Friday, October 24, 2014

How Ancient DNA Is Rewriting Human History

There are no written records of the most important developments in our history: the transition from hunting and gathering to farming, the initial colonization of regions outside Africa, and, most crucially, the appearance of modern humans and the vanishing of archaic ones.

Our primary information sources about these “pre-historic” events are ancient tools, weapons, bones, and, more recently, DNA. Like an ancient text that has picked up interpolations over the millennia, our genetic history can be difficult to recover from the DNA of people alive today. But with the invention of methods to read DNA taken from ancient bones, we now have access to much older copies of our genetic history, and it’s radically changing how we understand our deep past. What seemed like an episode of Lost turns out to be much more like Game of Thrones: instead of a story of small, isolated groups that colonized distant new territory, human history is a story of ancient populations that migrated and mixed all over the world.

There is no question that most human evolutionary history took place in Africa. But by one million years ago—long before modern humans evolved—archaic human species were already living throughout Asia and Europe. By 30,000 years ago, the archaic humans had vanished, and modern humans had taken their place. How did that happen?

From the results of early DNA studies in the late 1980s and early ’90s, scientists argued that anatomically modern humans evolved in Africa, and then expanded into Asia, Oceania, and Europe, beginning about 60,000 years ago. The idea was that modern humans colonized the rest of the world in a succession of small founding groups—each one a tiny sampling of the total modern human gene pool. These small, isolated groups settled new territory and replaced the archaic humans that lived there. As a result, humans in different parts of the world today have their own distinctive DNA signature, consisting of the genetic quirks of their ancestors who first settled the area, as well as the genetic adaptations to the local environment that evolved later.

This view of human history, called the “serial founder effect model,” has big implications for our understanding of how we came to be who we are. Most importantly, under this model, genetic differences between geographically separated human populations reflect deep branchings in the human family tree, branches that go back tens of thousands of years. It also declares that people have evolutionary adaptations that are matched to their geographical area, such as lighter skin in Asians and Europeans or high altitude tolerance among Andeans and Tibetans. With a few exceptions, such as the genetic mixing after Europeans colonized the Americas, our geography reflects our deep ancestry.

Well, it’s time to scrap this picture of human history. Looking over the stunning new data generated in just the last five years, geneticists Joseph Pickrell at the New York Genome Center and David Reich at Harvard University argue that the genetic record of the first modern humans leaving Africa has long been “overwritten” by later developments. “It is now clear that the data contradict any model in which the genetic structure of the world today is approximately the same as it was immediately following the out-of-Africa expansion,” they write. Present-day geography of human genes is not a good guide to our ancestry.

Pickrell and Reich lay out the case for “a systematic reevaluation of human history” in light of the new genetic data collected with new technologies. Much of this new data comes from recent large-scale collections of human genomes, which provide a much more comprehensive picture of geographical patterns in the DNA of living human populations. But the truly revolutionary findings come from studies that look directly at ancient DNA. Instead of trying to reconstruct our ancient genetic record with only modern sources, scientists can now, in some cases, examine the original source itself. The Neanderthal genome, published in 2010, is the most famous case, but researchers have published many more ancient DNA studies since then. The results are clear: There are very few isolated branches of the human family tree. People in nearly every part of the world are a product of many different ancient populations, and sometimes surprisingly close relationships span a wide geographical distance.

One surprising finding, published in January, is that the traces of European DNA in contemporary Native Americans can’t all be chalked up to the arrival of Christopher Columbus. A team of scientists led by Eske Willerslev at the University of Copenhagen sequenced DNA taken from the bones of a boy who died 24,000 years ago in south-central Siberia. Their results show that this boy was from an ancient population that contributed to the ancestry of both Europeans and Native Americans. Other ancient DNA studies published within the past year include analyses of Stone Age hunter-gatherers and farmers from Scandinavia and Spain, a Bronze-age population from the Ukrainian steppes, and a 12,000-year-old Native American that lived in what is now Western Montana. The story coming out of these genetic studies is still developing, but one feature is clear. As Pickrell and Reich put it, “Human history is not one of stasis.” We can easily see this in written history, which tells why most African Americans and Latinos have a mixed ancestry. The genetic record shows that for the past tens of thousands of years, mixed human ancestry is the rule and not the exception. This finding has implications for the role of evolution in shaping who we are. Genetic adaptations that first evolved in one environment were sometimes brought to other parts of the world with very different environments. This means that we need to be wary about accepting overly simple stories about how present-day people in a particular region carry genes that have evolved to fit their particular niche—those evolved genes may be recent arrivals from somewhere else.

