Indholdsfortegnelse for July - August 2018 i Discover

I love maps. Growing up in the isolated mid-mountain West, I’d spend hours poring over one of those classic Rand McNally road map books of the states. Its cover was tattered, not from years of cross-country car trips, but from my incessant perusing and my curiosity about life in the middle of New York City or Arizona or Louisiana. I’d imagine myself in the midst of the street grids that made up a city neighborhood or in the acres of rambling forests depicted as big blocks of green across much of Appalachia. The road maps for each state were my portal to a new place and my window into learning about what made it tick — and I always wanted to know more. Our crew of editors hopes you feel…

As the Curiosity rover climbs closer to the summit of Mars’ Mount Sharp (upper left), it paused in January to take a photo of the road ahead. Researchers are eager for a closer look at the light-gray area where the terrain dips, at center right. These layers of clay and other sediment, which Curiosity should reach in the coming months, may reveal more details about how water once shaped the terrain. If the view reminds you of an earthly desert, it’s by design. NASA technicians adjusted the color balance away from Mars’ reddish hues so that the landscape would appear as if illuminated by terrestrial sunshine — the better for Earth-trained geologists to recognize patterns.…

HUMAN ERRORS A Panorama of Our Glitches, From Pointless Bones to Broken Genes By Nathan H. Lents We are a mess. Every one of us is riddled with anatomical disadvantages and evolutionary missteps. Biology professor Lents provides a funny, fascinating catalog of our collective shortcomings that’s tough to put down. CHASING NEW HORIZONS Inside the Epic First Mission to Pluto By Alan Stern and David Grinspoon Journey to the far reaches of our solar system without leaving your chaise lounge through this insider’s view of an extraordinary space odyssey. STILL WATERS The Secret World of Lakes By Curt Stager From iconic Walden Pond to East Africa’s explosive Lake Kivu, natural sciences professor Stager takes a deep dive into the geological and cultural backstories of these bodies of water, many imperiled…

Knowledge really is power. The more we know, the better we understand how the world works. With a little context, we can figure out how things relate to each other and spot hidden connections. And we can win more trivia contests. But there’s so much! Who has enough time to know everything? How do you even know where to begin? Look no further than our annual collection of Everything Worth Knowing. Get up to speed on when autonomous cars will go mainstream, where your digital treasures go when you save them to the cloud, how the Milky Way has changed over the years, who really built the Egyptian pyramids, why pigeons are cooler than you think and more. Get in on the ground level of understanding for each topic with…

How did the Egyptians stack multipleton blocks to create a pyramid hundreds of feet high? Scientists and historians have proposed many theories, from elaborate ramps to pulleys tugging blocks up the slanted sides and fulcrums maneuvering them into place. But the exact methods remain unknown. Most researchers agree that the construction involved ramps of some kind, likely made of gypsum, clay and limestone debris, especially since ramp remnants are still on the plateau. But there’s little agreement how the ramps were used in pyramid construction. A Straight-on Ramp would have to be extremely long to achieve the low grade necessary to transport the blocks, extending far beyond the quarries — an engineering feat in itself. This type of ramp also doesn’t solve how the blocks were moved to specific spots…

The youngest conclusively dated Neanderthal fossils and artifacts clock in at around 40,000 years old. Researchers have put forth a range of possible explanations for their demise, including periods of extreme cold, a volcanic super-eruption or competition with a whole rogues’ gallery of carnivores, from scimitar cats to cave lions, that kept Neanderthal populations small. Other even less likely hypotheses include illnesses similar to mad cow disease, spread through cannibalism. However, most scholars believe modern humans played a role. “Neanderthals go extinct right at the time modern humans get there,” says Churchill. “I don’t think it’s a coincidence.” Although Neanderthals had survived previous encounters with modern humans migrating from Africa, the wave that arrived roughly 45,000 years ago was different: They came armed with stone projectile points that could be…

The closest living relative of the now-extinct dodo, pigeons supposedly originated from the Mediterranean, India and the Middle East. Now they live everywhere except the Sahara Desert, Antarctica and the high Arctic. Our shared history dates back further than you’d think. About 10,000 years ago The first hints of human-pigeon interactions date back to the Pleistocene era. Although evidence is scant, archaeologists believe our ancestors bred them for food. About 5,000 years ago The first proof of pigeon domestication appears in writings etched in ancient Mesopotamian cuneiform tablets and Egyptian hieroglyphics. About 4,500 years ago Records of pigeons performing special duties — as food, messengers and sporting targets — start showing up in ancient Mesopotamia. Even their droppings are used as ingredients in fertilizer and gunpowder. 1800s Businesses such as…

In December 2016, with the world marathon record at 2:02:57, Nike announced an audacious goal: to break the two-hour barrier. Experts initially balked at the mission. But last May, Eliud Kipchoge, a 2016 Olympic gold medalist marathoner from Kenya, ran 2:00:25 — just one second per mile off the necessary pace. The sport’s governing body doesn’t consider Kipchoge’s run a world record because it didn’t follow the regulations for official records. But physiologists are using it to devise ways to cross the threshold on a record-eligible course. Hutchinson guesses there are a few factors that helped Kipchoge. Nike’s new shoe technology, engineered for the project, probably shaved off a minute. He shed maybe another minute by drafting — reducing wind resistance by running behind someone else, pacers in this case…

Some 40,000 years ago, a slender bone flute was abandoned in a Central European cave. Carved with five finger holes and a tapered mouthpiece, the instrument dates from around the dawn of human settlement on the continent. Humans have been making music for a very long time. Even that flute is probably a recent example of our musical development. Its sophisticated design suggests knowledge of acoustics, likely drawing on long-standing musical customs. But earlier practices are elusive because the first music was most certainly made with the body and voice, dying with its creators. Charles Darwin considered our musical behaviors to be “amongst the most mysterious.” At least in terms of origins, his words still resonate. One way of exploring musicality before Stone Age flautists crashed Europe is to study…

Q: What is harmonic surprise? A: It’s the use of chords that are rare. Musicians use a large number of chords to compose their melodies. Some chords are used often, and some are used rarely. Harmonic surprise is a mathematical way to measure how often rare chords appear in a song. Q: How does this relate to a song’s popularity? A: We found two types of links between harmonic surprise and song popularity. In the first, songs with many surprising chords tended to reach near the top of the Billboard Hot 100 rankings more often than songs with less harmonic surprise. In the second, what helped the popularity of songs was the change in surprise across sections of the song. The two main sections of a song are verses and…

By 2040, annual sales of self-driving cars could exceed 33 million. Currently, only cars up to Level 2 are available to the public. By 2021, BMW says it will be selling Level 3, and Ford says it will be selling Level 4 to consumers. That’s all great, but regulations will need to keep pace. Since 2011, 21 states have passed autonomous vehicle legislation, and five others have governor-issued executive orders. In general, the laws limit the vehicles on public roads to Level 2, though some states have opened roads to researchers to test cars at Level 3 and higher. At the federal level, existing laws were written with human drivers in mind, but the U.S. Senate is considering a bill that would provide some regulatory framework for autonomous cars. Antsy?…

The early years of planetary detection sparked debate as discoveries accumulated. Of the first 19 planets discovered, half were actually brown dwarfs. The problem persists today, as more accurate mass measurements of hefty planets reveal instead brown dwarfs. In 2009, the Kepler telescope inundated astronomers with new data. Previous false detections were relabeled candidates, while some candidates became false detections. But only one confirmed Kepler planet has ever been retracted: Kepler-32e, the result of a clerical error. The Gliese 581 system has seen quite the volley back and forth. In 2010, astronomers found two or three potentially habitable planets: Gliese 581b, c, and e. But the proposed Gliese 581f was soon ruled out, while the status of Gliese 581g, the most potentially habitable planet, has long been cast in doubt.…

Wary of Wearable Tech (“Future Wear,” April 2018) I always read Discover from cover to cover and find the articles enlightening. Occasionally, however, I think the authors show that they are too enamored of what I think of as the “gee whiz” factor of new science advances. As a case in point, the article “Future Wear” paints a wonderful picture of the possibilities of electronic textiles. What is not mentioned is what is to be done with those textiles once the electronics stop working or the fabric tears or wears out. Will there be a mechanism in place to safely recycle or dispose of electronic textiles? I would encourage your writers to consider all the “what ifs” of science advances as a part of the articles they create. Paul Garrett Richmond,…

