EarthDate

Recently, scientists discovered the fossil of a hadrosaur, a duckbilled dinosaur, which was bitten by a Tyrannosaurus. A bite on a fossil is not that unusual, but this one helped settle an argument. Over the past few decades, some paleontologists maintained that T. rex was a ferocious hunter. Newer theories pointed to his useless forelimbs, small eyes, and huge olfactory chambers. He wouldn’t have been able to grasp prey and may have had poor vision—but he would have been able to smell a rotting carcass from miles away. In other words, he was likely a scavenger. But the hadrosaur tail vertebrae in this fossil were fused together around a T. rex tooth—the wound had healed. This meant that the hadrosaur was alive when it happened, and lived on. Which strongly suggests that T. rex did in fact chase and catch it—almost. This brought up another question: given his weaknesses, how did the tyrannosaur do it? A different set of scientists analyzed the leg mechanics of T. rex for bone stress. Proponents of “T. rex the hunter” had pointed to his speed, previously estimated at over 30 miles per hour. But this new research suggests that the foot bones, carrying his 7 tons of weight, would have shattered at that pace. The tyrannosaur’s top speed was probably just 12 miles per hour. And maybe that’s why the duckbill got away—T. rex may have been an occasional hunter, but maybe not a very good one.

Nickel is in demand because it’s used in lithium ion batteries, common alloys such as stainless steel, and new super alloys for the aerospace and wind turbine industry. But mining and smelting nickel is energy intensive, using a great deal of diesel fuel and coal. And the after-products are environmentally dangerous. Luckily, we’ve found that nickel can grow on trees. Or more specifically, shrubs. Metals are toxic to most plants, which don’t grow in metal-rich soils. But some 700 species are hyperaccumulators—they actually pull metal from the ground and concentrate it in their tissues. It’s thought they do this to ward off pests or to help absorb potassium from poor soil. Of these species, over 400 accumulate nickel. Their blue-green sap can be up to 25% nickel—a concentration twenty times greater than the nickel ore mined for smelting. These shrubs can be farmed and the metal harvested in a technique called phytomining. Farmers cut back the shrubs once or twice a year and either squeeze sap from the foliage or burn it and gather the ash. The farms can be sited on nickel-rich soils that have been corrupted with mine tailings or are otherwise unfit for agriculture. After a couple decades, the plants will deplete the nickel in the soil through a process called bioremediation, and the land can grow food crops. Nickel farming will never replace large-scale mining, but it can help small farmers earn a living in areas with toxic soils.

On another EarthDate you heard that bees are dying. While it’s common for a hive to lose 15% of its bees each winter, rates since 2007 have sometimes hit 40%. This has scientists concerned, and after a decade of research, they’ve traced the bees’ troubles to several factors. First, stress. A decrease in wild acreage means fewer wild bees, so that more commercial bees are needed for pollination. This has the hives traveling farther and more frequently. Rising temperatures also have an impact, making it harder for bees to maintain the constant temperature needed in the hive. Second, pesticides. A recent study of honey samples found most of them were contaminated. While the concentrations were too low to affect humans, they impacted the bees’ ability to navigate and find nectar. Finally, pests. The Asian Varroa mite has infested some U.S. and European bee colonies. They feed on larvae and bees, weakening their immunity systems and making them more susceptible to disease, like the viruses the mite carries—including one that renders bees flightless. But there is some good news on the horizon. Scientists are working on new bacteria for the bees’ microbiome that would kill the Varroa mite. And, since mites, disease, pesticides, and stress work synergistically, eliminating one or more of them may allow the colony to better manage the others. Humans need to get on the bee team so bees can continue to pollinate our global food supply.

Bees make over $300 million worth of honey, beeswax, propolis, and other products each year in the U.S., which we eat and use in medicines, cosmetics, even varnishes. But the real big business of bees is the billions of dollars keepers earn pollinating crops. Bee colonies are treated, and valued, like livestock. The keepers move the hives to the best positions for most effective pollination on a strict schedule, following the flowering of crops across the country. They start in February, in California, where almond growers need 2 million hives to pollinate their trees. A typical farmer could pay several hundred thousand dollars for this service. In March, keepers transport their colonies to pollinate plums, cherries, and apples in the Pacific Northwest and Midwest. In early April, the hives go to Maine to pollinate blueberries. And in late April, down to Florida to work the citrus crop. Finally, in May, bee colonies retire to the Dakotas, where they’ll spend the quiet rest of the year on fields of clover and sunflower. Here, the bees make most of their honey. North Dakota produces twice as much honey as any other state. Honeybees and other insects are the only pollinators for all these and many other crops—about a third of our agricultural harvest—putting food on the table around the world. But bees have come under threat recently from pesticides, pests, and disease. We’ll look at these dangers and possible solutions in our final episode on honeybees.

Honey is a miraculous substance, containing enzymes, vitamins, minerals, and antioxidants. But it’s not the only amazing thing bees make in the hive. Honey starts as nectar that bees gather from thousands of flowers on foraging flights. The bees store the nectar in a special sac next to the stomach. On returning to the hive, they transfer it to the mouths of waiting worker bees. Workers ingest and regurgitate the nectar over and over for several minutes. Their digestive enzymes convert the sucrose in the nectar to other forms of sugar and add gluconic acid and hydrogen peroxide that act as preservatives. Finally, they deposit the liquid in storage cells where other workers fan it with their wings to reduce its water content, till it takes on the thick consistency of honey. Honey provides the carbohydrate energy that powers the colony. But the hive requires other products too. Some bees gather water, which will be used for evaporative cooling. They’ll fan air across it to maintain a constant 93 degrees Fahrenheit within the hive. Others gather pollen, which is mixed with honey to ferment and create “bee bread,” the hive’s main source of protein. Still others gather tree resin, which they mix with wax and saliva to produce “bee glue,” or propolis. It’s used to mend the hive and line the brood area to keep it clean, since it has antibiotic qualities.

Even if you’ve watched documentaries about honeybees, you may know little of their remarkable life within the hive. A queen will lay a million eggs in her 5-year lifetime, which she places in wax brood cells. Fertilized eggs grow into sterile female workers. Unfertilized eggs become male drones. When the queen gets old, nurse bees bathe regular female larvae in royal jelly, which turns them into queen larvae. The queen that emerges first will kill the other larvae to become sole heir to the throne. Her first duty is to fly away and mate with up to a dozen drones, to ensure genetic diversity. She’ll store their sperm in her abdomen for the rest of her life, to fertilize eggs. When she returns to the hive, she takes the place of the old queen. Worker bees go through an apprenticeship of sorts. Their first job is to clean the nursery. Once they develop the glands that produce royal jelly, they become nurse bees, feeding and caring for larvae. When they develop wax glands, they become engineers, building and repairing the hive. Finally, they graduate to gathering nectar, and that’s when the work really begins. A field bee never sleeps and will work herself to death flying hundreds of miles in a thousand trips to and from the hive, carrying the precious cargo that will sustain the colony. We’ll have more on the fascinating process of how bees make honey—and how essential they are to our lives—on future EarthDates.

You’re about to hear what may be the oldest story ever told. In another EarthDate, we talked about how Australian Aboriginals remember star maps using songs. But their oral history has preserved much more in stories that corroborate ancient geological events. For instance, they tell of a dramatic sea-level rise long ago that inundated areas of the coast. Many tribes, separated by great distance and different languages, tell the same story. And the details match the geological record of 7,000 years ago. But there’s a far older tale. A tribe in South Australia tells the creation myth of Budj Bim, a god who took the form of a volcano. His teeth became lava that spat from his mouth and flowed to the sea, creating the land that has sustained the tribe since the beginning of time. The hill they call Budj Bim is in fact a long-extinct volcano. And its lava did flow to the sea, forming the coastal wetlands that the Aboriginals have used to practice aquaculture for thousands of years. But the last time it erupted was 37,000 years ago. And no other volcanoes have erupted there since. Archaeological and DNA testing have confirmed that this tribe has lived in the area for 40,000 years. It seems likely they witnessed the ancient eruption and preserved it in a legend that’s very much alive today. So, the next time you’re asked for a good story, tell them the 37,000-year-old tale of Budj Bim, the volcano god.

It seems that Australia’s modern highways may have been laid out according to the stars. Australian Aboriginals, like many ancient cultures, have an elaborate oral history passed down through generations to help them navigate and find food and water in their desert environment. This knowledge base uses visual memory aids from the land… and the sky. When ancient aboriginal navigators found a successful path through the desert, they looked for a path in the stars that mimicked it. They’d use stars to represent water holes and hilltops and gave them the same names. At night, they could point out the star patterns to others who had never made the trip, describing the path from one waypoint to the next. To help travelers remember the maps, First Nation clans preserved them in song, which they could sing along their journey to recall place names, orientations, and distances. In the process, they taught these songs—and the star maps they reflected—to younger generations. This navigation tool, used by First Nation tribes for millennia, was only disclosed to researchers a few years ago. Many of these so-called “songlines” are still used in Aboriginal treks today. And when researchers laid the songlines over a modern map of Australia, they found that many highways appeared to line up with the star patterns. These roads were set along cattle trails established by early immigrant ranchers who were probably following songlines shown to them by Aboriginal guides.

75 years ago, the U.S. exploded its first atomic bomb, in the New Mexico desert. It was the culmination of 5 years of hurried development. Throughout World War II, Germany hoped to use the incredible energy density of uranium and plutonium to build a devastating weapon. To beat them to the bomb, the U.S. assembled teams across the country—130,000 staff and scientists, many of whom had fled Europe to avoid Nazi persecution. In July 1945, team leaders gathered to watch that first detonation from 10 miles away. They were unsure whether it would detonate at all. The blast vaporized the 100-foot tower that held the bomb, turned the desert sand to glass for a mile around, and broke windows more than 100 miles away. It exceeded the force the scientists had expected by 2 to 4 times. To try to force Japan to surrender and end World War II, President Truman warned that the U.S. had created a weapon of “utter devastation.” The Japanese emperor was unmoved. Truman made the decision to drop a smaller uranium bomb, but Japan would still not capitulate. Three days later, the U.S. dropped a plutonium bomb like the one in the desert. Together they killed nearly 200,000 people, and Japan surrendered. Over the next 3 decades, America and other atomic powers developed more nuclear weapons. But they’ve never been used again in war, and let’s hope they never will. I’m Scott Tinker with a grim reminder of the power of science.

Do you wish you could have an extra hour in the day? Well, if you can wait a very long time, you’ll get it. That’s because the length of the day is increasing, and has been for the last billion-plus years. Scientists recently studied a large Cretaceous mollusk with unprecedented precision. Mollusk shells grow like tree rings, adding a little bit each day. The researchers used lasers to drill tiny holes in the shell, each the size of a red blood cell—like microscopic core samples. From these they could examine the shell’s growth not just by the day, but by the hour. They found that 80 million years ago, when this animal was alive, each day was half an hour shorter than today. Going back further, to 600-million-year-old tidal sediments in Australia, they determined the day was then 22 hours long. And 1.4-billion-year-old rocks in China suggested a 19-hour day. All this indicates that Earth was once spinning faster than today. What’s going on? Well, you can blame it on the moon. The moon’s gravity causes Earth’s tides, which pull on and bulge out the surface of the oceans. Like when a spinning skater decelerates by extending her arms, the expanding and contracting seas are slowly decelerating Earth’s rotation. But don’t worry, it’s happening very slowly—just 1.8 milliseconds per century. Meaning it will be 200 million years before you get that extra hour.

In many parts of the U.S., what we call “locusts” are actually cicadas—that plug-shaped insect that sings in the trees. But especially in Africa and the Middle East, “locusts” are large grasshoppers occurring in massive swarms that can devour crops across the region. These grasshoppers have undergone a strange metamorphosis. In normal times, they’re a shy, solitary desert hopper. Heat and drought control their numbers, and they’re not a threat to agriculture. But every few decades—when heavy rains span several seasons—vastly more eggs hatch, and the population explodes. So many insects in close contact causes serotonin to flood their brains, and profound changes occur. The juveniles band together in nomadic hordes, crawling across the landscape looking for food. They grow larger than normal, faster, and even change color. Adults grow larger wings and jaws and take to the sky, forming swarms of billions, devastating the vegetation in their path. These swarms can span a thousand square miles and fly 80 miles in a day. Aerial pesticide spraying can reduce their numbers but has problems of its own: contaminating crops and water. The insects are edible and considered a delicacy, and make excellent cattle fodder. But there are so many that eating them makes little difference. Eventually, dry conditions return and the swarms die. The eggs that hatch will again become the peaceful desert grasshopper… until the next unusually wet spell.

Machu Picchu, the Incan city built on a jagged mountain peak, is so remote that the Spanish conquistadors never found it. It’s difficult to get to, even today. We’ve long wondered why the Inca built it there. New research suggests they chose the site because it’s on the intersection of fault lines. That would seem like a terrible place to build any city! But the Inca had good reasons. The faults would have fractured the rocks there, making it easier for the Inca to dig and build flat terraces on which they built their structures and farmed their crops. The fractured rocks were also easier to shape into the precise blocks they used to build their earthquake-resistant architecture: thick, backward-sloping walls with small, trapezoidal windows. The faults drained water away from the site in this area prone to flash floods. But they also carried water to it from higher mountain ranges, important because between floods, there was often little water. In fact, scientists believe that’s how the Inca found the faults in the first place: by following water seeps and drainages in the valley farther up into the mountains, to the place the faults intersected. We’ve come to realize that one reason for the Inca’s remarkable success in the difficult Andean environment was a keen understanding of its fault systems. Perhaps it’s not surprising then, that Cusco and several of their other cities were also built near fracture zones.

Today, emeralds may be a bit less famous than their red, white, and blue cousins—diamonds, rubies, and sapphires. But they were once perhaps the most celebrated gemstone. 3,500 years ago, the Egyptians found emerald deposits in their kingdom. They ascribed to the stones many mystical properties. They were symbols of fertility and immortality, perhaps because of their “ever green” color. They were thought to increase eloquence and intuition. Some even thought they could cure malaria. Those who put emeralds under their tongue could supposedly see into the future. Perhaps for these reasons, Cleopatra was a big fan, as were other celebrities of her era, like Alexander the Great. Stars of a more recent time, like Elizabeth Taylor, also loved emeralds, but probably more for their rare color. And it is quite rare. Emeralds can only form when two scarce elements, beryllium and chromium, happen to occur in the same place in sufficient quantities. The resulting crystal, more accurately called “green beryl,” is not quite as hard as diamonds, sapphires, or rubies. Though rare, in the last few centuries we’ve found deposits in other countries, with Colombia producing the greenest stones. The largest emeralds ever found—nine staggering crystals the diameter of your forearm—sit in a vault in the LA County Sheriff’s office. These uncut stones, worth nearly 400 million dollars, are surrounded by intrigue, a story perhaps we’ll cover on another EarthDate.

On a previous EarthDate we talked about GPS, the Global Positioning System, and recent improvements that allow mapping down to the millimeter—accurate enough to detect the creeping movement of Earth’s tectonic plates. These advances have inspired scientists to use GPS in many new ways to better understand earthquakes and other Earth processes. The signals from GPS are very long—many thousands of digits—making them too slow to track seismic activity. But recently, scientists realized they could use a different, much shorter part of the GPS signal and combine that with faster refreshing of GPS receivers. This has allowed GPS to monitor earthquakes very accurately over a very broad area, enough to see their impact on distant communities. And hopefully with new developments, fast enough to warn them of an impending quake. Using similar technology, scientists can now measure and track other disruptions on Earth’s surface, such as sinkholes, landslides, and tidal waves. Volcanic ash can disrupt GPS signals, so scientists devised a way to use those disruptions to monitor ash plumes and warn airplanes. Similarly, water vapor in the atmosphere can delay GPS signals. Meteorologists are now reading that delay to predict heavy rainfall and advise communities about flash floods before they arrive. All very interesting examples of how improvements in technology allow for advances in science.

When you see white, you’re actually seeing all the visible colors of light at once. And when you see black, the object you’re looking at is absorbing light. White and black aren’t colors; they’re visual experiences. And a few rare animals can produce the visual experience of super-black. Most black surfaces are still slightly reflective. But these creatures have developed plumage or cells that absorb nearly all visible light. The male birds of paradise in Papua New Guinea have super-black feathers that, when examined with an electron microscope, have a three-dimensional structure like miniature bottle brushes. Their complex surfaces scatter and trap light until it’s absorbed and converted into heat energy. Even if these feathers are coated in shiny metal, they remain super-black—because it’s their structure, not a pigment, that’s absorbing the light. Super-black is so dark that features, angles, and textures disappear. So some birds, butterflies, spiders, and snakes use it as camouflage or to attract mates—making their brightly colored areas appear even more vivid. Today, scientists may be able to do them one better, creating ultra-black with carbon nanotubes, which would capture 99.995 percent of visible light, and infrared too. It could be used to camouflage military vehicles or keep stray light from bouncing into telescopes. Just one more instance of humans taking a visual cue from nature.

If you’ve ever walked through an aspen grove, you’ve seen hundreds or thousands of white trunks propping up a sky of silvery green leaves trembling in the wind. In the fall, all the leaves in one grove will go from green to gold at the same time. This is because the entire grove is really just one organism, a massive root system from which many trunks sprout, grow, die, and are replaced by new trunks. The largest aspen grove in the world, in Utah, is named Pando: Latin for “I spread out.” It sprouted 80,000 years ago from a seed the size of a pepper grain and now supports almost 50,000 trunks, making it the heaviest living thing in the world—and one of the oldest. But Pando is slowly declining. Most of its trunks are now more than 100 years old; new ones aren’t growing to take the places of those that die. Researchers think it has to do with elk and mule deer. A century ago, ranchers and trappers removed their natural predators from the area. Local populations of elk have grown to more than 77,000 and mule deer to 300,000. And the grazing elk and deer are eating the aspen saplings. Studies that fenced off sections of the grove have seen young trees return, growing 10 feet in just a few years. Ranchers don’t want to reintroduce non-human predators, who might endanger their livestock. So, the solution may be to fence Pando to protect it from deer. Or to change hunting practices to thin the herds.

In previous episodes, we’ve talked about geothermal energy—the heat of the earth. Where extreme heat is near the surface, it can be used to produce steam to drive electric generators. Where this heat warms groundwater, it makes hot springs. But there’s another type of geothermal energy that’s more widely available: not extreme heat, but constant, low-temperature heat. Anywhere in temperate latitudes, if you dig 10 feet or more below the surface, the ground is a near-constant mild temperature all year long. You may have experienced this in a cave. Caves are warmer than the surface in winter and cooler in summer. Low-temperature geothermal energy can work the same way in buildings, in place of conventional heat and air conditioning. The core of the system is a network of pipes laid in shallow horizontal trenches or somewhat deeper vertical wells. Through these, a fluid circulates, taking on the temperature of the earth—between 45 and 75 degrees Fahrenheit in the continental U.S., depending on latitude. That liquid then passes through a heat exchanger in the building. Air blows over the tubing, takes on the temperature of the fluid, then blows through the house, office, or school. These systems, supplemented as needed, can keep buildings a mild, constant temperature year-round. The network of pipes is more expensive to install than conventional systems, but the energy savings can pay off the difference in several years. Maybe that’s why 50,000 of these systems are installed in the U.S. each year.

North America’s Great Lakes are great indeed. They contain 20 percent of the planet’s surface freshwater—enough to cover the continental U.S. 10 feet deep. They formed at the end of the last Ice Age, when Canada was under an ice sheet 3,000 to 9,000 feet thick. This massively heavy continental glacier had flowed southward, depressing and carving the Earth as it passed over, pushing ahead of it huge piles of eroded rock and gravel called glacial moraines. 20,000 years ago, the ice sheet finally began to melt. As the glacier receded northward, floods of meltwater filled the deep depressions it had carved and were trapped in place by the banks of moraines it left behind. Over centuries, this formed the Great Lakes. But the areas the glacier eroded, and therefore the shape of the lakes, were determined by geology long before that. Lake Superior began life a billion years ago as a huge rift, a crack in the continental crust. Over millions of years it filled with sediment, which was soft and easy for the glacier to eventually scour away. Lakes Michigan and Huron were likewise carved out of softer sedimentary rock that surrounds the harder rock that makes up the state of Michigan. Lakes Erie and Ontario are the shallowest and smallest, both carved into weaker shales and connected by Niagara Falls, which flows over a harder dolomite shelf. The Great Lakes are truly one of America’s great places, in natural beauty and history.

Plains Indians depended on buffalo for everything: meat for food, hide for clothing, horns and bones for weapons and tools. One of the ways they hunted them was by stampeding them over cliffs. Scientists thought that humans practiced communal hunting drives like this as far back as 5,000 years ago. But a recent discovery has changed that. When constructing a new airport north of Mexico City, workers unearthed enormous bones and called in scientists, who discovered two massive pits 80 feet in diameter. They realized the 800 bones within the pits had come from woolly mammoths. There were herds that lived in the area long ago. They were also able to determine, based on sediment layers deposited within the pits and tool marks on their walls, that humans had dug them 15,000 years ago, by hand. It appeared that early tribes had driven the giant beasts into them, trapping them for slaughter. Like the Plains Indians, these hunters were resourceful with the animals, turning bones into knives and scrapers, which they used in butchering. Some of these were found in the pits. It also appeared that many generations of humans hunted mammoths here, using this site for more than 500 years. When they finally abandoned the pits, they left the mammoth bones artfully arranged inside, with tusks and shoulder blades encircling skulls, perhaps in tribute to the animals that fed and clothed them for centuries.

We often think that Thomas Edison invented the light bulb. While he certainly was the first to make it a commercial success, the invention took almost a century to “come to light.” The story begins long before household electricity. In 1800, an Italian scientist named Volta created the first primitive battery. And one of the first things he did was connect copper wire to it, which glowed faintly. Two years later, a different inventor ran current from a battery through carbon rods to create the first industrial bulb. But it was very bright, short lived, and not suited to household use. More scientists, over more decades, improved filaments and used a vacuum to remove oxygen, or filled the bulb with nitrogen to extend the filament’s life. Finally, in the late 1870’s, Edison bought a Canadian patent and formed a light bulb company. He and his workers tested more than 9,000 filament designs. Their first successful bulbs used carbonized bamboo. But they ultimately discovered that the rare metal tungsten, with its high melting point and electrical resistance, was the best choice. At first, Edison’s technology couldn’t make tungsten thin enough. Later advancements wound 6 feet of ultrathin wire down to a 1-inch-long filament. They mounted it on a glass support, and the commercial bulb was born. This design lasted nearly unchanged for over a century, only now being replaced by more efficient designs which themselves have taken more than 50 years to come to market.