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      <p>

            <figure class="richtext-image full-width"><img alt="River" class="richtext-image full-width" height="356" width="498"
            src="https://www.pbs.org/wgbh/nova/media/images/red-baron-theories-01.width-800.jpg"/><figcaption>Who put the fatal bullet into the Red Baron as he closed in on Canadian Wilfrid May along the Somme River on April 21, 1918? Theories abound. <div class="credit">&copy; WGBH/NOVA </div></figcaption>
            </figure>
            </p>
<h3>
	Mortally Wounded in Air Combat?</h3>
<p>
	The Royal Air Force (RAF) gave official credit for the Baron's death to No. 209 Squadron's Captain Roy Brown, whose combat report gives only the barest outline of the action: "Went back again and dived on pure red triplane which was firing on Lieut. May. I got a long burst into him and he went down vertical and was observed to crash by Lieut. Mellersh and Lieut. May."</p>
<p>
	In 1927, after gaining access to British Air Ministry files, Floyd Gibbons published a vivid account of Brown's victory in his best-selling popular book, <cite>The Red Knight of Germany.</cite> That same year, a first-person narrative of the action, "My Fight With Richthofen," was published in <cite>Liberty</cite> magazine. Although supposedly in Brown's own words, the article was clearly influenced by Gibbons and embroidered by <cite>Liberty</cite>'s copywriters.</p>
<p>
	While these popular accounts of Brown's attack are of doubtful value, his claim is supported by testimony from another 209 Squadron Captain, O. C. LeBoutillier, and from a few key eyewitnesses on the ground. However, most recent analysts conclude that the attack came at least a minute before the Baron's final crash, probably too early to have inflicted the fatal wound.</p>
<h3>
	Murdered On the Ground?</h3>
<p>
	In 1925, a New York-based magazine called <cite>The Progressive</cite> published an article titled "Richthofen Was Murdered." The article reported rumors circulating in Germany that Richthofen had landed unscathed and that Canadian soldiers had jumped from their trenches and killed the Baron before he could climb out of his triplane. The rumors may have begun when German pilots from the Baron's "circus" reported witnessing the triplane's relatively smooth crash landing; at first, this fueled hopes that the Baron had been captured alive, and later, the speculation that he had been murdered. However, eyewitness accounts by the first ground troops to reach the crash site make this highly implausible.</p>
<h3>
	Chasing Two Sopwith Camels?</h3>
<p>
	In accounts collected in the 1930s, at least three eyewitnesses claimed that the Baron was pursuing <em>two</em> Sopwith Camels at the time he was brought down by ground fire. One of the most detailed of these claims was by Sergeant A. G. Franklyn, who was in charge of an Australian antiaircraft battery and claims to have shot down the Baron with his Lewis gun. Subsequent research has suggested that Franklyn probably confused the Red Baron's demise with his battery's downing of a German airplane the day after the Baron's death in a slightly different location.</p>
<p>

            <figure class="richtext-image full-width"><img alt="Gunner" class="richtext-image full-width" height="363" width="509"
            src="https://www.pbs.org/wgbh/nova/media/images/red-baron-theories-02.width-800.jpg"/><figcaption>Various Allied gunners on the ground claimed to have shot the Baron down. To whom that honor truly belongs will likely never be known. <div class="credit">&copy; WGBH/NOVA </div></figcaption>
            </figure>
            </p>
<h3>
	Shot Down by a Two-Seater?</h3>
<p>
	On the morning of April 21, 1918, the crew of two RE8 observation planes of the Australian Flying Corps' No. 3 Squadron reported a skirmish with two red-nosed Fokker triplanes. The squadron's commanding officer, Major D. V. J. Blake, submitted his squadron's report with other details implying that one of the attackers was Richthofen and that fire by an RE8 observer had brought the Baron down. However, the attack was at too high an altitude and too early to have been connected with the Baron's death. One explanation is that a pair of triplanes from the Baron's "circus," perhaps including the Baron himself, briefly dived on the two RE8s prior to encountering the Sopwith Camels of RAF No. 209 Squadron.</p>
<h3>
	An Unknown Rifleman on the Ground?</h3>
<p>
	P. J. Carisella and James W. Ryan's popular book <cite>Who Killed the Red Baron?</cite>, published in 1969, includes an account by Lieut. R. A. Wood of the 51st Battalion asserting that an unknown gunner from his unit brought down the Baron. "As soon as the planes had passed overhead my platoon opened up with rifle fire, and two sets of [Vickers] machine or Lewis guns on my left opened fire. Richthofen was seen to crash soon after one of these bursts." Another eyewitness interviewed in detail in 1975, Private V. J. Emery of 40th Battalion, supported Wood's claim. Emery believed that an unknown rifleman from Wood's platoon was in a better position to have fired the fatal shot than any of the other gunners in the area.</p>
<h3>
	Shot Down by a Machine Gunner on the Ground?</h3>
<p>
	NOVA's program focuses on the two best-known claims attributing Richthofen's death to machine gun fire from the ground. These were made by two different Australian antiaircraft crews who were stationed on the Morlancourt Ridge. In 1956, Gunner R. Buie, a Lewis gunner of the 53rd Battery, wrote to Australian newspapers about how he and Gunner W. J. Evans had opened fire on a German plane chasing a British one toward their position. "I started firing at the body of the German pilot directly through my peep sight," Buie wrote. "Fragments flew from the plane and it lessened speed. It came down a few hundred yards away." Most researchers reconstruct Buie and Evans' firing position as facing the oncoming triplane, making it unlikely that either could have fired the side-on shot that killed the Baron.</p>
<p>
	Sergeant C. B. Popkin, a Vickers gunner with the 24th Machine Gun Company, was in a more plausible position had he fired, as he claimed, when the Baron gave up chasing May and turned back toward the German lines. According to Popkin's statement recorded soon after the event: "As it came towards me, I opened fire a second time and observed at once that my fire took effect. The machine swerved, attempted to bank and make for the ground, and immediately crashed. The distance from the spot where the plane crashed and my gun was about 600 yards."</p>
<p>
	While Popkin's position seems the best match for the evidence of the Baron's wound, the long range and wide deflection angle required has led some to doubt the plausibility of his claim. Even Popkin himself had doubts; he told the <cite>Brisbane Courier</cite> in 1964 that "I am fairly certain it was my fire which caused the Baron to crash but it would be impossible to say definitely that I was responsible...As to pinpointing without doubt the man who fired the fatal shot the controversy will never actually be resolved."</p>
<p>

            <figure class="richtext-image full-width"><img alt="85 years after" class="richtext-image full-width" height="297" width="567"
            src="https://www.pbs.org/wgbh/nova/media/images/red-baron-theories-03.width-800.jpg"/><figcaption>The Somme River valley today, 85 years after the Baron's demise there launched decades of speculation into his true killer <div class="credit">&copy; WGBH/NOVA </div></figcaption>
            </figure>
            </p>

  



Conflicting eyewitness accounts have led to many possible theories for the Red Baron's death.

How Did the Red Baron Die?





