For years, scientists thought they knew when H. sapiens became the only kind of human species in existence. The scientists thought that the big change happened about 24,000 years ago, with the extinction of the Neandertals (Homo neanderthalensis).

Recently, however, scientists have found evidence of a previously undiscovered species of humans. The scientists made the find on the island of Flores in Indonesia.

The skull of an adult person who lived long ago on the island of Flores (left) is much smaller than that of a modern human (right).

Peter Brown

The newly discovered species, called Homo floresiensis after the island of its discovery and nicknamed “hobbit” because of its tiny size, lived as recently as 12,000 years ago. Many scientists consider the hobbit to be the most important discovery in anthropology in 50 years.

The finds on Flores indicate that for thousands of years, “we were not alone as a human species,” says Bert Roberts, a senior research fellow at the University of Wollongong in Australia. “Until very recently, there would have been another type of walking, talking, interacting kind of human running around the planet,” he adds. Roberts was a member of the team that discovered H. floresiensis.

Flores, shown here in yellow, is an island that belongs to the country of Indonesia. Other regions of Indonesia are colored green, and other Asian countries are shown in white.

Wikipedia

Finding hobbits

The first signs of the hobbit’s existence emerged in 2001, when a team of Australian and Indonesian researchers started finding small teeth and bones on Flores. The scientists were looking for H. sapiens fossils at the time.

At first, the scientists didn’t suspect anything unusual. They thought that the small fossils belonged to H. sapiens children.

Then, on the last day of the digging season in September 2003, an Indonesian researcher named Thomas Sutikna stumbled across what looked like the top of a skull in the ground. To protect the fossil, he dug out the entire block of sand surrounding it.

“It was only when he started uncovering what was in this block of sand that [the team] realized [he] had [found] a whole new human species,” Roberts says. Skulls often reveal more about a species than other bones can, he adds, and this skull was a clincher. “This really was something completely, remarkably new.”

The tiny skull looked different from any Homo skull ever unearthed. It had a sloping forehead and thick ridges above the eye sockets. It had a receding chin. Its brain—about 23 cubic inches in volume—was just one-fourth as big as a modern human brain.

This photograph of a hobbit skull shows its distinctive sloping forehead and thick eyebrow ridges.

Peter Brown

Further excavations revealed that the creature’s skeleton was different from that of H. sapiens, too. The skull and bones belonged to a woman who was about 30 years old and about 3 feet tall—the size of a typical 4-year-old today. Her feet were flat and broad. And she had long arms, with hands that hung down to her knees.

Those features resembled those of some of our ancient ancestors who lived 2 or 3 million years ago, says Chris Turney, a research fellow at the University of Wollongong who became involved soon after the discovery. So, he expected the new fossils to be that old, too.

Much to everyone’s surprise, Turner’s analysis of the skeleton showed that the bones were just 18,000 years old. The hobbit was a completely new species of human. What’s more scientists had never seen anything like it living so recently. It was a huge discovery.

“I was blown away by this,” Turney says. “I just walked around with a great big grin all day.”

The great debate

The scientists announced their find in 2004. Some anthropologists, like Turner, were amazed by the news. But critics quickly disputed the findings. They claimed that the new skeleton was not a new species. It was simply a member of our own species suffering from a disease called microcephaly. Among other symptoms and deformities, people with microcephaly have smaller than average heads and bodies.

The debate gained steam. Meanwhile, further digging in the island’s limestone caves turned up bones from eight other hobbitlike people with similar bone structures. Analyses revealed that these individuals lived between 95,000 and 12,000 years ago, strengthening the case that the scientists had indeed discovered a new species. As Roberts says, it would be very unusual that an entire population would have microcephaly over that many years.

Most scientists do now believe that H. floresiensis was indeed a separate species from H. sapiens, Roberts says. “I’d say 99.5 percent [of scientists] are in our favor,” he claims.

But not everyone is convinced. Discoveries such as these shake up long-held theories about evolution. The discovery of H. floresiensis, for example, challenges the view of some experts that H. sapiens originated in Africa and then replaced all existing human species as it spread around the world. It suggests instead that H. floresiensis and H. sapiens actually shared the globe for tens of thousands of years.

Getting to the bones of the matter

Because of arguments between researchers, further excavations, which could answer the many remaining questions about the hobbits, stopped in 2004. But now, the anthropologists are ready to pick up their shovels again. This June and July, digging on Flores will resume.

The researchers hope to find more skeletons with features similar to those of H. floresiensis, as well as samples of DNA, which should “settle the dispute once and for all,” Roberts says. More fossils would also give more details about the lives of the hobbits.

