Ancient mound builders carefully timed their occupation of coastal Louisiana site

IMAGE: Hundreds of ancient mound sites, depicted here with yellow triangles, still survive in coastal Louisiana. A new study teases out the natural and human history of one of these mound-top villages, a site known as Grand Caillou, shown in red.

Credit: Graphic by Julie McMahon after Mehta and Chamberlain.

A study of ancient mound builders who lived hundreds of years ago on the Mississippi River Delta near present-day New Orleans offers new insights into how Native peoples selected the landforms that supported their villages and earthen mounds - and why these sites were later abandoned.

The study, reported in the Journal of Island and Coastal Archaeology, also offers a timeline of the natural and human events that shaped one particular site, said University of Illinois anthropology professor Jayur Mehta, who conducted the work with Vanderbilt University postdoctoral researcher Elizabeth Chamberlain while both were at Tulane University in New Orleans.

The site, now known as Grand Caillou, is one of hundreds of mound sites in coastal Louisiana, Mehta said. (Watch a video about the research and history of the site.)

"Louisiana is incredibly important in the history of ancient mound-building cultures," he said. "In what is now the United States, earthen monument and mound construction began on the Louisiana coast."
Ancient peoples began building mounds in North America as early as 4,500 B.C., Mehta said. They often situated their mounds near resource-rich waterways, which could support larger human settlements. As many as 500 people lived at Grand Caillou in its heyday. Some mounds also served ceremonial functions.

That so many mound sites have survived in coastal Louisiana is a testament to their careful construction, Mehta said. Neglect, however, and coastal subsidence - the result of engineered changes to the flow of the Mississippi River - are wearing away at the mounds.

"Louisiana loses about two ancient mounds and/or Native American villages a year," Mehta said.

The researchers used a variety of methods - sediment coring, radiocarbon dating, carbon-isotope analysis, the dating of ceramics found onsite and a method called optically stimulated luminescence - to figure out how and when the land underneath the Grand Caillou mound was formed by natural forces and when the mound builders arrived and established their settlement.

"We wanted to understand at a deeper level how Indigenous peoples of the coast were choosing where to build their villages," Mehta said.

Grand Caillou is situated on a natural levee of the Lafourche sub-delta, one of several major lobes of the Mississippi River Delta near New Orleans. Fed by sediments deposited by the river, Lafourche expanded in size over a period of several hundred years, a process that ended at about 800 A.D., the researchers found. The mound builders set up their village around 1200 A.D., long after the site was stable and covered over with vegetation, the team found.

Core samples and excavations revealed that the mound was built in distinct layers, with clay on the bottom, looser sediments piled in the middle and a clay cap on top. This finding confirms earlier archaeological reports that ancient mounds were engineered in layers to withstand the elements.
"The way they were constructed contributes to their durability," Mehta said.

The Grand Caillou mound was built on top of a river deposit that was naturally higher than surrounding land.

"It's only a few feet higher than nearby areas," Mehta said. "But in a landscape where there's no topography, one or two feet can make a world of difference."

Ceramics found at the site date to between 1000 and 1400 A.D. Radiocarbon dating of charcoal found evidence that the site was abandoned by about 1400. By looking at ratios of carbon isotopes - carbon atoms with differing masses - the team saw changes over time that were likely the result of saltwater incursion into the area. These changes coincided with the ultimate abandonment of the village site.

The new study is a much-needed addition to research on threatened cultural sites in coastal regions, said University of Tennessee anthropology professor David G. Anderson, an expert on U.S. Paleoindian archaeology who was not involved in the research.

"We are facing the loss of much of the record of human settlement and use of coastal zones - and must take steps to address the challenge," Anderson said. "Mehta and Chamberlain's study exemplifies the kind of work that will be needed."

When farmers migrated to southeast Asia, according to the DNA

By analyzing genome-wide DNA from the remains of ancient Southeast Asian individuals, scientists have shed new light on the past 4,000 years of genetic history from the region. Their analysis helps reveal potential migration events that may have led to the region's rich cultural and linguistic diversity observed today.