  
      <p>Sixty-six million years ago, the dinosaur age came to an abrupt and cataclysmic end. On that fateful day, a miles-wide asteroid slammed into Earth along the coast of modern Mexico, punching a hole some 20 miles deep and triggering an explosion equivalent to about 10 billion Hiroshima bombs. Fallout from the blast, consisting of tiny particles of melted bedrock raining down from space, heated the global atmosphere to the temperature of a pizza oven. About 75 percent of plant and animal species, including the nonavian dinosaurs, were incinerated or perished from other causes in the aftermath, clearing the way for the rise of birds, mammals and, ultimately, us.</p><p>Now, Robert DePalma, a paleontologist at the Palm Beach Museum of Natural History and a graduate student at the University of Kansas, claims to have unveiled an unprecedented time capsule of this apocalyptic event. Along with an international team of collaborators, DePalma describes the North Dakota site, called Tanis, in a <a href="https://www.pnas.org/content/early/2019/03/27/1817407116">paper published Monday</a> in the journal <i>PNAS</i>.</p>
  

  
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      <p>At Tanis, according to the study, over four feet of mud and sediment buried a dense tangle of species. Among them are scorched tree trunks and hundreds of extraordinarily well-preserved fossil fish, forming a unique snapshot of the first minutes and hours of the catastrophe. “This paper captures in one place, vividly, the devastation of this impact event,” says <a href="https://www.lpi.usra.edu/science/kring/">David Kring</a>, a geologist at Houston’s Lunar and Planetary Institute, who was one of the paper’s reviewers.</p><p>While many experts acknowledge the potential importance of the site, some remain cautious, due in part to the fact that DePalma’s discovery was first announced in a <i>New Yorker</i> article before publication of the peer-reviewed paper. The <i>New Yorker</i> colorfully describes a wealth of other astonishing finds at the site, including dinosaur fossils, feathers, ant nests, mammal burrows, and even a pterosaur egg containing an intact embryo, none of which are mentioned in the <i>PNAS</i> paper. DePalma <a href="https://www.nytimes.com/2019/03/29/science/dinosaurs-extinction-asteroid.html">told<i> The New York Times</i></a> that the initial paper was intended to establish the site’s chronology, and that publication of the dinosaurs and other finds would be forthcoming.</p>
            <figure class="richtext-image full-width"><img alt="14.jpg" class="richtext-image full-width" height="550" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/14.width-800.jpg"/><figcaption><p>A mass of fossilized fish from the Tanis site in North Dakota. Image courtesy of Robert DePalma, University of Kansas</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>Dinosaurs aside, the evidence described in the paper is certainly remarkable. Tanis lies within the Hell Creek Formation, one of the few locations in North America with a sequence of rock layers that straddles the final two million years of the Cretaceous period and the transition to the Paleogene and the rise of mammals. Hell Creek is famous for its exquisitely preserved fossils, including leaves that look freshly fallen. But the Tanis site holds a graveyard unlike anything unearthed before.</p>
  

  
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      <p>At the time of the asteroid impact, Tanis was a sandy bar in a meandering river that flowed into the Western Interior Seaway, a huge inland sea that split North America nearly in two. In the scenario outlined in the paper, the impact sent a pair of powerful waves at least 30 feet high surging over the site, while glassy beads of molten bedrock, called tektites, hailed down from the sky. Fragments of seafaring creatures were swept into the Tanis mud, including the teeth of ancient sharks and the shells of ocean-dwelling ammonites, which resemble today’s nautili.</p><p>In startling contrast, a mass of freshwater bottom-feeding fishes, including sturgeon and six-foot-long paddlefish, are strewn in chaos among a logjam of fossilized branches, their heads pointed seawards against the powerful flow of the incoming torrent. The gills of over half the fish are clogged with tiny tektites that had fallen from the sky and then sunk through the water, suggesting that the glassy, millimeter-sized beads—or the turbulence of the saltwater surge—might have killed the fish. Some of the bigger tektites penetrate multiple layers of sediment, hinting that they pelted still-sloshing waters as they fell; others were captured by sticky amber tree resin on downed branches and trunks.</p><p>“Just the idea of fish with impact particles stuck in their gills from 66 million years ago, and trees with amber with impact particles, it’s so extraordinary that you do a double take for sure,” Matthew Lamanna, a vertebrate paleontologist at the Carnegie Museum of Natural History in Pittsburgh who was not involved with the research, <a href="https://www.nytimes.com/2019/03/29/science/dinosaurs-extinction-asteroid.html">told <i>The New York Times</i></a>. “With the caveat that what they’re trying to show is really, really hard to show, I think they’ve done an excellent job of making that case.”</p><p>Tanis is certainly not the first site to capture the close of the Cretaceous. But in preserving what appears to be an entire ecosystem caught up in the catastrophe, it hints strongly at the wide-reaching and instantaneous devastation spurred by the asteroid’s arrival.</p><p>“I certainly was approaching it from a place of skepticism, but to be honest, having read through the paper, I’d be personally hard-pressed to come up with an alternate explanation,” Victoria Arbour, paleontology curator at the Royal B.C. Museum, who was not involved with the study, <a href="https://www.nationalgeographic.com/science/2019/03/fossils-found-from-day-dinosaurs-died-chicxulub-tanis-cretaceous-extinction/">told Michael Greshko at <i>National Geographic</i></a>.</p>
            <figure class="richtext-image full-width"><img alt="41.jpg" class="richtext-image full-width" height="518" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/41_MvoQJHJ.width-800.jpg"/><figcaption><p>A microscope slide containing tektites from the Tanis site. Image courtesy of Robert DePalma, University of Kansas</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>The evidence presented so far is primarily geological, but the findings described in the paper seem “very credible,” says Steve Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study. Given the “disconnect” between the paper and the <i>New Yorker</i> article, however, only time will tell what the site has to offer with regards to the demise of the dinosaurs, he says. “This is a very exciting discovery,” Brusatte says, “but there’s still a real mystery about the site.”</p><p>At Tanis, the mud layers containing the fossils are capped by a thin clay veneer rich with iridium, an element abundant in meteorites, but relatively rare on Earth. This and many other lines of evidence link the site directly to the asteroid impact, but the question of how pivotal a role the catastrophe played in the mass extinction will still stoke debate. Other scientists have theorized that, due to prolonged volcanic activity or climate fluctuations toward the end of the Cretaceous, the world of the dinosaurs might already have been in a fragile state.</p><p>“We get a snapshot of what happened, catastrophically, in this part of the world,” Kring says. But, he adds, the evidence so far “doesn&#x27;t really lend itself to a broader understanding of the mass extinction event, because killing a few organisms in this part of the world wouldn’t have caused the global extinction. Nonetheless, it paints a fascinating picture of what happened in this part of the world.”</p>
  

  
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Kylie Ruble and Robert DePalma excavate fossils from the Tanis site. Image courtesy of Robert DePalma, University of Kansas

<p>Fossils uncovered in North Dakota appear to preserve the catastrophic fallout of the asteroid impact that wiped out the dinosaurs–but experts remain cautious.</p>

New Fossils Might Capture the Moment of Mass Extinction That Wiped Out the Dinosaurs





  
      <section class="entry-content instapaper_body clearfix" itemprop="articleBody">
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 <p>
  The divers could scarcely believe their eyes.
 </p>
 <p>
  Swimming deep into a vast, pitch-dark underwater pit in a Yucatan cave, lead diver Alberto Nava felt like he was in “an outer space black hole.” Then their headlamps shone on a huge trove of ancient fossils scattered across the floor of the flooded pit. These included parts of over 30 animal skeletons, many of them extinct Ice Age megafauna such as saber-tooth cats and huge Shasta ground sloths. Preserved 130 feet down in cool water, the ancient bones were in pristine condition.
 </p>
 <p>
  But the real prize was an incredible rarity: the nearly intact skull and skeleton of one of the earliest humans in the Americas. The bones belonged to a teenage girl of around 16 who had fallen to her death in the pit at the end of the last Ice Age some 13,000 years ago. Barely half-a-dozen other human remains in the New World date back so far.
 </p>
 