Evidence to date suggests that the hobbits were clever, despite their small brains, Roberts says. Explorations of the sites where the bones were found shows that the hobbits used specialized stone tools. They hunted komodo dragons and pygmy elephants. They could make fires. And they found a way to travel to Flores, probably from the mainland of Asia, on their own.

Despite the enthusiasm of Roberts and many others, scientists still cannot prove that H. sapiens and H. floresiensis lived on Flores at the same time. Only more digging, and additional studies of the bones, will resolve this question.

Going Deeper:

Additional Information

Questions about the Article

Word Find: Hobbits

Between the ages of 4 and 6 months, babies can identify their native language from a foreign one by watching a speaker’s facial movements in silent video clips.

Science

A new study suggests that babies between 4 and 6 months old can tell the difference between two languages just by looking at the speaker’s face. They don’t need to hear a word. Sometime between 6 and 8 months of age, babies raised in homes where just one language is spoken lose this ability. Babies from bilingual homes, on the other hand, keep the face-reading ability until they’re at least 8 months old.

Researchers in Canada, at the University of British Columbia in Vancouver, studied 36 infants from English-speaking families. Twelve of the babies were 4 months old, 12 were 6 months old, and the rest were 8 months old. Each baby sat on his or her mother’s lap and watched video clips of a woman talking. The woman was fluent in both English and French. In some clips, she read from a storybook in English. In other clips, she read in French. In all of the videos, there was no sound.

After watching clip after clip of the woman reading in just one language, the babies eventually started to look away, apparently because they were bored. The researchers then showed the babies a new silent clip of the woman reading a story in the other language. At that point, the 4- and 6-month olds started looking at the screen again. The 8-month olds, by contrast, paid no attention.

The second study involved a different set of 36 infants of the same ages. These babies were from English-speaking homes. They watched silent clips of the woman reading one set of sentences in either English or French until they grew bored. Then, they saw clips showing the woman read different sentences, but in the same language that she had already been speaking. None of the babies showed a renewed interest.

A third trial included 24 infants of the same ages whose families spoke both English and French at home. In the first set of clips, the woman spoke in one language, and in the second set she used the other language. All babies in this study looked longer at clips after the woman switched languages. That suggests that, in bilingual families, a baby’s ability to distinguish between languages persists at least until eight months of age.

Together, these results suggest that “visual information about speech may play a more critical role [in language learning] than previously anticipated,” says lead researcher and psychologist Whitney M. Weikum. It’s not yet clear, she adds, which part of the speaker’s face babies are looking at for clues.

Next, scientists want to see whether babies can match faces with the voices of foreign-language speakers. If babies can do this, the scientists would then like to know if this ability also declines toward the end of the first year of life.—Emily Sohn

Going Deeper:

Bower, Bruce. 2007. Face talk: Babies see their way to language insights. Science News 171(May 26):325-326. Available at http://sciencenews.org/articles/20070526/fob6.asp .

Sohn, Emily. 2007. Talking with hands. Science News for Kids (May 9). Available at http://www.sciencenewsforkids.org/articles/20070509/Note2.asp .

The area of the Milky Way seen here, which scientists have nicknamed the Orion star-making factory, is one of the places closest to Earth where new stars are born. Evidence suggests that the sun was born in such a factory and that a massive neighbor explo

M. Robberto, NASA, ESA, HST Orion Treasury Project Team

Researchers from the University of Copenhagen in Denmark made the discovery while trying to figure out how much iron existed in the early days of our solar system. To do this, they looked at eight meteorites formed at different times during the 3 million years after the birth of our sun and the solar system’s planets.

In meteorites, a form of iron called iron-60 gradually turns into nickel-60. So, the researchers measured nickel-60 in all eight meteorites. They found that the younger meteorites contained far more nickel-60 than the older ones did. The oldest meteorites formed in the first million years after the solar system was born.

Only a supernova—the spectacularly exploding death of a giant star—could have produced the original iron-60 that eventually became the nickel-60 in the younger meteorites, scientists say. All the meteorites studied, on the other hand, contained about the same amount of aluminum. A supernova would not be necessary to supply the objects with that metal.

“This is a convincing argument that you had an injection of iron-60 about 1 to 2 million years after the birth of the sun,” says Steve Desch of Arizona State University in Tempe. The only source for that iron “that makes any sense whatsoever is a nearby supernova,” he adds.

A longstanding theory says that our sun formed when a nearby supernova triggered the collapse of a cloud of gas and dust. The new discovery challenges that theory. Instead, it suggests, our sun formed about a million years before that supernova.

