Weird place on Earth Mono Lake in eastern California is where researchers found a type of bacteria that appears to break the rules for how we think life should survive. Credit: NASA image gallery

You may not know phosphorus when you see it, but your body does. Phosphorus is a sturdy workhorse element. In DNA molecules, phosphorus helps support the whole double helix. Within cells, energy shows up as ATP — and the “P” stands for phosphorus (specifically, phosphate, a form of phosphorus).

All life as we know it, in other words, depends on phosphorus. For that reason, scientists around the world were shocked December 2 when a team of scientists announced finding life forms that didn’t necessarily depend on this all-important element. In laboratory tests, the scientists grew bacteria that were able to use arsenic — a different element with similar chemistry — in the place of phosphorus.

It’s a surprising discovery because living organisms have never been found without all six of the ingredients crucial to life: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (all together known as CHNOPS). Arsenic, though, is a potentially fatal poison.

Many scientists say they would like to see more evidence that the research team did in fact observe life forms using arsenic instead of phosphorus.

“This is an amazing result, a striking, very important and astonishing result — if true,” Alan Schwartz told Science News. Schwartz researches chemistry at Radboud University Nijmegen in the Netherlands. “I’m even more skeptical than usual, because of the implications. But it is fascinating work.”

The bacteria came from Mono Lake, a lake in eastern California that is well known for its unusual population of living organisms, including shrimp and algae. The lake doesn’t drain, so the only way for water to leave is through evaporation. As a result, the lake is much saltier than the ocean.

An up-close picture of the bacteria GFAJ-1 grown on arsenic. Credit: Jodi Switzer Blum, NASA

Several researchers had been studying a number of tiny organisms that lived in Mono Lake mud. Astrobiologists study life in the universe and want to know how it started, how it has changed, and what will happen to life in the future. They also want to know whether life exists on other planets and if so, what it might look like. Many astrobiologists study what lives in Earth’s strangest places, such as Mono Lake, as a way to understand the possibilities for life.

The study was led by Felisa Wolfe-Simon of NASA’s Astrobiology Institute and the U.S. Geological Survey in Menlo Park, Calif. She and her team removed organisms from the Mono samples and grew those bacteria in the lab. The scientists fed the microbes with sugar and vitamins — but left out phosphate. Then they changed the diet again, and gave the microbes arsenate, which is a form of arsenic.

In one type of bacteria, called GFAJ-1, the researchers observed that arsenic wasn’t fatal. The bacteria continued to grow, though not as fast as if they’d had phosphorus. After studying these bacteria, Wolfe-Simon and her team concluded that the organisms had begun to make use of the arsenic the way they usually used phosphorus. The researchers suggest that arsenic was being used as a building block in the bacteria’s DNA.

“This microbe, if we are correct, has solved the challenge of being alive in a different way,” Wolfe-Simon told Science News.

If the scientists are right, then “life as we know it” may not include all the life that actually is possible. For astrobiologists, that conclusion suggests that life on other planets may not necessarily look like life on Earth.

It’s possible that follow-up studies will show that the researchers were mistaken. Wolfe-Simon and her team could not get rid of all the phosphorus when they were growing the bacteria. Some scientists say minute amounts might be enough to keep the microbes alive. It’s possible that, in the experiment, the bacterium GFAJ-1 was still getting small amounts of phosphate.

Can life exist using poison instead of phosphorus? Life of a different type is an exciting prospect, so stay tuned to see how the scientific community reacts. Next up, scientists will want to know how, exactly, the arsenic substitution works.

POWER WORDS

arsenic A highly poisonous metallic element having three allotropic forms, yellow, black and gray, of which the brittle, crystalline gray is the most common. Used in insecticides.

phosphorus A highly reactive, nonmetallic element occurring naturally in phosphates.

DNA A nucleic acid that carries the genetic information in the cell. DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the bases.

molecule A group of like or of different atoms held together by chemical forces.

microbe A minute life form; a microorganism, especially a bacterium that causes disease.

bacterium A life form that is a single cell and too small to see without using a microscope. Bacteria (plural of bacterium) live in almost every environment on Earth, including very cold places, very warm places, in all types of water, in the air, even on and in plants and animals. These microorganisms can also cause disease in plants and animals.