            <figure class="richtext-image full-width"><img alt="Naia-diver" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/naia-diver.width-800.jpg"/><figcaption>
  The challenging dig deep in a cave in Mexico revealed new information about the First Americans. Photo: Roberto Chávez.
 <div class="credit"></div></figcaption>
            </figure>
            
 <p>
  The team named her Naia, after a water nymph in Greek mythology. As told in NOVA’s “First Face of America,” Naia’s skeleton was so complete that scientists are able to reconstruct her life and death in intimate detail and add a crucial new piece to the long-standing puzzle about when and how humans first populated the Americas.
 </p>
 <p>
  There was one serious problem, though: the 130-foot deep Hoyo Negro—“Black Hole”—was accessible only to highly experienced cave divers who could stay down in the flooded pit for no more than 90 minutes at a time. With such limitations, how could scientists properly map the cave, study the unique fossils in place, and then systematically retrieve them?
 </p>
 <p>
  The answer was a state-of-the art, high-resolution 3D virtual reality space also known as a
  <a href="http://hoyonegro.ucsd.edu">
   CAVE (Cave Automatic Virtual Environment)
  </a>
  that scientists could walk into, map and measure the fossils, and plan future diving missions. It was created by the University of California at San Diego’s
  <a href="http://chei.ucsd.edu">
   Cultural Heritage Engineering Initiative (CHEI)
  </a>
  , a lab dedicated to applying high end digital tools to analyzing and preserving evidence from the past. Archaeologist Dominique Rissolo, a lead member of the CHEI team, says that its aim is to take “an underwater archaeological site topside, so archaeologists and paleontologists can spend time looking at the relationships between a particular bone and another bone, for example.
 </p>
 <p>
  “If we can document all the fossils, make a photo map of the bottom of the pit, and create a 3D visualization that puts the archaeologists and paleontologists there without ever getting wet, those discoveries and interpretations are made possible.”
 </p>
 <p>
  The 3D virtual cave depended not only on high-tech ingenuity, but on the courage and dedication of Alberto Nava and his team. Since Hoyo Negro’s discovery in 2007, Nava has led repeated, risky missions back to the submerged pit. Team photographer Roberto Chávez has shot thousands of photos at every scale and angle to provide the raw data for the 3D cave. The CHEI team uses then uses what’s known as structure-from-motion photogrammetry software to track and line up features in the different photos. Using that information, the software then stitches the photos together to form the 3D model. It’s similar in principle to how our own eyes and brains determine the structure of objects in the real world. In areas around key fossils, the images have a resolution of less than a millimeter.
 </p>
 <p>
  The virtual model has transformed the sleuthing, according to archaeologists James Chatters and Pilar Luna of Mexico’s National Institute of Anthropology and History. The duo is co-directing the investigation. “The model is hugely important,” Chatters says. “You can resolve details that are simply not visible in normal photographs, and spot things that even the divers can’t see. We can peer in between and behind rocks that divers can’t do because of all the gear they’re wearing.”
 </p>
 
            <figure class="richtext-image full-width"><img alt="naia-virtual-cave" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/naia-virtual-cave.width-800.jpg"/><figcaption>
  Lead diver Alberto Nava inside the virtual cave. Photo: Dominque Rissolo
 <div class="credit"></div></figcaption>
            </figure>
            
 <p>
  Poring over images from the latest dive inside the computer cave, team members spotted bones from a pair of fossil bobcats and a coatimundi hidden behind rocks that “you could never have seen by just swimming around,” he says.
 </p>
 <p>
  Not only is the virtual cave essential for a comprehensive fossil inventory, Chatters says, it enables the team to take measurements and print accurate 3D replicas of specific bones, including Naia’s skull. Before divers finally retrieved the skull from the cave, the model helped Chatters design a padded box of exactly the right size to prevent damage during its journey to the surface.
 </p>
 <p>
  The most recent National Geographic-funded mission to the cave in November and December 2017—the result of intricate planning inside the virtual cave—was phenomenally productive. The team brought up parts of eleven animals, including bobcats, a previously unknown species of ground sloth, and rare limb bones of two Shasta ground sloths, not to mention two saber tooth cats, three bears, and a lot more.
 </p>
 <p>
  “It was a whole menagerie of creatures that we were able to target carefully beforehand, based on their research value,” Chatters says. “We’re busy narrowing down the age represented by the animals, but it’s pretty clear they could span at least 20,000 years of the last Ice Age.”
 </p>
 <p>
  Back then, sea levels were appreciably lower and most of the cave system was dry. Chatters thinks the animals—and Naia, too—were probably drawn to the cave to find water, then got lost in the dark and tumbled into the deep pit. “You just don’t see sites as rich as this. We don’t have as many fossils as the La Brea tar pits but ours are in almost perfect condition,” Chatters adds. “And we don’t have the tar.”
 </p>
 <p>
  The discovery of Hoyo Negro’s fossil treasures has come at a key moment in our understanding of the First Americans. Converging clues from genetics and archaeology are bringing new clarity to contentious debates about the timing and origins of their entry into the continent.
 </p>
 <p>
  Geneticists successfully extracted mitochondrial DNA, a significant indicator of ancestry passed down only through the female line, from one of Naia’s wisdom teeth. The results of that work confirm
  <a href="http://www.sciencemag.org/news/2018/01/ancient-americans-arrived-single-wave-alaskan-infants-genome-suggests">
   other recent findings
  </a>
  that suggest today’s Native Americans can trace their heritage to a single founding population somewhere on the Bering land bridge around 25,000 years ago. Eventually, this population began spreading south around 14, 000 years ago as the ice sheets retreated, opening up the new continent to the first humans. Naia’s people were relative newcomers in a very new world.
 </p>
</section>

  

  
      Photo credits: Roberto Chávez, Dominique Rissolo

  



How VR Helped Archaeologists Excavate a Fossil-Rich Submerged Cave





  
      <p>
	Neanderthals died out just as our species—<em>Homo sapiens</em>—spreading from Africa, arrived around 40,000 years ago. If the claim is correct, it helps cast doubt on previous assumptions that Neanderthals lacked the abilities of modern humans to plan ahead, innovate, and communicate through language, art, and symbolism. There is a growing weight of evidence that we may have underestimated Neanderthal skills and behavior, and that they were not the lumbering, dim-witted cartoon cavemen of popular legend. At the same time, many questions remain contentious—for instance, whether Neanderthals had language, intentionally buried their dead, or regularly used mineral pigments to decorate their bodies.</p>
<h3>
	Ingenious and Industrious</h3>
<p>
	The claim investigated by NOVA is that Neanderthals invented a glue essential to producing their most formidable hunting weapon, a flaked stone spear tip fitted to a wooden shaft. They attached the stone to the shaft by winding animal sinew or some other type of binding around the joint and then smearing glue over it. Discoveries at Neanderthal sites in Syria and Romania show that, to obtain glue, they sometimes used natural deposits of bitumen or asphalt, in one case, fetched from over a dozen miles away. At the Syrian site, the bitumen had been heated up to make the thick liquid easier to apply.</p>
<p>
	{{cove--1--}}</p>
<p>
	At other sites, the Neanderthals subjected sticky substances to a much more elaborate process. Birch bark contains a tacky resin known as pitch that is impossible to extract simply by tapping into the tree, as with pinesap or maple syrup. Instead, the pitch must be separated from the bark by a process known as dry distillation. Chemists have discovered that distilling pitch from birch bark requires an oxygen-free environment and sustained temperatures of over 650° F. How could Neanderthals, with their Stone Age technology, have produced such conditions? If they really did master this complex process, it is hard to resist the conclusion that they must have had language and a sophisticated ability to think and plan ahead.</p>
<blockquote>
	Two small, hardened lumps of black material were found during the dig, one bearing a fingerprint and the other the impression of a wooden haft or handle.</blockquote>
<p>
	Evidence indicates that they successfully developed such a technique. The first discovery was made in 1963 at Kínigsaue, in then-East Germany. This was the site of an ancient lakeside hunting camp, from which Neanderthals had hunted now extinct Ice Age creatures such as mammoth and woolly rhino as well as red deer, horses, and reindeer. Two small, hardened lumps of black material were found during the dig, one bearing a fingerprint and the other the impression of a wooden haft or handle.</p>
<p>

