Eyes in the Sky Look Back in Time

Charles Q. Choi is a science journalist who has also written for Scientific American, The New York Times, Wired, Science, and Nature. In his spare time, he has ventured to all seven continents.

The Fertile Crescent in the Near East was long known as “the cradle of civilization,” and at its heart lies Mesopotamia, home to the earliest known cities, such as Ur. Now satellite images are helping uncover the history of human settlements in this storied area between the Tigris and Euphrates rivers, the latest example of how two very modern technologies—sophisticated computing and images of Earth taken from space—are helping shed light on long-extinct species and the earliest complex human societies.

In a study published this week in PNAS, the fortuitously named Harvard archaeologist Jason Ur worked with Bjoern Menze at MIT to develop a computer algorithm that could detect types of soil known as anthrosols from satellite images. Anthrosols are created by long-term human activity, and are finer, lighter-colored and richer in organic material than surrounding soil. The algorithm was trained on what anthrosols from known sites look like based on the patterns of light they reflect, giving the software the chance to spot anthrosols in as-yet unknown sites.

This map shows Ur and Menze’s analysis of anthrosol probability for part of Mesopotamia.

Armed with this method to detect ancient human habitation from space, researchers analyzed a 23,000-square-kilometer area of northeastern Syria and mapped more than 14,000 sites spanning 8,000 years. To find out more about how the sites were used, Ur and Menze compared the satellite images with data on the elevation and volume of these sites previously gathered by the Space Shuttle. The ancient settlements the scientists analyzed were built atop the remains of their mostly mud-brick predecessors, so measuring the height and volume of sites could give an idea of the long-term attractiveness of each locale. Ur and Menze identified more than 9,500 elevated sites that cover 157 square kilometers and contain 700 million cubic meters of collapsed architecture and other settlement debris, more than 250 times the volume of concrete making up Hoover Dam.

“I could do this on the ground, but it would probably take me the rest of my life to survey an area this size,” Ur said. Indeed, field scientists that normally prospect for sites in an educated-guess, trial-by-error manner are increasingly leveraging satellite imagery to their advantage.

For instance, paleoanthropologist Lee Berger at the University of Witwatersrand in South Africa and his colleagues discovered Australopithecus sediba, a 1.98-million-year-old relative of humans, with the aid of Google Earth. The 3-D capabilities of the program—originally developed by a CIA-funded company that Google acquired—helped the scientists identify nearly 500 new caves for study from satellite images, which further research revealed had more than 25 fossil sites previously unknown to science. (Berger’s 9-year-old son was the one who actually uncovered the first fossils when they reached the site, by literally stumbling over the bones.)

Paleontologists are also developing an artificial intelligence network to scan satellite images for new fossil sites in the Wyoming desert. The computer program is a neural network that imitates the working of the human brain, and is scanning maps and satellite imagery that include known fossil sites to learn what they look like, relying on factors like color. It then uses this experience to point out areas that might hold hitherto unknown fossil sites in the Great Divide Basin, a large stretch of rocky desert in Wyoming.

Archaeology and paleontology have long been shovel- and pickaxe-dependent sciences, and will almost certainly stay so for the foreseeable future: Despite the occasional use of a backhoe or ground-penetrating radar, most digs simply lack the funding to bring anything they cannot carry in a bucket or the back of a pickup truck. But given the chance to use what once was classified military satellite imagery for free, it makes sense that researchers are leaping at the chance to prospect for sites using Google instead of boots on the ground.

So what might such a trend suggest for the future? Archaeologists and paleontologists are already working to bring the extraordinary power of publicly available satellite and other mapping technologies to bear on the unexplored wilds of the world. But there may be a more interesting development in aerial archaeology: Dilettantes and hobbyists could use the technology to make their own discoveries from afar. After all, amateur astronomers make monumental finds all the time in space, such as alien solar systems, and on Earth, mysterious mammoth structures spotted in China have drawn both amateur and professionally trained analysts to publicly speculate over their nature.

But as more amateurs swarm onto archaeological and paleontological sites, they may also be a risk that looters will come in with them. Hopefully the curious and careful will be more numerous than the greedy and grasping. As Indiana Jones said about such historical treasures, “That belongs in a museum!”

