Archaeology

71 cards about Archaeology, with explanations, methods and source links.

Cards about Archaeology

• What was found in the village where the pyramid builders lived?

  The familiar story of slaves driven to build the pyramids comes from sources written far later, not from the period of construction. At Giza, excavators found a large settlement right beside the pyramids, and the builders lived in it. What was in it?

  Source: Murray, Archaeology International

• Does every one of the 8,000 terracotta soldiers really have its own face?

  The First Emperor’s terracotta army runs to more than eight thousand clay soldiers, and the line everyone repeats is that no two faces are alike. Sculpting eight thousand different faces by hand is close to impossible. So how was it done?

  Source: Quinn, Zhang and Xia, Antiquity

• What is hiding under the jungle of Guatemala?

  Survey aircraft fire laser pulses at the ground and measure how long each takes to return. Some of the pulses find gaps between the treetops and reach the soil, so filtering out the vegetation leaves a model of the ground itself. What came up under the jungle?

  Source: Canuto et al., Science

• Can you tell who lived in a cave without finding a single bone there?

  Ancient humans left more than tools and bones in caves. They also shed tiny cells into the dirt. A bone you either find or do not, and the dirt is always there. What can be got out of it?

  Source: Slon et al., Science

• What pushed the arrival of people in America thousands of years back?

  The settled view in archaeology held that people reached North America some 13 to 16 thousand years ago, on the evidence of Clovis finds. Then footprints preserved at the edge of an ancient lake at White Sands were dated. What did they show?

  Source: Bennett et al., Science

• Where did the stone at the center of Stonehenge come from?

  Most of the bluestones at Stonehenge came from the Preseli hills in Wales, and the Altar Stone at the center was taken to be Welsh as well. To check, researchers took a geochemical fingerprint, the chemistry and the age of the mineral grains inside it, and looked for a matching source. Where did they lead?

  Source: Clarke et al., Nature

• What are the white lumps inside Roman concrete actually doing?

  Roman concrete is scattered with small white lumps of unreacted lime, and for years they were taken as evidence of careless mixing. Except that this is the concrete that lasted two thousand years, lumps and all. So what are they doing?

  Source: Seymour et al., Science Advances

• How did one finger bone reveal a branch of humanity nobody knew?

  A tiny finger bone was found in Denisova Cave in Siberia. A bone like that tells you almost nothing about anatomical shape, so ordinarily it stays an item in a store room. The researchers did something else with it. What?

  Source: Reich et al., Nature

• Did anyone bake bread before farming was invented?

  Bread is usually taken to be a product of farming: first you domesticate grain, and only then you bake. At Shubayqa in north-east Jordan, charred food remains were found lying there from before grain was domesticated. What were they?

  Source: Arranz-Otaegui et al., PNAS

• What did a meal from the past leave between the teeth?

  Dental calculus is a hard layer that builds up on teeth, and in people who lived centuries or millennia ago it can trap molecules from the food they ate. The difficulty is that plant food leaves almost no large remains. What can still be identified?

  Source: Hendy et al., Proceedings of the Royal Society B

• Can you tell what an ancient person ate from the DNA in their teeth?

  Calculus on ancient teeth sometimes preserves DNA from various organisms, and it is tempting to see a plant or animal sequence there and conclude it was in the meal. An examination of ancient and simulated data showed why that is risky. What can go wrong?

  Source: Mann et al., Quaternary International

• What cooked in the clay pots of hunter-gatherers in Japan for thousands of years?

  The site of Torihama in Japan yielded pottery made by hunter-gatherers across many periods, and the researchers did not stop at the shape of the vessels. They extracted from the clay itself the fat residues absorbed into the walls thousands of years ago, and tested them chemically. What was cooked there?

  Source: Lucquin et al., PNAS

• Who left footprints on an English beach almost a million years ago?

  Along the shore at Happisburgh in England an ancient layer of mud lay exposed for a few hours, and the researchers photographed it quickly before the waves wore it away. In the mud were elongated hollows, though whose they were cannot be known for certain. Who walked there, and when?

  Source: Ashton et al., PLOS ONE

• What can the walls of an ancient pot teach us about meals in the Indus cities?

  After thousands of years the food is gone, and some of its fats soak into the pores of the clay and stay there. Which is to say an ancient pot remembers what was cooked in it. What turned up in vessels from Indus Civilization sites?