            <figure class="richtext-image full-width"><img alt="One use of birch bark pitch glue" class="richtext-image full-width" height="394" width="672"
            src="https://www.pbs.org/wgbh/nova/media/images/defy-stereotypes-02.width-800.jpg"/><figcaption>Neanderthals used their manufactured glue to secure stone spearheads to wooden shafts.<div class="credit">WGBH Educational Foundation</div></figcaption>
            </figure>
            </p>
<p>
	In 2001, the lumps were dated to at least 40,000 years ago and were shown to have the chemical signature of birch bark pitch produced by the dry distillation process. Much older evidence was found at the Campitello quarry in central Italy. Here, the remains of an extinct elephant lay close to two large lumps of black pitch, which covered the end of two stone flakes crafted in a typical Neanderthal style. The Campitello find dates back over 200,000 years, a remarkably early origin for this complex process. A third Neanderthal site at Inden-Altdorf, overlooking the Inde River in Germany and dating to around 128,000 to 115,000 years ago, features more than 80 stone tools flecked with black material, but the chemical analysis indicating that this was distilled pitch requires further confirmation.</p>
<h3>
	Before Their Time</h3>
<p>
	Pitch production only began on a large scale in Europe during the Middle Ages, around 1,000 years ago. Pieces of birch bark were typically rolled up inside a double-walled clay pot, which was sealed to exclude the air and placed in a kiln or fireplace. But the process was known in Europe long before that. The famous 5,300 year-old "Iceman," nicknamed ítzi—a naturally mummified body found in 1991 on a high mountain pass in the Tyrolean Alps—carried some 20 items of equipment, including a copper axe and flint-tipped arrows. Birch bark pitch was used to glue the axe to a handle carved from yew, while the arrowheads were bound and glued to shafts made from shoots of the <em>Viburnum</em> tree. In addition, ítzi carried some of his gear in two bark containers, so during ítzi's time, birch bark was evidently a versatile and important material.</p>
<p>
	Special clay vessels like those used in the Middle Ages have not been found in ítzi's era, nor did pottery exist in Neanderthal times. But the archaeologists at Inden-Altdorf found an important clue: upon analyzing the pitch smeared on Neanderthal tools at the site, they detected traces of potassium, sulfur, and calcium, evidence that the material had been directly exposed to fire and ash during its manufacture. After some practical experiments, the team proposed that the Neanderthals had invented the following procedure: first, wrap a long strip of birch bark around a small pebble so that it forms a cigar-shaped roll. Next, dig a narrow pit, then set light to one end of the roll and place the burning end at the bottom of the pit. In the confined space at the bottom of the pit, the smoldering bark quickly uses up oxygen and causes the pitch to "sweat," or condense, out of the roll of bark onto the surface of the pebble. While still hot, the pitch is a sticky liquid that can be used immediately as glue.</p>
<blockquote>
	"Neanderthals were very capable pyrotechnologists."</blockquote>
<p>
	Simple though it sounds in theory, the technique is highly challenging in practice. Although German experimental archaeologist Friedrich Palmer succeeded in earlier published experiments, in the NOVA program, he fails to produce more than a thin smear of pitch. In 2010, another team reported success by a variation on the technique: lay strips of bark on a flat stone surface, cover them with a couple of inches of sand to exclude oxygen, then build a fire on top. After a little over an hour, the team dug up the stone and found that enough pitch had dripped onto its surface to haft two or three spears or tools. However, the team succeeded easily on their first attempt only because they had a thermometer to judge if the fire was hot enough. Without such an aid, managing the fire proved very difficult, particularly in windy weather. Even with a windbreak, it required multiple attempts over many days to achieve success.</p>
<h3>
	Tight Tolerances</h3>
<p>
	Whatever technique is used, procuring pitch today with Stone Age methods obviously calls for careful attention and considerable skill and judgment. Too low a temperature, and the bark fails to produce any pitch; too high, and the bark becomes hard and brittle; with too much oxygen, the bark burns up. As the experimental tests have shown, the temperature of the fire must be constantly monitored in varying wind conditions, the birch bark must be buried correctly with oxygen excluded and removed from the fire at the right time. Archaeologist Wil Roebroeks, who witnessed Palmer's NOVA experiment, comments that its failure underscores the complexity of the process, which "goes to show that they [the Neanderthals] were very capable pyrotechnologists. We're still learning how they did it a quarter of a million years ago."</p>
<p>
	Roebroeks adds that the significance of the Neanderthal pitches should not be overblown. "After all, they were produced by hunter-gatherers who survived in western Eurasia for hundreds of thousands of years in a wide variety of environments, successfully exploiting a wide range of mammals and other resources...That they discovered a trick or two which we are unable to reproduce nowadays should not come as a surprise—unless of course one assumes that they were 'complete idiots,' lacking the flexibility and learning capacities of other primates."</p>
<p>
	While Roebroeks warns about making too much of the glue finds, for other archaeologists, the mere fact that Neanderthals could make multi-part tools and weapons argues that they were capable of planning in depth, coordinating several tasks at once, and conceptualizing past and future. No single category of evidence can decide the case for the status of the Neanderthal mind, but the intriguing story of birch bark pitch joins a growing list of discoveries that indicate we may have underestimated the closeness of our bond with our long-vanished relatives from the Ice Age.</p>

  



A type of manufactured glue found on stone tools suggests Neanderthals were more advanced than previously thought.

Neanderthals Defy Stereotypes





  
      <p>

            <figure class="richtext-image full-width"><img alt="Arial View of Ship" class="richtext-image full-width" height="326" width="432"
            src="https://www.pbs.org/wgbh/nova/media/images/viking-ships-01.width-800.jpg"/><figcaption>With their invention of the longship, the Vikings spurred a literal sea change in medieval European affairs.<div class="credit">&copy; Svergies TV</div></figcaption>
            </figure>
            </p>
<p>
	The <em>drekar,</em> or dragon-headed longships, were stealthy troop-carriers. They could cross the open oceans under sail and then switch to oars for lightning-fast hit-and-run attacks on undefended towns and monasteries. Far surpassing contemporary English or Frankish vessels in lightness and efficiency, longships carried Viking raiders from northern England to north Africa.</p>
<p>
	Viking expertise in naval craftsmanship soon led to the evolution of other types of ship. Among these were the <em>knarr,</em> or ocean-going cargo vessel, which facilitated far-flung trade networks and the colonization of Iceland, Greenland, and America. The <em>knarr</em> drew on similar design principles as the longship but was higher and wider in relation to its length and had only limited numbers of oars to assist with maneuvers in narrow channels. Cargo decks were installed fore and aft.</p>
<h3>
	Proof in the planking</h3>
<p>
	The secret of the Viking ship lay in its unique construction. Using a broad ax rather than a saw, expert woodworkers would first split oak tree trunks into long, thin planks. They then fastened the boards with iron nails to a single sturdy keel and then to each other, one plank overlapping the next. The Vikings gave shape to the hull using this "clinker" technique rather than the more conventional method of first building an inner skeleton for the hull.</p>
<p>
	Next, the boatbuilders affixed evenly spaced floor timbers to the keel and not to the hull; this insured resilience and flexibility. They then added crossbeams to provide a deck and rowing benches, and secured a massive beam along the keel to support the mast.</p>
<p>

