New Uses for 5 Old Pests

Doctors, criminologists and even manicurists have been busy putting smaller, less cuddly members of the animal kingdom to work. From monitoring the water supply to treating callused feet, here are some examples.

1. Bluegill Fish Enlisted in War on Terror

During a meeting in 1960, Chicago Mayor Richard J. Daley presented Japanese Emperor Akihito with bluegill fish. It was a gift the Japanese people wish they never received. Since its induction to Japanese fisheries, the bluegill bred rapidly and killed native species. What's worse, the Japanese generally find its taste repugnant. [Image courtesy of Earthling.]

While it's marginally more popular in the United States, it's still not the freshwater fish of choice of foodies. But it is the fish of choice for the U.S. Army. Researchers created IAC 1090 Intelligent Aquatic Biomonitoring System, which uses eight juvenile bluegills to detect change in the water. Each fish resides in its own stall about the width of a mail slot. Sensors monitor the fishes' breathing and send the data to computer program, which analyzes the results. If six of the eight show abnormalities, the computer pages a technician. Officials swap out bluegills—perfectly matched for the task because they are sedentary and sensitive to contaminants—so the fish aren't affected by their duties for long periods of time. Currently New York, Washington, D.C., and San Francisco use the fish to protect the water sources—the fish in New York alerted officials to a diesel leak before it became calamitous. [Note: Some might claim that fish aren't pests, but my definition of pests is rather inclusive.]

2. Release the Wasp Hounds!

Training dogs to sniff out drugs, bombs, or chemicals takes months and costs thousands of dollars. But University of Georgia researcher Glen Rains and the U.S. Department of Agriculture's Joe Lewis discovered that wasps could easily replace dogs to detect bombs, chemicals, and drugs. The researchers created a handheld device called the "Wasp Hound," which is a 15-inch cylinder with a vent at one end and a camera connected to a computer. When the wasps—a parasitic variety called Microplitis croceipes—smell their target they congregate at the vent, alerting the humans. Rains and Lewis claim the wasps can also sniff out food toxins, crop fungus, bodies, drugs, and even 2,4-DNT, a volatile component in dynamite that dogs struggle to smell.

The wasps only cost $100 per unit and take about a half hour to train. Using basic Pavlovian methods, researchers associate the target smell, such as a crop fungus, with food so the wasps want to locate the fungus. However, they only work for 48 hours before researchers release them.

3. They're Gonna Suck that Pain Right out of Your Knee

leeches.jpgHippocrates believed that bloodletting controlled the blood humour, reducing illness and preventing death. Until the 19th century, physicians used leeches to bleed patients and cure diseases such as acne, cholera, the plague, the flu, smallpox, gangrene and hemorrhaging (I know, it sounds counterintuitive to cure excessive bleeding by bleeding someone.) In modern medicine, bloodletting with leeches has little use other than reducing blood pressure and healing bed sores—though most doctors feel modern prescriptions are just as effective (and less icky). [Image courtesy of]

However, researchers from Germany's Essen-Mitte Clinic discovered leeches sooth achy joints. Slap four leeches on your knee and after 80 minutes, the pain and stiffness of osteoarthritis melts away. Of the 16 patients in the trial, the 10 who received leech therapy felt instant relief after application, and the comfort lasted for four weeks. The control patients continued experiencing pain. Researchers claim the leeches' saliva works as an anti-inflammatory.

4. Crime-fighting Bees

When Nigel Raine decided to study how serial killers track their victims, he placed tiny RFID chips on honeybees. Raine hypothesized that serial killers forage for victims much like predatory animals, such as sharks, or pollinators, such as bees. The RFID chips showed that bees pollinate plants near their hive, but not too close. It appeared the insects created a buffer zone between the hive and their feeding grounds—this protected the hive from predators and parasites. In the same way, serial killers feel comfortable preying in their neighborhoods, but not too close to their homes.

So how will the police use this to find their serial killers? By creating a model of hunting, which criminologists can use to understand how serial killers work and geographically profile them. The model might help police track serial killers from crime scenes back to their homes.