Calculations show that the massive star that exploded was about 30 times as heavy as the sun. And it was relatively close to the sun—only about a light-year away. At first, the big star pummeled our sun with fierce winds. Then, when it exploded, it pounded our star with shock waves, driving iron into both the sun and the budding planets around it.

Huge stars often form as part of star clusters. This study suggests that our sun formed alongside thousands of others, including the one that exploded nearby, some 4.5 billion years ago.

How did our sun survive such a battering? Because newborn stars are tough. In fact, theorists say, such a star could survive a supernova as close as just a third of a light-year away.—Emily Sohn

Going Deeper:

Cowen, Ron. 2007. Violent past: Young sun withstood a supernova blast. Science News 171(May 26):323. Available at http://sciencenews.org/articles/20070526/fob1.asp .

Sohn, Emily. 2006. Dead star exploding. Science News for Kids (Aug. 9). Available at http://www.sciencenewsforkids.org/articles/20060809/Note2.asp .

The polar bear is one of the few species to visit the North Pole.

iStockphoto

But even if you never plan to visit the polar bears in the north or penguins in the south, now is a perfect time to start thinking about them. That’s because 2007 marks the beginning of the International Polar Year (IPY), a two-year-long bonanza of science projects that aim to illustrate how important the poles are to the health of our planet. During the IPY, which will last until March 2009, thousands of researchers from more than 60 countries will conduct more than 200 projects and expeditions to both the top and bottom of the world.

In recent years, the polar regions have begun to change drastically as a result of global warming. Temperatures there are rising faster than anywhere else on Earth. As a result, the ice and snow in these regions are melting at record-setting rates. One result is that sea levels are rising around the world, putting animals and people at risk.

The extent of ice in the Arctic is steadily shrinking. In this diagram, land masses are in green (with North America on the left and Asia on the right). Water is in dark blue. The pink line indicates the average wintertime ice extent from 1979 to 2000. Th

National Snow and Ice Data Center’s Sea Ice Index

Only by studying the poles, say IPY researchers, can we find ways to protect them and ourselves.

“The more we know about what is going to happen,” says Stephen Rintoul, an oceanographer at Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), “the more convincing the argument is to look at what we can do.”

Melting ice in the far north

Both the Arctic (in the far north) and the Antarctic (in the far south) are cold and remote, but the two regions have important differences, says biological oceanographer Louis Fortier of Laval University in Quebec, Canada. For one thing, the Arctic is an ice-covered ocean surrounded by land. The Antarctic, on the other hand, is a continent of ice-covered land surrounded by water.

Antarctica is a continent of ice-covered land surrounded by water.

iStockphoto

Most polar studies have focused on the Arctic, and that is where scientists have observed the most dramatic changes in the ice. During a typical year, Arctic ice expands in the winter and shrinks in the summer. But recently, the amount of ice covering the ocean has been steadily dropping in both seasons.

In the winter of 2005–2006, the winter ice mass hit an all-time recorded low for the second year in a row. The ice cover that year dropped 300,000 square kilometers (116,000 square miles), or 2 percent, from the previous year to a new low of 14.5 million square kilometers (5.6 million square miles). The amount of ice lost equaled the size of Italy.

The blue line shows the downward trend since 1979 of how much sea area is covered by ice. The extent of sea ice in March 2006 (indicated by the red dot) is 1.2 million square kilometers (463,000 square miles) less than the average ice extent from 1979 to

National Snow and Ice Data Center

In 2005, the summer low in the Arctic was 30 percent less than the low 20 years earlier.

Computer models show that summertime ice in the Arctic Ocean could vanish during this century.

iStockphoto

The rate of change

As more ice melts as a result of rising global temperatures, the rate of melting will most likely speed up as well. That’s because a sheet of ice acts like a huge mirror, reflecting sunlight back into space. But as the ice cover shrinks, the expanse of open ocean grows. Ocean water is darker than ice. Rather than reflecting the sun’s energy, it absorbs a lot of it. This causes the ocean to warm, which in turn hastens ice melting, which leads to even more open waters. The cycle continues–until all the ice is gone.

Most models, taking into account increasingly rapid melting, show an icefree Arctic summer happening as early as 2040, Fortier says, but some are more pessimistic.

“Most specialists believe we’ve reached the tipping point, after which things will accelerate very quickly,” he says. “Some models say the Arctic Ocean could be ice-free for a week or a month at the end of summer by as early as 2015.”

Satellite data shows that as much as 36 cubic miles of ice is melting in Antarctic each year, scientists announced last year. And NASA recently produced evidence that, in January 2005, unusually high temperatures led to the largest Antarctic snowmelt in three decades.