17 Best Places for a Geek to Go This Summer

by Emily Elert

A man was working on a plot of private land in Arkansas last fall when he uncovered a set of huge, fossilized dinosaur tracks. Also last year, interested amateurs photographed tides on low-lying stretches of the California coast to help predict the effects of climate change; they also checked up on local patches of milkweed, prime real estate for monarch butterflies, to keep tabs on the insects’ migration patterns.

Scientific wonders are accessible to anyone with the curiosity to seek them out, and summer is the perfect time to get exploring. In that spirit, we’ve brainstormed a whole season’s worth of places to go, sights to see, and things to do. There are destinations across the country, so whether you’re in Albany or Albuquerque, you should be able to find something nearby.

The adventurous among you may find yourselves strapping on an undersea helmet and strolling through a submarine kelp forest or wielding a Geiger counter in a field strewn with remnants of the atomic era, while those traveling with the family can swing by the bayou for a relaxed but rewarding swamp-by-boat tour. And plan to watch the sunset on June 5—there won’t be another like it for 105 years.


 The most exotic geological hot spots in the country

Grand Prismatic Spring Yellowstone 
National Park, Wyoming
The plume of molten rock that rises from more than 400 miles inside Earth beneath Yellowstone National Park powers the 10,000 springs, geysers, and other thermal features located where magma-heated water and steam come simmering to the surface. Yellowstone’s biggest hot spring, Grand Prismatic, also hosts some of the planet’s strangest, hardiest life.

“Yellowstone’s known for its bison and bald eagles,” says John Spear, an environmental microbiologist at the Colorado School of Mines, in Golden, “but it’s really a microbial wonderland.”

Brilliant green, yellow, brown, and orange bacterial mats encircle the spring. In each mat a small population of photosynthetic bacteria gather energy for the rest of the community, while the spring’s hot, mineral-rich water, flowing from the ground at 560 gallons a minute, provides the bacteria with other essential resources.

Spear says the best view of Grand Prismatic is from above: An offshoot of the Fairy Falls trail leads up a hill on the spring’s west side. For the full rainbow effect, summer afternoons are ideal. Spear also recommends going early or late in the day, “when all the steam rising out of it reflects the colors,” glowing turquoise, peach, and lime green. Hiking Yellowstone’s backcountry (permit required) yields a more intimate look at the park’s springs, but—chastened by a painful dip at a surprisingly acidic spring in Russia—Spear warns that it’s best to resist the temptation to go in.

Arches National Park

Sandstone Sojourns 
 Arches National Park, Utah
Famed environmental advocate and essayist Edward Abbey lived and worked in Utah’s Arches National Park as a ranger in the 1950s. Today you can follow in his footsteps through the park’s sandstone landscape, viewing features such as the Fiery Furnace, a labyrinth of dramatic red rock formations. Abbey wandered the park’s backcountry on his own, but times have changed: Due to the Fiery Furnace’s fragile soils and rare plants, access is limited to guided tours. Reserve tickets online up to six months in advance.

Fluorescent Minerals 
 Franklin and Ogdensburg, New Jersey
These neighboring towns share the title of fluorescent mineral capital of the world. Their two zinc mines have yielded more than 90 types of rare minerals that glow under ultraviolet light, due to trace amounts of manganese trapped when the crystals formed. Visitors to Sterling Hill Mining Museum in Ogdensburg, where UV lights expose glowing red calcite and green willemite in the mine’s walls, can take a chunk of the stuff home with them.

Subterranean Winery 
 Napa, California
Wine making is an art, but fickle fermenting grapes pose hefty technical challenges as well. Jarvis Winery built a 45,000-square-foot cave into the side of the Vacas Mountains to age their drink at high humidity and constant temperature. Tours of the cave include a visit to its underground chamber for aging wine—the world’s largest—and a formal tasting. (Non-oenophiles will appreciate the wine cave’s uncanny resemblance to the Star Wars rebel base on Hoth.)



