But our meticulous attention to cleanliness might have a down side. New research suggests that the chemicals we use to clean and disinfect could be damaging the environment by killing off algae at the base of the food chain.

Chemicals in cleansers go down the drain, ending up in lakes and streams where they can kill off algae.

Over the past decade, the war against bacteria has been escalating. From dish soap to toothpaste, cleaning products have become increasingly deadly to the tiny troublemakers. After getting dumped down the drain, those household chemicals usually go straight through the sewer system and into lakes and streams, ignored by wastewater treatment plants.

Curious about the environmental effects of all that chemical runoff, environmental scientist Brittan A. Wilson of the University of Kansas in Lawrence and colleagues collected algae from a Kansas stream. In the lab, the scientists doused the algae with three common household chemicals in concentrations comparable to levels often found in American streams.

The number of species of algae and overall growth of algae dropped in samples treated with the chemicals, but not in untreated samples, the researchers report.

Those results may be alarming, but they shouldn’t be a complete surprise. “It’s stupid to think that chemicals that keep toothpaste safe from bacteria won’t have an effect at the other end of the sewer pipe,” says ecologist Stanley I. Dodson of the University of Wisconsin-Madison. What is surprising is that even low concentrations of the chemicals can have a big effect.—E. Sohn

Going Deeper:

Morgan, Kendall. 2003. Clean casualties: Everyday chemicals may shift ecosystems. Science News 163(March 29):196. Available at http://www.sciencenews.org/20030329/fob3.asp .

Now, scientists say, it looks like some black holes actually spit out as much material as they suck in. Black-hole burps may even fill outer space with many of the building blocks of life.

Illustration of a massive black hole flanked by swirling gas (green).

Chandra/M. Weiss

The new observations come with the help of NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton satellite. George Chartas of Pennsylvania State University and his colleagues used the spacecraft to look at two quasars—extremely bright and distant beams of high-energy light powered by rotating black holes.

By looking at magnified light from the two quasars, Chartas and his team were able to detect for the first time high-energy winds coming out of black holes.

The winds travel at 20 to 40 percent of the speed of light (which is still really, really fast). And they spit out billions of suns worth of gas, including oxygen, carbon, and iron—important elements necessary for life. So, even though black holes make up only a tiny percentage of a galaxy’s mass, they may play an important role in galaxy evolution.

Still, with all the sucking, spitting, and burping they do, it probably wouldn’t be a good idea to try to look inside a black hole, even if you could get close enough!—E. Sohn

Going Deeper:

Cowen, Ron. 2003. Cosmic blowout: Black holes spew as much as they consume. Science News 163(April 5):214. Available at http://www.sciencenews.org/20030405/fob7.asp .

About 70 million years ago, dinosaurs called Majungatholus atopus roamed the plains of Madagascar—a large island off southeastern Africa. The fearsome creatures grew up to 30 feet in length. And like many meat-eating predators, they had sharp, knifelike teeth with jagged edges.

The size and spacing of notches on the teeth of Majungatholus atopus match the grooves on bones of another member of the dinosaur species.

R. Rogers, Macalester College

Many old animal bones found in Madagascar are scarred with grooved tooth marks, says Raymond R. Rogers, a paleontologist at Macalester College in St. Paul, Minn. This includes bones of the dinosaurs themselves.

To find out who made the tooth marks, Rogers and his colleagues measured the marks on some bone fossils. They also measured the spacing of notches on Majungatholus teeth. The two measurements matched almost exactly, the scientists report.

No other known animal could have made the same kind of grooves, Rogers says. The only other dinosaurs living in Madagascar at the time, five-foot-long Masiakasauraus knopfleri, were too small. And the island’s two meat-eating species of crocodile didn’t have the sharp, regularly spaced teeth necessary to make the marks.

Scientists still don’t know whether the dinosaurs actually killed each other or just ate the remains. But some reptiles today prey on each other. So it’s quite possible that certain dinos were safe nowhere, not even at home.—E. Sohn

Going Deeper:

Perkins, Sid. 2003. Family meal: Cannibal dinosaur known by its bones. Science News 163(April 5):211. Available at http://www.sciencenews.org/20030405/fob1.asp .

Climbers are often nature-loving people who flock to rock any chance they get. But new research suggests that even the most environmentally sensitive rock climbers may be hurting what they love most.

Cliff-dwelling snail species, represented here by their shells.