Reading deep human history from the record of our DNA is a tricky business, but it’s also a powerful way to answer some compelling questions about our past—a past that is more surprising and complex than we originally thought.
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White, Michael. 2014. “How Ancient DNA Is Rewriting Human History”. Pacific Standard Magazine. Posted: September 12, 2014. Available online: http://www.psmag.com/navigation/nature-and-technology/ancient-dna-rewriting-human-history-90578/

Thursday, October 23, 2014

Iberian Peninsula endured tropical storms in the 18th century and severe droughts in Islamic times

The first meteorological measurements were taken in the Iberian Peninsula in 1724, which coincides with the year in which Portugal suffered one of the worst storms ever. Later, in 1816, Spain felt the effects of the eruption of the Mount Tambora volcano and almost one thousand years before, in 898, a drought in Al-Andalus was so severe that communities even resorted to cannibalism. These are facts recovered from old documents by researchers at the University of Extremadura.

The official registry for meteorological series began in Spain around 1850, but occasional measurements had already been taken in some areas of the Iberian Peninsula. The initial ones were sent in 1724 by the Portuguese doctor Isaac Sequeira to the British physician James Jurin, who was trying to form a European network of meteorologists, according to documents kept in the Royal Society of London.

"These observations, covering a period between November 1724 and January 1725, are the oldest known on the Peninsula," Fernando Domínguez, from the University of Extremadura (Spain), said, "but even more interesting is what they tell us." The notes taken by the Portuguese doctor describe one of the strongest storms ever recorded in the peninsular region. It passed through Lisbon on 19 November 1724 and affected the entire centre and north of Portugal, damaging palaces, churches and buildings, as well as sinking boats or destroying a number of them on the coast and along the Tagus River.

"The effects of this 'meteorological bomb' the day before (18 November) in Madeira indicates that it was a tropical storm," points out Domínguez. In Spain, we only know of two other storms like this, which are related to hurricanes in the Atlantic: "One in 1842 and a more recent one caused by the Hurricane Vince in 2005, which also took place around Madeira and even reached our coastlines."

The results of this study have been published in the 'Climatic Change' journal, although the authors have also analysed the climatic variability in the Iberian Peninsula at later dates, during the 1750-1850 period. Together with researchers from other universities, they have studied documents from the 18th and 19th centuries, such as newspapers, which were used to publish barometric, temperature, wind and daily weather measurements in their headlines.

Over 100,000 observations from that period taken in 16 towns such as Cadiz, Madrid, Badajoz, Palma de Mallorca, Valencia, Zaragoza, Bilbao, Palencia or La Coruña have been digitalised. This has shown the existence of high rainfall anomalies, such as that of 1780 or the cold period felt throughout Europe the year after the great eruption of the Mount Tambora volcano (Indonesia) in 1815.

But meteorological studies have delved much further into the past. Specifically, the "first serious attempt to obtain climate information from Arab sources in the Iberian Peninsula" has been carried out, outlines José Manuel Vaquero, another of the authors, emphasizing that: "We are talking about the weather in Spain one thousand years ago!."

Arabs occupied the peninsula for a number of centuries, although the team has focused on chronicles available between 711 and 1010. In these texts, Arab historians described political and social events, but sometimes they included articles related to the weather when these were relevant for the community.

"By collecting these events, we can say that there were important droughts in Al-Andalus between the 748-754, 812-823 and 867-879 periods in which we have come across plenty of references to droughts and related famines, which even led to people emigrating to North Africa," states Domínguez.

The scientist points out the most striking reference: "In 898 a drought, that was probably short but extremely severe, led the Andalusians to resort to cannibalism in order to survive, according to some chronicles, although other socio-economic factors or plagues may have also had an influence."

