Cranium of a four-million-year-old hominin shows similarities to that of modern humans

A cranium of a four-million-year-old fossil, that, in 1995 was described as the oldest evidence of human evolution in South Africa, has shown similarities to that of our own, when scanned through high resolution imaging systems.
The cranium of the extinct Australopithecus genus was found in the lower-lying deposits of the Jacovec Cavern in the Sterkfontein Caves, about 40km North-West of Johannesburg in South Africa. Dr Amelie Beaudet from the School of Geography, Archaeology and Environmental Studies of the University of the Witwatersrand and her colleagues from the Sterkfontein team scanned the cranium at the Evolutionary Studies Institute, based at the University of the Witwatersrand, in 2016 and applied advanced imaging techniques in "virtual paleontology" to further explore the anatomy of the cranium. Their research was funded by the Centre of Excellence in Palaeosciences, the Claude Leon Foundation and the French Institute of South Africa and was published in the Journal of Human Evolution.
"The Jacovec cranium represents a unique opportunity to learn more about the biology and diversity of our ancestors and their relatives and, ultimately, about their evolution," says Beaudet. "Unfortunately, the cranium is highly fragmentary and not much could be said about the identity nor the anatomy of the Jacovec specimen before."
Through high resolution scanning, the researchers were able to quantitatively and non-invasively explore fine details of the inner anatomy of the Jacovec specimen and to report previously unknown information about the genus Australopithecus.
"Our study revealed that the cranium of the Jacovec specimen and of the Ausralopithecus specimens from Sterkfontein in general was thick and essentially composed of spongy bone," says Beaudet. "This large portion of spongy bone, also found in our own cranium, may indicate that blood flow in the brain of Australopithecus may have been comparable to us, and/or that the braincase had an important role in the protection of the evolving brain."
In comparing this cranium to that of another extinct group of our family tree, Paranthropus, that lived in South Africa along with the first humans less than two-million-years ago, their study revealed an intriguing and unexpected aspect of the cranial anatomy in this genus.
"We also found that the Paranthropus cranium was relatively thin and essentially composed of compact bone. This result is of particular interest, as it may suggest a different biology," says Beaudet.
Situated in the Cradle of humankind, a Unesco World Heritage Site, the South African paleontological sites have played a pivotal role in the exploration of our origins. In particular, the Sterkfontein Caves site has been one of the most prolific fossil localities in Africa, with over 800 hominin remains representing 3 genera of hominin recovered since 1936, including the first adult Australopithecus, the iconic "Mrs Ples" and "Little Foot", the most complete single skeleton of an early hominin yet found.
"The Jacovec cranium exemplifies the relevance of the Sterkfontein fossil specimens for our understanding of human evolution," says Beaudet. "Imaging techniques open unique perspectives for revisiting the South African fossil assemblage."

Stone tools from ancient mummy reveal how Copper Age mountain people lived

IMAGE: This is a stone tool. view more 

Credit: Wierer et al (2018)

Stone tools found with a 5,300-year-old frozen mummy from Northern Italy reveal how alpine Copper Age communities lived, according to a study published June 20, 2018 in the open-access journal PLOS ONE by Ursula Wierer from the Soprintendenza Archeologia, Florence, Italy, and colleagues. The freely available article in PLOS ONE: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0198292

The Tyrolean Iceman is a mummified body of a 45-year-old man originally discovered with his clothes and personal belongings in a glacier of the Alps mountains, in the South Tyrol region, Italy. Previous research showed that the Iceman lived during the Copper Age, between 3370-3100 BC, and was probably killed by an arrow. In this study, the researchers analyzed the Iceman's chert tools to learn more about his life and the events that led to his tragic death.

The team used high-power microscopes and computed tomography to examine the chert tools in microscopic detail, including a dagger, borer, flake, antler retoucher, and arrowheads. The structure of the tools' chert reveals that the stone was collected from several different outcrops in what is now the Trentino region (Italy), about 70km away from where the Iceman was thought to live. Comparing this ancient toolkit with other Copper Age artefacts revealed stylistic influences from distant alpine cultures.

By carefully analyzing the wear traces of the Iceman's chert tools, the authors concluded he was right-handed and probably had recently resharpened and reshaped some of his equipment.
These findings shed light into the Iceman's personal history and support previous evidence suggesting that alpine Copper Age communities maintained long-distance cultural contacts and were well provisioned with chert.

