Genes from Icelanda's first settlers reveal the origin of their population

In just over 1,000 years, Icelanders have gone through numerous changes in their gene pool, to the extent that Iceland's first settlers, who came to the island from Norway and the British and Irish isles between the years 870 and 930, are much more similar to the inhabitants of their original home countries than to Iceland's present-day inhabitants.

This is one of the main conclusions of a study carried out by an international team of scientists which included members of the Spanish National Research Council (CSIC). For the first time, the researchers, whose results are published in the journal Science, analysed the ancient genomes of 25 individuals who lived in Iceland during the colonisation of the island.

With a population of 330,000, Iceland is a country with its own peculiarities. Genes are no exception: isolation and inbreeding throughout its history make this northern Atlantic island a paradise for genetic studies.

The analysis of ancient skeletal remains- more specifically the teeth belonging to the first generations to populate the island- has shed more light on the genetic evolution which led to a combination of genes coming from Scotland, Ireland and Scandinavia. According to the conclusions of this study, the Norwegian genetic fingerprint of present day Icelanders stands at 70%, while, in the case of the island's original founders, it was 57%.

As CSIC researcher Carles Lalueza-Fox, who works at the Institute of Evolutionary Biology (a joint institute between CSIC and Pompeu Fabra University) explains, "This work takes an in-depth look at the process which makes small, isolated populations go through random changes in their genetic variability over time. Present-day Icelanders have been affected by 1,100 years of profound genetic drift. This means they are more similar to each other, yet different to modern populations of continental Europe."
Gender bias
The work, led by researchers from deCODE Genetics- the biotechnology company based in Reykjavik which claims to have genealogical records going back for up to seven centuries in the history of most families on the island, confirms a gender bias in Iceland's population.
"The settlers of Celtic origin had fewer offspring compared with those of Norwegian origin. This is probably because there were more men of Scandinavian origin compared to more women - who would probably have come to the country as slaves and servants - from Scotland and the rest of Britain," explains Lalueza-Fox.
"We have always known that Icelanders descended from Norwegians and Celts, and the analysis of the ancient genomes from the first colonists allows us to see what they were like, both before mixing started, as well as throughout the whole process," explains Sunna Ebeneserdóttir, a researcher from deCODE Genetics. "It's like having a time machine. Now it is possible to study the actual people who participated in the founding of Iceland," adds Agnar Helgason, also from deCODE Genetics, and another of the study's authors.
Iceland, a genetic laboratory
These results provide a detailed view of the origin of a human population, an aspect, according to scientists, which is key to discovering associations of genotype (genetic information in the form of DNA) and phenotype (the expression of the genotype plus the influence of the mean) to continue making advances in finding ways to diagnose, treat and prevent diseases.
"Iceland is big enough for the diseases that affect Europeans to be represented, yet small enough to easily carry out genetic studies which lead to discovering the roots of these complex pathologies. In the not too distant future, we will be able to study the actual individuals who had a certain mutation 1,000 years ago and make a comparison with current patients", concludes the CSIC researcher.

In ancient boulders, new clues about the story of human migration to the Americas

When and how did the first people come to the Americas?

The conventional story says that the earliest settlers came via Siberia, crossing the now-defunct Bering land bridge on foot and trekking through Canada when an ice-free corridor opened up between massive ice sheets toward the end of the last ice age.

But with recent archaeological evidence casting doubt on this thinking, scientists are seeking new explanations. One dominant, new theory: The first Americans took a coastal route along Alaska's Pacific border to enter the continent.

A new geological study provides compelling evidence to support this hypothesis.

By analyzing boulders and bedrock, a research team led by the University at Buffalo shows that part of a coastal migration route became accessible to humans 17,000 years ago. During this period, ancient glaciers receded, exposing islands of southern Alaska's Alexander Archipelago to air and sun -- and, possibly, to human migration.

The timing of these events is key: Recent genetic and archaeological estimates suggest that settlers may have begun traveling deeper into the Americas some 16,000 years ago, soon after the coastal gateway opened up.

The research will be published online on May 30 in the journal Science Advances.

"People are fascinated by these questions of where they come from and how they got there," says lead scientist Jason Briner, PhD, professor of geology in UB's College of Arts and Sciences. "Our research contributes to the debate about how humans came to the Americas. It's potentially adding to what we know about our ancestry and how we colonized our planet."

"Our study provides some of the first geologic evidence that a coastal migration route was available for early humans as they colonized the New World," says UB geology PhD candidate Alia Lesnek, the study's first author. "There was a coastal route available, and the appearance of this newly ice-free terrain may have spurred early humans to migrate southward."

The findings do not mean that early settlers definitely traversed Alaska's southern coast to spread into the Americas: The project examined just one section of the coast, and scientists would need to study multiple locations up and down the coastline to draw firmer conclusions.

Still, the work is exciting because it hints that the seafaring theory of migration is viable.

The bones of an ancient ringed seal -- previously discovered in a nearby cave by other researchers -- provide further, tantalizing clues. They hint that the area was capable of supporting human life at the time that early settlers may have been passing through, Briner says. The new study calculates that the seal bones are about 17,000 years old. This indicates that the region was ecologically vibrant soon after the ice retreated, with resources including food becoming available.

Co-authors on the research included Briner; Lesnek; Charlotte Lindqvist, PhD, an associate professor of biological sciences at UB and a visiting associate professor at Nanyang Technological University; James Baichtal of Tongass National Forest; and Timothy Heaton, PhD, of the University of South Dakota.

A landscape, touched by ice, that tells a story
To conduct their study, the scientists journeyed to four islands within the Alexander Archipelago that lie about 200 miles south/southeast of Juneau.

The team traveled by helicopter to reach these remote destinations. As soon as the researchers arrived, Briner knew that the islands had once been covered by ice.

"The landscape is glacial," he says. "The rock surfaces are smooth and scratched from when the ice moved over it, and there are erratic boulders everywhere. When you are a geologist, it hits you in the face. You know it immediately: The glacier was here."

To pinpoint when the ice receded from the region, the team collected bits of rock from the surfaces of boulders and bedrock. Later, the scientists ran tests to figure out how long the samples -- and thus the islands as a whole -- had been free of ice.

The researchers used a method called surface exposure dating. As Lesnek explains, "When land is covered by a glacier, the bedrock in the area is hidden under ice. As soon as the ice disappears, however, the bedrock is exposed to cosmic radiation from space, which causes it to accumulate certain chemicals on their surface. The longer the surface has been exposed, the more of these chemicals you get. By testing for these chemicals, we were able to determine when our rock surfaces were exposed, which tells us when the ice retreated.

"We use the same dating method for huge boulders called erratics. These are big rocks that are plucked from the Earth and carried to new locations by glaciers, which actually consist of moving ice. When glaciers melt and disappear from a specific region, they leave these erratics behind, and surface exposure dating can tell us when the ice retreated."

For the region that was studied, this happened roughly 17,000 years ago.

The case for a coastal migration route
In recent years, evidence has mounted against the conventional thinking that humans populated North America by taking an inland route through Canada. To do so, they would have needed to walk through a narrow, ice-free ribbon of terrain that appeared when two major ice sheets started to separate. But recent research suggests that while this path may have opened up more than 14,000 years ago, it did not develop enough biological diversity to support human life until about 13,000 years ago, Briner says.

That clashes with archaeological findings that suggest humans were already living in Chile about 15,000 years ago or more and in Florida 14,500 years ago.

The coastal migration theory provides an alternative narrative, and the new study may mark a step toward solving the mystery of how humans came to the Americas.

"Where we looked at it, the coastal route was not only open -- it opened at just the right time," Lindqvist says. "The timing coincides almost exactly with the time in human history that the migration into the Americas is thought to have occurred."

Italy's oldest olive oil discovered in peculiar pot

IMAGE: Chemical analysis conducted on ancient pottery proves olive oil existed in Italy 700 years sooner than what's previously been recorded. view more 

Credit: Polo Regionale di Siracusa per i siti e musei archeologici Museo Paolo Orsi

Olive oil is a staple of Italian cuisine. It's been that way for thousands of years. And new chemical analysis conducted on ancient pottery proves the liquid gold has existed in Italy hundreds of years longer than what anthropologists have previously recorded.

A team of researchers lead by Davide Tanasi, PhD, assistant professor of history at the University of South Florida, carried out chemical analyses to identify the content of a large jar, found in the 90s by Giuseppe Voza during the excavations at the site of Castelluccio. Conservators at the Archaeological Museum of Siracusa restored and reassembled 400 ceramic fragments, resulting in an egg-shaped 3 ½ foot storage container adorned with rope bands and three vertical handles on each side.

At the same architectural site in Castelluccio in Sicily, researchers found two fragmented basins with an internal septum, indicating it was used to keep multiple substances together, but separate, along with a large terracotta cooking plate.

"The shape of this storage container and the nearby septum was like nothing else Voza found at the site in Castelluccio," said Dr. Tanasi. "It had the signature of Sicilian tableware dated to the end of the 3rd and beginning of the 2nd millennium BCE (Early Bronze Age). We wanted to learn how it was used, so we conducted chemical analysis on organic residues found inside."

In the study published in Analytical Methods, Dr. Tanasi tested the three artifacts using techniques traditionally and successfully used on archaeological pottery: Gas Chromatography, Mass Spectrometry and Nuclear Magnetic Resonance. His team found organic residue from all three samples contained oleic and linoleic acids, signatures of olive oil. They conclude the artifacts are from the Sicilian Early Bronze Age due to their location and peculiar shapes.

"The results obtained with the three samples from Castelluccio become the first chemical evidence of the oldest olive oil in Italian prehistory, pushing back the hands of the clock for the systematic olive oil production by at least 700 years," said Tanasi.

The only known identification of chemical signatures of olive oil are from storage jars discovered in southern Italy in Cosenza and Lecce believed to be from the 12th and 11th century BCE (Copper Age).

Wars and clan structure may explain a strange biological event 7,000 years ago

Starting about 7,000 years ago, something weird seems to have happened to men: Over the next two millennia, recent studies suggest, their genetic diversity -specifically, the diversity of their Y chromosomes - collapsed. So extreme was that collapse that it was as if there was only one man left to mate for every 17 women.
Anthropologists and biologists were perplexed, but Stanford researchers now believe they've found a simple - if revealing - explanation. The collapse, they argue, was the result of generations of war between patrilineal clans, whose membership is determined by male ancestors.
The outlines of that idea came to Tian Chen Zeng, a Stanford undergraduate in sociology, after spending hours reading blog posts that speculated - unconvincingly, Zeng thought - on the origins of the "Neolithic Y-chromosome bottleneck," as the event is known. He soon shared his ideas with his high school classmate Alan Aw, also a Stanford undergraduate in mathematical and computational science.
"He was really waxing lyrical about it," Aw said, so the pair took their idea to Marcus Feldman, a professor of biology in Stanford's School of Humanities and Sciences. Zeng, Aw and Feldman published their results May 25 in Nature Communications.
A cultural culprit
It's not unprecedented for human genetic diversity to take a nosedive once in a while, but the Y-chromosome bottleneck, which was inferred from genetic patterns in modern humans, was an odd one. First, it was observed only in men - more precisely, it was detected only through genes on the Y chromosome, which fathers pass to their sons. Second, the bottleneck is much more recent than other biologically similar events, hinting that its origins might have something to do with changing social structures.
Certainly, the researchers point out, social structures were changing. After the onset of farming and herding around 12,000 years ago, societies grew increasingly organized around extended kinship groups, many of them patrilineal clans - a cultural fact with potentially significant biological consequences. The key is how clan members are related to each other. While women may have married into a clan, men in such clans are all related through male ancestors and therefore tend to have the same Y chromosomes. From the point of view of those chromosomes at least, it's almost as if everyone in a clan has the same father.
That only applies within one clan, however, and there could still be considerable variation between clans. To explain why even between-clan variation might have declined during the bottleneck, the researchers hypothesized that wars, if they repeatedly wiped out entire clans over time, would also wipe out a good many male lineages and their unique Y chromosomes in the process.
Computing clans
To test their ideas, the researchers turned to mathematical models and computer simulations in which men fought - and died - for the resources their clans needed to survive. As the team expected, wars between patrilineal clans drastically reduced Y chromosome diversity over time, while conflict between non-patrilineal clans - groups where both men and women could move between clans - did not.
Zeng, Aw and Feldman's model also accounted for the observation that among the male lineages that survived the Y-chromosome bottleneck, a few lineages underwent dramatic expansions, consistent with the patrilineal clan model, but not others.
Now the researchers are looking at applying the framework in other areas - anywhere "historical and geographical patterns of cultural interactions could explain the patterns you see in genetics," said Feldman, who is also the Burnet C. and Mildred Finley Wohlford Professor.
Feldman said the work was a unusual example of undergraduates driving research that was broad both in terms of the academic disciplines spanned - in this case, sociology, mathematics and biology - and in terms of its potential implications for understanding the role of culture in shaping human evolution. And, he said, "Working with these talented guys is a lot of fun."