  Source: Suryanarayan et al., Journal of Archaeological Science

• Was pharaoh Ahmose’s great storm the eruption of Santorini?

  An Egyptian inscription from the time of pharaoh Ahmose describes an extraordinary storm, and for years it was tied to the vast eruption of the Thera volcano at Santorini. To find out whether the dates even meet, Egyptian brick, linen and wooden objects from that period were radiocarbon dated. What came out?

  Source: Bruins & van der Plicht, PLOS ONE

• Could only the Maya nobility enjoy cacao?

  Cacao is identified with Maya rulers and ceremonies, partly because it was looked for mainly in decorated vessels. That is a test that finds what it looked in. So pottery sherds from ordinary houses were tested too. What was in them?

  Source: Ford et al., PNAS

• What was hiding inside animal mummies from ancient Egypt?

  The wrappings of a mummy hide far more than bones, and opening them means destroying them. So three animal mummies from ancient Egypt were scanned with micro-CT, which produces tiny slices without touching them. What appeared inside?

  Source: Johnston et al., Scientific Reports

• How do we know that early China made fermented drinks in two different ways?

  Ancient alcohol left no bottle with a recipe on the label, and it did leave marks in the pottery itself. Starches, plant remains and fungi were examined in vessels from two sites in northern China. What turned up in them?

  Source: Liu et al., PNAS

• Could flour be made thousands of years before anyone farmed grain?

  Flour is thought of as a product of a cultivated field, and therefore as a sign of farming. At a Natufian site in the eastern Mediterranean, deep stone mortars were found that predate the growing of cereals. To find out what they were for, researchers harvested wild barley and reconstructed the processing. What came out?

  Source: Eitam et al., PLOS ONE

• Why did ancient pots hide some of the plants cooked in them?

  When food burns and sticks to a clay vessel it leaves a thin crust that can be studied thousands of years later. Except that lipid analysis alone mainly identifies animal food, so the menu it produces is biased. How do you see the rest?

  Source: González Carretero et al., PLOS ONE

• How do we know Iron Age salt miners knew blue cheese and beer?

  In the salt mines of Hallstatt in Austria, ancient fecal samples survived, among them one from the Iron Age. Which is to say there is direct documentation of a meal here, rather than vessels or bones. What was in it?

  Source: Maixner et al., Current Biology

• What could expert trackers identify in rock engravings thousands of years old?

  Rock engravings in the Doro! nawas mountains in Namibia include hundreds of marks that look like tracks, and archaeologists used to record them as general shapes. Then Indigenous tracking experts from the Kalahari region were invited to examine them. What did they see there?

  Source: Lenssen-Erz et al., PLOS ONE

• Do you need food surpluses and rich patrons before skilled crafts appear?

  A common story ties skilled craftworkers to farming: only once there are food surpluses can anyone be spared to make objects. At Shubayqa 6 in Jordan, a site older than pottery, thousands of green stone fragments and beads at every stage of manufacture were found. What does that say?

  Source: Thuesen et al., PLOS ONE

• Was the dog tamed once, or did two separate peoples do it?

  The usual assumption is that the dog was tamed once, in one place, and spread from there with the people who kept it. To test that, geneticists sequenced DNA from 59 ancient dogs plus the full genome of an Irish dog about 4,800 years old, and set the eastern lineages against the western ones. What did the family tree show?

  Source: Frantz et al., Science

• Why did people bury lumps of butter in bogs for 3,500 years?

  In the peat bogs of Ireland people keep turning up white or yellow waxy lumps, sometimes inside a wooden vessel, sometimes wrapped in an animal bladder. The fat has altered chemically over the centuries, so the eye cannot say what it once was. Chemists went at it with isotopes and carbon dating. What turned up?

  Source: Smyth et al., Scientific Reports

• Did the people of Easter Island really destroy themselves before Europeans arrived?

  Rapa Nui gets told as a parable, a society that felled its forests and collapsed before it ever met Europe. A crash that severe should leave a signature in the genome, because a shrinking population loses genetic variety and the loss stays visible for generations. Researchers sequenced 15 ancient islanders. What did they find?

  Source: Moreno-Mayar et al., Nature

• Jurassic Park begins with a mosquito in amber. Where does the plan break?

  Amber can hold the shape of an insect in astonishing detail, and from there it is a short step to assuming the DNA kept just as well. Reports of ancient genetic sequences out of amber appeared in the 1990s, and another team set out to repeat them, using bees and flies in amber and in younger resin. What did they get?