            <figure class="richtext-image full-width"><img alt="Ship in Room" class="richtext-image full-width" height="446" width="590"
            src="https://www.pbs.org/wgbh/nova/media/images/viking-ships-02.width-800.jpg"/><figcaption>Discovered in Norway in 1906, the Oseberg ship, the best preserved Viking ship ever found, reveals its Norse shipbuilders' graceful construction style.<div class="credit">&copy; Svergies TV</div></figcaption>
            </figure>
            </p>
<p>
	The longships' light, economic construction was a major factor behind their success. Modern replicas have achieved speeds of up to 14 knots. In marked contrast to modern sailboats, the ships' lack of a big, vertical keel meant that they were highly maneuverable and could easily penetrate shallow surf and river estuaries. Seafarers steered using a single side rudder on the right, the 'starboard' or "steering board" side. (The term 'starboard' is thought to have originated in the Viking era.) They could also reef the square sails in strong winds and adjust them to permit rapid tacking.</p>
<h3>
	Preserved to the present</h3>
<p>
	Famous discoveries of Viking ships at Gokstad and Oseberg, Norway, in 1880 and 1906, respectively, established the classic image of the dragon-headed warship. Longships from both sites were preserved almost intact, with lavish carved decoration, in the waterlogged clay of royal burial mounds. Built around A.D. 890, three quarters of a century after the Oseberg ship, the Gokstad vessel shows great improvements in design, particularly in the sturdiness of the mast supports. Not surprisingly, this era, during which the Norse perfected longship design, coincides with the eruption of seaborne Viking raids on the monasteries and towns of Europe.</p>
<p>

            <figure class="richtext-image full-width"><img alt="ships in bay" class="richtext-image full-width" height="460" width="606"
            src="https://www.pbs.org/wgbh/nova/media/images/viking-ships-03.width-800.jpg"/><figcaption>Astoundingly, a veritable flotilla of sunken Viking vessels turned up on the grounds of the very museum being built to house other Viking boats.<div class="credit">&copy; Svergies TV</div></figcaption>
            </figure>
            </p>
<p>
	The modern phase of Viking ship investigation began with the recovery of five vessels at Skuldelev in Roskilde fjord, Denmark, between 1957 and 1962. The excavation involved building a coffer dam around the ships, which Norsemen deliberately sunk in a desperate bid to barricade the fjord against invaders.</p>
<p>
	The major revelation at Skuldelev was the variety of the vessels, which ranged from a stocky cargo ship with a capacity of 24 tons to two sleek longships. The larger of the longships, measuring 95 feet in length, had made at least one successful crossing of the North Sea, for <a href="http://www.pbs.org/wgbh/nova/vikings/treering.html">tree-ring analysis</a> of its oak timbers revealed that they had been cut down around A.D. 1060-70 near Dublin, suggesting the presence of a major shipyard at this key Viking stronghold in Ireland.</p>
<p>
	Even more remarkable discoveries were to follow in 1996, when contractors began expanding Roskilde's waterfront museum, originally built to house the finds from Skuldelev. As astonishing as it sounds, no fewer than nine wrecked medieval ships eventually turned up in different spots around the building site, including one under the museum's car park.</p>
<h3>
	A stunning find</h3>
<p>
	The most striking discovery was the biggest longship yet found, 119 feet long, with room for at least 72 oars and a crew of 100. With its draft of only about three feet and a huge, 2,175-square-foot sail, the ship must have been swift and formidable. The excavators speculate that this ship, like the others in Roskilde harbor, may have gone down in a severe storm, then become hidden in silt. Tree-ring analysis of the high-quality oak used for its timbers suggests a construction date of around A.D. 1025.</p>
<p>

            <figure class="richtext-image full-width"><img alt="tapestry" class="richtext-image full-width" height="434" width="589"
            src="https://www.pbs.org/wgbh/nova/media/images/viking-ships-04.width-800.jpg"/><figcaption>A detail from the Bayeux Tapestry, which commemorates the Norman invasion of England<div class="credit">&copy; WGBH Educational Foundation  </div></figcaption>
            </figure>
            </p>
<p>
	Countless sailing experiments with replica ships continue to confirm the excellence of Viking ship design. Much less is known about Viking navigation methods on the high seas, although one of the Icelandic sagas—narratives of Norse history and legends written in Iceland in the 12th and 13th centuries—includes sailing directions from Norway to Greenland that rely on distant landmarks and the presence of birds and whales to signal the position of land. The Vikings had no compass but undoubtedly steered by the sun and stars.</p>
<p>
	Did they have other aids? The sagas contain intriguing references to a <em>solarsteinn</em> or 'sunstone' used for navigation. Scholars believe it possible this stone was feldspar, a mineral found in Iceland that polarizes light. Theoretically, a polarizing stone might have helped indicate the direction of the sun when clouds obscured the view. Its practicality is doubtful, however, since it would require some blue sky to work and would thus have proved useless in total overcast.</p>
<p>

            <figure class="richtext-image full-width"><img alt="inside ship" class="richtext-image full-width" height="431" width="578"
            src="https://www.pbs.org/wgbh/nova/media/images/viking-ships-05.width-800.jpg"/><figcaption>Did the Vikings, as the sagas suggest, really use a sun compass for navigation? If so, what form did it take?<div class="credit">&copy; WGBH Educational Foundation</div></figcaption>
            </figure>
            </p>
<p>
	The evidence for a so-called "suncompass" is equally shaky. Some have viewed a fragment of a small wooden disk found in a Greenland monastery as a kind of bearing dial for finding north and south. The disk has a hole in its center, and the theory suggests that it originally fitted over a central pin or gnomon to cast a shadow. Markings around the edge of the disk could then have helped the navigator determine north-south. While similar modern devices do work successfully (as seen in the NOVA program "The Vikings"), many have questioned if the Greenland disc was actually used in this way. It is less than three inches across and the markings around the perimeter are so crudely carved as to make the interpretation doubtful.</p>
<h3>
	"The towered ships"</h3>
<p>
	The impression that a Viking fleet must have made under full sail can scarcely be imagined today, but a rhapsodizing monk at the monastery of St. Omer, France, tried his best to evoke the sailing of the royal Danish fleet in A.D. 1013:</p>
<p class="article-indent article-quote">
	When at length they were all gathered, they went on board the towered ships...On one side lions molded in gold were to be seen on the ships, on the other birds on the tops of the masts indicated by their movements the winds as they blew, or dragons of various kinds poured fire from their nostrils...But why should I now dwell upon the sides of the ships, which were not only painted with ornate colors but were covered with gold and silver figures?...The blue water, smitten by many oars, might be seen foaming far and wide, and the sunlight, cast back in the gleam of metal, spread a double radiance in the air.</p>

  



How did longships and other vessels help the Norsemen navigate distant waters so successfully?