1,000-year-old mummy found in Peru

A team from the Université libre de Bruxelles's centre for archaeological research (CReA-Patrimoine) has completed a significant excavation in Pachacamac, Peru, where they have discovered an intact mummy in especially good condition. Pachacamac's status as a Pre-Colombian pilgrimage site under the Inca empire. is confirmed by further evidence.

Peter Eeckhout and his team's latest campaign of archaeological excavations has concluded with an exciting surprise: after nine weeks spent exploring the Pre-Colombian site of Pachacamac, in Peru, the researchers from CReA-Patrimoine (ULB Faculty of Philosophy and Social Sciences) have unearthed a mummy in especially good condition. 'The deceased is still wrapped in the enormous funeral bundle that served as a coffin,' points out professor Peter Eeckhout. 'Discoveries like this one are exceptionally scarce, and this mummy is incredibly well preserved. Samples were collected for carbon-14 dating, but the area in which it was discovered and the type of tomb suggest this individual was buried between 1000 and 1200 AD.'

The excavation was carried out as a part of the 'Ychsma' project, named after the region's native people, under the supervision of professor Eeckhout. Three monumental structures were explored during the campaign, including a sanctuary dedicated to the local ancestors. Under Inca rule, in the late 15th century, it appears to have been transformed into a water and healing temple. The archaeologists have discovered many offerings left by worshippers, such as Spondylus shells imported from Ecuador; these are associated with the influx of water during El Niño, and they symbolise fertility and abundance.

Before the Inca settled in the area, the sanctuary included large funerary chambers and numerous mummies, most of which were looted during the Spanish conquest. Miraculously, though, one of the chambers was found intact during the latest round of excavations: this is the funeral chamber that held the mummy. Due to how well it was preserved, the researchers will be able to study it without needing to unwrap the bundle. Together with Christophe Moulherat (Musée du Quai Branly, Paris), they will soon examine the mummy using the latest techniques in medical imaging (X-ray scans, axial tomography, 3D reconstruction, etc.). This will enable them to determine the individual's position, any pathologies they might have suffered from, but also what offerings might be inside the bundle.

The other structures that were excavated are also related to worship: the first one, an Inca monument intended to host pilgrims and rituals, was built in several phases, each identified with a series of offerings such as seashells and precious objects. The last structure explored was probably one of the 'chapels' for foreign pilgrims, referred to by Spanish monk Antonio de la Calancha in his 17th-century description of the site. There, the excavations also uncovered many 'foundation' offerings, including vases, dogs, and other animals, as well as a platform with a hole in the centre, where an idol was likely placed. The complex appears to have been designed around this idol, involved in religious activities with pilgrims.