  Source: Austin et al., Proceedings of the Royal Society B

• What did a scan that never touches the wall find in cave paintings?

  The Dordogne holds more than 200 decorated cave sites, and all of its figures were thought to be drawn in mineral pigment. Iron and manganese oxides carry no carbon, so nothing there could be dated directly. Researchers examined the walls of Font-de-Gaume with instruments that identify a material without scraping it. What was hiding in the paint?

  Source: Reiche et al., Scientific Reports

• Were the people buried together in an ancient village necessarily family?

  Neolithic communities in Anatolia often buried their dead beneath the floors of houses, which makes it tempting to read each house as one biological family. Material culture cannot settle that, so researchers sequenced 59 ancient genomes from several villages and worked out who was related to whom. Did the graves hold families?

  Source: Yaka et al., Current Biology

• How do you find traces of beer once the liquid is long gone?

  Brewing is hard to identify archaeologically without pictures or distinctive vessels, and molecular methods run into problems of preservation and specificity. Brewing does leave a hard residue on the vessel, a calcium oxalate deposit called beerstone. Researchers ran shotgun proteomics on modern beerstone to see what it holds. Could this mark ancient beer?

  Source: Paskulin et al., Journal of Archaeological Science

• What can be learned from a 5,700-year-old piece of chewing gum?

  Ancient genomics depends on having a suitable sample, which usually means a bone. A lump of birch pitch from Denmark, chewed and spat out about 5,700 years ago, came with no human remains anywhere near it. Normally that is where the story ends. What was in the pitch?

  Source: Jensen et al., Nature Communications

• Where did the horses people ride today come from?

  Domesticating the horse changed how far people could travel and how they fought. The oldest archaeological evidence of bridling, milking and corralling comes from Botai in Central Asia around 3500 BC, and modern breeds turn out not to descend from that lineage. Iberia and Anatolia have been ruled out too.

  Source: Librado et al., Nature

• What is the oldest yellow paint anybody has identified?

  Flinders Petrie excavated painted limestone reliefs from the Palace of Apries between 1908 and 1910, and the fragments kept their color. A battery of modern methods went over them to map which pigments sit where. Nobody had ever reported two of the yellows from ancient Egypt at all.

  Source: Hedegaard et al., Heritage Science

• Where did the tin in a Bronze Age cargo come from?

  Bronze needs tin, tin is rare, and the Late Bronze Age used it across a continent. A ship that sank off the Turkish coast at Uluburun around 1320 BCE went down carrying ingots of it. Nobody had traced the metal in that cargo to its ores until this analysis.

  Source: Powell et al., Science Advances

• What did gladiators drink after a fight?

  A gladiator cemetery found at Ephesus in 1993 dates to the second and third centuries AD, which gives a rare chance to compare one occupation against the city around it. Bones carry chemistry, not menus. The isotopes said the diet was mostly grain, like everyone else’s. Then came a trace element.

  Source: Lösch et al., PLOS ONE

• Did a supervolcano nearly wipe out humanity?

  Mount Toba in Sumatra produced the most explosive volcanic event of the Quaternary 75,000 years ago, with ash across the Indian Ocean, the Indian Peninsula and the South China Sea. A climatic downturn in the Greenland ice cores has been attributed to it, and that roughly coincides with a hypothesized human genetic bottleneck.

  Source: Lane, Chorn and Johnson, PNAS

• How do you track a chicken through the ancient world?

  The origins and dispersal of the chicken remain among the most enigmatic questions about Eurasian domesticated animals. The reasons are practical: morphological identifications are contested, direct dating is scarce, and thin brittle bird bones preserve badly. So the bones are the wrong thing to count.

  Source: Peters et al., Nature Communications

• How do you date a painting that contains no carbon?

  Paleolithic cave art is an exceptional archive of early human symbolic behavior, and after more than a century of study its chronology is still poorly understood. Radiocarbon needs carbon, and much of this art contains almost none. The rock around it, though, keeps growing.

  Source: Pike et al., Science

• How many separate visits made the art at Chauvet?

  Chauvet-Pont d’Arc holds some of the oldest known painted walls, and a rockfall sealed its entrance long ago. A single date on a single charcoal line says when that line was drawn, and nothing more. Putting the drawings, the fires and the cave bear bones on one timeline needs many dates at once.