###

In your coverage please use this URL to provide access to the 

Swedes have been brewing beer since the Iron Age

Archaeologists at Lund University in Sweden have found carbonised germinated grains showing that malt was produced for beer brewing as early as the Iron Age in the Nordic region. The findings made in Uppåkra in southern Sweden indicate a large-scale production of beer, possibly for feasting and trade.

"We found carbonised malt in an area with low-temperature ovens located in a separate part of the settlement. The findings are from the 400-600s, making them one of the earliest evidence of beer brewing in Sweden", says Mikael Larsson, who specialises in archaeobotany, the archaeology of human-plant interactions.

Archaeologists have long known that beer was an important product in ancient societies in many parts of the world. Through legal documents and images, it has been found, for example, that beer was produced in Mesopotamia as early as 4 000 BCE. However, as written sources in the Nordic region are absent prior to the Middle Ages (before ca 1200 CE), knowledge of earlier beer production is dependent on botanical evidence.

"We often find cereal grains on archaeological sites, but very rarely from contexts that testify as to how they were processed. These germinated grains found around a low-temperature oven indicate that they were used to become malt for brewing beer", says Mikael Larsson.

Beer is made in two stages. The first is the malting process, followed by the actual brewing. The process of malting starts by wetting the grain with water, allowing the grain to germinate. During germination, enzymatic activities starts to convert both proteins and starches of the grain into fermentable sugars. Once enough sugar has been formed, the germinated grain is dried in an oven with hot air, arresting the germination process. This is what happened in the oven in Uppåkra.

"Because the investigated oven and carbonised grain was situated in an area on the site with several similar ovens, but absent of remains to indicate a living quarter, it is likely that large-scale production of malt was allocated to a specific area on the settlement, intended for feasting and/or trading", explains Mikael Larsson.

Early traces of malt in connection with beer brewing have only been discovered in two other places in the Nordic region. One is in Denmark from 100 CE and one is in Eketorp on Öland from around 500 CE.

"From other archaeological sites in the Nordic region, traces of the bog-myrtle plant have been found, which indicates beer brewing. Back then, bog-myrtle was used to preserve and flavour beer. It wasn't until later during the Middle Ages that hops took over as beer flavouring", Mikael Larsson concludes.

Facts: Method
Two-litre soil samples are taken from various archaeological contexts - in houses, in pits, around hearths and ovens. The plant material found is usually preserved in a carbonised state. The soil is mixed with water and the carbon rises to the surface and is sieved through a fine mesh. The particles extracted are dried and studied under a microscope.

Facts: Uppåkra
Uppåkra is currently the largest Iron Age settlements in southern Scandinavia and served as a densely populated political and religious centre of power for more than 1 000 years, from 100s BCE to the 1 000s CE. The many findings made of imported luxury items such as jewellery and glass bowls, and from a developed production of crafts, indicate that the location was both rich and a significant trading centre.

Montana burial site answers questions about early humans Reassessing the chronology of the archaeological site of Anzick