Transit of Venus 
 All of the U.S. (and most of the world)

In 1716 the astronomer Edmond Halley, of comet fame, had a brilliant idea: Observations of the transit of Venus, a rare event in which our sister planet crosses between Earth and the sun, could be used to calculate the distance between us and our star. That epic experiment, conducted during the next two transits half a century later, sent dozens of observers to far-flung corners of the world. Their remarkable stories include that of French astronomer Guillaume le Gentil, who was driven to the brink of insanity after being foiled—twice—in his attempts to witness the event in India.

If you want to try observing the famous transit yourself, clear your calendar for June 5: Your next chance won’t come around until 2117. In the continental U.S., anyone with a clear, cloudless view of the horizon should be able to see the black dot of Venus late in the day as it begins to move over the solar disk.

The in-progress transit will make for a spectacular sunset, but to view the entire event, you’ll need to head farther west. The full transit will be visible from just east of Hawaii to just west of Hong Kong. Several travel companies are running educational island trips and cruises in Hawaii and the South Pacific. Our sister Kalmbach publication, Astronomy, is offering a tour to see the transit from Hawaii’s Big Island.

True transit die-hards may want to follow Louisiana State University astronomer Brad Schaefer’s lead and set out for the 
Australian outback, where the risk of inclement weather is slim. Of course, wherever you are, never stare directly into the sun. Bring viewing equipment, like a sheet of number 14 welder’s glass, or project an image with a telescope.

Volcanic Eruption 
 Montserrat, Lesser Antilles

The eruption of Mount Vesuvius in A.D. 79 buried the city of Pompeii in a single day. By comparison, the Soufrière Hills volcano on Montserrat, a 60-square-mile island in the Caribbean, has been erupting sporadically since 1995, slowly entombing the lower two-thirds of the island in ash. Visitors can look down on the destroyed capital city of Plymouth from the Montserrat Volcano Observatory, where scientists monitor the volcano’s rumblings and issue hazard warnings to the island’s depleted population. Ferries from nearby Antigua can take you to the island or around it, depending on your appetite for risk.

Swamp Tours 
 Near New Orleans, Louisiana
The delicate Mississippi River delta ecosystems have been taking a beating from pollution, stream diversion, and other human activities upstream. But there is, for now, still some intact marsh to see, including the 35,000 protected acres of the Honey Island Swamp, 30 miles northeast of New Orleans. To admire the moss-hung Seussian cypress trees and deceptively lethargic alligators from a dry, safe distance, sign up for one of the flat-bottomed boat tours in the area. Tours run year-round, but local guide Paul Wagner says that spring, which brings a wealth of wildflowers and migratory birds to the swamp, is particularly magical. No word on which season is best for spotting the Honey Island Swamp Monster, a hairy, Bigfoot-like creature fabled to live in the wetland.

Ice-capped peaks encircle Lake McDonald in Glacier National Park

Retreating Ice 
Glacier National Park, Montana
Most of the ice that carved Glacier National Park’s ridges and valleys melted more than 10,000 years ago, but by the time fur trappers ventured into the area in the 1800s, new glaciers had formed. Now those, too, are disappearing, and researchers say the handful of holdouts could be gone within a decade. So go now to see these glacial remnants in the hollows at the heads of valleys or under mountain peaks—or to take a dip in the lakes that collect downslope in summer.

Side Trip Science Museum of Minnesota St. Paul, Minnesota 

When the Museum of Questionable Medical Devices in Minneapolis closed in 2002, curator Bob McCoy donated his incredible collection of quackery to the science museum. The devices on display include a vibratory chair, which supposedly cured constipation and headaches through shaking so violent that patients had to hold tight to its handles, and a fluoroscope, once casually used in shoe stores to X-ray customers’ feet. Other exhibits include a miniature golf course that teaches visitors about both landscape evolution and biodiversity.