  Source: Quiles et al., PNAS

• How long did it take to realize the body was not a lost climber?

  On 19 September 1991 two German hikers found a human corpse at 3,210 meters near Tisenjoch, in the Schnalstal valley, with only the upper body protruding from the ice. The obvious reading was a mountaineering accident. Everything that followed over the next days was run on that assumption.

  Source: South Tyrol Museum of Archaeology

• What is inside the plaster figures of Pompeii?

  Mount Vesuvius buried Pompeii in ash and volcanic debris in 79 C.E., freezing the city in time, and historians think around 2,000 people died there. The famous figures of victims are not statues and not bodies. What they are is a consequence of what happened to the bodies over the centuries that followed.

  Source: Smithsonian Magazine

• Was Angkor Wat ever really lost in the jungle?

  The story most people know ends with a French explorer parting the vines in the nineteenth century to reveal a forgotten temple. Angkor itself was abandoned in the early fifteenth century. What happened to the largest religious structure in the world in between is the part the story skips.

  Source: Encyclopaedia Britannica

• How many people does it take to fake a missing link?

  In 1912 the palaeontologist Arthur Smith Woodward and the amateur antiquarian Charles Dawson announced a fossil that supposedly linked apes and humans, Eoanthropus dawsoni, Dawson’s dawn man. The publication generated huge interest from scientists and the public alike. Its celebrity has long since been overshadowed by its infamy.

  Source: De Groote et al., Royal Society Open Science

• What shape did a Greek baby bottle take?

  Everyday objects survive badly, and the things a household used most are usually the things archaeology sees least. A small terracotta vessel in the Met, 13.2 cm tall and probably made in Crete in the 3rd century BCE, is catalogued as a feeding bottle. Its form is borrowed from somewhere unexpected.

  Source: The Metropolitan Museum of Art

• What did opening Lascaux to the public cost?

  Four teenage boys found the cave above the Vezere valley in September of nineteen forty, and it was in perfect condition. Inside are some six hundred painted and drawn animals and symbols and nearly fifteen hundred engravings, done in reds, blacks, browns and yellows on a light background. The cave opened to visitors in nineteen forty-eight. What happened to it?

  Source: Britannica

• What does a town with no streets look like?

  Catalhoyuk rises from the Konya plain on the Southern Anatolian Plateau as two mounds, the taller holding eighteen levels of Neolithic occupation between seven thousand four hundred and six thousand two hundred BC. People lived on the same spot for over two thousand years, moving from settled village toward something closer to a town. The layout is what makes it strange. How did anybody get indoors?

  Source: UNESCO World Heritage Centre

• What was actually inside the Sutton Hoo burial mound?

  In nineteen thirty-nine the amateur archaeologist Basil Brown brushed away Suffolk soil on Edith Pretty’s land and found the richest intact early medieval grave in Europe. It held feasting vessels, hanging bowls, silverware from Byzantium, textiles, gold set with Sri Lankan garnets and a helmet with a human mask. Around all of it ran something harder to see. What was it?

  Source: The British Museum

• Why does Georgian wine ferment in a buried pot?

  A qvevri is an egg-shaped earthenware vessel used for making, ageing and storing wine, and the method built around it was inscribed on UNESCO’s Representative List in two thousand thirteen. Grapes are pressed, and then the juice goes into the qvevri along with the grape skins, stalks and pips. What happens to the vessel next is the part that sets the method apart.

  Source: UNESCO Intangible Cultural Heritage

• Why has nobody read the Phaistos Disc?

  Luigi Pernier found it in a room of the Palace of Phaistos on the third of July, nineteen hundred and eight: a clay disc from around seventeen hundred BC, with signs arranged in a spiral. Both sides were impressed with tiny seals while the clay was still wet. A vertical line with five dots marks where to start and which way to go. So why is it still unread?

  Source: Heraklion Archaeological Museum

• What did people on the edge of the Roman empire write to each other about?

  Vindolanda was a fort in Northumberland, near what became Hadrian’s Wall, and writing from there survives on thin sheets of wood inked between about ninety-seven and one hundred and three. One tablet, now in the British Museum, carries a letter from Claudia Severa to Sulpicia Lepidina, the commander’s wife. Two different hands wrote it. What is it about?

  Source: British Museum

• What were ancient Egyptians doing when they played senet?