Now, scientists say the microbes that live on our hands could be useful in a surprising way: fighting crime.

When police visit the scene of a crime, they often look for fingerprints to try to identify the culprit. They can also look for other things, like hair, to figure out who was there. But according to a recent study, investigators could even use microbes to help crack a case.

Every person has his or her own set of microbes that live on their hands, according to scientists at the University of Colorado at Boulder. That means that if you and your best friend were able to see and compare all the microbes that lived on both of your hands, your hands probably would look different. Some microbes would show up on your hand; others would live only on your friend’s hand. Your mix of different kinds of hand microbes is unique — much like your fingerprint.

The scientists in Colorado wanted to know whether this microbe mix could be used as a new kind of fingerprint — especially in a crime scene where fingerprints might be hard to find. The use of science to figure out what happened — such as studying fingerprints — is called forensics.

In the study, the mix of germs on each person’s keyboard matched the unique mix living on that person’s hands.

bluestocking/iStock

Noah Fierer, one of the scientists, says microbe fingerprints are harder to hide. “You only need to smudge a fingerprint, but you can’t sterilize a surface just by wiping it off,” he told Science News.

Fierer and the team of scientists knew that when people work on a computer, the microbes from their hands end up on the keyboard. (Think about the microbes that are on your keyboard — especially if many different people use it!)

So to do their experiment, the scientists compared the bacteria on the hands of three people to the bacteria found on each person’s computer keyboard. For the study, the keyboards had been used only by the people who were being tested. The mix of microbes from each person’s hands matched the mix of microbes on that person’s keyboard. The scientists were easily able to tell the three people apart — just by looking at their keyboards.

But that experiment was only on three people, so the scientists knew they had to test their idea against a larger population. Their next step was to collect bacteria samples from the palms and computer mice of nine people. When they compared those samples to the known microbe mix from the hands of 270 other people, the team again found a match. Nine times out of nine, the bacteria patterns lined up — and it was again easy to tell who had been using which mice. (The information on the microbe mixes from 270 people already existed as part of the Human Skin Microbiome project. The microbiome is the population of microbes that live in and on the human body.)

So far, so good — but there are a lot more than 270 criminals out there. Other scientists wonder whether the microbe fingerprint can really be that useful. “Right now we really have no idea how unique a person’s skin microbiome is,” Elizabeth Grice told Science News. Grice is a geneticist at the National Human Genome Research Institute, part of the National Institutes of Health in Bethesda, Md.

Fierer agrees that scientists have a lot more work to do before the microbe fingerprint will be a useful tool.

In any case, it’s something to think about. Even if you don’t leave your fingerprints behind, your microbes may give you away.

Going Deeper:

Sanders, Laura. 2009. “Bacteria flourish in favorite ecosystems on the human body,” Science News, November 5. http://sciencenews.org/view/generic/id/49242/title/Bacteria_flourish_in_favorite_ecosystems_on_the_human_body

Sohn, Emily. 2008. “Cell phone tattlers,” Science News for Kids, March 12. http://sciencenewsforkids.org/articles/20080312/Note3.asp

Sohn, Emily. 2006. “Fingerprint evidence,” Science News for Kids, May 3. http://sciencenewsforkids.org/articles/20060503/Feature1.asp

A casemaking clothes moth caterpillar crawls around partly surrounded by its long, lumpy case. Now scientists have found a caterpillar case (not this one) that incorporated hair from a nearby abandoned human body. Using the DNA in the hair can help invest

Clothes moth caterpillars may be a nuisance for your wardrobe, munching holes through sweaters and socks. But the pests don’t just eat clothing, they also feast on human hair. And though that may not sound as tasty as a glass of milk and cookies, the insects’ ghoulish appetite could help detectives who want to identify dead bodies.

Just like butterflies, casemaking clothes moths, Tinea pellionella, start as caterpillars. They transform to their moth namesake later in life. These insects are known best for the holes they leave in wool garments. But scientists have known that clothes moths also dine on dead animals in the wild, according to entomologist Sybil Bucheli of Sam Houston State University in Huntsville, Texas. “They had to eat something before people invented wool sweaters,” Bucheli said.