Larson/Conservation Biology

Douglas W. Larson of the University of Guelph in Ontario, Canada, and his colleagues have been studying a popular climbing area in southern Ontario called the Niagara Escarpment, a 700-kilometer-long stretch of limestone cliffs. In a previous study, the researchers counted fewer plants and lichens growing on areas of rock that had been climbed most.

Now, Larson has found that climbers can wipe out communities of snails, too. Compared to commonly climbed routes of rock in the Niagara Escarpment, soil
collected from unclimbed areas had five times as many snail shells, Larson and colleagues report.

Snails thrive in rocky cracks and crevices. On a cliff in Wisconsin, for example, scientists found one-quarter of the state’s land-snail species in just a plate-sized area. Rock climbers probably root out snails all the time without even realizing it.

The new studies suggest that rock climbing should be more restricted and better regulated, some researchers say. “I’m amazed by the size of the effect,” says conservation biologist Menno Schilthuizen of the University of Malaysia in Sabah.—E. Sohn

Going Deeper:

Morgan, Kendall. 2003. At a snail’s place: Rock climbing cuts mollusk diversity. Science News 162(April 12):228-229. Available at http://www.sciencenews.org/20030412/fob4.asp .

The most distant galaxy (bottom arrow) identified so far, imaged as a faint splotch.

Subaru

Two groups of scientists have glimpsed some of the most distant galaxies yet, giving new insights into what the universe was like soon after the Big Bang. “We are seeing some of the first galaxies to be born,” says Richard G. McMahon of the University of Cambridge in England.

McMahon’s team looked at images taken with a special camera on the Hubble Space Telescope. The pictures showed six extremely distant galaxies, one as far as 12.7 billion light-years away, the researchers report.

The other team, led by Yoshiaki Taniguchi of Tohoku University in Sendai, Japan, went to Mauna Kea in Hawaii to look through the Subaru telescope, which measures about 25 feet across. They identified 73 galaxies. One turned out to be the most distant galaxy ever seen, at 12.8 billion light-years from Earth, the team reports.

The Subaru telescope in Hawaii.

Subaru

Both groups noticed that the distant galaxies were much dimmer and less dense than similar, closer galaxies. Some scientists speculate that, early on, the universe was filled with smaller galaxies that merged to build the large ones we know today.—E. Sohn

Going Deeper:

Cowen, Ron. 2003. Once upon a time in the cosmos: Using distant galaxies to study the early universe. Science News 163(April 12):227-228. Available at http://www.sciencenews.org/20030412/fob2.asp .

New studies pinpoint an inner-brain region called the hippocampus as the root of memory for both experiences and facts. Researchers have disagreed, however, about which kind of information the hippocampus remembers best.

An inner-brain region called the hippocampus may be the root of memory for both experiences and facts.

In a recent journal, scientists led by Larry R. Squire of the University of California, San Diego, described six adults with hippocampus damage.

In one study, the six patients and 14 healthy adults read a list of names-some famous, some made up. The healthy-brained adults were able to pick out the famous people and say which ones were still alive. The brain-damaged patients remembered little about people who became famous after they suffered their injuries or in the 10 years before those injuries.

In a second study, the six brain-damaged patients could remember events from their childhood just as well as 25 healthy adults. But personal memories slacked off in the years just before and after their injuries. Together, the two studies suggest that the hippocampus controls memories of both facts and events.

The hippocampus may not be essential for kids’ ability to remember facts, though. One study of hippocampus-damaged children showed that they could retain new facts well enough to do okay in school. This might be because kids’ brains are able to reorganize themselves a lot.

Still, no matter how healthy your hippocampus may be, there’s no excuse to stop studying for your social studies tests!—E. Sohn

Going Deeper:

Bower, Bruce. 2003. Neural recall: Brain area may support fact and event memory. Science News 163(April 19):244-245. Available at http://www.sciencenews.org/20030419/fob4.asp .

One of the reasons this could never really happen is that DNA is incredibly fragile. Every speck of dino DNA has probably broken down during the 65 million years since the giant reptiles disappeared.

Soil from this permafrost plain, shown in an aerial shot along Siberia’s Arctic coast, has yielded identifiable DNA of animals and plants that lived up to 400,000 years ago.

Science

But now, new DNA discoveries are opening windows into ancient worlds. In tiny samples of soil from New Zealand and Siberia, molecular biologist Eske Willerslev of the University of Copenhagen and his colleagues have found the oldest bits of identifiable DNA ever.

In Siberia, the researchers drilled into ice and dirt dating back 2 million years. In sediment that was 30,000 years old, they found DNA from eight animal species, including horses, reindeer, bison, and woolly mammoths. In DNA extracted from 400,000-year-old soil, the researchers found at least 28 species of trees, shrubs, herbs, and mosses.

Willerslev guesses that the DNA made its way into the soil through animal poop. He hopes the new findings will help reveal what life was like long ago.

Unfortunately, the chances of any DNA in dinosaur poop lasting that long are pretty slim.—E. Sohn

Going Deeper:

Perkins, Sid. 2003. Fertile ground: Snippets of DNA persist in soil for millennia. Science News 163(April 19):244. Available at http://www.sciencenews.org/20030419/fob3.asp .

In cases of severe bone damage, surgeons sometimes take bone from one part of the body and use it for repairs in other parts. Thanks to the wonders of bone biology, the procedure works, but it can be painful and expensive.

Cross section of a healed piece of rat’s skull.

Hubbell et al./Nature Biotechnology

Now, scientists have invented a promising new material that could help encourage bones to grow back without many of the usual complications.

The researchers, from Switzerland, made a framework structure with a combination of star-shaped molecules, proteins, and protein fragments. Inside the framework, they put proteins called BMPs, which spark bone regrowth. When the structure is then attached to the site of an injury, bone-forming cells attach themselves to the framework and dissolve parts of it, allowing BMPs out as needed to fix the bone.

In tests with rats, the new framework structure encouraged bone regrowth in places where fragments of the animals’ skulls had been removed.

Someday, the new structure might eliminate the weeks of pain and tedium that most people face after breaking a bone. You’ll be climbing trees again in no time!—E. Sohn

Going Deeper:

Gorman, Jessica. 2003. Bone fix: New material responds to growing tissue. Science News 163(April 26):261. Available at http://www.sciencenews.org/20030426/fob6.asp .

A long-term study in Central America gives one more reason for concern. Adult trees in a rain forest in Costa Rica grew more slowly in warm years than they did in cold ones. Such a shift toward slower-growing trees might make the climate warm up even faster.

View across the forest canopy at La Selva in Costa Rica.

Alan Campbell/Oak Ridge National Laboratory

From 1984 to 2000, biologist Deborah A. Clark of the University of Missouri-St. Louis and colleagues measured the width of old trees in a 2-square-kilometer plot of rain forest at La Selva, Costa Rica. During the coolest years, a time period running from 1984 to 1986, the trees grew 81 percent faster than they did during a heat wave that struck in 1997. The trees also grew slowly in 1987, another warm year.

In addition, scientists found that, during warm years, Earth’s atmosphere contained less carbon dioxide produced by tropical land plants. Carbon dioxide is a heat-trapping gas, which plants normally use up to make food.

The new results reinforce how important trees are to the health of the planet and how devastating a continued rise in temperatures might be to their future—and ours.—E. Sohn

Going Deeper:

Perkins, Sid. 2003. Feel the heat: Rain forests may slow their growth in warmer world. Science News 163(April 26):260. Available at http://www.sciencenews.org/20030426/fob3.asp .

That’s exactly what’s happened in recent years to Africa’s Lake Tanganyika, scientists are reporting. Rising water temperatures have interfered with the lake’s normal mixing. As a result, the tiny organisms at the base of the food chain aren’t as abundant as they used to be.

Lake Tanganyika in Africa, as seen from space.

NASA/Goddard Space Flight Center

Lake Tanganyika is the second-largest body of fresh water in the world, after Lake Baikal in Russia. The African lake is more than 1 kilometer deep in some places.

In such a large lake, nutrients tend to sink to the bottom. That’s bad news for the microorganisms called plankton, which live near the surface. Normally, these microscopic creatures rely on winds to churn the lake water and bring valuable nutrients back up.

But times have changed. Since 1913, the water temperature at the bottom of Lake Tanganyika has risen by about 0.2 Celsius degrees. Water near the surface has warmed by almost a full degree. Cold water is more dense than warm water, so the lake has grown more resistant to mixing.

With smaller amounts of nutrients coming up to the surface, the tiny creatures are suffering. Researchers found that populations of several species of plankton dropped 70 percent from 1975 to 2001.

A view across Lake Tanganyika.

(c) Science

Scientists are worried because plankton are at the base of the food chain in lake ecosystems. So if plankton disappear, bigger creatures may run out of food and die out, too.

Waves of extinction, if they continue, could be far worse than burning your tongue on an unevenly heated bowl of chili.—E. Sohn

Going Deeper:

Perkins, Sid. 2003. Slow turnover: Warming trend affects African ecosystem. Science News 163(June 28):404-405. Available at http://www.sciencenews.org/20030628/fob4.asp .