IMAGE: These are artifacts from the Anzick site. view more 

Credit: Texas A&M University

Scientists have shown that at the Anzick site in Montana - the only known Clovis burial site - the skeletal remains of a young child and the antler and stone artifacts found there were buried at the same time, raising new questions about the early inhabitants of North America, says a Texas A&M University professor involved in the research.
Michael Waters, director of the Center for the Study of the First Americans and colleagues from the University of Oxford and Stafford Research of Colorado have had their work published in the current issue of PNAS (Proceedings of the National Academy of Sciences).
The main focus of the team's research centered on properly dating the Anzick site which is named after the family who own the land. The site was discovered in 1968 by construction workers, who found the human remains and stone tools which include Clovis spear points and antler tools. It is the only known Clovis burial site and is associated with Clovis stone and antler artifacts.
"One thing that has always been a problem has been the accurate dating of the human remains from the site," explains Waters.
"The human remains yielded a younger age that was not in agreement with the ages from the antler artifacts which dated older than the human remains. If the human remains and Clovis artifacts were contemporaneous, they should be the same age." To resolve the issue, the team used a process called Specific Amino Acid Radiocarbon Dating, which allows a specific amino acid, in this case hydroxyproline, to be isolated from the human bones.
"This amino acid could only have come from the human skeleton and could not be contaminated," Waters adds.
"The other previous ages suffered from some sort of contamination. With the new method, we got very accurate and secure ages for the human remains based on dating hydroxyproline. As a test, we also redated the antler artifacts using this technique."
The results prove that both the human remains and antler Clovis artifacts are of the same date.
"The human remains and Clovis artifacts can now be confidently shown to be the same age and date between 12,725 to 12,900 years ago," Waters notes. "This is right in the middle to the end of the Clovis time period which ranges from 13,000 to 12,700 years ago.
"This is important because we have resolved the dating issues at the site. Some researchers had argued that the human remains were not Clovis and were younger than the Clovis artifacts, based on the earlier radiocarbon dates. We have shown that they are the same age and confirmed that the Anzick site represents a Clovis burial."
While not the earliest inhabitants of the Americas, Clovis is the first widespread prehistoric culture that first appeared 13,000 years ago. Clovis originated south of the large Ice Sheets that covered Canada at that time and are the direct descendants of the earliest people who arrived in the New World around 15,000 years ago. Clovis people fashioned their stone spear tips with grooved, or fluted, bases. They invented the "Clovis point,' a spear-shaped weapon made of stone that is found in Texas and other portions of the United States and northern Mexico, and these weapons were used to hunt animals
The researchers say the findings will also help geneticists in their estimates of the timing of the peopling of the Americas because the Anzick genome is critical to understanding early settlements and the origin of modern Native peoples.

Remarkable skill of ancient Peru's cranial surgeons

---

 

More ancient skulls bearing evidence of trepanation -- a telltale hole surgically cut into the cranium -- have been found in Peru than the combined number found in the rest of the world.

Credit: University of Miami

 

Even with a highly skilled neurosurgeon, the most effective anesthesia, and all the other advances of modern medicine, most of us would cringe at the thought of undergoing cranial surgery today.

After all, who needs a hole in the head? Yet for thousands of years, trepanation -- the act of scraping, cutting, or drilling an opening into the cranium -- was practiced around the world, primarily to treat head trauma, but possibly to quell headaches, seizures and mental illnesses, or even to expel perceived demons.

But, according to a new study led by the University of Miami Miller School of Medicine's David S. Kushner, M.D., clinical professor of physical medicine and rehabilitation, trepanation was so expertly practiced in ancient Peru that the survival rate for the procedure during the Incan Empire was about twice that of the American Civil War -- when, more three centuries later, soldiers were trepanned presumably by better trained, educated and equipped surgeons.

"There are still many unknowns about the procedure and the individuals on whom trepanation was performed, but the outcomes during the Civil War were dismal compared to Incan times," said Kushner, a neurologist who has helped scores of patients recover from modern-day traumatic brain injuries and cranial surgeries. "In Incan times, the mortality rate was between 17 and 25 percent, and during the Civil War, it was between 46 and 56 percent. That's a big difference. The question is how did the ancient Peruvian surgeons have outcomes that far surpassed those of surgeons during the American Civil War?"

In their study published in the June issue of World Neurosurgery, "Trepanation Procedures/Outcomes: Comparison of Prehistoric Peru with Other Ancient, Medieval, and American Civil War Cranial Surgery," Kushner and his co-authors -- biological anthropologists John W. Verano, a world authority on Peruvian trepanation at Tulane University, and his former graduate student, Anne R. Titelbaum, now of the University of Arizona College of Medicine -- can only speculate on the answer.

But hygiene, or more accurately the lack of it during the Civil War, may have contributed to the higher mortality rates in the later time period. According to the study, which relied on Verano's extensive field research on trepanation over a nearly 2,000-year period in Peru and a review of the scientific literature about trepanation around the world, Civil War surgeons often used unsterilized medical tools and their bare fingers to probe open cranial wounds or break up blood clots.

"If there was an opening in the skull they would poke a finger into the wound and feel around, exploring for clots and bone fragments," Kushner said, adding that nearly every Civil War soldier with a gunshot wound subsequently suffered from infection. "We do not know how the ancient Peruvians prevented infection, but it seems that they did a good job of it. Neither do we know what they used as anesthesia, but since there were so many (cranial surgeries) they must have used something -- possibly coca leaves. Maybe there was something else, maybe a fermented beverage. There are no written records, so we just don't know."