Now, though, Bucheli is showing how to use the moths’ leftovers as a forensic tool to solve mysteries. Little stubs of hair chewed up by a clothes moth caterpillar contain enough DNA, or genetic material, to identify the person the hair came from. That can help police sleuth out the identity of dead bodies, or even figure out where a person died.

To keep cozy and safe, the clothes moth caterpillar builds itself a case of woolly fibers and hair. The caterpillar burrows inside the case, dragging it around while feeding. The insect pokes its front end out to eat, growing bigger by the day. To adjust, the caterpillar expands its case with snips of hair and fiber found along the way.

Once it’s time to change into a moth, the caterpillar shuffles off into an out-of-the-way place and sheds the woolly case. The new moth may fly away, but it leaves its cast-off case behind.

And that’s precisely what forensic scientists could use to put a name to a dead body. These cases have enough bits of DNA-carrying hair that police can determine the identity of the person the hair belongs to — even if the person’s body gets moved to another location, away from the caterpillar’s case.

Already, the moths have showed their worth in a real case. They collected enough hair for DNA testing from an unlucky person found dead in Galveston County, Texas in 2007, Bucheli said.

Going Deeper:

Particularly challenging are the crimes that involve poaching—taking animals from the wild that are protected by law. Poachers can make a lot of money selling meat, tusks, fur, fins, and other parts of protected animals.

Federal inspectors took this suitcase from a traveler passing through Miami’s airport. Inside were poached shark fins and seahorses that NOAA enforcement officers later sent to researchers at Nova Southeastern University in Florida for identification.

R. Horn/Nova Southeastern Univ. Oceanographic Ctr.

Poaching can devastate even large wildlife populations if too many animals are taken in any year or from any area. The problem becomes even more serious when a species is endangered. Then, losing even a few animals can make it harder for the species to survive.

What’s really bad is that poaching creates an unfortunate cycle: As the animals become more rare, their parts become more valuable. So, poachers earn even greater rewards for their collection of protected species.

Now, scientists are helping fight back. Using the genetic material DNA, they are finding ways to clinch hard-to-solve cases involving a wide range of creatures, from elephants to seahorses.

If you’ve ever read a legal thriller or watched shows on TV such as CSI: Crime Scene Investigation, you know that DNA plays a big part in solving human crimes. The molecule appears in every cell. Like fingerprints, DNA is unique to every person. So, by analyzing DNA in blood, saliva, or hair left behind at the scene of a crime, detectives can identify criminals and victims.

When authorities find poached animal parts, they aren’t usually interested in identifying individual creatures. Instead, they want to know what species the parts belong to. That may not be obvious if all you have is a bit of meat, bone, or perhaps a fish fin. DNA can also prove helpful in figuring out where an animal came from. That’s because members of one local group of animals tend to share more DNA in common with each other than they do with more distant groups of their species.

Based on concepts such as these, scientists are developing new tests to untangle complicated webs of animal-related crime.

Tusk trackers

Elephants have been particularly devastated by poachers in recent decades. Between 1979 and 1987, poachers killed hundreds of thousands of wild elephants in Africa and Asia. This poaching reduced the animals’ numbers by more than half, says Samuel Wasser, director of the Center for Conservation Biology at the University of Washington, Seattle.

The motivation? Ivory. Elephant tusks are made of the hard, white material, which has long been used in jewelry and art, among other applications.

Poaching slowed down after an international ban on the ivory trade was passed in 1989. For a variety of reasons, however, the practice started creeping up again a few years later. By 2005, Wasser says, “the illegal ivory trade had come back with a vengeance.”

Even though it’s against the law to buy newly harvested ivory, people prize it so much that some are willing to buy it illegally. Such sales are said to be on the “black market.” In the past few years, the black-market price of ivory has quadrupled to about $850 per kilogram (2.2 pounds). A tusk can weigh 11 kg (24 pounds) or more.

Tens of thousands of elephants are dying each year as a result. There are fewer than 500,000 elephants living in the wild today.