According to researchers, all these discoveries indicate that Incas made considerable changes to the Pachacamac site, in order to create a large pilgrimage centre on Peru's Pacific coast. 'Deities and their worship played a major part in the life of Pre-Colombian societies,' concludes Peter Eeckhout. 'The Inca understood this very well, and integrated it into how they wielded their power. By promoting empire-wide worship, they contributed to creating a common sense of identity among the many different peoples that made up the empire. Pachacamac is one of the most striking examples of this.'

A shipwreck and an 800-year-old 'made in China' label reveal lost history

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Chinese ceramic bowls in situ at the Java Sea Shipwreck site.

Credit: © The Field Museum, Anthropology, Photographer Pacific Sea Resources

Centuries ago, a ship sank in the Java Sea off the coast of Indonesia. The wooden hull disintegrated over time, leaving only a treasure trove of cargo. The ship had been carrying thousands of ceramics and luxury goods for trade, and they remained on the ocean floor until the 1980s when the wreck was discovered by fishermen. In the years since, archaeologists have been studying artifacts retrieved from the shipwreck to piece together where the ship was from and when it departed. The equivalent of a "Made in China" label on a piece of pottery helped archaeologists reevaluate when the ship went down and how it fits in with China's history.

"Initial investigations in the 1990s dated the shipwreck to the mid- to late 13th century, but we've found evidence that it's probably a century older than that," says Lisa Niziolek, an archaeologist at the Field Museum in Chicago and lead author of the study in the Journal of Archaeological Science: Reports. "Eight hundred years ago, someone put a label on these ceramics that essentially says 'Made in China' -- because of the particular place mentioned, we're able to date this shipwreck better."

The ship was carrying ceramics marked with an inscription that might indicate they were made in Jianning Fu, a government district in China. But after the invasion of the Mongols around 1278, the area was reclassified as Jianning Lu. The slight change in the name tipped Niziolek and her colleagues off that the shipwreck may have occurred earlier than the late 1200s, as early as 1162.

Niziolek notes that the likelihood of a ship in the later "Jianning Lu" days carrying old pottery with the outdated name is slim. "There were probably about a hundred thousand pieces of ceramics onboard. It seems unlikely a merchant would have paid to store those for long prior to shipment -- they were probably made not long before the ship sank," says Niziolek.

Plus, ceramics weren't the only cargo onboard. The ship was also carrying elephant tusks for use in medicine or art and sweet-smelling resin for use in incense or for caulking ships. Both of these materials were critical to re-dating the wreck.

The resins and the tusks come from living things, and all living things contain carbon. A type of carbon atom called C-14 is unstable and decays relatively steadily over time. Scientists can use the amount of C-14 in a sample to determine how old it is. This analysis, known as radiocarbon dating, had been done decades ago and pointed to the shipwreck being about 700-750 years old. However, analytical techniques have improved, and the scientists wanted to see if the date held.

The amount of decayed carbon found in the resins and tusks revealed that the cargo was older than previously thought. When taken together with the place name inscribed on the ceramics, stylistic analysis of ceramics from known time periods, and input from experts overseas, the researchers concluded that the shipwreck was indeed older than previously thought -- somewhere in the neighborhood of 800 years old.

"When we got the results back and learned that the resin and tusk samples were older than previously thought, we were excited," says Niziolek. "We had suspected that based on inscriptions on the ceramics and conversations with colleagues in China and Japan, and it was great to have all these different types of data coming together to support it."

The fact that the Java Sea Shipwreck happened 800 years ago instead of 700 years ago is a big deal for archaeologists.

"This was a time when Chinese merchants became more active in maritime trade, more reliant upon oversea routes than on the overland Silk Road," says Niziolek. "The shipwreck occurred at a time of important transition."

Niziolek also notes the importance of the Java Sea Shipwreck collection. "The salvage company Pacific Sea Resources recovered these artifacts in the 1990s, and they donated them to the Field Museum for education and research. There's often a stigma around doing research with artifacts salvaged by commercial companies, but we've given this collection a home and have been able to do all this research with it. It's really great that we're able to use new technology to re-examine really old materials. These collections have a lot of stories to tell and should not be entirely discounted."

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."