Whatever their methods, ancient Peruvians had plenty of practice. More than 800 prehistoric skulls with evidence of trepanation -- at least one but as many as seven telltale holes -- have been found in the coastal regions and the Andean highlands of Peru, the earliest dating back to about 400 B.C.

That's more than the combined total number of prehistoric trepanned skulls found in the rest of the world. Which is why Verano devoted an entire book, Holes in the Head -- The Art and Archeology of Trepanation in Ancient Peru, to the 800-plus skulls, most of which were collected from burial caves and archaeological digs in the late 1800s and early 1900s and reside in museums and private collections today.

It's also why Kushner, a medical history buff and Tulane alumnus, jumped at the chance to join Titelbaum in co-authoring one of the book's chapters, "Trepanation from the Perspective of Modern Neurosurgery," and continues to research the subject.

Published in 2016, the book analyzes the techniques and survival rates of trepanation in Peru through the demise of the Incan Empire in the early 1500s. The researchers gauged survival by classifying the extent of bone remodeling around the trepanned holes, which indicates healing. If there was no evidence of healing the researchers assumed the patient died during or within days of the surgery. If the margins of the trepanation openings showed extensive remodeling, they considered the operation successful and the patient long-lived.

Those classifications, Kushner, Verano and Titelbaum reported in the World Neurosurgery paper, show how ancient Peruvians significantly refined their trepanation techniques over the centuries. They learned, for example, not to perforate the protective membrane surrounding the brain -- a guideline Hippocrates codified in ancient Greece at about the same time, 5th century, B.C., that trepanning is thought to have begun in ancient Peru.

The long-term survival rates from such "shallow surgeries" in Peru during those early years, from about 400 to 200 B.C., proved to be worse than those in the Civil War, when about half the patients died. But, from 1000 to 1400 A.D., survival rates improved dramatically, to as high as 91 percent in some samples, to an average of 75 to 83 percent during the Incan period, the study showed.
"Over time, from the earliest to the latest, they learned which techniques were better, and less likely to perforate the dura," said Kushner, who has written extensively about modern-day neurosurgical outcomes. "They seemed to understand head anatomy and purposefully avoided the areas where there would be more bleeding. They also realized that larger-sized trepanations were less likely to be as successful as smaller ones. Physical evidence definitely shows that these ancient surgeons refined the procedure over time. Their success is truly remarkable."

Almost as remarkable is how, by the end of World War I, cranial surgery evolved into the distinct profession of neurosurgery, which continues to improve our understanding of brain anatomy,
physiology and pathology. As Kushner notes, today's neurosurgeons regularly cut into the brain to remove tumors and blood clots, reduce intracranial pressure from massive strokes and trauma, repair vascular and structural anomalies and treat a myriad of other complex problems -- with great success.
"Today, neurosurgical mortality rates are very, very low; there is always a risk but the likelihood of a good outcome is very high," he said. "And just like in ancient Peru, we continue to advance our neurosurgical techniques, our skills, our tools, and our knowledge."

---

Mesomerican turquoise may have different origin than previously thought

New research published today in the journal Science Advances overturns more than a century of thought about the source of turquoise used by ancient civilizations in Mesoamerica, the vast region that extends from Central Mexico to Central America. For more than 150 years, scholars have argued that the Aztec and Mixtec civilizations, which revered the precious, blue-green mineral, acquired it through import from the American Southwest. However, extensive geochemical analyses reveal that the true geologic source of Aztec and Mixtec turquoise lies within Mesoamerica.

Geochemist Alyson Thibodeau, assistant professor of earth sciences at Dickinson College, and a team of researchers from the University of Arizona, California State University at San Bernardino, and the Museo del Templo Mayor in Mexico City, measured the isotopic signatures of Mesoamerican turquoise artifacts associated with both the Aztecs and Mixtecs. These isotopic signatures function like fingerprints that can be used to determine the geologic origins of the turquoise.