Southeast Asia has a complex history of human occupation, yet studying this history through genetics has remained a challenge because, for one, its humid and tropical environment presents unfavorable conditions for DNA preservation. As such, hypotheses based on archaeological findings - predicting the human origins of cultural shifts (like the use of tools and pottery) brought on by the introduction of farming, for example - remain unresolved by genetic studies.

Here, Mark Lipson, David Reich and colleagues obtained DNA data of 18 ancient Southeast Asian individuals from the Neolithic period to the Iron Age (4,100 to 1,700 years ago), found in modern-day Vietnam, Myanmar, Thailand and Cambodia.

With additional support from archaeological and linguistic data, the researchers identified two major waves of genetic mixture indicative of specific migration events. The first wave, occurring during the Neolithic period, consisted of early farmer migrants from South China who mixed with local Southeast Asian hunter-gatherers.

A couple thousand years afterwards, during the Bronze Age, an additional "pulse" of genes flowed from China to Southeast Asia, reflecting another influx of farmers, the researchers say. Interestingly, the pattern of human movement in Southeast Asia parallels that observed in Europe, where ancient DNA studies have also revealed genetic mixture associated with transitions in agricultural culture.

Details:


An international team led by researchers at HMS and the University of Vienna extracted and analyzed DNA from the remains of 18 people who lived between about 4,100 and 1,700 years ago in what are now Vietnam, Thailand, Myanmar and Cambodia.

The team found that the first migration took place about 45,000 years ago, bringing in people who became hunter-gatherers.

Then, during the Neolithic Period, around 4,500 years ago, there was a large-scale influx of people from China who introduced farming practices to Southeast Asia and mixed with the local hunter-gatherers.

People today with this ancestry mix tend to speak Austroasiatic languages, leading the researchers to propose that the farmers who came from the north were early Austroasiatic speakers.

"This study reveals a complex interplay between archaeology, genetics and language, which is critical for understanding the history of Southeast Asian populations," said co-senior author Ron Pinhasi of the University of Vienna.

The research revealed that subsequent waves of migration during the Bronze Age, again from China, arrived in Myanmar by about 3,000 years ago, in Vietnam by 2,000 years ago and in Thailand within the last 1,000 years. These movements introduced ancestry types that are today associated with speakers of different languages.

The identification of three ancestral populations--hunter-gatherers, first farmers and Bronze Age migrants--echoes a pattern first uncovered in ancient DNA studies of Europeans, but with at least one major difference: Much of the ancestral diversity in Europe has faded over time as populations mingled, while Southeast Asian populations have retained far more variation.

"People who are nearly direct descendants of each of the three source populations are still living in the region today, including people with significant hunter-gatherer ancestry who live in Thailand, Malaysia, the Philippines and the Andaman Islands," said Reich, professor of genetics at HMS and co-senior author of the study. "Whereas in Europe, no one living today has more than a small fraction of ancestry from the European hunter-gatherers."

Reich hypothesizes that the high diversity of Southeast Asia today can be partly explained by the fact that farmers arrived much more recently than in Europe--around 4,500 years ago compared with 8,000 years ago--leaving less time for populations to mix and genetic variation to even out.
The new findings make it clear that the multiple waves of migration, each of which occurred during a key transition period of Southeast Asian history, shaped the genetics of the region to a remarkable extent.

"The major population turnover that came with the arrival of farmers is unsurprising, but the magnitudes of replacement during the Bronze Age are much higher than many people would have guessed," said Reich.

Also unexpected were the linguistic implications raised by analyses of the ancestry of people in western Indonesia.

"The evidence suggests that the first farmers of western Indonesia spoke Austroasiatic languages rather than the Austronesian languages spoken there today," Reich added. "Thus, Austronesian languages were probably later arrivals."

Additional samples from western Indonesia before and after 4,000 years ago should settle the question, Reich said.

Ancient human remains and a mystery: Cornish barrow gives up 4,000-year-old secrets

IMAGE: ANU Archaeologist Dr Catherine Frieman & co-director James Lewis with funerary pot in situ. view more 

Credit: (c)SEKAS

An archaeologist from The Australian National University (ANU) has hailed her excavation of a Bronze Age burial mound in south west England a huge success with the discovery of an intact 4,000 year old human cremation as well as evidence of unaccountable activity from the medieval period on the same site.