Life in the deep south

Disappearing ice could be devastating for wildlife in many ways. As the ice melts, water drains into the oceans, diluting them and making them less salty. That, along with warmer water temperatures, can harm the diverse creatures that live in, under, and near the ice, says zoologist Michael Stoddard, Chief Scientist with the Australian Antarctic Division. Cold-adapted animals—including polar bears, foxes, hares, and seals—also need ice for travel and survival.

Most species of fish, worms, sea spiders, and other animals, plants, and other organisms that live in the waters of Antarctica don’t live anywhere else, Stoddard says. Many of these creatures have special proteins in their bodies that keep them from freezing to death and have other adaptations to the cold that have yet to be explored.

Aboard research ships, scientists are exploring the far southern waters.

iStockphoto

Scientists such as Stoddard have learned a good deal about Antarctica. But overall, research on animal diversity in the area has been scarce. To learn more, scientists on a fleet of research ships are using underwater robots, cameras, and other high-tech equipment to see what else lives in these far southern waters.

A recent 10-week expedition turned up 15 potentially new shrimplike species, 4 potentially new corallike species, and lots of sea cucumbers, sea squirts, sponges, and more. Results of this IPY-timed census will help scientists track changes in these creatures.

“We want to look at everything from the 6 thousand million tons of plankton down to the insignificant, paltry organisms like penguins,” Stoddard jokes. Seriously, he adds, “we don’t know a lot about the Antarctic. We’re hoping the census will be able to fill up some of these holes.”

Being large, polar bears are relatively easy to count. Conducting a census of smaller organisms is more challenging.

iStockphoto

During the IPY, other groups are studying caribou, wolves, shrubs, and underwater mountains in the Arctic, microbes, krill, algae, and penguins in the Antarctic, and every other aspect of biology, geology, and ice-themed research you can imagine.

Saving the ice

As studies on the impact of climate change on the polar regions continue, experts are urging us to reconsider the way we live. The fossil fuels that we burn in cars, power plants, and factories are largely to blame for the carbon dioxide and other greenhouse gases that are trapping excess heat in our atmosphere. If we can produce fewer of these gases, we can help save the polar ice. And saving the polar ice will help protect the oceans and us.

Biking, walking, and taking public transportation, for example, are pole-friendly activities. Encourage your parents to switch to efficient, compact fluorescent light bulbs, and turn the lights off in rooms when you’re not using them. Urging your politicians to fight for the environment can help too.

“Small things would make a difference,” Rintoul says, “if everyone did them.”

Going Deeper:

Additional Information

Questions about the Article

Word Find: Polar

Food can still look appetizing after it has fallen on the floor. But is it safe to eat?

iStockphoto

If you’re like most people, you eat it. Maybe you follow the “5-second rule,” which claims foods are safe to eat if you pick them up within 5 seconds of dropping them.

But you might want to think again. Scientists now say that 5 seconds are all it takes for foods to become contaminated with enough bacteria to make you sick.

Bacteria are single-celled organisms that can cause many kinds of illnesses. Some kinds of bacteria can grow on food. If we eat foods on which these bacteria are growing, we can become sick. Common symptoms include vomiting and diarrhea.

One of these food-borne bacteria is Salmonella. It makes 1.4 million people sick every year. Earlier this year, 370 people became sick after eating peanut butter that had been contaminated with Salmonella at the manufacturing plant. Salmonella are often found in raw eggs and chicken. Cooking kills these bacteria, which is why it is so important to cook eggs, chicken, and other foods thoroughly.

Being a good housekeeper is a second tip for preventing infection. If household surfaces aren’t washed thoroughly, they can support Salmonella for weeks.

But how long does it take these bacteria to attach to food? To answer that question, a team of scientists at Clemson University in South Carolina decided to test the 5-second rule, using sandwich ingredients. First, they placed a known amount of Salmonella cells on three surfaces: wood, tile, and carpet. They placed a slice of bread and a slice of bologna on each surface for 5, 30, or 60 seconds.

After just 5 seconds, both the bread and bologna picked up enough bacteria to make you sick.

Dropped a morsel? It may have bacteria on it even if you pick it up immediately.

iStockphoto

“Someone making a sandwich might follow someone who, a day before, used that surface to cut meat or another raw food. It might not look contaminated, but could have bacteria that would be harmful,” said Paul Dawson, the food scientist who led the study.

So, forget the 5-second rule. If your toast lands on the floor, toss it out. Stick a fresh slice of bread in the toaster. And this time, be careful not to drop it!—Jennifer Cutraro

Going Deeper:

Sohn, Emily. 2006. Germ zapper. Science News for Kids (May 24). Available at http://sciencenewsforkids.org/articles/20060524/Note2.asp .