Specifically, Thibodeau and her research team carried out analyses of lead and strontium isotopes on fragments of turquoise-encrusted mosaics, which are one of the most iconic forms of ancient Mesoamerican art. Their samples include dozens of turquoise mosaic tiles excavated from offerings within the Templo Mayor, the ceremonial and ritual center of the Aztec empire, and which is located in present-day Mexico City. They also analyzed five tiles associated with Mixteca-style objects held by the Smithsonian's National Museum of the American Indian. The analyses revealed that turquoise artifacts had isotopic signatures consistent with geology of Mesoamerica, not the Southwestern United States.

"This work revises our understanding of these relatively rare objects and provides a new perspective on the availability of turquoise, which was a highly valued luxury resource in ancient Mesoamerica," said Thibodeau. The work is the result of a decade-long collaboration between archaeologists and isotope geochemists to understand the nature of turquoise circulation and trade across southwestern North America. In earlier published research, Thibodeau showed that isotopic signatures could distinguish among turquoise deposits across the southwestern U.S. and identified the geologic sources of turquoise artifacts from archaeological sites in Arizona and New Mexico.

Thibodeau said that long-standing assumption that Mesoamerican civilizations imported turquoise from the Southwest had not been fully substantiated with evidence and that the new geochemical measurements unveil a different story. "These findings potentially re-shape our understanding of both the nature and extent of long-distance contacts between Mesoamerican and Southwestern societies, said Thibodeau. "I hope this inspires people to be skeptical of claims."


Though scholars have long assumed that Aztec and Mixtec turquoise artifacts uncovered in Mesoamerica were imported from the American Southwest, a new isotopic analysis suggests these artifacts likely derived from Mesoamerican sources. The results provide insights into the origin and circulation of turquoise across Southwestern North America. Artifacts made of turquoise - a blue-green mineral extremely valued by prehispanic societies, including the Aztecs and Mixtecs - have been uncovered in Mesoamerica, a region of the Americas that spans from central Mexico to parts of South America.

Experts have hypothesized that turquoise was brought to Mesoamerica from prehistoric mines of the Greater Southwest (present-day American southwest and northwestern Mexico), in part because no remnants of turquoise mines have been discovered in Mesoamerica and also because goods were known to be exchanged between the two cultures. Yet, some have questioned this hypothesis, particularly as geochemical data from Southwestern turquoise mines have not been fully published.

Taking advantage of the way turquoise deposits harbor distinct isotopic characteristics depending on surrounding rock, Alyson M. Thibodeau et al. analyzed the lead (Pb) and strontium (Sr) isotopic ratios in 43 Mesoamerican turquoise mosaic tiles (tesserae) from the Sacred Precinct of Tenochtitlan, most of which date to the late 15th century, as well as five tesserae associated with Mixtec turquoise mosaics. They were able to collect both Pb and Sr isotopic data for 31 samples, and out of those, 29 fall outside the distribution of ratios for turquoise deposits in the Southwest. What is more, these turquoise deposits match well with copper deposits and crustal rocks of Mesoamerica, suggesting that Mesoamerica was the source of this Aztec and Mixtec turquoise.

Large-scale whaling in north Scandinavia may date back to 6th century Uppsala University

IMAGE: Left: a board-game piece made from whalebone at the end of the 6th century CE, found in Gnistahögen near Uppsala, Sweden (photograph by Bengt Backlund, Uppland County Museum). Right: the... view more 

Credit: Bengt Backlund/Rudolf Gustavsson

The intensive whaling that has pushed many species to the brink of extinction today may be several centuries older than previously assumed. This view is held by archaeologists from Uppsala and York whose findings are presented in the European Journal of Archaeology.

Museum collections in Sweden contain thousands of Iron Age board-game pieces. New studies of the raw material composing them show that most were made of whalebone from the mid-6th century CE. They were produced in large volumes and standardised forms. The researchers therefore believe that a regular supply of whalebone was needed. Since the producers would hardly have found the carcasses of beached whales a reliable source, the gaming pieces are interpreted as evidence for whaling.

Apart from an osteological survey, species origin has been determined for a small number of game pieces, using ZooMS (short for Zooarchaeology by Mass Spectrometer). The method shows that all the pieces analysed were derived from the North Atlantic right whale (Eubalaena glacialis), a massive whale weighing 50-80 tonnes. It got the name because it was the right whale to hunt: it swam slowly, close to shore, and contained so much blubber as to float after being killed.