Secrets of Viking Ships





  
      <p>
	If Kristof's supposition is correct, then this remote African outpost retains an echo of one of history's most astonishing episodes of maritime exploration.</p>
<p>

            <figure class="richtext-image full-width"><img alt="painting of zheng he" class="richtext-image full-width" height="447" width="672"
            src="https://www.pbs.org/wgbh/nova/media/images/ancient-chinese-explorers-01.width-800.jpg"/><figcaption>In the 15th century, Zheng He, seen here with one of his massive ships in a painting at a temple shrine in Malaysia, led seven enormous seafaring expeditions.<div class="credit">&copy; Chris Hellier/Corbis</div></figcaption>
            </figure>
            </p>
<h3>
	An Oriental armada</h3>
<p>
	Six centuries ago, a mighty armada of Chinese ships crossed the China Sea, then ventured west to Ceylon, Arabia, and East Africa. The fleet consisted of giant nine-masted junks, escorted by dozens of supply ships, water tankers, transports for cavalry horses, and patrol boats. The armada's crew totaled more than 27,000 sailors and soldiers. The largest of the junks were said to be over 400 feet long and 150 feet wide. (The <em>Santa Maria,</em> Columbus's largest ship, was a mere 90 by 30 feet and his crew numbered only 90.)</p>
<p>
	Loaded with Chinese silk, porcelain, and lacquerware, the junks visited ports around the Indian Ocean. Here, Arab and African merchants exchanged the spices, ivory, medicines, rare woods, and pearls so eagerly sought by the Chinese imperial court.</p>
<p>
	Seven times, from 1405 to 1433, the treasure fleets set off for the unknown. These seven great expeditions brought a vast web of trading links—from Taiwan to the Persian Gulf—under Chinese imperial control. This took place half a century before the first Europeans, rounding the tip of Africa in frail Portuguese caravels, "discovered" the Indian Ocean.</p>
<p>

            <figure class="richtext-image full-width"><img alt="Santa Maria &amp; Nina ships" class="richtext-image full-width" height="448" width="672"
            src="https://www.pbs.org/wgbh/nova/media/images/ancient-chinese-explorers-02.width-800.jpg"/><figcaption>Columbus's ships <em>Santa Maria</em> (foreground) and <em>Nina</em> would have appeared pint-sized next to Zheng He's largest vessels.<div class="credit">&copy; Dorling_Kindersley/iStockphoto</div></figcaption>
            </figure>
            </p>
<p>
	With unrivaled nautical technology and countless other inventions to their credit, the Chinese were now poised to expand their influence beyond India and Africa. Here was one of history's great turning points. Had the Chinese emperors continued their huge investments in the treasure fleets, there is little reason why they, rather than the Portuguese, Spanish, Dutch and British, should not have colonized the world. Yet less than a century later, all overseas trade was banned, and it became a capital offense to set sail from China in a multi-masted ship. What explains this astonishing reversal of policy?</p>
<h3>
	Roots of Chinese seapower</h3>
<p>
	The first Chinese oceangoing trade ships were built far back in the Song dynasty (c. 960-1270). But it was the subsequent Mongol emperors (the Yuan dynasty of c. 1271-1368) who commissioned the first imperial treasure fleets and founded trading posts in Sumatra, Ceylon, and southern India. When Marco Polo made his famous journey to the Mongol court, he described four-masted junks with 60 individual cabins for merchants, watertight bulkheads, and crews of up to 300.</p>
<p>

            <figure class="richtext-image full-width"><img alt="map" class="richtext-image full-width" height="446" width="500"
            src="https://www.pbs.org/wgbh/nova/media/images/ancient-chinese-explorers-03.width-800.jpg"/><figcaption>Despite the strength and prosperity that marked their empire, Ming emperors deliberately chose not to try to colonize lands beyond the Middle Kingdom. Why? <div class="credit">Pierre Corrade</div></figcaption>
            </figure>
            </p>
<p>
	When the Han Chinese overthrew the Mongols and founded the Ming dynasty in the later 14th century, they took over the fleet and an already extensive trade network. The enterprising spirit of the Ming era reached a climax following the rebellion of the warrior prince Zhu Di, who usurped the throne in 1402. Disapproved of by the Confucian "establishment," Zhu Di put his trust in the worldly eunuchs who had always sought their fortunes in commerce. During his revolt, Zhu Di's right-hand man had been the Muslim eunuch Zheng He, whom he now appointed to command the treasure fleet.</p>
<blockquote>
	If accurate, these dimensions would signal the biggest wooden ships ever built.</blockquote>
<p>
	At the start of the first of Zheng He's epic voyages in 1403, it is said that 317 ships gathered in the port of Nanjing. As sociologist Janet Abu-Lughod notes, "The impressive show of force that paraded around the Indian Ocean during the first three decades of the 15th century was intended to signal the 'barbarian nations' that China had reassumed her rightful place in the firmament of nations—had once again become the 'Middle Kingdom' of the world."</p>
<h3>
	Treasure junks: fact or fiction?</h3>
<p>
	The Ming account of the voyages that followed strains credulity: "The ships which sail the Southern Sea are like houses. When their sails are spread they are like great clouds in the sky." Were the reported dimensions of the biggest galleons—over 400 feet long by 150 wide—gross exaggerations? If accurate, these dimensions would signal the biggest wooden ships ever built. Only the mightiest wooden warships of the Victorian age approached these lengths, and several of these vessels suffered from structural problems that required extensive internal iron supports to hold the hull together. No such structures are reported in the Chinese sources.</p>
<p>

            <figure class="richtext-image full-width"><img alt="Zheng He&#x27;s ships" class="richtext-image full-width" height="464" width="405"
            src="https://www.pbs.org/wgbh/nova/media/images/ancient-chinese-explorers-04.width-800.jpg"/><figcaption>Zheng He's ships, as depicted in a Chinese woodblock print thought to date to the early 17th century<div class="credit">Courtesy of Instructional Resources Corporation, www.historypictures.com</div></figcaption>
            </figure>
            </p>
<p>
	However, in 1962, the rudderpost of a treasure ship was excavated in the ruins of one of the Ming boatyards in Nanjing. This timber was no less than 36 feet long. Reverse engineering using the proportions typical of a traditional junk indicated a hull length of around 500 feet.</p>
<p>
	Unfortunately, other archeological traces of this "golden age" of Chinese seafaring remain elusive. One of the most intensively studied wrecks, found at Quanzhou in 1973, dates from the earlier Song period; this substantial double-masted ship probably sank sometime in the 1270s. Its V-shaped hull is framed around a pine keel over 100 feet long and covered with a double layer of intricately fitted cedar planking, thus clearly indicating its oceangoing character. Inside, 13 compartments held the residue of an exotic cargo of spices, shells, and fragrant woods, much of it originating in east Africa (see <a href="/wgbh/nova/sultan/archeology.html" target="_top">Asia's Undersea Archeology</a>).</p>
<p>
	The Quanzhou wreck suggests that over a century before Zheng He's fabled voyages, the Chinese were already involved in ambitious trading exploits across the Indian Ocean. Even back then, their sturdy ships equaled the largest known European vessels of the period. By inventing watertight compartments and efficient "lugsails" that enabled them to steer close to the wind, Chinese shipbuilders remained ahead of the West in the following centuries.</p>
<p>