Dr Catherine Frieman recently excavated an untouched ancient barrow near the town of Looe in South East Cornwall. Her 14 day-dig over Easter was the first time such a site in the area has been excavated to modern archaeological standards.

She said when digging began, local farmers told her they'd ploughed the field in their childhood, so she didn't expect the site to be so well preserved.

"We were so excited to find such a lot of archaeology on the site despite scores of generations of ploughing, but to find an intact clay urn buried 4,000 years ago just 25 centimetres beneath the surface is nothing short of a miracle," said Dr Frieman.

This and other evidence from the site has led her to conclude there was most likely a large mound over the burial which existed from prehistory well into the middle ages protecting the centre of the barrow.

"This is a sealed, intact cremation so it has the potential to tell us a lot about the cremation rite as it was practiced 4,000 years ago. We also appear to have some identifiable fragments of bone among the cremated remains so we'll potentially be able to tell a lot about the individual themselves," she said.

"We'll be able to say what gender they were, possibly their age, or an age range, and depending on the bone preservation we can conduct analyses to examine where they were from, what their diet was like, where this food was coming from and what they ate and drank as a child when their teeth were forming. This is a very beautiful, very complete burial, and we're very excited," she said.

Other items found include various examples of Cornish Bronze Age pottery, flint tools and two high-quality hammer stones, used to make flint tools. However, what has puzzled Dr Frieman and her team was the discovery of medieval activity on the same site.

"The site has thrown up a big mystery for us because we found what we believe is an entire - albeit crushed - medieval pot from the 12th or 13th century AD, carefully placed under a couple of layers of flat stones. It had some cooked food remains adhering to it and we don't know what it's doing there or why."

"Hundreds of years after the barrow was built, someone from the 12th or 13th century came back to this site and dug into it to bury this pot.

"At that stage there were two local monasteries in view of this site, as Looe Island was a satellite monastery of the Glastonbury Abbey, so it would be very strange to have non-Christian activity on this site. The evidence looks quite ritualistic, but what the ritual was, we don't know," she said.
The team also excavated a round house - an ancient dwelling or land marker nearby, possibly from 500 BC and are trying to deduce possible reasons for the location of the barrow.

"This was a traversed place and regularly visited over the millennia, it affords a sweeping view of the south coast of England and we know that there are a series of Bronze Age shipwrecks off this coast, so this was an important shipping highway in prehistory."

The analysis of soil, pollen, flint and other samples is underway but it will probably be a year before a comprehensive story of the find is possible.

Dr Frieman said the dig would not have been possible without the help of a team of enthusiastic and skilled volunteers from the Cornwall Archaeological Society, the tenant farmers, John and Vanessa Hutchings and the strong support of the National Trust who own and manage the site and their Regional Archaeologist James Parry.

The excavation was funded through a Discovery Early Career Researcher Award (DECRA) and a contribution from the ANU College of Archaeology and Anthropology.

Archaeologists uncover earliest evidence for equid bit wear in the ancient Near East

An international team of archaeologists has uncovered the earliest example of the use of a bridle bit with an equid (horse family) in the Near East. The discovery provides first evidence of the use of the bit (mouth piece) to control an animal long before the appearance of the horse in the Near East.

Evidence of the bridle bit was derived from the skeleton of a donkey dating to the Early Bronze Age III (approximately 2700 BCE) found at the excavations of the biblical city Gath (modern Tell es-Safi) of the Philistines, the home of Goliath, located in central Israel. The donkey was laid as a sacrificial offering before the construction of a house in a domestic neighborhood.

The international team, including archaeologists from Bar-Ilan University, the University of Manitoba (St. Paul's College), University of Saskatchewan (St. Thomas More College), Ariel University and Grand Valley State University published their findings today in the journal PLOS ONE.