Other information reveals that the climate in Cordoba, one of the most important cities in the world at that time, had more snow and hail during the 971-975 period compared with current averages. This study has been published in the 'The Holocene' journal. "It is important to know about the climate in the past in order to understand the variability of the entire climatic system, which has interacting sub-systems on different levels and goes far beyond the 'official' meteorological records of the last 150 years, which are also affected by the burning of fossil fuels and do not reflect the natural weather variability," according to the authors, who also point out that: "Many of our ancestors' observations are waiting to be rescued from files and libraries."
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Science Daily. 2014. “Iberian Peninsula endured tropical storms in the 18th century and severe droughts in Islamic times”. Science Daily. Posted: September 12, 2014. Available online: http://www.sciencedaily.com/releases/2014/09/140912085316.htm

Wednesday, October 22, 2014

Religion Doesn't Make People More Moral, Study Finds

The moral high ground seems to be a crowded place. A new study suggests that religious people aren't more likely to do good than their nonreligious counterparts. And while they may vehemently disagree with one another at times, liberals and conservatives also tend to be on par when it comes to behaving morally.

Researchers asked 1,252 adults of different religious and political backgrounds in the United States and Canada to record the good and bad deeds they committed, witnessed, learned about or were the target of throughout the day.

The goal of the study was to assess how morality plays out in everyday life for different people, said Dan Wisneski, a professor of psychology at Saint Peter's University in Jersey City, New Jersey, who helped conduct the study during his tenure at the University of Illinois at Chicago.

The study's findings may come as a shock to those who think religious or political affiliationhelps dictate a person's understanding of right and wrong. Wisneski and his fellow researchers found that religious and nonreligious people commit similar numbers of moral acts. The same was found to be true for people on both ends of the political spectrum. And regardless of their political or religious leanings, participants were all found to be more likely to report committing, or being the target of, a moral act rather than an immoral act. They were also much more likely to report having heard about immoral acts rather than moral acts.

However, there were some differences in how people in different groups responded emotionally to so-called "moral phenomena," Wisneski said. For example, religious people reported experiencing more intense self-conscious emotions — such as guilt, embarrassment, and disgust — after committing an immoral act than did nonreligious people. Religious people also reported experiencing a greater sense of pride and gratefulness after committing moral deeds than their nonreligious counterparts.

Liberals and conservatives also tended to think of moral phenomena in different ways. In other words, though they seemed to experience the same amount of moral and immoral acts, they had different ways of talking about these experiences.

"Liberals more often mention moral phenomena related to fairness and honesty," Wisneski said. "Conservatives more often mention moral phenomena related to loyalty and disloyalty or sanctity and degradation."

For three days, participants received five text messages a day that included a link to the study's mobile website, where they could record any moral phenomena that they had experienced in the past hour via their smartphones. On average, participants reported one moral experience per day, Wisneski said.

This approach to studying morality is a far cry from previous studies, most of which have been conducted in a laboratory setting and have focused on studying peoples' responses to hypothetical moral dilemmas, according to Wisneski.

"As far as I know, this is the first study that's used this kind of lived-experience approach to track morality as it's happening," he said.

In the future, Wisneski and his colleagues hope to use their smartphone-enabled approach to study morality in a more nationally representative sample of people, he said. They also think this method could be applied to studying morality in different parts of the world, such as Asia and the Middle East, where religious and political beliefs may have different influences than on people in North America.

The morality study, which was conducted by psychologists at the University of Illinois at Chicago, the University of Cologne, in Germany, and the University of Tilburg, in the Netherlands, was published online today (Sept. 11) in the journal Science.
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Palermo, Elizabeth. 2014. “Religion Doesn't Make People More Moral, Study Finds”. Live Science. Posted: September 11, 2014. Available online: http://www.livescience.com/47799-morality-religion-political-beliefs.html

Tuesday, October 21, 2014

Lost Ship from Ill-Fated Arctic Quest Discovered

In 1845, two doomed British ships set sail for the Canadian Arctic to end a legendary quest for the Northwest Passage to the Pacific Ocean. After the expedition became trapped in ice, both vessels and all 129 men on board were lost. Now, nearly 170 years later, one of the shipwrecks has been found.

Canadian authorities have released sonar images that show the skeleton of one of the two ships lost during the Franklin Expedition. (The voyage was named after the expedition's leader, British Royal Navy officer and explorer John Franklin.) Canadian Prime Minister Stephen Harper said that the discovery "has solved one of Canada's greatest mysteries."

"Although we do not know yet whether the discovery is Her Majesty's Ship (HMS) Erebus or HMS Terror, we do have enough information to confirm its authenticity," Harper said in a statement. "This is truly a historic moment for Canada. Franklin's ships are an important part of Canadian history given that his expeditions, which took place nearly 200 years ago, laid the foundations of Canada's Arctic sovereignty."