            <figure class="richtext-image full-width"><img alt="statue" class="richtext-image full-width" height="370" width="491"
            src="https://www.pbs.org/wgbh/nova/media/images/ancient-chinese-explorers-05.width-800.jpg"/><figcaption>Zheng He (1371-1433), the great Ming navigator<div class="credit">Courtesy of Instructional Resources Corporation, www.historypictures.com</div></figcaption>
            </figure>
            </p>
<h3>
	Exploits of the eunuch admiral</h3>
<p>
	Zheng He commemorated his adventures on a stone pillar discovered in Fujian province in the 1930s. His mission, according to the pillar, was to flaunt the might of Chinese power and collect tribute from the "barbarians from beyond the seas." On his first trip, leading more than 60 massive galleons, Zheng He visited what would later become Vietnam and reached the port of Calicut, India. On his return, he battled pirates and established massive warehouses in the Straits of Malacca for sorting all the goods accumulated on this and subsequent voyages.</p>
<blockquote>
	Landing at Somalia, he found himself offered such exotic items as "dragon saliva, incense, and golden amber."</blockquote>
<p>
	While voyaging to India, the ships encountered a ferocious hurricane. Zheng He prayed to the Taoist Goddess known as the Celestial Spouse. In response, a "divine light" shone at the tips of the mast, and the storm subsided. This heavenly sign—perhaps the static electrical phenomenon known as St. Elmo's fire—led Zheng He to believe that his missions were under special divine protection.</p>
<p>
	The emperor launched Zheng He's fourth and most ambitious voyage in January 1414. Its destination was Hormuz on the Persian Gulf, where artisans strung together exquisite pearls and merchants dealt in precious stones and metals. While Zheng He lingered in the city to amass treasure for the emperor, another branch of the fleet sailed to the kingdom of Bengal in present-day Bangladesh.</p>
<p>

            <figure class="richtext-image full-width"><img alt="compass" class="richtext-image full-width" height="345" width="589"
            src="https://www.pbs.org/wgbh/nova/media/images/ancient-chinese-explorers-06.width-800.jpg"/><figcaption>To navigate throughout the Indian Ocean, Zheng He would have made use of the magnetic compass, invented in China during the Song dynasty. <div class="credit">&copy; WGBH Educational Foundation</div></figcaption>
            </figure>
            </p>
<p>
	Here the travelers saw a giraffe that the east African potentate of Malindi had presented to the Bengal ruler. The Chinese persuaded their hosts to part with the giraffe as a gift to the emperor and to procure another like it from Africa. When the giraffe arrived at the court in Nanjing in 1415, the emperor's philosophers identified it, despite its pair of horns, as the fabled <em>chi'i-lin</em> or unicorn, an animal associated with an age of exceptional peace and prosperity. As the fleet's merchants laid treasures from Arabia and India at the feet of the emperor, this omen must surely have seemed fitting.</p>
<p>
	The initial diplomatic contact with Malindi now encouraged Zheng He to plan a direct trading voyage to eastern Africa. Landing at Somalia on the coast, he found himself offered such exotic items as "dragon saliva, incense, and golden amber." But even these substances paled before the extraordinary beasts that were loaded on board his ships. Lions, leopards, "camel-birds" (ostriches), "celestial horses" (zebras), and a "celestial stag" (oryx) were shipped back to the imperial court. Here officials showered congratulations on Zheng He and bowed low in awe before the divine creatures that accompanied him.</p>
<h3>
	End of an era</h3>
<p>
	Toward the end of his seventh voyage in 1433, the 62-year-old Zheng He died and was said to have been buried at sea. Although he had extended the wealth and power of China over a vast realm and is even today revered as a god in remote parts of Indonesia, the tide was already turning against foreign ventures.</p>
<p>

            <figure class="richtext-image full-width"><img alt="ships" class="richtext-image full-width" height="320" width="564"
            src="https://www.pbs.org/wgbh/nova/media/images/ancient-chinese-explorers-07.width-800.jpg"/><figcaption>Impressive as they are, Chinese junks today are but pale shadows of medieval Chinese ships. <div class="credit">&copy; WGBH Educational Foundation</div></figcaption>
            </figure>
            </p>
<p>
	The conservative Confucian faction now had the upper hand. In its worldview, it was improper to go abroad while one's parents were still alive. "Barbarian" nations were seen as offering little of value to add to the prosperity already present in the Middle Kingdom.</p>
<p>
	The renovation of the massive Grand Canal in 1411 offered a quicker and safer route for transporting grain than along the coast, so the demand for oceangoing vessels plummeted.</p>
<blockquote>
	Old men's folktales of shipwreck are among the few tangible relics of China's epic voyages of adventure.</blockquote>
<p>
	In addition, the threat of a new Mongol invasion drew military investment away from the expensive maintenance of the treasure fleets. By 1503 the navy had shrunk to one-tenth of its size in the early Ming. The final blow came in 1525 with the order to destroy all the larger classes of ships. China was now set on its centuries-long course of xenophobic isolation.</p>
<p>
	Historians can only speculate on how differently world history might have turned out had the Ming emperors pursued a vigorous colonial policy. As it is, porcelain shards washed up on the beaches of east Africa and old men's folktales of shipwreck are among the few tangible relics of China's epic voyages of adventure.</p>

  



A century before Europeans "discovered" the Indian Ocean, huge Chinese trading ships were sailing as far as Africa.

Ancient Chinese Explorers





  
      <p>
 On October 5, 2015, the world watched in horror as Islamic State forces blew up the iconic 2,000 year-old Arch of Triumph in the ancient city of Palmyra, Syria. This carefully orchestrated act was the climax of a 10-month rampage of destruction and mass executions perpetrated by ISIS at the UNESCO World Heritage site. With Palmyra secured and a fragile Syrian truce in place, some news stories have given the impression that the worst wave of heritage destruction is over.
</p>

            <figure class="richtext-image full-width"><img alt="DGAM.TriumphalArch" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/dgam.triumphalarch.width-800.jpg"/><figcaption>
  The Arch of Triumph in Palmyra as seen on January 15, 2013.
 <div class="credit"></div></figcaption>
            </figure>
            
<p>
 In fact, satellite photography is revealing a shocking picture of the ongoing, systematic destruction of churches, mosques, antiquities, and museums throughout Syria and parts of Iraq and threats to heritage sites elsewhere in the Middle East. But that hasn’t stopped courageous local archaeologists and citizens from risking their lives to combat the devastation, aided by specialists outside the war zone who are deploying satellite and 3D imaging to help monitor, record, and replicate ancient sites.
</p>
  

  
      <div class="ad"></div>
  

  
      <p>
</p>

            <figure class="richtext-image full-width"><img alt="2-Palmyra_Arch_BlastRestitution1" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/2-palmyra_arch_blastrestitution1.width-800.jpg"/><figcaption>
  A digital reconstruction of the Arch of Triumph.
 <div class="credit"></div></figcaption>
            </figure>
            
<p>
 “It’s the worst cultural heritage crisis since World War II,” says Michael Danti, an archaeologist at Boston University. “And technology can help us keep up with the destruction and expose who’s responsible.”
</p>
<h2>
 Documenting the Destruction
</h2>
<p>
 Danti leads a team that publishes a weekly report documenting attacks on sites in Syria and northern Iraq. Known as ASOR Heritage Cultural Initiatives and funded by the U.S. State Department, the team draws on a wide range of images, from Cold War-era CORONA spy photos to constantly updated, high-resolution coverage provided by the commercial satellite operator DigitalGlobe. Since the full extent of damage to ancient sites is not always visible from space, ASOR’s bulletins are also based on a network of over fifty on-the-ground informants, including local citizens, refugees, Syrian archaeologists, and NGO workers. Some informants report from inside ISIS-controlled areas at great personal risk. (Danti lived in Raqqa, the ISIS “capital,” for 20 years, and many of his contacts spring from personal connections made during that time.) Social media from inside Syria and Iraq is another rich source of tips for the ASOR team; sometimes, they get to know about acts of destruction before ISIS can publicize them.
</p>
  