Elephant poaching is hard to squelch because hunters often work in remote areas. Middlemen gather tusks from a variety of places. And well-hidden shipments follow complicated routes to destinations far from where they started. A single shipment can contain hundreds of tusks, thousands of pounds, and many millions of dollars worth of ivory.

Authorities intercept just 10 percent of these shipments, Wasser estimates. But even when officials retrieve the ivory, they usually don’t know where it came from.

To answer this question, Wasser has been looking for clues in elephant DNA. First, he collected elephant dung from 28 regions in 16 countries throughout Africa. He analyzed DNA in the dung samples. Then, he used the results to start mapping connections between an elephant’s DNA and its home range. Finally, he used statistics to fill in the blanks (see “Gene Sleuths Track Down Ivory Sources”).

“I’ve been working for 8 years on building this map,” Wasser says. “It has taken a while, but we’ve done it.”

But poachers trade tusks, not poop. And getting the genetic material out of ivory is more difficult. That’s because the outside of a tusk is made of dead cells, while the DNA is in living cells on the inside of the tusk. But smashing or drilling into the tusk destroys the DNA.

To overcome this problem, Wasser developed a way to extract DNA from ivory under supercold conditions. With liquid nitrogen, he was able to freeze the material. Then, he used a magnet and alternating magnetic fields to grind up the sample without destroying the DNA.

Using the technique, Wasser helped trace the origins of one of the largest ivory seizures ever made. The shipment, which contained 13,000 pounds (5,900 kilograms) of ivory, was seized in Singapore in 2002.

Wasser’s analysis showed that nearly all the seized ivory had come from a small region in Zambia. It was an important discovery because wildlife officials originally thought the shipment’s contents had come from many different places.

Investigators can use genetic techniques to trace tusks or their ivory back to the population of elephants from which they were poached.

Photodisc

Findings like these are helping authorities narrow the hunt for elephant hunters.

“DNA can really help us stop the [ivory] trade at its source,” Wasser says. “For the first time, we don’t just have information about shipping and receiving, but about where the ivory comes from. This has completely changed the way law enforcement thinks about how to deal with these cases.”

Something’s fishy

Authorities are also getting better at nabbing shark poachers, thanks to Mahmood Shivji, a conservation geneticist at a shark conservation consortium at Nova Southeastern University’s Oceanographic Center in Dania Beach, Fla. Trained as both an oceanographer and geneticist, Shivji is now a DNA detective of the sea.

There are more than 400 species of sharks in the world’s oceans, Shivji says. Fishermen kill about 50 of those fish species for their fins, which people eat. The fins of some species are especially valuable. Sometimes sharks are also killed for their meat.

As a result of hunting pressures, shark numbers have dropped 70 percent in the past 2 decades. Many populations are now threatened and a few are even endangered.

It is legal to fish for most sharks, especially if the fish will be sold for meat. However, most sharks are killed for their fins—not meat. Fishers haul in the animals, slice off their fins and then throw the rest of the still living shark back in the water to slowly die.

It’s gruesome. It’s also a tremendous waste of majestic animals that help keep ocean ecosystems healthy. That’s why it is now illegal to kill a shark in the United States—unless the entire animal is kept for sale. Any ship containing fins without the rest of the animal is automatically guilty of shark “finning”, an illegal activity (poaching).

King Diamond II. Although it had no fishing gear on board, it was carrying 32 tons of rotting shark fins. Nearly all had been neatly bundled into roped bales. Shown here is j” />

On Aug. 23, NOAA took possession of the “fishing boat” King Diamond II. Although it had no fishing gear on board, it was carrying 32 tons of rotting shark fins. Nearly all had been neatly bundled into roped bales. Shown here is j

U.S. Coast Guard

To protect sharks from poachers, Shivji says, authorities must first figure out which species are being hit hardest. But that’s hard to do when the only evidence is fins—which pretty much look alike, regardless of which shark species they came from.

“Markets are supplied from all over the world,” he says. “No one is keeping track of whether populations in certain parts of the world are being overfished relative to other populations.”