For more information about food safety for kids, go to www.agr.state.nc.us/cyber/kidswrld/foodsafe/ (North Carolina Department of Agriculture & Consumer Services).

For information about the disease caused by Salmonella bacteria, go to www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_g.htm (Centers for Disease Control and Prevention).

But conditions in the deep ocean are so extreme that very little is known about life at the bottom of the sea. The deep sea is one of Earth’s last frontiers.

Now, a team of scientists from eight countries has completed the first survey of life in the deep waters off Antarctica.

This isopod from the depths of the Southern Ocean has long legs, unlike the stubby ones of pill bugs, which are its terrestrial cousins.

W. Brökeland

The team worked aboard a German icebreaker called Polarstern. An icebreaker is a special ship that can withstand strong storms and push through ice on the water’s surface.

To catch deep-sea creatures, the team lowered a scoop to the ocean floor. It took 6 to 8 hours to lower and raise the scoop just once. The sampling sites were up to 4 miles below the ocean’s surface.

The effort was worthwhile. Before this expedition, researchers had thought that few creatures would be able to live in the harsh Antarctic ocean conditions. They thought deep-sea life would be less diverse than life in warmer waters.

But the scientists were in for a surprise. They found unexpected diversity among deep-sea creatures. What’s more, many of these creatures had never before been seen. For example, of the 674 species of isopods picked up by the team, 585 were new to science. (Isopods are a type of crustacean that includes pill bugs, little grey bugs found in many gardens.) That’s more new isopod species than have been found in shallower Antarctic waters in the entire past century.

Researchers also found other surprises, including carnivorous (meat-eating) sponges.

The sponges and most of the other bottom dwellers that the researchers found were largely white. No light reaches such depths, so most are blind.

How do these organisms survive in the frigid, inky-black waters? First of all, their bodies are specially adapted to the cold. And when it comes to food, many are scavengers. Their diets consist mainly of debris (little pieces of carcasses and food excreted by other animals) that drifts down from above. Scientists call this debris “marine snow.” By the time some of this debris gets to these deep-water creatures, it’s already made its way through the bodies of two or three other sea creatures, the researchers say.

Many questions remain about how the creatures can survive in such harsh conditions. The deep-sea dwellers collected by the team may provide answers. The data will also help scientists figure out how ocean species migrate and how their ecosystems develop. There’s a lot of ocean left to explore!—J.L. Pegg

Going Deeper:

Milius, Susan. 2007. Low life: Cold, polar ocean looks surprisingly rich. Science News 171(May 19):308. Available at http://sciencenews.org/articles/20070519/fob3.asp .

Sohn, Emily. 2004. Explorer of the extreme deep. Science News for Kids (Nov. 10). Available at http://sciencenewsforkids.org/articles/20041110/Feature1.asp .

I try not to think about where those legs have been. Why? Because I know that Armin Moczek, a biologist at Indiana University at Bloomington, just dug up the beetle from a container of dirt and cow manure.

Roberta Kwok holds dung beetles in her hands.

Armin Moczek

Moczek studies beetles in his lab, and he takes good care of his bugs. “We go out every couple of months, collect a lot of cow dung, freeze it, defrost it as needed, and feed it to them,” he explains.

Caring for dung beetles is dirty work. Moczek’s lab members—including (from left to right) Melanie O’Day, Debra Rose, Bethany Kesselring, and Morgan Peters—have to scoop cow manure into bags.

Armin Moczek

Moczek doesn’t mind the beetles’ smelly diet. He’s focused on what makes beetles unique in the insect world: their ability to grow horns.

Scientists have recently discovered that beetles use their horns in surprising ways. And, says Moczek, there’s still a lot to learn about how beetles evolved horns in the first place.

“We have a pretty good idea of what needs to happen for legs to become longer, or wings to become wider,” he says. But scientists don’t know how animals develop a completely new body part. Studying how beetle horns evolved might help answer that question.

Horn-to-horn combat

Beetle horns come in a variety of shapes and sizes. Some beetle horns snap together, like pincers. Others are low and curved, like an elephant’s tusk. And watch out—a dung beetle’s horns can be longer than the rest of its body.

In fact, some horns are so big that “it looks like the beetles are going to tip over,” says Douglas Emlen, a biologist at the University of Montana-Missoula who also studies beetles.

A beetle’s horns can weigh more than one-third of its entire body weight.

Armin Moczek

In most species, only the male beetles grow full adult horns. They use their horns to fight for mates. A horned male will guard the entrance to a tunnel housing a female and fight off intruders.

Beetle horns can be impressive weapons. Beetles use their horns to grab other beetles, lift them in the air, and even throw them off trees. Sometimes a beetle will slide its horn underneath another beetle and flip it over. “They beat each other up,” says Moczek.

