April 26, 2013
Your breath says a lot about you. Recent research has found that the chemicals present in each person’s breath can provide a unique “breathprint” that differs from person to person, while other scientists have worked on breathalyzer-like tests that can indicate the presence of a bacterial infection inside someone’s body.
In the decades since the 1960s, though, when the first electronic breathalyzer for blood alcohol content was developed, research has led to relatively little advancement in the use of chemical breath analysis for law enforcement purposes. Police have long been able to instantly test a person’s level of alcoholic intoxication by the side of a road, but testing for other drugs has required blood or saliva—substances that are more invasive acquire and that typically have to be sent to a crime lab for processing. Both factors make it difficult to figure out who’s under the influence at, say, the scene of a car accident right after it occurs.
But new research suggests that the status quo might be changing in a hurry. A study published yesterday in the Journal of Breath Research reveals that scientists can now use breath analysis to test for the presence of 12 different drugs in the body, including cocaine, marijuana and amphetamines. Previous work has shown that such technology can reliably test for several of these drugs, and this new study is the first time the drugs alprazolam (commercially known as Xanax, useful for treating anxiety disorders) and benzoylecgonine (a topical pain killer) have been detected. Members of the research group, from Sweden’s Karolinska Institutet, have already created a commercially-available breath testing system, called SensAbues—and it’s easy to speculate that law enforcement across the U.S. (and around the world) would love to get their hands on such technology as soon as possible.
The research team, led by Olof Beck, conducted the new study by testing the breath of 46 individuals who were checked into a drug addiction emergency clinic, had taken drugs about 24 hours earlier and volunteered to participate in the study. Each participant exhaled about 20 deep breaths into the SensAbues filter (which takes 2-3 minutes), and the solid and liquid microparticles suspended in their breath were trapped on a disk for analysis.
These tiny quantities of microparticles reflect the substances in a person’s bloodstream, because small amounts of the molecules from our blood diffuse into the fluid that lines our lungs’ bronchioles and then into our breath. By isolating these particles and analyzing them with liquid chromatography and mass spectrometry, the research team was able to determine the drugs present in each person’s body with a decent level of accuracy.
They compared the results to blood and urine samples taken from each of the participants, as well as their own reports of what drugs they’d taken in the previous 24 hours, and on the whole, the tests performed pretty well—although some progress clearly still needs to be made. All 46 people had reported taking one of the 12 detectable illegal substances, and drugs were detected in the breath of 40 of them (87 percent). Most of the particular drugs detected matched with self-reports and blood tests, but 23 percent of the time, the breath tests also indicated the presence of a drug that hadn’t actually been taken. This level of accuracy was higher than previous studies the team has done, as they’ve slowly refined the system to cut down on false positives and improve the detection rate.
Currently, using the SensAbues system would only allow officials to collect a sample and send it elsewhere for analysis. But the researchers say that advances in the cost and portability of chemical analysis could eventually allow for the same sort of roadside breath testing for drugs that we currently have for alcohol.
Another scientific hurdle is data: Unlike for alcohol, we still don’t know what a given quantity of drug molecules detected on someone’s breath means in terms of how much of the drug is actually in their bloodstream (although an accurate detection of any illegal substance might be all law enforcement officials may be after). We also don’t know how long traces of these drugs remain on a person’s breath, and how quickly they degrade.
If scientists are able to make some progress in figuring this all out, though—and if they can make the testing procedure more accurate—roadside drug tests could become a routine part of law enforcement protocol.
April 24, 2013
Who you’re physically attracted to might seem like a frivolous, random preference. In recent years, though, science has told us that our seemingly arbitrary tastes often reflect unconscious choices that are based upon very relevant biological traits.
In general, we find symmetric faces more attractive, likely because they reflect a healthy underlying genome. Women typically prefer men with more distinctively masculine facial features because they indicate high testosterone levels and physical strength, while men prefer women with exaggerated youthful features, possibly because of the evolutionary advantages a male gets when coupling with a younger mate.
Despite all this research into our visual appearances, though, scientists have done relatively little digging into our auditory preferences when it comes to sexual attraction. Why do we find certain peoples’ voices attractive–and why do we sometimes find other types of voices such a turn-off? Specifically, why do women generally prefer men with deep voices, and men prefer women with higher ones?
At least according to a paper published today in PLOS ONE, the explanation is relatively simple: It’s all about body size. Researchers from University College London found that, at least among a sample of 32 participants, high-pitched female voices females were found to be attractive because they indicated the speaker had a small body. Deep male voices, on the other hand, were judged as more attractive because they conveyed that the speaker had a large frame—but were found to be most attractive when tempered by a touch of “breathiness,” suggesting the speaker had a low level of aggression despite his large size.
The group, led by Yi Xu, figured this out by playing recordings of digitally manipulated voices to the participants. The males in the study heard a computer-generated female voice saying phrases such as “I owe you a yo-yo” in which the voice was manipulated with a number of digital alterations in terms of pitch, formant (the particular peaks and valleys in a sound’s frequency spectrum) and other qualities.