SWIM WITH THE FISHES Intimate looks at underwater life

Spearhunting Cozumel, Mexico
On the surface, the island of Cozumel—a 30-minute ferry ride from Playa del Carmen on Mexico’s Yucatán peninsula—is a peaceful tropical paradise. But off the island’s shore, it is under siege from the beautiful, exotic lionfish, which is encroaching on the world’s second-largest coral reef.
Invulnerable to virtually all predators due to poisonous spines that cover its body, the lionfish has spread from the North Atlantic—where it was accidentally introduced by the aquarium trade in the 1980s—to the Caribbean and across the Gulf of Mexico. When it reached the Cozumel reefs in 2009, its voracious appetite for more than 50 fish species made it a threat to the local ecosystem.
Scuba instructor Gabriel Santana Perez is one of many local divers fighting the invasion. He leads awestruck tourists around the reefs, most of the time as a conventional tour guide—navigating narrow swim-throughs in the coral and spotting sharks, eels, rays, and other exciting sea life. But he is always on the hunt for lionfish.
 When he spies a group of the interlopers lurking under the coral, the dive master darts toward them, readying the spear he carries on every dive. He impales the fish one after another, snips off their poisonous spines, and feeds them to other fish, including groupers that circle suspiciously before swallowing their meal whole.
Visitors can sign up to accompany Santana Perez at Del Mar Aquatics or take spear-hunting classes at several local dive shops. For those who prefer to keep a safe distance from the fray, some area restaurants cook up and serve the lionfish.

Marine Safari Catalina Island, California

Visitors here, an hour out to sea from Los Angeles, can decide just how close they want to get to the rich marine life thriving in the area’s kelp forests and coral reefs. Glass-bottomed boat tours provide a glimpse down into a marine conservation area called Lover’s Cove. To get an even closer look, clamber into a semisubmersible vessel and view the ocean from a few feet below the surface, or strap on an undersea helmet (complete with speakers and an air-supply hose) and stroll on the seafloor with a biologist guide.

Salmon Spotting 
 Warm Springs Reservation, Oregon
A wild run of spring chinook salmon make their annual 300-mile journey from the Pacific Ocean to the Warm Springs National Fish Hatchery in central Oregon, arriving each spring and summer. Visitors can walk the grounds, watch salmon climb the fish ladders, and tour the facilities. Nearby, guided tours in inflatable kayaks travel the last leg of the salmon’s route along the river.

Side Trip US Space and Rocket Center Huntsville, Alabama

You’re never too old for space camp, and the U.S. Space and Rocket Center knows it. Adults can register for a weekend filled with model rocket building, spaceflight history classes, and, upon special request, underwater astronaut training. Students also pilot a flight simulator and climb into the camp’s centrifuge to experience the 3g force astro­nauts feel during launch. For a less intense NASA experience, the center also features an extensive collection of rocketry, including the Apollo 16 capsule and a full-size replica of the Apollo 11 Saturn V, the largest rocket ever launched.


DIG IN AND GET DIRTY Adventures for the hands-on type

Trinity test explosion, 1945; Los Alamos National Laboratories

Atomic Artifacts Bayo Canyon, New Mexico 

Three miles east of Los Alamos, this canyon lies between two volcanic mesas. There, the U.S. military perfected the implosion mechanism used in the Fat Man bomb detonated over Nagasaki, Japan, in 1945.
These days, a hiker passing through the canyon might not notice anything unusual, other than a few posted signs instructing visitors not to collect firewood in the area. Closer inspection of the ground will reveal bits of “interesting-looking metal,” says Carl Willis, a nuclear engineer at Qynergy Corporation in Albuquerque. These bits include sockets for photomultiplier tubes from the radiation detectors, and coaxial cables used for signals and timing purposes. The detritus is fair game for anyone who wants to take home a piece of the Manhattan Project (Native American artifacts at the site are strictly off-limits, however). Most of the items aren’t radioactive, Willis says, “but there is hot stuff for people who get down on their knees with a Geiger counter and sort through all that rubble.”
Several other hot spots dot the surrounding mesas and valleys. A two-hour drive south from Los Alamos lands visitors at the National Museum of Nuclear Science and History in Albuquerque. For those willing to venture even farther, Willis says, there is a remarkable site just south of town, a half mile west of the government-run Sandia National Lab, where in 1957 a bomber accidentally dropped a mammoth Mark-17 hydrogen bomb. “There’s a huge swath of debris, and anyone can go out there and look for stuff,” Willis says. Ever-so-slightly radioactive bits of white plastic, chunks of lead, and green-painted pieces of the bomb’s casing are among the most common finds.