"This is significant because it demonstrates how early domestic donkeys were controlled, and adds substantially to our knowledge of the history of donkey (Equus asinus) domestication and evolution of riding and equestrian technology. It is also significant that it was discovered on the remains of an early domestic donkey that was sacrificed probably as an offering to protect what we interpret to be a merchant domestic residence uncovered during our excavations," said Prof. Haskel Greenfield, of the University of Manitoba, the paper's lead author.

"The use of a bridle bit on a donkey during this period is surprising, since it was commonly assumed that donkeys were controlled with nose rings, as depicted in Mesopotamian art," said Prof. Aren Maeir, from Bar-Ilan University's Martin (Szusz) Department of Land of Israel Studies and Archaeology. Prof. Maeir has led the Tell es-Safi/Gath Archaeological Project since its inception more than 20 years ago. The excavations take place every summer in the Tel Zafit National Park, about halfway between Jerusalem and the coastal city of Ashkelon.

The authors propose that the wear on the tooth of the donkey was made with a soft bit, likely made from rope or wood. "Only later, from the Middle Bronze Age and onward (after 2000 BCE), was it thought that bits, in particular metal bits, were used - first with horses that were introduced to the Near East at the time, and subsequently with other equids, such as donkeys," added Maeir. Examples of these later bits were found in Israel at Tel Haror.

The donkey is one of four that were found buried under neighborhood houses, which indicates the importance of the donkey in this society -- most likely as a beast of burden used in trade, the researchers said.

In a previously-published study the researchers provided evidence, based on isotopic analyses, that this very donkey was born in Egypt and brought to Canaan sometime during its lifetime. This demonstrates that this animal -- and most likely others -- was transported over large distances. Using bits allowed donkey herders to control the animals more easily during their transport.

Studies of the dental isotopes from the same donkey demonstrate, as well, that it was born and raised in Egypt and brought to the site only in the last few months of its life, before it was sacrificed and buried beneath the floor of the house as it was being rebuilt. Domestic horses were not yet present in the Near East at that time. As a result, donkeys were not only used as beasts of burden, but also were used to pull and be ridden by the newly emerging elites in these early city-states.

Lead pollution in Greenland ice shows rise and fall of ancient European civilizations

To learn about the rise and fall of ancient European civilizations, researchers sometimes find clues in unlikely places: deep inside of the Greenland ice sheet, for example.

Thousands of years ago, during the height of the ancient Greek and Roman empires, lead emissions from sources such as the mining and smelting of lead-silver ores in Europe drifted with the winds over the ocean to Greenland - a distance of more than 2800 miles (4600 km) - and settled onto the ice. Year after year, as fallen snow added layers to the ice sheet, lead emissions were captured along with dust and other airborne particles, and became part of the ice-core record that scientists use today to learn about conditions of the past.

In a new study published in PNAS, a team of scientists, archaeologists and economists from the Desert Research Institute (DRI), the University of Oxford, NILU - Norwegian Institute for Air Research and the University of Copenhagen used ice samples from the North Greenland Ice Core Project (NGRIP) to measure, date and analyze European lead emissions that were captured in Greenland ice between 1100 BC and AD 800. Their results provide new insight for historians about how European civilizations and their economies fared over time.

"Our record of sub-annually resolved, accurately dated measurements in the ice core starts in 1100 BC during the late Iron Age and extends through antiquity and late antiquity to the early Middle Ages in Europe - a period that included the rise and fall of the Greek and Roman civilizations," said the study's lead author Joe McConnell, Ph.D., Research Professor of Hydrology at DRI. "We found that lead pollution in Greenland very closely tracked known plagues, wars, social unrest and imperial expansions during European antiquity."

A previous study from the mid-1990s examined lead levels in Greenland ice using only 18 measurements between 1100 BC and AD 800; the new study provides a much more complete record that included more than 21,000 precise lead and other chemical measurements to develop an accurately dated, continuous record for the same 1900-year period.

To determine the magnitude of European emissions from the lead pollution levels measured in the Greenland ice, the team used state-of-the-art atmospheric transport model simulations.

"We believe this is the first time such detailed modeling has been used to interpret an ice-core record of human-made pollution and identify the most likely source region of the pollution," said coauthor Andreas Stohl, Ph.D., Senior Scientist at NILU.

Most of the lead emissions from this time period are believed to have been linked to the production of silver, which was a key component of currency.

"Because most of the emissions during these periods resulted from mining and smelting of lead-silver ores, lead emissions can be seen as a proxy or indicator of overall economic activity," McConnell explained.

Using their detailed ice-core chronology, the research team looked for linkages between lead emissions and significant historical events.

Their results show that lead pollution emissions began to rise as early as 900 BC, as Phoenicians expanded their trading routes into the western Mediterranean. Lead emissions accelerated during a period of increased mining activity by the Carthaginians and Romans primarily in the Iberian Peninsula, and reached a maximum under the Roman Empire.

The team's extensive measurements provide a different picture of ancient economic activity than previous research had provided. Some historians, for example, had argued that the sparse Greenland lead record provided evidence of better economic performance during the Roman Republic than during the Roman Empire.

According to the findings of this study, the highest sustained levels of lead pollution emissions coincided with the height of the Roman Empire during the 1st and 2nd centuries AD, a period of economic prosperity known as the Pax Romana. The record also shows that lead emissions were very low during the last 80 years of the Roman Republic, a period known as the Crisis of the Roman Republic.

"The nearly four-fold higher lead emissions during the first two centuries of the Roman Empire compared to the last decades of the Roman Republic indicate substantial economic growth under Imperial rule," said coauthor Andrew Wilson, Professor of the Archaeology of the Roman Empire at Oxford.

The team also found that lead emissions rose and fell along with wars and political instability, particularly during the Roman Republic, and took sharp dives when two major plagues struck the Roman Empire in the 2nd and 3rd centuries. The first, called the Antonine Plague, was probably smallpox. The second, called the Plague of Cyprian, struck during a period of political instability called the third-century crisis.

"The great Antonine Plague struck the Roman Empire in AD 165 and lasted at least 15 years. The high lead emissions of the Pax Romana ended exactly at that time and didn't recover until the early Middle Ages more than 500 years later," Wilson explained.

The research team for this study included ice-core specialists, atmospheric scientists, archaeologists, and economic historians - an unusual combination of expertise.

"Working with such a diverse team was a unique experience in my career as a scientist," McConnell said. "I think that our results show that there can be great value in collaborating across disciplines."

Where hominid brains are concerned, size doesn't matter

The human-like features of Homo nalei's brain surprise research team that examined fossil's brain imprints

University of the Witwatersrand

IMAGE: The skulls of Homo naledi bear traces on their inside surfaces of the shape of naledi's brain. Only a third the size of human brains, they nonetheless had some surprisingly... view more 