With those two goals in mind, Shivji started by studying DNA from 70 shark species, including all the varieties that end up in the fin trade. He found a small region of DNA that differs between species. Then, he created a simple test that identifies species on the basis of DNA taken from a meat or fin sample.

Next, Shivji found a different region of DNA that varies between members of the same species. He developed another test that identifies whether a sand tiger shark, for example, came from the northwest Atlantic, the southwest Atlantic, Australia, or South Africa. Finally, he combined the two tests.

The biggest advantage of Shivji’s technique is that it spits out results quickly. In just 2 days, he says, he and his team can identify the sources, by geography and species, for 50 fins.

Right now, the rapid tests can reliably identify 30 shark species. And they can distinguish between geographic populations of two of those species—sand tiger sharks and porbeagle sharks.

Shivji is working on incorporating more groups into the tests. And he wants to make the process even faster by eventually replacing much of the work that humans do with robotic technologies.

This Asian market boasts a range of shark fins sold by size and type. A recent estimate indicates that some 40 million sharks are harvested each year for their fins, which would translate into an estimated 1.7 million metric tons of dead sharks.

Shelley C. Clarke/Imperial College London

The technique has already helped solve a number of suspicious cases for the National Oceanic and Atmospheric Administration. NOAA’s Office for Law Enforcement is responsible for inspecting fishing boats that enter U.S. ports. Shivji is also working on cases in foreign waters and helping train foreign colleagues.

As the tests get better and faster, word is spreading that it might not be so easy to get away with shark poaching anymore.

“Now, fishermen can’t say, ‘They’re never going to be able to tell the difference’” between legal and illegal catches, Shivji says. This “is having a positive impact on reducing the amount of illegal activity.”

It usually takes a long time for basic research to make an impact in the real world, Shivji adds. But animal-DNA detective work has quickly made the transition from science lab to crime lab. Scientists are now doing similar work to protect seahorses, seals, and other animals.

If the world’s poaching victims could talk, they would probably thank these scientists for their detective work.

Going Deeper:

Additional Information

Word Find: Poach and Get Caught

Scientists have found a way to use hair to figure out where a person is from and where that person has been. The finding could help solve crimes, among other useful applications.

Water is central to the new technique. The liquid makes up more than half an adult human’s body weight. Our bodies break water down into its parts—hydrogen and oxygen. Atoms of these two elements end up in our tissues, fingernails, and hair.

These maps illustrate how the concentrations of certain hydrogen isotopes (top) and oxygen isotopes (bottom) in water differ throughout the United States. Red areas are where concentrations of these isotopes are highest. Blue points to regions having the

Proceedings of the National Academy of Sciences

But not all water is the same. Hydrogen and oxygen atoms can vary in how much they weigh. Different forms of a single element are called isotopes. And depending on where you live, tap water contains unique proportions of the heavier and lighter isotopes of hydrogen and oxygen.

Might hair record these watery quirks? That’s what James R. Ehleringer, an environmental chemist at the University of Utah in Salt Lake City, wondered.

To find out, he and his colleagues collected hair from barbers and hair stylists in 65 cities in 18 states across the United States. The researchers assumed that the hair they collected came from people who lived in the area.

Even though people drink a lot of bottled water these days, the scientists found that hair overwhelmingly reflected the concentrations of hydrogen and oxygen isotopes in local tap water. That’s probably because people usually cook their food in the local water. What’s more, most of the other liquids we drink—including milk and soft drinks—contain large amounts of water that also come from sources within their region.

Scientists already knew how the composition of water varies throughout the country. Ehleringer and colleagues combined that information with their results to predict the composition of hair in people from different regions.

The new technique can’t point to exactly where a person is from, because similar types of water appear in different regions that span a broad area. But authorities can now use the information to analyze hair samples from criminals or crime victims and narrow their search for clues.

“This [technique] doesn’t allow you to find the needle in a haystack, but it reduces the size of the haystack,” says Wolfram Meier-Augenstein, an analytical chemist at Queen’s University Belfast in Northern Ireland.

For example, one hair sample used in Ehleringer’s study came from a man who had recently moved from Beijing, China, to Salt Lake City. As his hair grew, it reflected his change in location.