The graves of Erebus and Terror jointly had the distinction of being Canada's only undiscovered national historical site. Dozens of search crews have looked for the ships since they went missing. Just since 2008, Parks Canada led six major expeditions to look for the ships, peering at hundreds of square miles of the Arctic seabed with underwater robots and sonar. Success finally came this week for the 2014 Victoria Strait Expedition.

The fate of the Franklin Expedition has been an enduring mystery and fodder for much speculation. The three-masted ships Erebus and Terror had steam engines and iron-reinforced bows to punch through sea ice. The vessels had successfully completed a mission in Antarctica, but they were apparently no match for the ice-choked waterways of the Canadian Arctic.

It's believed that many of Franklin's men died of some combination of exposure to the elements, starvation, scurvy and lead poisoning (possibly from eating poorly canned foods) in the months and weeks after the ships became icebound near King William Island. In the 1850s, Britain was scandalized by reports that some of the crew resorted to cannibalism, based on stories an Inuit relayed to explorer John Rae, according to Canadian Geographic. Archaeologists later found cut marks on skeletal remains of crew members buried in shallow graves in the Arctic, suggesting there might be some truth to those grisly reports.

"The discovery of a Franklin expedition ship raises the possibility that some of the enduring mysteries surrounding the expedition's destruction can be solved," John Geiger, CEO of the Royal Canadian Geographical Society, said in a statement. "It's a wonderful and exciting discovery that promises to shed more light on the ill-fated expedition's final months, weeks and days."
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Gannon, Megan. 2014. “Lost Ship from Ill-Fated Arctic Quest Discovered”. Live Science. Posted: September 10, 2014. Available online: http://www.livescience.com/47776-lost-ship-from-ill-fated-arctic-quest-discovered.html

Monday, October 20, 2014

Islamic State's 'Medieval' Ideology Owes A Lot To Revolutionary France

Over recent weeks there has been a constant background noise that Islamic State and its ideology are some sort of throwback to a distant past. It is often framed in language used last week by the deputy prime minister, Nick Clegg, who claimed that ISIS is “medieval”. In fact, the terrorist group’s thinking is very much in a more modern western tradition.

Clegg’s intervention is not surprising. Given the extreme violence of Islamic State fighters and the frequent images of decapitated bodies, it is understandable that we attempt to make sense of this violence as somehow radically “other”.

But this does not necessarily help us understand what is at stake. Above all, this tends to accept one of the core assertions of contemporary jihadism, namely its claim that it reaches back to the origins of Islam. As one Islamic State supporter I follow on Twitter is fond of saying: “the world changes, Islam doesn’t”.

Generation gap

This is not just a question for academic debate. It has real impact. One of the attractions of jihadist ideology to many young people is that it shifts generational power in their communities. Jihadists and, more broadly, Islamists present themselves as true to their religion, while their parents, so they argue, are mired in tradition or “culture”.

It needs to be said very clearly: contemporary jihadism is not a return to the past. It is a modern, anti-traditional ideology, with a very significant debt to western political history and culture.

When he made his speech in July at Mosul’s Great Mosque, declaring the creation of an Islamic State with himself as its caliph, Abu Bakr al-Baghdadi quoted at length from the Indian/Pakistani thinker, Abul A’la Maududi, the founder of the Jamaat-e-Islami party in 1941 and originator of the contemporary term “Islamic State”.

Maududi’s Islamic State is profoundly shaped by western ideas and concepts. He takes a belief shared between Islam and other religious traditions, namely that God alone is the ultimate judge of a person, and transforms this – reframing God’s possession of judgment into possession of, and ultimately monopoly of, “sovereignty”. 



Maududi also draws upon understandings of the natural world governed by laws that are expressions of the power of God – ideas at the heart of the 17th-century scientific revolution. He combines these in a vision of the sovereignty of God, then goes on to define this sovereignty in political terms, affirming that “God alone is the sovereign” (The Islamic Way of Life). The State and the divine thus fuse together, so that as God becomes political and politics becomes sacred.

Western tradition

Such sovereignty is completely absent in medieval culture, with its fragmented world and multiple sources of power. Its origins lie instead in the Westphalian system of states and the modern scientific revolution.