Whalebone gaming pieces appear at the same time as production features for blubber and large boathouses were multiplying in northern Norway. The gaming pieces were probably made in this region, from where they were transported south and ultimately used as burial gifts in Sweden.
The origins of large-scale whaling in northern Europe have long been shrouded in mystery. Written sources refer to whaling on a large scale during periods corresponding to the Viking Age in Scandinavia. Ninth-century sagas about the Norwegian merchant Ohthere/Ottar (a guest and informant at the court of King Alfred the Great) mention his extensive hunt for large whales, but these stories have long been controversial as factual sources.

The gaming pieces not only indicate early whaling. To the archaeologists, they are an important component in research on extensive early trading networks. These were well-functioning several centuries before the formation of towns in Viking times. The new study, along with several other archaeological studies over the past few years, shows increasingly substantial exploitation of marine resources, and also of inland resources in northern Scandinavia. In a supplementary in-depth study, the results will also be used to study human influence on the marine ecosystems in relation to whale population trends, since it is now realised that the inception of large-scale whaling took place further back in time than was previously known.

On the origins of agriculture

The invention of agriculture changed humans and the environment forever, and over several thousand years, the practice originated independently in a least a dozen different places. But why did agriculture begin in those places, at those particular times in human history?

Using a new methodological approach, researchers at Colorado State University and Washington University in St. Louis have uncovered evidence that underscores one long-debated theory: that agriculture arose out of moments of surplus, when environmental conditions were improving, and populations lived in greater densities.

The first-of-its-kind study, "Hindcasting global population densities reveals forces enabling the origin of agriculture," published in Nature Human Behaviour, lends support to existing ideas about the origins of human agriculture. In contrast, they found little support for two other, longstanding theories: One, that during desperate times, when environmental conditions worsened and populations lived at lower densities, agriculture was born out of necessity, as people needed a new way of getting food. And two, that no general pattern exists, but instead the story of agriculture's origins is tied to unique social and environmental conditions in each place.

Senior author Michael Gavin, an associate professor in CSU's Department of Human Dimensions of Natural Resources, said the findings and the general methodological approach may help explain other watershed events in human history.

"There have been several key threshold events in our history that changed the entire course of our species," Gavin said. "Agriculture is a link to so many other components for what the world is like today for billions of people. This begins to help us explain a key moment in human history."

Predicting into the past
Studying the depths of human history is challenging, as little data are available when looking back tens of thousands of years. Scientists typically rely on archeological evidence, but getting a broad picture is difficult, since archeological digs cover relatively small areas.

To overcome these limitations, the researchers modeled correlations between the environment, cultural traits and population densities of relatively recent foraging societies, which used hunting, fishing and gathering to obtain food.

Among the factors they considered as possible predictors of population density: environmental productivity; environmental stability; the average distance travelled when people in a community moved to a new location; whether people owned land or other resources; and distance to the nearest coast.

This model, the team found, did a remarkably good job at predicting recent population densities, which led the researchers to pair the model with data on past climate. In doing so, they could hindcast, or predict into the past, the potential population density of the entire globe dating back thousands of years.

Population maps
This study was the first to produce maps of potential population densities dating back as far as 21,000 years. The researchers used these maps to examine conditions that existed in each of the 12 centers of origin, at the point in time agricultural practices began.

Patrick Kavanagh, a CSU postdoctoral scientist and one of the study's lead authors, said the different centers of origin for agriculture all showed improving environmental conditions and increasing population densities.

"All regions that developed agriculture showed the same pattern," he said.

Researchers believe that improving environmental conditions may have allowed people the luxury of tinkering with new ideas, and that having more people living in one place would allow ideas to be shared and honed, with sparks of innovation following.

While the researchers found commonalities in the surplus aspect of what was occurring in different locations, that doesn't mean the exact same conditions existed in each center of origin. Socially, the places and people studied were probably very different. In addition, the timing of when agriculture began in these major centers varied over thousands of years, and the species of plants they were working with was different.

But, amazingly, although the centers of origin varied in time by thousands of years and ranged from the New Guinea Highlands to Central America and the Middle East, they all had one thing in common: improving environmental conditions, and the potential for higher population densities.