Based on the finding, Jurian A. Hoogewerff, a chemist at the University of East Anglia in Norwich, England, offers this advice: “If you’re a criminal, shave.”

Going Deeper:

Perkins, Sid. 2008. Hairy forensics: Isotopes can identify the regions where a person may have lived. Science News 173(March 1):131. Available at http://www.sciencenews.org/articles/20080301/fob1.asp .

Most kids already have a ton of energy, but kids who drink a lot of cola often end up even more wired than usual. The soda’s high sugar content is partly to blame, but cola also usually includes an energy-sparking chemical called caffeine.

Drinking caffeinated soda can give kids a burst of hyperactive energy.

iStockphoto.com

Like cola, coffee is full of caffeine. That’s why many adults drink it first thing in the morning to help them wake up. The chemical is also naturally found in tea, chocolate, and hot cocoa. Because people crave the caffeine kick—and may even become addicted to it—food manufacturers add the chemical to many other sodas as well as to energy drinks and snacks.

Parents and teachers usually try to keep kids away from caffeine. But is this chemical actually bad for your health? The answer is complicated.

Good caffeine, bad caffeine

First the plus side. Some studies have shown that caffeine might help people respond to things more quickly and even run longer. Scientists have also recently found evidence that caffeinated coffee and tea can help protect the heart, brain, and other organs from disease.

On the other hand, too much caffeine can make people anxious and unable to sleep. A 2003 survey of more than 200 students in grades seven through nine found that kids who drank a 16-ounce bottle of cola slept less, woke up more often, and felt more tired the next day than kids who drank less caffeine. This is worrisome because sleeping well is an important part of staying healthy (See “Getting Enough Sleep”).

Caffeine can also raise your blood pressure, increase your heart rate, and make you feel more stressed, which may eventually lead to heart disease and other health problems.

“If you feel a lot of pressure at school, caffeine is going to make you feel even more anxious,” says Jim Lane, a psychologist at Duke University Medical Center in Durham, N.C.

Roasted coffee beans, like these, are ground and brewed into steaming cups of coffee. The fragrant beverage is the main source of caffeine for most adults.

Wikipedia

Love it or hate it, caffeine is hard to avoid. Coffee shops crowd city streets and malls. Vending machines offer caffeinated sodas in schools. And even though caffeine-free versions of coffee, tea, and cola are widely available, more than 80 percent of adults consume caffeine regularly in North America, according to a 2004 study, mostly in the form of coffee. And kids today are drinking more and more soda, caffeinated or not.

Some 30 percent of 8-to-13-year-olds surveyed by researchers at the University of Minnesota said that they drink soft drinks every day, according to a study published last year. And more probably would if they could: 95 percent of kids in the survey said they “like” or “strongly like” the taste of soda.

You’re feeling sleepy . . . NOT!

Caffeine works by blocking the effects of a sleep-inducing substance produced by your body called adenosine. The substance accumulates inside you throughout the day.

As adenosine levels rise, you become calm and drowsy. Later, as you sleep, adenosine levels drop. When you wake up, the cycle starts again. By not allowing adenosine to build up, caffeine keeps you feeling fired up—as if you’re ready to face a tiger attack.

Human brains aren’t the only ones that feel the effects of caffeine. These images show how an extreme amount caffeine affects the brain of a tiny creature. In this case, the top picture shows how a spider spins its web before caffeine and after (bottom).

NASA; Wikipedia

Caffeine raises the amount of sugar in your bloodstream, even if there is no sugar in your caffeinated drink. That’s what gives you extra energy. The chemical also increases your blood pressure, which may make you feel as if your chest is pounding. But if you consume too much caffeine, you will probably feel nervous and sick.

Caffeine claims for brains

People say they like caffeine because it makes them feel alert. In experiments, people who are given caffeine say they feel more awake than do people who have been given a caffeinefree pill or beverage instead, says psychologist Peter Rogers of the University of Bristol in England.

The caffeine in cola beverages like this one affects your brain and nervous system in ways that have nothing to do with sugar or other ingredients.

National Cancer Institute/Wikipedia

In other studies, caffeine appears to shorten reaction times: People press a button more quickly after seeing a symbol appear on a computer screen after they’ve had some caffeine.

On the basis of such findings, it’s tempting to conclude that caffeine helps people respond more quickly and pay better attention. However, says Rogers, there is another, more likely, conclusion.

Studies show that the people who do better on tests after taking caffeine tend to be regular caffeine users already. In other words, they are probably addicted to the chemical.

Taking caffeine away from habitual users causes them to have symptoms of withdrawal, such as headaches and sleepiness. It also slows their reaction times. So, when these people are given their daily dose of caffeine, they feel better and perform better on reaction-time tests than they do without it.

Coffee and other caffeinated beverages can be addictive, even for children.

iStockphoto.com

People who aren’t addicted, on the other hand, may feel jittery and more awake after taking caffeine, but the chemical doesn’t improve their performance on reaction-time tests. And regular caffeine users who get caffeine before the tests aren’t any more alert or quicker to react than people who don’t normally use the chemical and haven’t taken any.

Giving athletes a jolt

Caffeine has become popular with exercisers looking for an extra boost of energy. Research shows, however, that caffeine helps only athletes who are already in top condition and only when they are pushing themselves as hard as possible, says Terry Graham, a caffeine researcher at the University of Guelph in Canada.

In one study, Graham challenged nine runners to run on a treadmill at a very fast pace. On average, these athletes were able to run for about 32 minutes without caffeine. With caffeine in their systems, they ran 7 to 10 minutes longer.

Athletes often take caffeine for an extra boost of energy. But the chemical doesn’t necessarily make them faster or stronger.

iStockphoto.com

Though caffeine may help the performance of world-class athletes, it may harm the health of people who are overweight. Graham’s other research has shown that caffeine interferes with the body’s ability to process sugars, which may lead to a disease called type 2 diabetes.

Kids, who tend to be smaller than adults, feel the various effects of caffeine more strongly than adults do. And just like adults, kids and teens can become addicted to the chemical.

A can of caffeinated soda every now and then is probably OK, nutritionists say, but sip carefully!

The following list shows how many milligrams (mg) of caffeine are contained in some popular products. All beverages refer to an 8-ounce (1-cup) serving, unless otherwise noted.

Regular brewed coffee: 135 mg
Red Bull (8.5 oz): 80 mg
Black tea: 40-70 mg
Java Water: 62 mg
Starbucks Coffee Ice cream (1 cup): 40-60 mg
Espresso (1 oz): 30-50 mg
Green tea: 25-40 mg
Mountain Dew and Diet Mountain Dew: 37 mg
Diet Coke: 34 mg
Hershey’s Special Dark Chocolate Bar (1 bar – 1.5 oz): 31 mg
Pepsi: 28 mg
Diet Pepsi: 27 mg
Coca-Cola Classic: 26 mg
Snapple Iced Tea: 24 mg
Jolt gum (1 piece): 20 mg
Hershey’s Milk Chocolate Bar (1 bar – 1.5 oz): 10 mg
Hot cocoa: 5 mg
Chocolate milk: 5 mg
Decaffeinated coffee: 5 mg
Decaffeinated black tea: 4 mg

Going Deeper:

Additional Information

Questions about the Article

Word Find: Feel the Buzz

But Mayfield was innocent. When the truth emerged 2 weeks later, he was released from jail. Still, Mayfield had suffered unnecessarily, and he’s not alone.

Police often use fingerprints to nab criminals.

iStockphoto.com

Police officers often use fingerprints successfully to nab criminals. However, according to a recent study by criminologist Simon Cole of the University of California, Irvine, authorities may make as many as 1,000 incorrect fingerprint matches each year in the United States.

“The cost of a wrong decision is very high,” says Anil K. Jain, a computer scientist at Michigan State University in East Lansing.

Jain is one of a number of researchers around the world who are trying to develop improved computer systems for making accurate fingerprint matches. These scientists sometimes even engage in competitions in which they test their fingerprint-verification software to see which approach works best.

The work is important because fingerprints have a role not just in crime solving but also in everyday life. A fingerprint scan may someday be your ticket to getting into a building, logging on to a computer, withdrawing money from an ATM, or getting your lunch at school.

Different prints

Everyone’s fingerprints are different, and we leave marks on everything we touch. This makes fingerprints useful for identifying individuals.

Everyone’s fingerprints are different.

en.wikipedia.com/wiki/Fingerprint

People recognized the uniqueness of fingerprints as far back as 1,000 years ago, says Jim Wayman. He’s director of the biometric-identification research program at San Jose State University in California.

It wasn’t until the late 1800s, however, that police in Great Britain started using fingerprints to help solve crimes. In the United States, the FBI began collecting prints in the 1920s.

In those early days, police officers or agents coated a person’s fingers with ink. Using gentle pressure, they then rolled the inked fingers on a paper card. The FBI organized the prints on the basis of patterns of lines, called ridges. They stored the cards in filing cabinets.

In the fingers and thumbs, ridges and valleys generally form three types of patterns: loops (left), whorls (middle), and arches (right).

FBI

Today, computers play an important role in storing fingerprint records. Many people getting fingerprinted simply press their fingers on electronic sensors that scan their fingertips and create digital images, which are stored in a database.

The FBI’s computer system now holds about 600 million images, Wayman says. The records include the fingerprints of anyone who immigrates to the United States, works for the government, or gets arrested.

Looking for a match

TV series such as CSI: Crime Scene Investigation often show computers searching for matches between FBI records and fingerprints found at crime scenes.

To make such searches possible, the FBI has developed the Integrated Automated Fingerprint Identification System. For each search, computers run through millions of possibilities and spit out the 20 records that most closely match a crime-scene print. Forensics experts make the final call on which print is the most likely match.

The Integrated Automated Fingerprint Identification System allows law enforcement officials to look for fingerprint matches.

FBI

Despite these advances, fingerprinting is not an exact science. Prints left at a crime scene are often incomplete or smeared. And our fingerprints are always changing in slight ways. “Sometimes they’re wet, sometimes dry, sometimes damaged,” Wayman says.

The process of taking a fingerprint can itself change the print that’s recorded, he adds. For example, the skin may shift or roll when a print is taken, or the amount of pressure may vary. Each time, the resulting fingerprint is a little bit different.

Computer scientists have to be careful when they write programs to analyze prints. If a program requires too exact a match, it won’t find any possibilities. If it looks too broadly, it will produce too many choices. To keep these requirements in balance, programmers are constantly refining their techniques for sorting and matching patterns.

Researchers are also trying to find better ways to collect fingerprints. One idea is to invent a scanner that would allow you to simply hold your finger in the air, without putting pressure on a surface.

Further improvements are necessary because, as Mayfield’s case demonstrates, things can go wrong. The FBI did find several similarities between Mayfield’s fingerprint and the crime-scene print, but the print found at the bomb site turned out to belong to someone else. In this case, the FBI experts initially jumped to the wrong conclusion.

Getting in

Fingerprint scans aren’t just for solving crimes. They can also play a role in controlling access to buildings, computers, or information.

Fingerprints aren’t just for solving crimes.

iStockphoto.com

At the door of Jain’s lab at Michigan State, for example, researchers enter an ID number into a keypad and swipe their fingers across a scanner to enter. No key or password is required.

At Walt Disney World, admission passes now include fingerprint scans that identify holders of annual or seasonal tickets. Some grocery stores are experimenting with fingerprint scanners to make it easier and faster for customers to pay for groceries. Fingerprint readers at certain ATMs control cash withdrawals, foiling criminals who might try using a stolen card and pin number.

Schools are starting to use finger-identification technology to speed students through lunch lines and to track library books. One school system has installed an electronic-fingerprint system to keep tabs on students riding on school buses.

The number of potential applications of fingerprint scans for identifying people is huge, but privacy is a concern. The more information that stores, banks, and governments collect about us, the easier it may be for them to track what we are doing. That makes many people uncomfortable.

Your fingerprint says a lot about you. Every time you use your hands, you leave a little bit of yourself behind.

Going Deeper:

Additional Information

Questions about the Article

Word Find: Fingerprints