But some of the smaller males don’t grow horns at all. Emlen says that instead of fighting for mates, these beetles use “sneaking behavior.” As an unsuspecting horned male stands guard at the entrance to a female’s tunnel, a hornless male digs a horizontal side tunnel that connects to it. He finds the female underground, mates with her, and sneaks away before the guard notices.

Dung beetles’ horns come in a wide array of shapes and sizes.

Armin Moczek

Emlen thinks that hornless males might be naturally better at sneaking through underground tunnels than the horned beetles are. Large horns can slow a beetle down because they scrape the tunnel walls. And without horns, a beetle might run faster and more quietly underground.

Baby horns

Scientists have studied adult-beetle horns for a long time. But Moczek found something surprising when he looked at immature beetles, called larvae. In the species that he studied, the large male larvae grew horns—but so did the female and smaller male larvae. When these beetles matured, their horns disappeared.

“You wonder why,” Moczek says. “Why bother making these structures?”

To answer this question, he raised beetle larvae in the lab. Larvae normally grow inside little balls of packed dung, called brood balls. Moczek made artificial brood balls for his beetles by collecting cow dung and squeezing out the moisture with cheesecloth.

“You don’t want to squeeze too hard,” he says, “because the cheesecloth will rip, and then you have projectile dung.”

Beetles crawl around in cow dung. Some species eat the dung of horses, dogs, monkeys, and even millipedes.

Armin Moczek

Inside their cozy brood balls, the larvae grow thick, protective helmets called larval head capsules. But the larvae eventually have to break out of these capsules to become full-grown adults. Moczek noticed that the larvae seemed to use their horns to poke their way out of their capsules.

He tested his idea by zapping some larvae with electricity in the places where their horns normally appear. This stopped the horns from growing. Sure enough, these hornless larvae couldn’t shed their head capsules.

An eye for a horn

Beetles can grow horns in several places. Some horns are located on the front of a beetle’s face. Others grow from the back of the head. And still others grow from the thorax, which is between the beetle’s “shoulder blades.”

This beetle has one horn growing from its head (right) and another from its thorax (left).

Armin Moczek

Emlen discovered that the location of a beetle’s horns can affect the size of its other body parts. For example, a beetle with horns on the back of the head, near its eyes, often has smaller eyes than a beetle with no such horns. If the horns are on the front of the head, the beetle may have normal eyes, but relatively small antennae. And if the horns are on the thorax, the beetle has smaller-than-average wings.

This makes sense, because growing a horn takes a lot of energy. “The horns are expensive,” says Emlen. There’s a trade-off: If a beetle uses a lot of energy to grow a big horn, its nearby body parts won’t grow as much.

Going back in time

By studying how horns grow and how the beetles use them, scientists such as Moczek and Emlen are unraveling beetle history. Were the first horns used as weapons or as tools for opening larval head capsules? Did hornless males evolve because sneaking works better without horns or because horns take too much energy to grow? Thinking about horns “forces you to go back in time,” says Emlen.

In the illustration at left, two horned males fight at the entrance to a tunnel. In the illustration at right, two hornless males try to sneak toward a female from the sides, while a horned male guards the top of the tunnel.

Barrett Klein

If you live near cows, you can find dung beetles on your own. Go to a pasture, put on some gloves, and peek underneath the cow droppings. You might see dung beetle tunnels—and, if you’re lucky, even some dung beetles.

Studying dung beetles can be fascinating. “You just need to get over the poop factor,” says Moczek.

Going Deeper:

Additional Information

Questions about the Article

Word Find: Beetles

A soon-to-be-launched Web site might help. An international team of researchers has announced the creation of a Web-based Encyclopedia of Life (EoL). The project aims to catalog every species on Earth in a single, easy-to-use reference guide.

A sample page from the Encyclopedia of Life enables people to read about the recently discovered Yeti crab. Eventually, readers will be able to add comments pages such as this one.

Encyclopedia of Life

To get the encyclopedia started, the creators will use information from scientific databases that already exist. And eventually, in special sections of the site, nonscientists with specialized knowledge will get to chime in. Gardeners, for example, will be able to record the dates that their flowers first bloom each year. Bird-watchers will be able to input which birds they’ve seen and where. The technology for this kind of tool has only recently become available.

As the EoL develops, you might find it useful for school projects. The site will feature special pages for kids who are studying ecosystems in their neighborhoods. To make sure the encyclopedia is accurate, scientists will review much of the information added to it. People who visit the site will be able to choose to skip pages that haven’t been reviewed.