5. Feed Your Feet to Fish

doctorfish.jpgRemoving tough foot calluses has never been easy. Manicurists use files and razors to shave off dead skin. John Ho—owner of Yvonne Hair, Nail and Tan Salon—spent $40,000 to stock his Northern Virginian spa with 1,000 doctor fish or Garra rufa, which are tiny and toothless. For 15 to 30 minutes, patrons soak their feet in warm water while about 100 doctor fish nibble at their dry skin. Some compare the tingling sensation to the feeling of a foot falling asleep. After the fish feast on calluses, a manicurist massages and rubs lotions into the feet just like a regular pedicure. [Image courtesy of Doctor Fish Massage, Inc.]

Detractors think that most people will shy away from a fish pedicure because letting fish eat your feet is widely considered gross. But Ho has sold about 5,000 doctor fish pedicures, and spas in Turkey and throughout Asia offer the unique treatment to an increasing number of consumers. Ho hopes to offer full body doctor fish treatments to help people suffering from skin ailments and plans on selling franchising rights to his doctor fish pedicures.

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Live Smarter
Nervous About Asking for a Job Referral? LinkedIn Can Now Do It for You

For most people, asking for a job referral can be daunting. What if the person being approached shoots you down? What if you ask the "wrong" way? LinkedIn, which has been aggressively establishing itself as a catch-all hub for employment opportunities, has a solution, as Mashable reports.

The company recently launched "Ask for a Referral," an option that will appear to those browsing job listings. When you click on a job listed by a business that also employs one of your LinkedIn first-degree connections, you'll have the opportunity to solicit a referral from that individual.

The default message that LinkedIn creates is somewhat generic, but it hits the main topics—namely, prompting you to explain how you and your connection know one another and why you'd be a good fit for the position. If you're the one being asked for a referral, the site will direct you to the job posting and offer three prompts for a response, ranging from "Sure…" to "Sorry…".

LinkedIn says the referral option may not be available for all posts or all users, as the feature is still being rolled out. If you do see the option, it will likely pay to take advantage of it: LinkedIn reports that recruiters who receive both a referral and a job application from a prospective hire are four times more likely to contact that individual.

[h/t Mashable]

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Essential Science
What Is a Scientific Theory?
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Dean Mouhtaropoulos/Getty Images

In casual conversation, people often use the word theory to mean "hunch" or "guess": If you see the same man riding the northbound bus every morning, you might theorize that he has a job in the north end of the city; if you forget to put the bread in the breadbox and discover chunks have been taken out of it the next morning, you might theorize that you have mice in your kitchen.

In science, a theory is a stronger assertion. Typically, it's a claim about the relationship between various facts; a way of providing a concise explanation for what's been observed. The American Museum of Natural History puts it this way: "A theory is a well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses and facts."

For example, Newton's theory of gravity—also known as his law of universal gravitation—says that every object, anywhere in the universe, responds to the force of gravity in the same way. Observational data from the Moon's motion around the Earth, the motion of Jupiter's moons around Jupiter, and the downward fall of a dropped hammer are all consistent with Newton's theory. So Newton's theory provides a concise way of summarizing what we know about the motion of these objects—indeed, of any object responding to the force of gravity.

A scientific theory "organizes experience," James Robert Brown, a philosopher of science at the University of Toronto, tells Mental Floss. "It puts it into some kind of systematic form."


A theory's ability to account for already known facts lays a solid foundation for its acceptance. Let's take a closer look at Newton's theory of gravity as an example.

In the late 17th century, the planets were known to move in elliptical orbits around the Sun, but no one had a clear idea of why the orbits had to be shaped like ellipses. Similarly, the movement of falling objects had been well understood since the work of Galileo a half-century earlier; the Italian scientist had worked out a mathematical formula that describes how the speed of a falling object increases over time. Newton's great breakthrough was to tie all of this together. According to legend, his moment of insight came as he gazed upon a falling apple in his native Lincolnshire.

In Newton's theory, every object is attracted to every other object with a force that’s proportional to the masses of the objects, but inversely proportional to the square of the distance between them. This is known as an “inverse square” law. For example, if the distance between the Sun and the Earth were doubled, the gravitational attraction between the Earth and the Sun would be cut to one-quarter of its current strength. Newton, using his theories and a bit of calculus, was able to show that the gravitational force between the Sun and the planets as they move through space meant that orbits had to be elliptical.