"In all of these major origin centers of agriculture, there were some critical environmental changes that needed to occur," Kavanagh added. "Environmental conditions needed to improve -- which we saw in all 12 centers of origin -- despite variation in the timing and the diverse geographic locations in which they occurred."

The research team is now exploring other applications for the maps they produced.

"It is amazing to examine these maps of the potential population density of the world dating back tens of thousands of years," said Gavin. "We could potentially create them going back to the dawn of our species. This provides a new tool to explore many unanswered questions about human history."

Hats on for Easter Island statues

IMAGE: Restored statue platform with standing moai on the south coast of Rapa Nui. Note that one of the moai is adorned with a red scoria pukao. view more 

Credit: Sean Hixon

How do you put a 13-ton hat on a giant statue? That's what a team of researchers is trying to figure out with their study of Easter Island statues and the red hats that sit atop some of them.
"Lots of people have come up with ideas, but we are the first to come up with an idea that uses archaeological evidence," said Sean W. Hixon, graduate student in anthropology, Penn State.

Rapa Nui --Easter Island, Chile -- sits in the Southern Pacific Ocean more than 2,000 miles from Chile in South America. The island is about 15 miles long and 7.6 miles wide at its widest with an area of about 63 square miles. According to the researchers, the island was first inhabited in the 13th century by Polynesian travelers.

The statues, carved from volcanic tuff, came from one quarry on the island, while the hats, made of red scoria, came from a different quarry 7.5 miles away on the other side of the island.

Previous research by Carl P. Lipo, professor of anthropology, Binghamton University, and Terry Hunt, professor of anthropology and dean of the Honors College, University of Arizona, determined that the statues, which can be up to 33 feet tall and weigh 81 tons, were moved into place along well-prepared roads using a walking/rocking motion, similar to the way a refrigerator is moved.

"The statues were moved in a fashion using simple physics-based processes in a way that was elegant and remarkably effective," said Lipo. Not all statues made it to their final locations, and the fallen and/or broken ones showed that, to move them, the statues were carved so they leaned forward and were later leveled off for final placement.

The hats, with diameters up to 6.5 feet and weighing 13 tons, might have been rolled across the island, but once they arrived at their intended statues, they still needed to be lifted onto the statues' heads. The islanders probably carved the hats cylindrically and rolled them to the statues before further carving the hats to attain the final shapes, which vary from cylindrical to conical and which usually have a smaller cylindrical projection on the top. Chips of red scoria are found in the platform of some of the statue hat combinations.

"We were interested in figuring out the method of hat transport and placement of the hats that best agrees with the archaeological record," said Hixon.

The researchers took multiple photographs of many Rapa Nui hats to see what attributes of the hats were the same throughout. Using photogrammetry and 3-D imaging, they created images of the hats with all their details.

"We assumed they were all transported and placed in the same way," said Hixon. "So we looked for features that were the same on all the hats and all the statues."

The only features they found the same were indentations at the bases of the hats, and these indentations fit the tops of the statues' heads. If the hats had been slid in place on top of the statues, then the soft stone ridges on the margin of the indentations would have been destroyed. So the islanders must have used some other method.

Previous researchers suggested that the statues and the hats were united before they were lifted in place, but the remnants of broken or abandoned statues, and other evidence for walking the statues, indicates this was not the approach used and that the hats were most likely raised to the top of standing statues.

Many of the hats left around the island are much larger than those placed on statues.

"The best explanation for the transport of the pukao (hats) from the quarry is by rolling the raw material to the location of the moai (statues)," said Lipo. "Once at the moai, the pukao were rolled up large ramps to the top of a standing statue using a parbuckling technique." Parbuckling is a simple and efficient technique for rolling objects and is often used to right ships that have capsized. The center of a long rope is fixed to the top of a ramp and the two trailing ends are wrapped around the cylinder to be moved. The rope ends are then brought to the top where workers pull on the ropes to move the cylinder up the ramp.

Besides reducing the force needed to move the hats, this arrangement also makes it easier to stabilize the hat on the trip up because the hat typically will not roll back down the slope. The researchers report in the current issue of the Journal of Archaeological Science, that 15 or fewer workers could move the largest preform hats up the ramps.