Another convenient feature of the EoL is that you’ll be able to pick the level of detail you see to match your interests, age, and current knowledge. If you wanted to learn about polar bears for a science class report, for example, you could use the “novice” setting to get basic information about the animals. On the “expert” setting, on the other hand, you could get much more detailed information about the history, literature, and exploration of polar bears.

It now takes years for scientists to collect all the data they need to describe and analyze species. The creators of the Encyclopedia of Life hope that their new tool will speed that process.

Keep an eye on www.eol.org. Pages will begin to go up sometime next year, and you might find them useful for your school reports. The EoL team might have the basics for all 1.8 million entries online as early as 2017. Someday, you might add your own notes.—Emily Sohn

Going Deeper:

Milius, Susan. 2007. Extreme encyclopedia: Every living thing will get its own page. Science News 171(May 12):294. Available at http://www.sciencenews.org/articles/20070512/fob7.asp .

Sohn, Emily. 2005.
Nature’s alphabet. Science News for Kids (Nov. 16). Available at http://www.sciencenewsforkids.org/articles/20051116/Feature1.asp .

The supernova called SN 2006gy, drawn here by an artist, is the brightest exploding star ever noticed by astronomers.

NASA

When a really big star (some are 10 times as big as our sun) runs out of fuel, it dies in a dramatic explosion called a supernova. Scientists have observed supernovas before, but this latest outburst had 100 times as much energy as a typical explosion. In just 2 months, it spit out more radiation than the sun will emit during its 10-billion-year lifetime.

Calculations suggest that the star that exploded had more than 150 times as much mass as our sun. That makes it the heaviest star on record (For comparison, our sun is more than 333,000 times more massive than Earth.).

Two teams of scientists—one led by researchers from the University of California, Berkeley, the other led by researchers from the California Institute of Technology in Pasadena—recently announced their observations of the eruption, now called SN 2006gy. (SN stands for “supernova.”) Astronomers had first observed the SN 2006gy last September. It lies in a galaxy 240 million light-years from Earth.

An X-ray image shows that the supernova (top right) is as bright as the center of its home galaxy (bottom left).

CSX

Because of SN 2006gy’s immense size, astronomers’ usual theories of star death don’t work. One popular theory, for example, says that after a supernova has blown off its steam, its core collapses into a superdense body like a neutron star or a black hole. This model can’t account for the extreme brightness of SN 2006gy.

Instead, the two teams that reported the blast propose that the huge star’s core was unusually hot. That heat, they think, caused high-energy gamma rays inside the core to destroy each other. Gamma rays help keep stars intact, so their destruction made the star unstable. The star would have then collapsed and blown up, leaving nothing behind but a huge, very bright explosion.

This type of supernova, called a pair-instability supernova, was probably common among the universe’s very first stars, scientists suspect. SN 2006gy may then be a rare, modern example of an ancient phenomenon. Eta Carinae, a star in our own galaxy, might be poised to undergo the same type of explosion, researchers say.

But there are also some problems with the pair-instability model, and still other theories are possible. For example, theorist Stan Woosley of the University of California, Santa Cruz proposes that a series of instabilities over the course of a year, rather than a single huge explosion, spewed material out of the dying star. The final blast would have then lit up all the previously ejected material. Woosley’s theory would explain the brightness without requiring that the star be so freakishly large.

Whatever the explanation for the explosion, the display it left behind was out of this world.—Emily Sohn

Going Deeper:

Cowen, Ron. 2007. Stellar spectacular: Brightest supernova. Science News 171(May 12):293. Available at http://www.sciencenews.org/articles/20070512/fob5.asp .

Sohn, Emily. 2006. Dead star exploding. Science News for Kids (Aug. 9). Available at http://www.sciencenewsforkids.org/articles/20060809/Note2.asp .

______. 2006. Spotlight on an exploding star. Science News for Kids (March 8). Available at http://www.sciencenewsforkids.org/articles/20060308/Note3.asp .

Astronomers at the University of Arizona in Tucson have found evidence of planetlike objects around binary stars—pairs of stars that closely orbit each other. The new research suggests that there may be many worlds with sunsets far more spectacular than our own.

If this illustration looks familiar, perhaps you saw a similar image in Star Wars. In that movie, Luke Skywalker’s home planet, Tatooine, orbits a binary star system. A planet that orbits two stars could have a double sunset.

NASA/JPL-Caltech/R. Hurt (Spitzer Space Telescope)

“This opens up the poetic possibility of life on planets in binary star systems where, when the sun rises or sets, it is not one star, but two stars going up and down,” says Alan Boss, an astronomer and theorist at the Carnegie Institution of Washington, D.C.

The new discovery also greatly increases the number of places where scientists might find planets orbiting other stars. As many as 75 percent of sunlike stars in the Milky Way have at least one nearby companion star.