In a dimly lit warehouse in Austin, Texas, a team of robots and scientists is raising millions of six-legged livestock every month. Once fully grown, they’re roasted and seasoned, mixed into granola or ground into flour. The quarry? Crickets. This semi-automated, commercial-scale cricket farm is the brainchild of Aspire Food Group founders Gabe Mott, Shobhita Soor and Mohammed Ashour. When they were MBA students at McGill University in 2013, the idea won them the $1 million Hult Prize for social good. To launch the farm, they had to think big about Acheta domesticus, the house cricket. No one had reared them for human consumption on this scale before. “We had to walk away from everything in the scientific literature,” Mott says. The group now runs constant tests on every bin…

It’s All Fun and Games Until Someone Gets Hurt Exciting new gadgets are fun to play with, but sometimes they can get us into trouble. Hoverboards are a prime example. The two-wheeled toys — sadly, more like fancy skateboards than true hoverboards à la Back to the Future — have led to injuries in thousands of kids since arriving on the market, according to a new study published in the journal Pediatrics. Degrees of Separation From spotting moon craters to a rooster’s crow. 6,000 The number of new craters an artificial intelligence system was able to spot on our moon. That’s nearly twice as many craters as we mere mortals could pick out on our own, saving astronomers time and resources. 92% How accurate another AI-based approach was at classifying…

My supervising physician was worried. He popped his head into the room and motioned for me to join him in the hallway. “We need to page child protection,” he whispered. Bobby was an 8-year-old who lived with his family in a small town. His mother, Mary, took him to their family doctor to examine a limp the boy had developed. The doctor suspected a broken bone and referred him to a local emergency room. X-rays showed he had a fractured left shin, which doctors placed in a cast. Bobby was then admitted to our ward at a children’s hospital because of concerns about possible child abuse. His mother said he was running and fell on the carpeted living room floor. But most boys don’t break their leg from that. Mary…

Knowing that Neanderthals and modern humans interbred, a minority of researchers now prefer subspecies classifications: Homo sapiens neanderthalensis and Homo sapiens sapiens. The names don’t change our evolutionary relations. While geographically separated, Neanderthals and modern humans evolved enough differences to be easily distinguished by DNA and physical traits, but not enough to make interbreeding impossible. They were in the process of becoming distinct species, but not quite there. As for pronunciation, King named the first scientifically described specimen for where it was discovered: Neander Valley, or Neanderthal — thal being a spelling variation of the word for valley. When Germany standardized spelling in the early 20th century, thal became tal. While the formal scientific name remains Homo neanderthalensis, scholars diverge on the colloquial, writing Neandertal or Neanderthal. But regardless of…

The uncanny intelligence of pigeons has been an obsession of many scientists. In the 1950s, psychologist B.F. Skinner, known for his work on learning and behavior, taught the birds to play pingpong. He also trained them to guide missiles through the sky by pecking at a screen when they saw the weapons’ intended targets. But military officials were skeptical of the feathered pilots’ reliability and accuracy, and scrapped the idea. Still, the birds are one of the few species to pass the “mirror test,” which assesses a critter’s ability to recognize its own reflection, indicating it has a concept of self. Only about six other animals have this ability. Pigeons also beat out babies and toddlers in recognizing the letters of the alphabet and understanding categories. They can even distinguish…

Self-Editing Octopuses can make significant changes to their RNA — the messengers that ferry instructions from DNA to cells. This ability helps them adapt to the cold, and may even play a role in why they’re so clever. Octopia? In 2017, researchers reported that members of one octopus species lived in close proximity to each other, the first time such behavior has been documented among the famously solitary creatures. The octopuses apparently gathered to exploit ample food resources: scallops. So numerous were the emptied and discarded scallop shells that they could be mistaken for mini-cities on the ocean floor. But it was no utopia — evictions by larger octopuses were common. Tasty! Octopus arms are muscular and boneless; the best human analog would be the tongue, and the comparison is…

Tone A single musical sound of specific pitch, also known as a note. Pitch The musical quality of a tone, sounding higher or lower based on the frequency of its sound waves. Resonance Amplification of a musical tone by interaction of sound vibrations with a surface or enclosed space. Volume The pressure of sound vibrations, heard in terms of the loudness of music. Tempo The pace of a composition’s performance, not tied to individual notes. Often measured in beats per minute. Rhythm An arrangement of tones of different durations and stresses. Melody A succession of individual tones arranged to musical effect, aka a tune. Chord Two or more tones sounded simultaneously. Chords are the ingredients of harmony. Harmony The musical arrangement of chords. Harmony is the organization of tones played…

Listen to these songs at DiscoverMagazine.com/MusicSemantics When the pitch of an instrument is lower than surrounding sounds … Meaning: The sound source is larger. Reason: Larger sound sources have larger resonance chambers. Real-world example: Trumpeting elephants Musical example: “The Elephant” in The Carnival of the Animals by Camille Saint-Saëns When the pitch of the music decreases … Meaning: The sound source is losing energy. Reason: Slowing movement produces lower-frequency sounds. Real-world example: A tape player with a dying battery Musical example: The last two measures of Frédéric Chopin’s Nocturne Op. 9, No. 2 When the volume of an instrument is quieter than surrounding sounds … Meaning: The sound source is less energetic. Reason: Lower-energy sound sources produce less sound pressure, thus lower volume. Real-world example: A gently-blown whistle Musical example:…

Would you be comfortable riding in a driverless car? Fifty-six percent of Americans say no, citing lack of trust and safety concerns, according to a 2017 Pew Research Center survey. In March, an Uber self-driving vehicle in Tempe, Arizona, hit and killed a woman crossing a street, further stoking public fear. Another study, using machine learning to analyze the language in more than 1 trillion social media posts, found that Americans are most afraid of autonomous cars being hijacked by hackers.…

Incisors are front and center, and they are for biting. They’re the first baby teeth to emerge. Canines are sharp and used for shredding and ripping apart food. Premolars are more substantial than canines or incisors, and they are used for grinding and chewing food. Molars tend to be flatter and wider than premolars, but their function is the same. Wisdom teeth might have been molar teeth in the days before agriculture, when human jaws were bigger because raw, wild plants and meat were tougher to break down. Changes in culture and diet caused jaws to shrink, leading to overcrowding and impacted wisdom teeth, which may then grow in sideways due to lack of room.…

It’ll Get Inside Your Head Imagine replacing the bulky, restrictive brain scanners we use today with one you could pop right onto your head like a helmet. Editor Nathaniel Scharping gave us the lowdown on this innovative — and funky-looking — new piece of tech. We asked our Twitter followers to caption an image of the scanner. Here are some of our faves: @WSUVoiland (WSU Voiland Eng&Arch) Phantom of the Operating System @chrisbrueske (Chris Brueske) @facebook’s new data mining hat. It’s a free hat!! @johnkowalsky (John Kowalsky) Hello, Clarice In case you missed the story, check it out at DiscoverMagazine.com/BrainScanner Feedback is edited for space and clarity.…

KETCHUP FAN? Then you know you’ve got to shake that bottle of your favorite brand before you squeeze it onto your food of choice. Otherwise, you’ll be met with a watery mess followed by some gunky globs. That’s because ketchup — along with a whole host of other substances ranging from clay face masks to printing inks — is thixotropic. When it sits too long, lonely and unused on a diner table or in the dark abyss that is your refrigerator, the concoction separates and the tomato-y part thickens up, becoming more viscous. But when you shake it, everything mixes back up, thins out, and you’re good to go.…

BOOKS SUMMER’S HERE, and the time is right for reading. So slather on the sunscreen, sink your toes into the sand or soft grass, and dig in to these new books. BEST FOR THE BEACH SPYING ON WHALES The Past, Present, and Future of Earth’s Most Awesome Creatures By Nick Pyenson From thrilling fossil finds in Chile’s Atacama Desert to ad hoc dissections during an Icelandic commercial operation, Smithsonian Institution curator Pyenson tells, ahem, a whale of a tale about these beloved — and besieged — marine mammals. TAKE ME CAMPING ATLAS OF A LOST WORLD Travels in Ice Age America By Craig Childs Part paleoanthropological investigation, part travelogue: Childs and his family and friends kayak, hike and minivan their way along the routes likely taken by the first humans…

On a drizzly December afternoon in western Massachusetts, U.S. Geological Survey wildlife biologists Evan Grant and Adrianne Brand stop their car on the side of the road and plod into the wet forest through a break in the oaks and white pines. It’s a bit late in the year to find the predators they’re searching for, but this forest is teeming with them. In fact, as soon as they walk past the first tree, they’re probably never more than a few feet from one. You’d never know it, though. If you walk into almost any forest, like this one in the northeastern United States, and stand still, you’ll start to hear animals. At first, the songs of birds from afar will reach you. Then, the ones nearby that went silent…

Within about 500 years, grave markers in ancient Egypt progressed from simple mounds to timeless architectural wonders. Predynastic 4600-3000 B.C. Dirt Mounds The ancient Egyptians believe that creation sprang from a primeval mound. This might have prompted them to bury their dead beneath piles of dirt, perhaps believing that this aids rebirth to the afterlife. Early Dynastic 3000-2686 B.C. Mastabas The mounds grow into massive rectangular mud-brick monuments called mastabas, Arabic for “bench.” Mastabas become the final resting place for Egyptian royalty, whose bodies are placed in underground chambers beneath the structures. Later, mastabas are also built of stone. Third Dynasty 2686-2613 B.C. Step Pyramids Builders begin stacking mastabas one on top the other, each smaller than the one below it. Pharaoh Djoser builds a six-step pyramid at Saqqara, 10…

In 2016, a genetic study of more than 50 Homo sapiens fossils 7,000 to 45,000 years old showed the proportion of Neanderthal DNA in our species diminished over time. This pattern suggests that most Neanderthal genes were harmful to modern humans and were weeded from our gene pool: Individuals with those Neanderthal genes were less likely to survive and reproduce. Some Neanderthal DNA persists today, comprising roughly 2 percent of the genomes of all non-Africans, but it’s generally confined to “junk” regions that do not contain vital genes. However, Neanderthals do contribute a small number of our functioning genes. To understand their effect on living humans, researchers have analyzed tens of thousands of modern genomes to determine whether individuals with Neanderthal genes are more likely to have certain traits. The…

Often dubbed “the rats of the sky,” pigeons have a bad — but mostly unearned — rap in modern society. Despite the stigma, these birds have some impressive skills. Birds of a Feather Pigeons refuse to be pigeonholed. They come in an eccentric array, with around 350 recorded breeds. All are part of the family Columbidae, which also includes doves. Here are some of the most popular traits these birds are bred for. Utility Many pigeons are bred as a food source in the U.S. and elsewhere. Special Skills Some birds are selected for their abilities, such as homing pigeons, which have an incredible knack for finding home. Or there are flying tumblers and highflyers, which can roll over backward in flight — perfect for flying competitions and shows. Display…

It’s no secret these avians are adept at finding their way home — a skill known, fittingly, as homing. But how they do it still stumps experts. Some scientists think pigeons navigate using Earth’s magnetic field. In 2012, a group reported that when pigeons were exposed to magnetic fields, certain brain-stem cells for their inner ears activated. The scientists theorized these cells could signal the direction, intensity and polarity of our planet’s magnetic field, giving pigeons a built-in GPS. Because pigeons have sensitive hearing and remarkable memory, some experts suspect the fliers actually create sound maps, allowing them to navigate using specific audio signatures as landmarks. Other research suggests they use the sun, certain environmental cues or even their sense of smell for direction. And yet another camp claims the…

Humans are pretty quick. In 2009, Usain Bolt flew down the track at over 23 mph; in 2014, Dennis Kimetto, the marathon world record-holder, cruised along at 12.8 mph — about a 4:42-per-mile pace — for 26.2 miles. Scientists are uncovering what makes the Bolts and Kimettos of the world tick, and how we evolved to do both. That knowledge is redefining what’s possible and may help you speed up, too. MUSCLE FIBER TYPES Muscle fibers come in two general types, fast- and slow-twitch, and everyone has a mix of both. Fast-twitch fibers are for short, powerful bursts; they contract quickly but also fatigue quickly. Slow-twitch fibers have more mitochondria — the cells’ powerhouses that use oxygen to make energy — so they don’t fatigue as easily and are ideal…

In the 1990s, paleontologist and famed conservationist Richard Leakey warned that human activity was causing a “sixth extinction.” In the decades since Leakey’s observation, with piles of new supporting evidence, many more researchers have signed on to the idea. Across time and around the planet, extinctions of one or another individual species are always occurring. Known as the “background rate” and documented both historically and in the fossil record, these extinctions are like low-volume static compared with the sudden cymbal crash of a mass die-off. Determining extinction rates as they are unfolding is difficult, but a 2015 Science Advances study, using a range of conservative estimates, placed the current pace at up to 100 times the normal background rate. Human activities are to blame, including population growth, increased resource consumption…

Friendly-Looking Flapjack Some octopuses are downright cute, like this deepwater species, about the size of a baseball, found in California's Monterey Bay. Researcher Stephanie Bush proposes a fitting moniker for the still-unnamed species of flapjack octopus: Opisthoteuthis adorabilis. Helicopter Parenting Dedicated octopus moms stop eating after their eggs are fertilized; they simply stand guard until the eggs hatch. The process normally takes a few months, but one species endures a much longer vigil. One Graneledone boreopacifica octopus was observed with her eggs for 53 months — about four and a half years — making it by far the longest recorded brooding period of any animal. Inky’s Great Escape Octopuses are known to be smart and slippery creatures, but Inky, a former resident of a New Zealand aquarium, is downright legendary.…

Level 0 You’re driving. Level 1 You’re driving, but ADAS helps with acceleration and steering. Level 2 You’re driving, but ADAS can fully control acceleration, braking and steering under some circumstances. Level 3 ADS fully controls the car in some circumstances, but you’re ready to take over. Level 4 ADS performs all driving functions in certain situations, and you don’t need to pay attention. Level 5 The vehicle drives, and you sit as passenger.…

The spiraling tusk of the narwhal inspired illustrations for the horn of the mythical unicorn. However, this horn is actually an overgrown tooth that projects from the whale’s jaw. The narwhal has no teeth inside its mouth — unexpectedly, since its diet is mostly fish. Even more surprising: The tooth functions as a sensory organ, with millions of nerve connections running through it. Because the tusk can sense changes in seawater salinity, it can help narwhals navigate through different marine environments. They can also use their tusk like a club to stun prey. The Chinese water deer is the only deer species without antlers, but don’t worry — they have a different defense mechanism going for them. The male deer brandish tiny tusks — 2 inches long, on average —…

Fractals often have the rare property of existing between our ordinary dimensions. The Koch snowflake, for example, consists of ordinary one-dimensional lines, but with more and more iterations, it appears fuzzy, as if it had breadth. The Sierpinski triangle is built from an ordinary two-dimensional triangle, but with all the area carved out, it doesn’t quite have the heft of two dimensions. Mandelbrot captured this through the idea of a fractional dimension — hence the name fractal. Essentially, it captures how complex and squiggly a fractal is. Think again of a coastline: As you shrink your measuring stick, the apparent length of a craggy coastline will grow much faster than that of a smooth beach, so it will accordingly have a higher fractal dimension. The Koch snowflake has a fractal…

OUR GALAXY IS LOUSY WITH PLANETS. NASA’s exoplanet archive lists more than 3,400 confirmed planets outside our solar system, with more added every day. Nearly 4,500 planetary candidates from NASA’s Kepler spacecraft await confirmation, meaning thousands more could make the list in the near future. Before 1995, there were only 11 known planets. There were the nine classical planets in our solar system, from Mercury through Pluto (then still a planet), and two bizarre objects that had been found around a distant pulsar. But in 1995, we discovered 51 Pegasi b, the first confirmed planet around a Sun-like star. It was a weird one. It circled its star every four days and was eight times more massive than Jupiter. At the time, it received a lukewarm reception. “In 1995, 51…