thebes, and it may well have belonged to a priestly library like the papyri studied here, thus providing insights into some of the chemical arts applied by Egyptian priests of the late Roman period."

Friday, October 23, 2020

Ancient Maya built sophisticated water filters

Ancient Maya in the once-bustling city of Tikal built sophisticated water filters using natural materials they imported from miles away, according to the University of Cincinnati.

UC researchers discovered evidence of a filter system at the Corriental reservoir, an important source of drinking water for the ancient Maya in what is now northern Guatemala.

A multidisciplinary team of UC anthropologists, geographers and biologists identified crystalline quartz and zeolite imported miles from the city. The quartz found in the coarse sand along with zeolite, a crystalline compound consisting of silicon and aluminum, create a natural molecular sieve. Both minerals are used in modern water filtration.

The filters would have removed harmful microbes, nitrogen-rich compounds, heavy metals such as mercury and other toxins from the water, said Kenneth Barnett Tankersley, associate professor of anthropology and lead author of the study.

"What's interesting is this system would still be effective today and the Maya discovered it more than 2,000 years ago," Tankersley said.

UC's discovery was published in the journal Scientific Reports.

The Maya created this water filtration system nearly 2,000 years before similar systems were used in Europe, making it one of the oldest water treatment systems of its kind in the world, Tankersley said.

Researchers from UC's College of Arts and Sciences traced the zeolite and quartz to steep ridges around the Bajo de Azúcar about 18 miles northeast of Tikal. They used X-ray diffraction analysis to identify zeolite and crystalline quartz in the reservoir sediments.

At Tikal, zeolite was found exclusively in the Corriental reservoir. 

For the ancient Maya, finding ways to collect and store clean water was of critical importance. Tikal and other Maya cities were built atop porous limestone that made ready access to drinking water difficult to obtain for much of the year during seasonal droughts.

UC geography professor and co-author Nicholas Dunning, who has studied ancient civilizations most of his career, found a likely source of the quartz and zeolite about 10 years ago while conducting fieldwork in Guatemala.

"It was an exposed, weathered volcanic tuff of quartz grains and zeolite. It was bleeding water at a good rate," he said. "Workers refilled their water bottles with it. It was locally famous for how clean and sweet the water was."

Dunning took samples of the material. UC researchers later determined the quartz and zeolite closely matched the minerals found at Tikal. 

UC assistant research professor Christopher Carr, an expert in geographic information system mapping, also conducted work on the UC projects at Bajo de Azúcar and Corriental.

"It was probably through very clever empirical observation that the ancient Maya saw this particular material was associated with clean water and made some effort to carry it back," Dunning said.

UC anthropology professor emeritus Vernon Scarborough, another co-author, said most research on ancient water management has tried to explain how civilizations conserved, collected or diverted water. 

"The quality of water put to potable ends has remained difficult to address," Scarborough said. "This study by our UC team has opened the research agenda by way of identifying the quality of a water source and how that might have been established and maintained."

Of course, reconstructing the lives, habits and motivations of a civilization 1,000 years ago is tricky.

"We don't have absolute proof, but we have strong circumstantial evidence," Dunning said. "Our explanation makes logical sense."

"This is what you have to do as an archaeologist," UC biologist and co-author David Lentz said. "You have to put together a puzzle with some of the pieces missing."

Lentz said the filtration system would have protected the ancient Maya from harmful cyanobacteria and other toxins that might otherwise have made people who drank from the reservoir sick.

"The ancient Maya figured out that this material produced pools of clear water," he said.

Complex water filtration systems have been observed in other ancient civilizations from Greece to Egypt to South Asia, but this is the first observed in the ancient New World, Tankersley said.

"The ancient Maya lived in a tropical environment and had to be innovators. This is a remarkable innovation," Tankersley said. "A lot of people look at Native Americans in the Western Hemisphere as not having the same engineering or technological muscle of places like Greece, Rome, India or China. But when it comes to water management, the Maya were millennia ahead."

New clues revealed about Clovis people

A study by professor Michael Waters shows that tools made by some of North America's earliest inhabitants were made only during a 300-year period.




There is much debate surrounding the age of the Clovis -- a prehistoric culture named for stone tools found near Clovis, New Mexico in the early 1930s -- who once occupied North America during the end of the last Ice Age. New testing of bones and artifacts show that Clovis tools were made only during a brief, 300-year period from 13,050 to 12,750 years ago.

Michael Waters, distinguished professor of anthropology and director of the Center for the Study of the First Americans, along with Texas A&M anthropologist David Carlson and Thomas Stafford of Stafford Research in Colorado, have had their new work published in the current issue of Science Advances.

The team used the radiocarbon method to date bone, charcoal and carbonized plant remains from 10 known Clovis sites in South Dakota, Colorado, Pennsylvania, Ohio, Virginia, Montana and two sites in Oklahoma and Wyoming. An analysis of the dates showed that people made and used the iconic Clovis spear-point and other distinctive tools for only 300 years.

"We still do not know how or why Clovis technology emerged and why it disappeared so quickly," Waters said.

"It is intriguing to note that Clovis people first appears 300 years before the demise of the last of the megafauna that once roamed North America during a time of great climatic and environmental change," he said. "The disappearance of Clovis from the archaeological record at 12,750 years ago is coincident with the extinction of mammoth and mastodon, the last of the megafauna. Perhaps Clovis weaponry was developed to hunt the last of these large beasts."

Waters said that until recently, Clovis was thought to represent the initial group of indigenous people to enter the Americas and that people carrying Clovis weapons and tools spread quickly across the continent and then moved swiftly all the way to the southern tip of South America. However, a short age range for Clovis does not provide sufficient time for people to colonize both North and South America. Furthermore, strong archaeological evidence "amassed over the last few decades shows that people were in the Americas thousands of years before Clovis, but Clovis still remains important because it is so distinctive and widespread across North America," he said.

Waters said the revised age for Clovis tools reveals that, "Clovis with its distinctive fluted lanceolate spear point, typically found in the Plains and eastern United States, is contemporaneous with stemmed point-making people in the Western United States and the earliest spear points, called Fishtail points, in South America.

"Having an accurate age for Clovis shows that people using different toolkits were well settled into multiple areas of North and South America by 13,000 years ago and had developed their own adaptation to these various environments."

Waters noted that a new accurate and precise age for Clovis and their tools provides a baseline to try to understand the mystery surrounding the origin and demise of these people.