Once the hat was at the top of the ramp, it could not simply be pushed into place because of the ridges on the margin of the hat base indentation. Rather, the researchers believe that the hats were tipped up onto the statues.

First the hat would be modified to its final form, some including a second, smaller cylindrical piece on top.

The hats could be rotated 90 degrees and then levered up with small wooden levers to sit on the statue tops, or the ramp could be slightly to the side, so that rotation in the small space at the top of the ramp would be unnecessary. Then the hat would simply be levered and pivoted on edge and into place.

The ramps were then disassembled and became the wings of the platform surrounding the statues.

"This is the first time anyone has systematically explored the evidence for how the giant hats were placed on the top of the heads of the massive statues of Easter Island," said Lipo. "Our work combines cutting-edge 3-D modeling with artifact analysis and models drawn from physics to arrive at the best answer."

Earliest European evidence of lead pollution uncovered in the Balkans

New research from Northumbria University has revealed that metal-related pollution began in the Balkans more than 500 years before it appeared in western Europe, and persisted throughout the Dark Ages and Medieval Period, meaning the region played a far bigger role in mineral exploitation than previously believed.

The study provides a new perspective on both the timing and extent of metallurgy - the technique of extracting metal from ores prior to heating or working with metals to give them a desired shape - in the Balkans, and the associated economic change this brought to the region, such as the inception of the Metal Ages.

The findings are published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS) Monday 28 May 2018.

The exploitation of mineral resources has a broad range of environmental impacts, including metal-contaminated wastewater and the release of microscopic chemical particles into the atmosphere from mining and smelting. As these particles settle on to the surface of a peat bog, an environment in which the sediment develops year on year, a clear history of the bog's development may be established.

Samples recovered from the Crveni Potok peat bog, located on the Serbia/Montenegro border, were geochemically examined by researchers from Northumbria's Department of Geography and Environmental Sciences alongside colleagues from the University of Montpellier and the Romanian Academy. They found the first clear evidence of metal pollution originating from lead in the region dating back to approximately 3600 BC.

The evidence is supported by a concurrent rise in charcoal concentration, which suggests an increase in biomass burning which is potentially related to a broad range of economic activities, including fuel production for metal smelting.

Previously, the oldest European environmental pollution dating to circa 3000 BC had been found in southern Spain, but the new data from Crveni Potok show that metal pollution was evident in this region of eastern Europe more than 500 years earlier. This evidence is the earliest documented in European environmental records and indicates environmental pollution from metallurgy at a time when Britons were still in the Stone Age. This confirms that the Balkans were not only the birthplace of metallurgy in Europe, but also of metallic pollution.

Furthermore, levels of lead pollution decreased dramatically in western Europe after the collapse of the Roman Empire, a feature not observed in this Balkan record. This suggests that the region - which is metal rich - should be considered more of a major player in environmental metal pollution through Dark and Middle Ages than previously thought.

This contrast between eastern and western Europe indicates that while western Europe was in the 'Dark Ages' there was significant economic development in the Balkan area with high levels of metal environmental pollution throughout the Medieval period. This confirms the large extent and size of the metalworking industry in the Balkans during this era.

As part of his PhD research Jack Longman uncovered these findings supervised by Dr Vasile Ersek, Senior Lecturer in Physical Geography in the University's Department of Geography and Environmental Sciences.

Dr Ersek explained:

 "Much of the focus in determining sources of ancient pollution has been on established sources such as the Romans or ancient Greeks, but these findings highlight the crucial role that the Balkan metallurgy has played in the economic development of the area.

"Metallurgy and mining is intimately linked to socioeconomic development, therefore improving our knowledge of how these resources were exploited in the past can help us understand better how societies developed over time. In this respect, the peat bog record from Crveni Potok provides a fascinating history of pollution from the early Bronze Age through to the Industrial Revolution."

Dr Longman added:

"What is most interesting is that after the Roman Empire falls in the third and fourth centuries AD, lead pollution continues and even increases, indicating that the strong mining and smelting culture developed by the Romans was continued by the local population. This goes against the long-held view of barbaric hordes with little technological know-how ousting the Romans leading to the Dark Ages - as we term the 1,000 years following the Roman period. These Dark Ages may well have been true in much of western Europe, but in the Balkans, it seems that this period was, in fact, rather 'well-lit'."