  
      

<div class='pullquote'>
  <p>
 “Cultural heritage always suffers during conflict.”
</p>
</div>

  

  
      <p>
 In its first year of operation, ASOR recorded 722 heritage attacks in Syria and 90 in Iraq. During that period, ISIS grabbed global headlines with its flagrant acts of demolition at World Heritage sites including the blowing up of Palmyra’s Temple of Bel, the smashing of sculptures in the Mosul Museum, and the destruction of the Assyrian city of Nimrud with sledgehammers, power tools, and finally explosives. But the satellite images reveal a huge increase in less conspicuous acts of destruction: looters’ pits that are visible from space as pockmarks disfiguring sites across the region.
</p>
<h2>
 Looting as Organized Crime
</h2>
<p>
 ASOR’s analysis shows that in the first four years of the Syrian conflict, more than 3,000 sites have been looted, nearly an order of magnitude increase over the pre-war period. The evidence implicates all parties in the Syrian war, including Assad’s military, but the most intensively ransacked sites are clearly the handiwork of ISIS. “Cultural heritage always suffers during conflict,” Danti says, “but what’s new is that ISIS has turned cultural destruction into a systematic business.” For instance, ISIS issues “dig” permits and hires contractors to bulldoze sites, while charging 20% sales tax on looted items.
</p>
<p>
 “The international community has still not fully woken up to the industrial scale of the looting,” Danti says. “It’s a highly organized trafficking organization that provides a major source of income to ISIS.”
</p>
  

  
      <div class="related"></div>
  

  
      <p>
 Beyond the illegal antiquities trade, ISIS engages in “cultural cleansing,” destroying historic and modern churches and mosques to demoralize the Shia, Christian, Yezzidi, and other minorities that their ideology brands as “apostate.” Space imagery has again proven crucial in tracking the destruction. Such images have helped a team of Czech scholars to assess the impact of a demolition campaign targeting sacred structures in Mosul following the city’s capture by ISIS in June 2014.
</p>
<p>
 “Mosul was a crossroads of culture and peaceful co-existence during medieval times,” says Karl Novacek, an archaeologist at the University of Olomouc in Moravia. “Many different ethnic traditions gave rise to a unique style of sacred architecture that’s barely been studied.” The space images show that 38 monuments—mostly early Islamic mosques—have either been reduced to ruins or completely razed and turned into car parks. The images are part of a database in which the team is assembling all the records, archives, and photos they can find of the lost monuments, many of them scattered among scholars and the collections of local people. “If we succeed, we could create a base for future architectural restoration,” Novacek says.
</p>
<h2>
 The Promise of Digital Restoration
</h2>
<p>
 Besides tracking what’s been lost, digital technology opens up new possibilities for a post-war future that’s faced with the challenge of restoring iconic structures. The Syrian government’s Directorate-General of Antiquities and Museums is already collaborating with ICONEM, a Paris-based architecture firm, to produce “before” and “after” 3D models that anyone can access to zoom in and study wrecked sites in extraordinary, stone-by-stone detail. For example,
 <a href="http://iconem.com/the-krak-des-chevaliers/">
  Krak des Chevaliers
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 , one of Syria’s best known 11 th century Crusader castles, was severely damaged when government forces finally drove rebels from the hilltop in 2014. ICONEM programmers designed a “bot” to roam the web and harvest thousands of pre-war photos of the castle, which they then assembled and used to generate a “point cloud” representing a partial 3D model of the Castle. They can superimpose a layer showing recent damage on top of the pre-war model. This may well provide an indispensable visual guide for any eventual attempt to restore the site.
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    <iframe src="https://player.vimeo.com/video/160714858?app_id=122963" width="640" height="360" frameborder="0" title="Le Krak des Chevaliers" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>
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 The potential of 3D printing to replicate sites generated worldwide headlines in April, when a two-thirds scale model of Palmyra’s Arch of Triumph was erected in London’s Trafalgar Square; the Arch may travel to New York in the Fall. The model was, again, recreated from pre-war photos and was programmed to drive a massive stonecutting machine at a quarry at Carrara in northern Italy, next door to where Michelangelo obtained marble for his statue of David.
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            <figure class="richtext-image full-width"><img alt="Restitution 3D du Temple de Bel_Iconem" class="richtext-image full-width" height="511" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/restitution-3d-du-temple-de-bel_iconem.width-800.jpg"/><figcaption>
  ICONEM used pre-war photographs to build a 3D model of the Temple of Bel.
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 The aim of the project was to erect a symbol of cultural resistance in the face of ISIS and to raise public awareness of the heritage threat and was partly the work of an innovative Oxford-based venture known as the Institute for Digital Archaeology. In collaboration with UNESCO and leading universities and foundations, the institute’s major goal is to compile a comprehensive library of 3D imagery of threatened sites across the Middle East that they’re calling the Million Image Database. To create the image bank, the plan is to distribute 5,000 pocket 3D cameras to volunteers and heritage workers across the region. The Institute’s director, Roger Michel, says their ambitious mission is “to rebuild the landscape of the Middle East and the great symbols of our shared cultural heritage that have been destroyed.”
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 Can Replicas Replace What’s Lost?
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 But when peace finally comes, will the new replication techniques match the quality of what’s been lost? And how will local communities respond to the results? “That’s part of a wider debate about the changing meaning of these places,” says Allison Cuneo, a member of the ASOR team. “Palmyra is no longer simply a tourist site. ISIS child soldiers carried out executions in the amphitheater and left behind a mass grave of civilians. How can clean-up and restoration efforts pay homage to that fact?”
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            <figure class="richtext-image full-width"><img alt="DCIM100MEDIADJI_0050.JPG" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/dji_0050.width-800.jpg"/><figcaption>
  A satellite image of Palmyra's amphitheater.
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 Meanwhile, ISIS and other extremist groups still pose a dire threat to the Middle East’s ancient cultural treasures. Among the most serious current threats outside Syria, Libya poses the gravest concern. As a shaky coalition government is still taking shape, ISIS forces are converging on coastal Greco-Roman cities such as Cyrene and Leptis Magna that are scarcely less imposing or extensive than Palmyra itself. Meanwhile, in Egypt, security at ancient sites is unraveling. Space archaeologist Sarah Parcak, who used satellite imagery to detect a possible new Norse site in Newfoundland in NOVA’s recent show “
 <a href="http://www.pbs.org/wgbh/nova/ancient/vikings-unearthed.html">
  Vikings Unearthed
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 ," recently applied the same techniques to study the looting of ancient Egyptian sites. She has documented a 50% jump in looting at four major sites since the 2011 revolution.
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 With all the human suffering of the Syrian war and the refugee crisis, why should we care about endangered heritage? Michael Danti stresses that the issue goes far beyond the concerns of archaeologists. “ISIS is practicing cultural terrorism,” he says, “as they target and eliminate the identity of entire sections of society in a way that’s directly comparable with Nazi atrocities.” By supporting the efforts of local heritage workers to protect and reclaim sites, scientists can help embattled communities hang on to hope and a sense of community in a time of terror.
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 Image credits: Directorate-General of Antiquities and Museums of Syria/Michael Danti, ICONEM
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The Technology That Will Resurrect ISIS-Destroyed Antiquities

<p>Teams of Syrian and international archaeologists are racing to rebuild the country’s cultural heritage.</p>

Evan Hadingham

Articles