Newton's theory is powerful because it explains so much: the falling apple, the motion of the Moon around the Earth, and the motion of all of the planets—and even comets—around the Sun. All of it now made sense.


A theory gains even more support if it predicts new, observable phenomena. The English astronomer Edmond Halley used Newton's theory of gravity to calculate the orbit of the comet that now bears his name. Taking into account the gravitational pull of the Sun, Jupiter, and Saturn, in 1705, he predicted that the comet, which had last been seen in 1682, would return in 1758. Sure enough, it did, reappearing in December of that year. (Unfortunately, Halley didn't live to see it; he died in 1742.) The predicted return of Halley's Comet, Brown says, was "a spectacular triumph" of Newton's theory.

In the early 20th century, Newton's theory of gravity would itself be superseded—as physicists put it—by Einstein's, known as general relativity. (Where Newton envisioned gravity as a force acting between objects, Einstein described gravity as the result of a curving or warping of space itself.) General relativity was able to explain certain phenomena that Newton's theory couldn't account for, such as an anomaly in the orbit of Mercury, which slowly rotates—the technical term for this is "precession"—so that while each loop the planet takes around the Sun is an ellipse, over the years Mercury traces out a spiral path similar to one you may have made as a kid on a Spirograph.

Significantly, Einstein’s theory also made predictions that differed from Newton's. One was the idea that gravity can bend starlight, which was spectacularly confirmed during a solar eclipse in 1919 (and made Einstein an overnight celebrity). Nearly 100 years later, in 2016, the discovery of gravitational waves confirmed yet another prediction. In the century between, at least eight predictions of Einstein's theory have been confirmed.


And yet physicists believe that Einstein's theory will one day give way to a new, more complete theory. It already seems to conflict with quantum mechanics, the theory that provides our best description of the subatomic world. The way the two theories describe the world is very different. General relativity describes the universe as containing particles with definite positions and speeds, moving about in response to gravitational fields that permeate all of space. Quantum mechanics, in contrast, yields only the probability that each particle will be found in some particular location at some particular time.

What would a "unified theory of physics"—one that combines quantum mechanics and Einstein's theory of gravity—look like? Presumably it would combine the explanatory power of both theories, allowing scientists to make sense of both the very large and the very small in the universe.


Let's shift from physics to biology for a moment. It is precisely because of its vast explanatory power that biologists hold Darwin's theory of evolution—which allows scientists to make sense of data from genetics, physiology, biochemistry, paleontology, biogeography, and many other fields—in such high esteem. As the biologist Theodosius Dobzhansky put it in an influential essay in 1973, "Nothing in biology makes sense except in the light of evolution."

Interestingly, the word evolution can be used to refer to both a theory and a fact—something Darwin himself realized. "Darwin, when he was talking about evolution, distinguished between the fact of evolution and the theory of evolution," Brown says. "The fact of evolution was that species had, in fact, evolved [i.e. changed over time]—and he had all sorts of evidence for this. The theory of evolution is an attempt to explain this evolutionary process." The explanation that Darwin eventually came up with was the idea of natural selection—roughly, the idea that an organism's offspring will vary, and that those offspring with more favorable traits will be more likely to survive, thus passing those traits on to the next generation.


Many theories are rock-solid: Scientists have just as much confidence in the theories of relativity, quantum mechanics, evolution, plate tectonics, and thermodynamics as they do in the statement that the Earth revolves around the Sun.

Other theories, closer to the cutting-edge of current research, are more tentative, like string theory (the idea that everything in the universe is made up of tiny, vibrating strings or loops of pure energy) or the various multiverse theories (the idea that our entire universe is just one of many). String theory and multiverse theories remain controversial because of the lack of direct experimental evidence for them, and some critics claim that multiverse theories aren't even testable in principle. They argue that there's no conceivable experiment that one could perform that would reveal the existence of these other universes.

Sometimes more than one theory is put forward to explain observations of natural phenomena; these theories might be said to "compete," with scientists judging which one provides the best explanation for the observations.

"That's how it should ideally work," Brown says. "You put forward your theory, I put forward my theory; we accumulate a lot of evidence. Eventually, one of our theories might prove to obviously be better than the other, over some period of time. At that point, the losing theory sort of falls away. And the winning theory will probably fight battles in the future."


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