Cooking with Science 
 Brooklyn, New York, and other cities

Spanish chef Ferran Adrià made complex chemistry a star in the kitchen when he started molecular gastronomy, a culinary movement that uses sophisticated science to create imaginative dishes, such as foams made from solids like mushrooms and “spheres” of liquid that hold their shape. Cooking classes inspired by his ideas are now cropping up in major cities.

Devonian Fossils 
 Petoskey, Michigan

Some 350 million years ago, Michigan lay under a shallow ocean in which coral, trilobites, and other marine life thrived. Today fossilized coral makes its way into Lake Michigan from Little Traverse Bay, near the northern tip of the state’s Lower Peninsula, where the ancient rock layer is exposed. Polished and smoothed by eons of roiling water and sand, these fossils—called Petoskey stones—are strewn along Lake Michigan’s shore. Collectors will have the most luck spotting the stones after summer windstorms, which reveal the long-buried 
treasures littering the shore.

 All across the United States

The American Association of Zoos and Aquariums’ FrogWatch program enlists amphibian fans from coast to coast to track local frog and toad species by identifying the animals’ mating calls. To distinguish the ribbits and croaks, 
volunteers take a short training course at one of 43 participating nature organizations across the country. Then they check in at 
designated posts at least twice a 
week during the breeding season to listen for the amphibians’ calls. Researchers use the data they submit to develop conservation strategies for the animals.

Superfreak of Evolution: The Lizard With a Humanlike Placenta

by Ed Yong

Trachylepis ivensi nurtures its fetus much like humans do.
Courtesy: Dr. Philipp Wagner

In central Africa, an unassuming little lizard has evolved a spectacular and oddly human feature of gestation: a complex placenta. It is the first time that scientists have observed such an advanced version of this organ connecting the fetus to the womb in nonmammals.

Biologist Alexander Flemming made the anatomical find, announced late last year, while sorting through specimens at the Port Elizabeth natural history museum in South Africa. Flemming and his collaborator, Daniel Blackburn, knew that about 20 percent of lizards give birth to live young, but finding the placenta came as a shock.

Whereas virtually all cold-blooded reptiles supply embryos with nutrients from a large egg yolk, five-inch-long Trachylepis ivensi females ovulate small, yolk-poor eggs that implant in the uterus. As the fetus develops, its tissues become intimately entangled with the blood vessels of its mother, providing ready access to nutrients and oxygen in the mother’s blood. Sound familiar? “The fetal tissues actually invade the uterine ones, much like in humans,” Blackburn says. “It’s totally unexpected.”

Blackburn wants to reconstruct the evolution of this complex organ from simpler versions in other lizards. Doing so might even tell us about how the human placenta evolved. “It goes to show,” he says, “that you never know what diversity may be out there until you look.”

Plants Repel Bacteria’s Assaults by Spying on Their Chatter

Researchers discover an impressive ability never seen in plants before.
by Veronique Greenwood

Some rice plants have evolved a leg up on their microbial adversaries by
breaking the chemical code bacteria use to communicate.

Bacteria are quite the talkers. Lying low inside their hosts, they scheme up attacks through coded biochemical messages that are largely imperceptible to the immune systems of plants and animals. But in December researchers published the first evidence that some plants have broken the code, allowing them to listen in on chatter and thwart infection.

Evidence for this reconnaissance emerged in 2009, when University of California, Davis, plant pathologist Pamela Ronald discovered a bacterial protein called Ax21 in some strains of rice. Whenever Ax21 was present, the plants flooded their tissues with antibacterial chemicals. The mere presence of an immunity-inducing protein like Ax21 was not that unusual—the immune systems of most organisms identify a microbial intruder through proteins protruding from its outer membrane. But last year Ronald discovered that Ax21 is not part of the bacterial cells themselves. Instead, it is a secreted chemical rallying cry. When Ax21 chatter reaches a certain level, the microbes pack into a thin layer called a biofilm that protects them from immune defenses and many antibiotics. These rice plants are the only known organisms able to intercept the messages and act before the bacteria can form their biological bunker.

Ronald’s discovery may spark similar finds. University of North Carolina plant immunologist Jeff Dangl says plants have many immune receptors with unknown functions: “There may be a vast listening apparatus just waiting to be discovered.”