Scientists had long neglected binary- and multiple-star systems in their search for distant planets, because they are much more complicated to study than single stars. But now it appears that the extra work may pay off.

“The big splash from our work is that the number of potential sites for planetary-system formation has just gone up enormously,” says University of Arizona astronomer David Trilling, who led the research.

Star dust

Stars form out of huge clouds of gas and dust. The leftovers form a dusty disk around the new star. Within a few million years, some of the dust may clump and form asteroids and asteroid belts, comets, and even planets, all of which orbit the parent star. The rest of the dust gets blown out of the system.

Astronomers have found a solar system in which a dusty disk orbits a pair of stars. The disk might contain planets.

NASA/JPL-Caltech/T. Pyle (Spitzer Space Telescope)

Then, over the next few billion years, collisions between asteroids and other bodies produce new sprays of dust, which hover within the asteroid belt. When scientists detect a dusty disk around a star, it usually means that asteroids are there, crashing into each other and creating the dust.

Planets and asteroids form out of the same original stuff, so the presence of asteroids suggests that planets or planetlike objects are there too. At least 20 percent of stars in our galaxy, the Milky Way, have dusty disks around them, Trilling says.

No telescope is powerful enough to see a planet or an asteroid outside our solar system. However, telescopes can see the dusty disks around faraway stars. A disk indicates that asteroids and comets orbit a star.

Using various methods, scientists have found about 200 planets orbiting stars in recent years. About 50 of those planets are in binary star systems. But in every case, a vast distance—a distance much greater than the diameter of our entire solar system—separates the two stars. And all those planets orbit just one star, not a pair of stars.

If you could travel to one of those planets, one sun would look big in the sky, just as our sun does when viewed from Earth. The distant twin would simply look like another twinkling star.

Searching for a doubly sunny planet

Trilling and his colleagues wanted to find out whether planets formed around binary stars that lie close together. They used the Spitzer Space Telescope, which is in orbit around the Earth, to take pictures of 69 binary star systems. Some star pairs were as close to each other as Earth is to the sun. Others were farther away from each other than Neptune is from our sun.

An animated video (click here, or on image above, to watch) shows how a pair of stars might raise a family of planets.

NASA/JPL-Caltech/T. Pyle (Spitzer Space Telescope)

With telescopes that use visible light, scientists have trouble taking pictures of dusty disks because the stars are so much brighter than the dust. The particles of dust, however, absorb heat from the star and emit a type of energy called infrared light. Our eyes can’t see infrared light, but the Spitzer telescope can. In the images it produces, the dust looks much brighter than the stars.

Still, the researchers can’t usually tell what the pictures mean at first. “We see a fuzzy blob,” Trilling says.

But by calculating how much brighter a star with dust looks in the image than it would look without dust, astronomers get a sense of where the dust is within the binary system. Calculations also show how much dust there is. The calculations don’t show for sure whether planets are out there, but chances are high that at least some of these disks contain planets.

When the pictures from the binary study started arriving, the scientists at Arizona saw pretty much what they had expected. “At first, it was kind of a little bit ho-hum because we know that dust is out there around some stars,” Trilling says.

However, after the study ended and the scientists started to analyze their data, they found some surprises. Dusty disks, their results showed, are remarkably common around binary stars that lie close together.

Dusty disks are common around binary stars that lie close together (top). Disks either don’t exist (middle) or orbit only one of the two stars (bottom) when the stars are far apart.

NASA/JPL-Caltech/T. Pyle (Spitzer Space Telescope)

“The number of these stars that have this dust is much, much higher than we expected,” Trilling says. Binary stars that are close to each other have far more dusty disks around them than do single stars or binary stars that are distant from each other, he adds.

That discovery suggests that close binary stars may be the best places of all to look for planets and for life on other planets.

The finding is also forcing scientists to reconsider long-held assumptions about how and where planets form. It is not yet clear, for example, why dusty disks are so common in close binary systems.

“The theory is totally up in the air,” Trilling says. “Nobody knows.”

Life under two suns

Scientists still have doubts about how a binary-orbiting planet forms. But one thing is sure: Life on such a planet would be interesting. Every day, one sun would appear to chase the other across the sky. The suns would rise and set just minutes apart. Sometimes, one sun might dip behind the other, affecting the amount of light and heat on the planet’s surface.

“It would be a weird place to grow up,” Boss says. “Every day would be different.”

And with more suns in the sky, he adds, any intelligent creatures on these planets would have at least double the opportunities to become fascinated with astronomy.

Additional Information

Questions about the Article

Word Find: Binary

Going Deeper: