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Planet Earth

Science News


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Neanderthal Eats Neanderthal

Neanderthals along the Rhône river in southeastern France 100,000 years ago ate a lot of venison. There, in a cave called Baume Moula-Guercy, prehistorian Alban Defleur and his colleagues found an abundance of ancient deer bones that had been hacked and smashed with stone tools. Also in the cave, and bearing the same butchering marks, were Neanderthal bones. Apparently Neanderthals ate other Neanderthals as well.

"To prove that cannibalism took place, you have to prove that the human bones were treated just like the animal bones," says Defleur, whose lab is at the University of the Mediterranean, in Marseille. Fragments from six skeletons display such characteristic cuts and fractures. Two Neanderthal skulls had been shattered to get at the nutritious brains. Marks on the jawbone of an adolescent Neanderthal indicate the tongue had been removed. Would they have eaten that too? "Absolutely. C'est très, très bon," says Defleur.

Animals will eat others of their species if they're hungry enough, but the Neanderthals at Moula-Guercy probably had access to plenty of game. Cannibals who aren't warding off starvation might be trying to become what they eat (such as a deceased family member) or appropriate its strength (from a vanquished enemy, say). Either way, the meal is a symbolic act. Yet symbolic behavior is generally thought to have emerged only tens of thousands of years later, when humans started wearing jewelry and painting caves. Could Neanderthal cannibalism be considered an early sign of modernity? "I think this cannibalism suggests a very elaborate intellectual behavior," says Defleur.

======================================================== Hamburger Helper

Tall fescue grasses have long been a favorite grazing food for cattle in the southeastern United States, but a fungus that produces toxic compounds similar to LSD likes the grass too. If cattle feed on infested blades, they give less milk, produce fewer offspring, and often develop a degenerative hoof disease. "It's a huge problem in the East," says Vivien Allen, an animal-foraging expert at Texas Tech University.

Trying to rid the grass of fungus would help eradicate this $600-million-a-year scourge but would raise other problems, because the fungus also protects the grass against insects and helps it tolerate stress from drought and overgrazing. Fortunately, nature may have provided a better remedy, in the form of a brown seaweed called Ascophyllum nodosum. Allen and her colleagues at Virginia Tech and Mississippi State discovered that an extract from the seaweed, when sprayed on a pasture, activates the innate defense mechanisms of both the grass and the animals that eat it. It also boosts cattle's immune systems and improves the quality of their meat.

"This has large economic implications," says Allen. The researchers now plan to determine whether they can treat the animals with a seaweed supplement in their feed, thus saving the cost of spraying.

========================================================= As Dry as Mars

The Earth's oceans are drying up, and there's nothing we can do about it, say a group of Japanese geologists. Each year, the movement of Earth's crust plunges more than a billion tons of water into the mantle, where it is mostly absorbed into the rocks. As a result, the geologists say, someday Earth will likely end up as dry as Mars.

Shigenori Maruyama at the Tokyo Institute of Technology and his colleagues reached their dour conclusion after constructing a detailed budget of how material circulates between the crust and the mantle below. Shortly after our planet formed some 4.6 billion years ago, minerals just below the crust were too hot to trap water. Then about 750 million years ago, Maruyama says, the minerals cooled enough to ferry water to depths where it would be permanently buried.

Sea levels have since dropped by 2,000 feet, Maruyama estimates, and in another billion years the oceans will be gone. He suggests a similar process took place on Mars. Because it is smaller than Earth, Mars cooled faster and so dried up sooner, about 2 billion to 3 billion years ago. "I hope the idea will promote discussion among the biologists who think about the evolution of life," Maruyama says. Environmental changes associated with the initial draining of the oceans, for instance, may have triggered the abrupt diversification of life that eventually led to us.

======================================================== We Need the Worms

People who live in developing countries often have parasitic worms in their intestines. On the other hand, they rarely get inflammatory bowel diseases such as ulcerative colitis. Immunoparasitologist Joel Weinstock of the University of Iowa suspected a connection, so he asked six patients with these diseases to quaff a brew of worm eggs. Five of the six went into complete remission within three weeks and stayed symptom-free for up to five months. The sixth patient, who already had permanent bowel damage, improved significantly.

Animal studies suggest the worms modulate an aspect of the body's immune system called the Th1 response, which can mistakenly attack healthy tissue. The worms seem to suppress Th1 and enhance the related Th2 response, creating a better environment for them - and for the host. "For all of our existence these parasites have been with us. They need us, and we need them," Weinstock says. He believes the absence of the worms in affluent persons' guts could influence diseases such as multiple sclerosis and rheumatoid arthritis.

========================================================= Discover Dialogue: Witness to a Century

Over his long career, Hans Bethe has shaped quantum physics, won the Nobel prize for elucidating how stars shine, collaborated on the development of the atom bomb, and then fought for nuclear arms control. At 93, he continues his investigations at Cornell University, where he began lecturing in 1935.

What are the most important scientific discoveries of the twentieth century? Quantum theory was the most significant, followed by DNA and Einstein's theory of special relativity. Quantum theory gives you the key to all atomic phenomena, and that in turn gives you the key to chemistry and biology. dna is fundamental to biology, and special relativity is essential for exploring nuclear physics.

And the century's greatest inventions? The airplane, the transistor, and the computer. The airplane gives us communication with the whole world. The transistor is fundamental to all electronic communication. And computers - it's obvious.

Was it right to build the atom bomb? Yes, because it ended the war against Japan quickly, with fewer Japanese casualties than would have occurred if firebombing of Japanese cities had continued. Atom bombs also helped ensure that the cold war between the United States and the Soviet Union never became a hot war.

How do you feel about President Clinton's push to revive the Strategic Defense Initiative ("Star Wars")? I argued strongly against Star Wars when President Reagan first proposed it. I have not changed my opinion. At best it is a great waste of money. It could not work as originally foreseen.

What scientific problems are you working on now? I am studying how pressure waves trigger supernovas - sudden, brilliant flare-ups of stars. I am also working on detecting gravitational waves - ripples in the fabric of space and time produced by violent events in the distant universe - with the upcoming Laser Interferometer Gravitational Wave Observatory.

If you hadn't become a scientist, what would you have done? I would have worked in a bank or an investment firm.

========================================================= ...But Will They Do Windows?

We'd all be knee-deep in sewage if it weren't for bacteria that break down ammonia, one of the most common and noxious waste products. And a novel bacterium found in the Dutch town of Delft could make the job a lot easier.

Ordinary bacteria digest ammonia by combining it with oxygen from the air, but researchers noticed that something at a sewage plant in Delft was consuming ammonia where there was no oxygen. Microbiologist Mike Jetten of the Delft University of Technology tracked down the secret benefactor: a strange bacterium that breathes nitrite instead of oxygen.

Ammonia runoff from incompletely treated sewage promotes the growth of toxic algae, which suffocate watersheds and estuaries. Gijs Kuenen, a microbiologist at Delft, thinks the little bug could ease the environmental problems by making sewage treatment cheaper. "It could save a medium-sized Dutch town $500,000 a year," he says.

========================================================= Resonating Rugs

Magnetic resonance imaging is good for medical diagnosis because it peers well into wet stuff, and people are mostly water. It occurred to Haskell Beckham, a polymer scientist at Georgia Tech, that mri might also be perfect for looking at his own interest - wet carpeting. Beckham and his colleagues have been trying to understand how carpets dry after they're dyed. Using a high-powered mri machine and watching in real time, Beckham found that moisture in a carpet flows into the backing through the centers of individual tufts of fiber, even against gravity. "For the first time, we can see where the moisture is, and then we can design carpets that are much easier to clean," says Beckham.

========================================================= Weak With Laughter

Ever get wobbly in the knees when you laugh out loud? According to a team of Dutch neurologists, that feeling is no joke.

G.J. Lammers and his colleagues at the University of Leiden study narcolepsy, a neurological disorder that causes sleeplike seizures. When narcoleptics laugh, they often experience a sudden loss of muscle strength. To figure out why, Lammers and his colleagues tried to trigger the response in the lab by telling jokes to patients. At the same time, they monitored a muscle reflex in the patients' lower legs. When the narcoleptics laughed, the reflex all but disappeared. But the reflex also vanished in a non-narcoleptic control group.

"We became convinced we had proof that people really do become weak with laughter," Lammers says. "When muscles are weak from laughter, it is easy for susceptible people to go on laughing till they fall down."

========================================================= First Light

Ten billion years ago, the infant universe convulsed with activity. Small, chaotic, yet intensely bright galaxies suddenly came alive. These strange objects blazed as brightly as our Milky Way, although they were less than one-fifth its size. A new supercomputer simulation shows why: Collisions between giant gas clouds - the precursors of galaxies - violently collapsed the material into clusters of hot, energetic, newborn stars.

"As two of these [gassy] galaxies collide, the clouds of gas stream together, producing a very high density of gas at the center," explains cosmologist James Bullock of Ohio State University, who analyzed the simulation along with Tsafrir Kolatt of the University of California at Santa Cruz. "From a little bit of gas, you get a whole lot of stars and a very bright galaxy." These interactions churned out as many as a thousand new stars each year in the early galaxies. A typical galaxy now births just one new star per year.

The computer model is helping astronomers make sense of the many faint blobs of light that dot the most sensitive deep-space images from the Hubble Space Telescope. "When we look at these objects, we are seeing massive galaxies being assembled out of smaller parts. And so what we are really seeing is the structure of the universe forming," Bullock says.

========================================================= VR in the ER

A new medical tool will help doctors who are literally losing their touch. Modern laparoscopic surgical tools make simple procedures like gallbladder removal far less traumatic, but break the physical bond between surgeon and patient. "The surgeons can't localize pulsing blood vessels or search for tumors beneath the surface," says Jonathan Thierman, a graduate student at MIT. "Anything they can't see, they can't find."

Thierman and Harvard University electrical engineer Roger Brockett have found a way to give surgeons back their sense of touch. First they affix a small, speckled latex bubble to the tip of an endoscope. When the probe moves over tissue, any hard lumps beneath the surface deform the bubble, changing the position of about a dozen small dots on its inner surface. A mini-camera monitors the dots and relays the movement to a computer, which then calculates the dimensions of the lump.

Right now their contraption merely displays a lump as a wire-mesh graphic on a video screen. Eventually, Thierman and Brockett will link the sensor to a mechanical arm that can guide the surgeon's hand. "When we hook up the two devices," Thierman says, "the surgeon will be able to feel everything, like virtual reality in terms of touch."

========================================================= Bendable Light

Light could be better than electricity to make a computer run faster and more efficiently, but light is also much more difficult to control. Engineers have long lusted after a material that could manipulate light the way silicon chips organize electricity. "The problem is that light propagates too easily," says Sajeev John, a physicist at the University of Toronto.

But he and his colleagues say they have found a solution. They poured silicon into a tray full of glass balls and used acid to dissolve the balls, leaving an array of spherical holes. Then they coated the holes in liquid crystals, whose light-scattering properties change in the presence of an electric field. The resulting structure should allow the scientists to control the path of light and to reprogram it at will. John hopes to use this material as the basis for light-powered computers, which he believes could be on the market within a decade.

========================================================= Getting the Skinny on TV

Teen eating disorders are often blamed on the endless parade of skinny actresses on television. Still, there are so many cultural factors to consider that it is nearly impossible to make the charges stick. Harvard anthropologist Anne Becker may have found some proof in the Fiji Islands, where television first arrived just four years ago.

More than four-fifths of Fijian women are overweight by American standards but, until recently, it didn't seem to bother them. Fijians have traditionally glorified larger proportions and worried more about being too thin than about getting fat, Becker says. Thirty-eight months after Western TV shows were introduced in Fiji via satellite, however, she found that the number of teenage girls who vomited to control their weight increased fivefold, along with a general rise in abnormal attitudes toward eating. Her surveys revealed that Fijian girls who clock the most hours of TV (Melrose Place and Beverly Hills 90210 are especially popular) are half again as likely to feel fat and a third more likely to be on a diet than their peers.

"They see they're much bigger than these rich, successful Americans. Add to that a culture attuned to weight changes, and the results are disastrous," says Becker.

========================================================= Robot Watch: Radioactive Wall Crawler

If there's one place robots make sense, it's in a nuclear facility, where inspections are essential but potentially lethal. Enter robicen III, a tank-climbing machine built by Joan Savall and his colleagues at the University of Navarra and CEIT, a research center, both in Spain. This little robot grabs the outsides of storage tank walls with its four suction-cup feet and uses cameras and ultrasonic sensors to inspect welds and detect cracks. Its left foot and right foot are attached to an axle that slides back and forth and swivels to make turns. robicen III fixes its front foot and back foot to the tank, lifts the left and right feet, and then slides them forward and seals them again to the tank. It then unsticks the front and back feet and pulls itself forward. Each foot is hinged so that the robot can grab onto the curved portions of a tank.

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