But Maududi’s debt to European political history extends beyond his understanding of sovereignty. Central to his thought is his understanding of the French Revolution, which he believed offered the promise of a “state founded on a set of principles” as opposed to one based upon a nation or a people. For Maududi this potential withered in France, its achievement would have to await an Islamic state (The Process of the Islamic Revolution). In revolutionary France, it is the state that creates its citizens and nothing should be allowed to stand between the citizen and the state. That is why still today French government agencies are prevented by law from collecting data about ethnicity, considered a potential intermediary community between state and citizen.

This universal citizen, separated from community, nation or history, lies at the heart of Maududi’s vision of “citizenship in Islam” (Islamic Way of Life). Just as the revolutionary French state created its citizens, with the citizen unthinkable outside the state, so too the Islamic state creates its citizens. 



This is at the basis of Maududi’s otherwise unintelligible argument that one can only be a Muslim in an Islamic state.

Modern violence

Don’t look to the Koran to understand this – look to the French Revolution and ultimately to the secularization of an idea that finds its origins in European Christianity: Extra ecclesia nulla salus (outside the church there is no salvation), an idea that became transformed with the birth of modern European states into Extra stato nulla persona (outside the state there is no legal personhood). This idea still demonstrates extraordinary power today, the source of what it means to be a refugee.

If IS’s Islamic State is profoundly modern, so too is its violence. IS fighters do not simply kill. They seek to humiliate as we saw last week as they herded Syrian reservists wearing only their underpants to their death. And they seek to dishonor the bodies of their victims, in particular through postmortem manipulations.

Such manipulations aim at destroying the body as a singularity. The body becomes a manifestation of a collectivity to be obliterated, its manipulation rendering what was once a human person into an “abominable stranger”. Such practices are increasingly evident in war today, from the Colombian necktie to troops trading images of body parts to access pornographic websites during the Iraq war.

Central to IS’s program is its claim to Muslim heritage (witness al-Baghdadi’s dress). Part of countering this requires understanding the contemporary sources of its ideology and its violence. In no way can it be understood as a return to the origins of Islam. 



This is a core thesis of its supporters, one that should not be given any credence at all. 

Nazism wasn’t medieval, nor is Islamic State.
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McDonald, Kevin. 2014. “Islamic State's 'Medieval' Ideology Owes A Lot To Revolutionary France”. Science 2.0. Posted: Available online: http://www.science20.com/the_conversation/islamic_states_medieval_ideology_owes_a_lot_to_revolutionary_france-144430

Sunday, October 19, 2014

China Exclusive: Teenager stumbles on 3,000-year-old bronze sword in river

A child in east China's Jiangsu Province had a stroke of luck after lunging into a river and stumbling upon a 3,000-year-old bronze sword.

Yang Junxi, an 11-year-old boy, discovered upon the rusty sword on July 2 when he was playing near the Laozhoulin River in Linze Township of Gaoyou County, according to the Gaoyou Cultural Relics Bureau.

While washing hands in the river, Yang touched the tip of something hard and fished out the metal sword. He took it home and gave it to his father Yang Jinhai.

Upon hearing the news, people began flocking to Yang's home, the father said.

"Some people even offered high prices to buy the the sword, but I felt it would be illegal to sell the cultural relic," Yang said.

After considering his options, the father sent the sword to the Gaoyou Cultural Relics Bureau on Sept. 3.

The bureau arranged initial identifications on the sword with a joint team of local cultural relics experts on the sword's material, length, shape and other major factors.

Initial identifications found the 26 cm-long yellow-brown sword could be dated back to more than 3,000 years ago, around the time of the Shang and Zhou dynasties, said Lyu Zhiwei, head of the cultural relics office of the bureau.

"There was no characteristic or decorative pattern on the exquisite bronze sword. Made in a time of relatively low productivity, its owner would have been an able man with the qualification to have such artifact," he said.

"The short sword seems a status symbol of a civil official. It has both decorative and practical functions, but is not in the shape of sword for military officers."

It is the second bronze artifact found in the region after a bronze instrument was excavated in the nearby Sanduo Township.

The sword was found in the Laozhoulin River, which crosses the ancient Ziying River which was excavated in the Qin Dynasty (221 BC-206 BC).