  Egyptians enjoyed board games and senet most of all. The name means passing. A board holds thirty squares and the game took fourteen pieces, spool-shaped and cone-shaped, with throw sticks standing in for dice. During the eighteenth dynasty something happened to it that does not usually happen to board games. What changed?

  Source: The Walters Art Museum

• How do you find a ship that sank under moving ice a century ago?

  Ernest Shackleton’s Endurance was trapped and crushed by ice and sank in the Weddell Sea in nineteen fifteen. Captain Frank Worsley registered a position before she went down. The problem with searching there is the ice itself: winds and currents can compress huge masses of it within hours, closing open channels and throwing up pressure ridges impassable even to icebreakers. How did the Endurance22 expedition get through?

  Source: German Aerospace Center, DLR

• Where did the silk in a Viking grave come from?

  More than a hundred small silk fragments came out of the Oseberg ship, excavated nearly a century ago and still the oldest Viking Age silk found in Norway. At the time nobody considered that it might have been imported from Persia. The assumption was that most of it had been looted from churches and monasteries in England and Ireland. Was it?

  Source: University of Oslo

• Was the land under the North Sea a route or a home?

  Doggerland is the drowned stretch of Europe that once joined Britain to the mainland, now lying roughly twenty to thirty meters below the North Sea. Archaeologists have mostly treated it as a land bridge, a thing people crossed between two more interesting places about twelve thousand years ago. Vincent Gaffney has spent two decades mapping it without ever standing on it. What does the map show?

  Source: Hakai Magazine

• Why did experts first assume the Nebra sky disc was a forgery?

  Treasure hunters dug a bronze disc out of a hill called Mittelberg in Germany in nineteen ninety-nine, as part of a hoard with two axes, two swords and a chisel. Their crude excavation damaged the rim and lost a piece of the gold and one of the stars, and they sold it in Switzerland to a dealer in illegal antiquities. Experts recovered it only in two thousand two. Why the suspicion?

  Source: All That’s Interesting

• Which came first, farming or temples?

  The standard account ran one way: agriculture produced surplus, surplus produced villages, villages produced cities and eventually writing, art and religion. On a ridge in southern Turkey called Potbelly Hill stand dozens of carved limestone pillars arranged in rings, splashed with bas-reliefs of gazelles, snakes, foxes, scorpions and wild boars. They are eleven thousand six hundred years old. What does that do to the sequence?

  Source: National Geographic

• Why did Howard Carter wait five years to dig the most promising spot he had?

  In early nineteen eighteen, Carter’s workmen uncovered a group of ancient workmen’s huts in the Valley of the Kings, undisturbed, forty feet from a known cache tied to Tutankhamun. Nobody had broken through the flood debris beneath them since the second millennium BCE. It was the perfect place to look for an intact tomb. Carter left it alone and worked elsewhere for five seasons. Why?

  Source: Smithsonian Magazine

• What were the Nasca lines for?

  Across a stretch of Peruvian desert that gets less than an inch of rain a year run over eight hundred straight lines, three hundred geometric figures and seventy animal and plant designs. Some lines run thirty miles. They are nearly impossible to make out from the ground, and only came to public attention when pilots began flying over Peru in the nineteen thirties. So who were they drawn for?

  Source: National Geographic

• Why can nobody read the Voynich manuscript?

  The book was written in Central Europe in the fifteenth century: two hundred and forty-six pages of vellum covered in a looping script of twenty-five to thirty characters. Drawings of plants, planets, castles, dragons and naked figures run among them. Alan Turing could not unscramble it. In two thousand eighteen a pair of computing scientists at Alberta ran an algorithm at it. Did that settle anything?

  Source: National Geographic

• How do you read a scroll that turns to fragments if you open it?

  Vesuvius buried Herculaneum under twenty meters of volcanic ash in October of AD seventy-nine, and the scrolls in a villa library there were carbonized. Early attempts to open them produced a mess of fragments, and more than six hundred remain intact and unopened. X-ray scanning can see inside. The difficulty is that the ink is carbon, the same density as the papyrus under it. How do you find letters that do not show up?

  Source: Scientific American

• Why does a two thousand year old face still have stubble on it?

  A family cutting peat for fuel in a Danish bog in nineteen fifty unearthed a body so well preserved they assumed it was a local murderer’s recent victim. Radiocarbon dating put his death between four hundred and five and three hundred and eighty BC. He lay in a sleeping position with a rope around his neck, and an autopsy found he had died of hanging. Why is he still there at all?