Credit: Credit: John Hawks

The recently-discovered species Homo naledi may have had a pint-sized brain, but that brain packed a big punch. New research by Ralph Holloway and colleagues - that include researchers from the University of the Witwatersrand, Johannesburg, South Africa - published in the Proceedings of the National Academy of Sciences examines the imprints of the brain upon the skulls of this species, called endocasts. The research highlights the humanlike shape of naledi's tiny brain, surprising scientists who studied the fossils. These findings draw further into question the long-held belief that human evolution was an inevitable march towards bigger, more complex brains.
The discovery of Homo naledi by Professor Lee Berger of Wits University and his team at the Rising Star caves in the Cradle of Human Kind in 2013 was one of the largest hominin discoveries ever made and hailed as one of the most significant hominid discoveries of the 21st Century. Berger and Professor John Hawkes who was also part of the original Rising Star team who made the naledi discovery, as well as Professor Heather Garvin from Des Moines University in the US, are associated with the Evolutionary Studies Institute (ESI), based at Wits University. They are all co-authors of the current study.
In 2017, geologists demonstrated that this species existed in southern Africa between 236,000 and 335,000 years ago--potentially the same time that modern humans first emerged in Africa. This is a puzzle to scientists, who long held that there was only one species in Africa at this late time period - Homo sapiens. How did this species exist alongside others with brains three times its size? The new study suggests that naledi's behavior may have reflected the shape and structure of the brain more than its size.
The researchers pieced together traces of Homo naledi's brain shape from an extraordinary collection of skull fragments and partial crania, from at least five adult individuals. One of these bore a very clear imprint of the convolutions on the surface of the brain's left frontal lobe. "This is the skull I've been waiting for my whole career," said lead author Ralph Holloway, of Columbia University.
The anatomy of naledi's frontal lobe was similar to humans, and very different from great apes. Naledi wasn't alone. Other members of our genus, from Homo erectus to Homo habilis and the small-brained "hobbits", Homo floresiensis, also share features of the frontal lobe with living humans. But earlier human relatives, like Australopithecus africanus, had a much more apelike shape in this part of the brain, suggesting that functional changes in this brain region emerged with Homo. "It's too soon to speculate about language or communication in Homo naledi," said coauthor Shawn Hurst, "but today human language relies upon this brain region."
The back of the brain also showed humanlike changes in naledi compared to more primitive hominins like Australopithecus. Human brains are usually asymmetrical, with the left brain displaced forward relative to the right. The team found signs of this asymmetry in one of the most complete naledi skull fragments. They also found hints that the visual area of the brain, in the back of the cortex, was relatively smaller in naledi than in chimpanzees--another humanlike trait.
The small brains of Homo naledi raise new questions about the evolution of human brain size. Big brains were costly to human ancestors, and some species may have paid the costs with richer diets, hunting and gathering, and longer childhoods. But that scenario doesn't seem to work well for Homo naledi, which had hands well-suited for toolmaking, long legs, humanlike feet, and teeth suggesting a high-quality diet. According to study coauthor John Hawks, "Naledi's brain seems like one you might predict for Homo habilis, two million years ago. But habilis didn't have such a tiny brain--naledi did."
A humanlike brain organisation might mean that naledi shared some behaviours with humans despite having a much smaller brain size. Lee Berger, a co-author on the paper, suggests that the recognition of naledi's small but complex brain will also have a significant impact on the study of African archaeology. "Archaeologists have been too quick to assume that complex stone tool industries were made by modern humans. With naledi being found in southern Africa, at the same time and place that the Middle Stone Age industry emerged, maybe we've had the story wrong the whole time."

How our ancestors with autistic traits led a revolution in Ice Age art

IMAGE: This is a drawing of a horse by Nadia, a gifted autistic child artist (left) and by a typically developing child of the same age (right). view more 

Credit: Penny Spikins, University of York

The ability to focus on detail, a common trait among people with autism, allowed realism to flourish in Ice Age art, according to researchers at the University of York.

Around 30,000 years ago realistic art suddenly flourished in Europe. Extremely accurate depictions of bears, bison, horses and lions decorate the walls of Ice Age archaeological sites such as Chauvet Cave in southern France.

Why our ice age ancestors created exceptionally realistic art rather than the very simple or stylised art of earlier modern humans has long perplexed researchers.

Many have argued that psychotropic drugs were behind the detailed illustrations. The popular idea that drugs might make people better at art led to a number of ethically-dubious studies in the 60s where participants were given art materials and LSD.

The authors of the new study discount that theory, arguing instead that individuals with "detail focus", a trait linked to autism, kicked off an artistic movement that led to the proliferation of realistic cave drawings across Europe.

Lead author of the paper, Dr Penny Spikins from the Department of Archaeology at the University of York, said: "Detail focus is what determines whether you can draw realistically; you need it in order to be a talented realistic artist. This trait is found very commonly in people with autism and rarely occurs in people without it.

"We looked at the evidence from studies attempting to identify a link between artistic talent and drug use, and found that drugs can only serve to dis-inhibit individuals with a pre-existing ability. The idea that people with a high degree of detail focus, many of which may have had autism, set a trend for extreme realism in ice age art is a more convincing explanation."

The research adds to a growing body of evidence that people with autistic traits played an important role in human evolution.

Dr Spikins added: "Individuals with this trait - both those who would be diagnosed with autism in the modern day and those that wouldn't - likely played an important part in human evolution and survival as we colonised Europe.

"As well as contributing to early culture, people with the attention to detail needed to paint realistic art would also have had the focus to create complex tools from materials such as bone, rock and wood. These skills became increasingly important in enabling us to adapt to the harsh environments we encountered in Europe."