It also interlinks the ancient Han Ditch as the "predecessor" of China's Grand Canal, the world's longest artificial waterway with a history of more than 2,400 years.

The 1,794-km canal runs from Beijing to Hangzhou in China's eastern Zhejiang Province. It was entered into the World Heritage list in June 2014.

The city has conducted several rounds of dredging in the Laozhoulin River, which might surface the sword from the river bottom, said Lyu, adding that the township government has prepared a further archeological dig into the river and in the nearby areas.

The relics bureau and municipal museum of Gaoyou City have sent the collection certificates and bonus for the boy and his father in honor of their deeds of protecting and donating cultural relic.
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Yi, Yang. 2014. “China Exclusive: Teenager stumbles on 3,000-year-old bronze sword in river”. Xinhua Net. Posted: September 6, 2014. Available online: http://news.xinhuanet.com/english/sci/2014-09/06/c_133625745.htm

Saturday, October 18, 2014

Analysing Jawoyn rock-art in Arnhem Land

Researchers are working with archaeologists, anthropologists and the Northern Territory’s Jawoyn community to chemically analyse ancient rock art and uncover its secrets.

University of Technology Sydney Associate Professor Barbara Stuart and PhD student Alexandria Hunt are applying sophisticated techniques to understand the materials used by the artists and how their work has changed over time.

“One of my areas of interest has been working with archaeologists and applying chemical and analytical techniques to the study of archaeological problems,” said Associate Professor Stuart.

While chemistry and archaeology are not a usual pairing, Associate Professor Stuart said that chemistry plays an important role in understanding archaeological sites. “We are applying chemistry in an area that is a little less traditional. The chemistry tells you where materials were coming from, what types of materials they used and different practices at different times.”

Visiting rock art sites

Alexandria was working on her honours project in forensic science in 2012 when she was presented with the opportunity to join the team. In June of that year Alexandria and her two supervisors, Associate Professor Stuart and Dr Paul Thomas, visited the rock art sites in Arnhem Land for a week, where they worked with other professionals including archaeologists, environmental scientists, geologists and rock art experts.

“We need to take samples but we try to take as small amount as we can so that we don’t visually alter the paintings at all,” Alexandria said.

“We were blessed before we could go to the sites… they are amazing and you can see how important they are.”

During the trip, the team used a community campsite and worked in collaboration with an Indigenous elder, Aunty Margaret, who was pleased that people were interested in the Jawoyn culture.

“They have been very supportive of the whole process. It was a great privilege to go up and visit the site, which is very isolated,” Associate Professor Stuart said.

“It’s enjoyable from our point of view as scientists working in teams, but it was extra special going to such a historical and spiritual place and working on something that means so much to that community.”

Collaboration important

Alexandria said that the collaboration between specialists and the Indigenous community was important as it provided a fundamental cultural understanding that helped their research.

“We are lucky that there are still Aboriginal people who know about the sites. With chemistry you can link it to their studies and find out a lot more,” she said.

Sample sizes taken from the sites were very small and will be returned after analysis, in accordance with tradition.

“I am running some tests to characterise the pigments,” Alexandria said. “We are looking at what they were actually made from. Once I have that information I’ll be able to work out the age of the paintings.”

The study differs from previous Indigenous site analyses as it accounts for how pigments change over time due to biological processes.

“Traditionally such analyses have been more about elemental analysis, whereas we are looking at more sophisticated techniques to understand the whole of the paint and pigment structure and looking at chemical changes over time,” said Associate Professor Stuart.

Infrared beam

To gain complex data from the samples Alexandria used the infrared beam at the Australian Synchrotron in Melbourne, which provides a powerful light source that enables small samples to be examined with precision. Associate Professor Stuart said that it is only because of such developments in technology that this type of study is possible.

“Our key strength is our quality analytical equipment and that is something that UTS specialises in. I think the field in general is advancing and we are playing a part in that,” she said.

Associate Professor Stuart hopes the project will lead to future collaborations and ongoing work in the field.

“They only rediscovered these indigenous rock art sites about six or seven years ago, almost accidentally, and this is just the tip of the iceberg.”
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Past Horizons. 2014. “Analysing Jawoyn rock-art in Arnhem Land”. Past Horizons. Posted: September 8, 2014. Available online: http://www.pasthorizonspr.com/index.php/archives/09/2014/analysing-jawoyn-rock-art-in-arnhem-land