  Source: National Geographic

• How do you date a wooden statue that keeps getting older?

  Gold miners pulled ten wooden fragments out of the Shigir peat bog north of Yekaterinburg in January of eighteen ninety-four, four meters below ground. Reassembled, they make a carved anthropomorphic figure that Tolmachev put at five point three meters in nineteen fourteen. Its character is so unusual that typology could not date it, and it sat undated for decades. Radiocarbon in nineteen ninety-seven put it in the Mesolithic. Then came a second attempt.

  Source: Zhilin et al., Antiquity

• How do you find a color that has worn away?

  Painted limestone reliefs from the Palace of Apries, excavated by Flinders Petrie between nineteen oh eight and nineteen ten, survive as fragments in Copenhagen. What remains of the paint is patchy, and sampling a sculpture weighing about a thousand kilograms is not something anybody wants to do often. One of the pigments on them has an unusual property. What is it?

  Source: Hedegaard et al., Heritage Science

• Why is a radiocarbon date not a date?

  Most radioactive dating methods measure a daughter product and get an absolute age out of it. Radiocarbon cannot. The nitrogen produced by carbon-14 decay is not captured in most materials, and even if it were it would be swamped by the nitrogen everywhere else. So a radiocarbon measurement gives a number that is not yet a calendar age. What has to happen to it?

  Source: Reimer et al., Radiocarbon

• Was an ancient Egyptian artificial toe a real prosthesis or a funeral prop?

  The British Museum holds an artificial big toe for the right foot, made from cartonnage and dated to before six hundred BC, with distinct signs of wear. The Egyptian Museum in Cairo holds a second, found strapped to the right foot of a female mummy and made in three laced sections. It dates between nine hundred and fifty and seven hundred and ten BC. Wear suggests use. How would you test that?

  Source: Finch et al., Journal of Prosthetics and Orthotics

• How do you let everyone see a manuscript without anybody handling it?

  The Dead Sea Scrolls collection runs to about nine hundred and thirty manuscripts, comprising thousands of fragments. Every physical examination costs something: exposure, handling, slow damage. Scholars still need to read them, and so does everybody else. The Israel Antiquities Authority set out to resolve that with the Leon Levy Digital Library, in partnership with Google. What does the imaging actually do?

  Source: Israel Antiquities Authority, Leon Levy Dead Sea Scrolls Digital Library

• What can a Roman sewer tell you that a villa cannot?

  Writing about Roman food came from people who could afford to write, which skews the picture toward banquets. Beneath Cardo V at Herculaneum runs a sewer, with relatively small apartments above it. What went down from those apartments is still there as archaeobotanical remains. Erica Rowan worked through them. Who was eating what?

  Source: Rowan, The Economy of Pompeii, Oxford University Press

• What can you learn from a cooking pot that was last used four thousand years ago?

  Cooking drives fats into the wall of an unglazed pot, where they can survive long after everything else has gone. That makes a broken vessel a record of what was cooked in it, which is a different kind of evidence from bones or seeds. Suryanarayan and colleagues took lipid residue analysis to Indus sites in northwest India, where the conditions are about as unhelpful as they get.

  Source: Suryanarayan et al., Journal of Archaeological Science

• What was the Roman twelve-sided bronze object for?

  A Roman dodecahedron is a hollow twelve-sided object of copper alloy, each face pierced with a hole and each corner carrying a knob. They are complex enough to need a skilled craftsman and enough metal to have been expensive, so they were probably made to order. Archaeologists have been puzzling over them since the 18th century, when the first was found. Nobody has settled what they are.

  Source: English Heritage

• Who actually knew where Machu Picchu was?

  Local people did, and the published pictures left them out. Reviewing Amy Cox Hall’s study of the Yale Peruvian Expedition archives, the reviewer picks out a count. Of the 244 illustrations in the 1913 National Geographic issue on the expedition, only six show local workers, whose labor and knowledge were essential to it.

  Source: Hispanic American Historical Review

• Why does one Roman cup change color depending on the light?

  Because the glass contains metal nanoparticles. The British Museum catalogues the fourth-century Lycurgus Cup as green and red, which is the whole oddity: it is both. Dichroic nanoparticles show different colors when illuminated from the front, by scattering, or from the back, by transmission, and that effect is unique to nanoparticles and nanostructures.

  Source: Chemistry Teacher International

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