The specific manipulations either conveyed a smaller body size or a larger one, based upon previous research that matched various voice qualities with different body sizes in humans. When asked to rate the voice’s attractiveness on a 1 to 5 scale, the men preferred the voices that suggested a smaller female. Past a certain point, though, higher voices were judged as no more attractive that slightly deeper ones. Listen to the most and least attractive (both, admittedly creepy) voices below:
The female participants’ voice preferences were similar, but slightly more nuanced. On the whole, they preferred deeper voices, which signaled a large body size, but another trait was also crucial: “breathiness.” The researchers hypothesized that this breathiness effectively takes the edge off a voice, making a man with a presumed large frame seem less aggressive and angry. They also polled the participants on whether they thought the simulated voices sounded angry or happy, and the breathy deep males voices were generally perceived as much happier and less angry than the less breathy (i.e. “pressed”) deep ones. Listen to the most and least attractive male voices below:
Beyond explaining the popularity of Barry White, the researchers say these findings correspond to much of what we know about voice preferences in the rest of the animal kingdom. Birds and other mammals, it turns out, have long been known to advertise their physical characteristics via the sound qualities in their mating calls.
All this points to an obvious question, though: Why would males prefer smaller females, and females prefer larger males in the first place? The researchers don’t attempt to address this question, but this duality reflects the sexual dimorphism present in most animal species. These differences generally result from sexual selection giving incentive to different mating strategies—so in this case, our voice preferences suggest that women benefit, in evolutionary terms, by mating with larger, but less aggressive men, while males benefit from mating with smaller females.
As the same time, what we commonly consider attractive varies dramatically over time and location—for example, dozens of prehistoric “Venus figurines,” discovered all over the world, portray extremely voluptuous female figures. So, if we tested the preferences of all humans throughout history, we might find a less obvious trend. This preference for small-voiced females and big-voiced males, then, might simply be an artifact of our contemporary cultural concepts of “attractiveness,” rather than a deep-seated evolutionary choice after all.
Pop quiz: Why are flamingos pink?
If you answered that it’s because of what they eat—namely shrimp—you’re right. But there’s more to the story than you might think.
naturally synthesize a pigment called melanin, which determines the color of their eyes, fur (or feathers) and skin. Pigments are chemical compounds that create color in animals by absorbing certain wavelengths of light while reflecting others. Many animals can’t create pigments other than melanin on their own. Plant life, on the other hand, can produce a variety of them, and if a large quantity is ingested, those pigments can sometimes mask the melanin produced by the animal. Thus, some animals are often colored by the flowers, roots, seeds and fruits they consume
Flamingos are born with gray plumage. They get their rosy hue pink by ingesting a type of organic pigment called a carotenoid. They obtain this through their main food source, brine shrimp, which feast on microscopic algae that
naturally produce carotenoids. Enzymes in the flamingos’ liver break down the compounds into pink and orange pigment molecules, which are then deposited into the birds’ feathers, legs and beaks. If flamingos didn’t feed on brine shrimp, their blushing plumage would eventually fade.
In captivity, the birds’ diets are supplemented with carotenoids such as beta-carotene and and canthaxanthin. Beta-carotene, responsible for the orange of carrots, pumpkins and sweet potatoes, is converted in the body to vitamin A. Canthaxanthin is responsible for the color of apples, peaches, strawberries and many flowers.
Shrimp can’t produce these compounds either, so they too depend on their diet to color their tiny bodies. Flamingos, though, are arguably the best-known examples of animals dyed by what they eat. What others species get pigment from their food? Here’s a quick list:
Northern cardinals and yellow goldfinches: When these birds consume berries from the dogwood tree, they metabolize carotenoids found inside the seeds of the fruit. The red, orange and yellow pigments contribute to the birds’ vibrant red and gold plumage, which would fade in intensity with each molt if cardinals were fed a carotenoid-free diet.
Salmon: Wild salmon consume small fish and crustaceans that feed on carotenoid-producing algae, accumulating enough of the chemical compounds to turn pink. Farmed salmon are fed color additives to achieve a deeper shades of red and pink.
Nudibranchs: These shell-less mollusks absorb the pigments of their food sources into their normally white bodies, reflecting the bright colors of sponges and cnidarians, which include jellyfish and corals.
Canaries: The birds’ normal diet doesn’t alter the color of its yellow feathers, but they can turn a deep orange if they regularly consume paprika, cayenne or red pepper. These spices each contain multiple carotenoids responsible for creating and red and yellow.
Ghost ants: There’s not much more than meets the eye with ghost ants: these tropical insects get their name from their transparent abdomens. Feed them water mixed with food coloring and watch their tiny, translucent lower halves fill up with brilliantly colored liquid.
Humans: Believe it or not, if a person eats large quantities of carrots, pumpkin or anything else with tons of carotenoids, his or her skin will turn yellow-orange. In fact, the help book Baby 411 includes this question and answer:
Q: My six-month-old started solids and now his skin is turning yellow. HELP!
A: You are what you eat! Babies are often first introduced to a series of yellow vegetables (carrots, squash, sweet potatoes). All these vegetables are rich in vitamin A (carotene). This vitamin has a pigment that can collect harmlessly on the skin, producing a condition called carotinemia.
How to tell that yellow-orange skin isn’t an indication of jaundice? The National Institutes of Health explain that “If the whites of your eyes are not yellow, you may not have jaundice.”
April 23, 2013
One morning a couple of years ago, I decided to take a jog around the perimeter of my hotel in Delhi, India. A little bit of exercise might mitigate the crushing jetlag after my 24-hour flight from California, I thought. Within a minute or two of sucking in the city’s soot-filled air, my lungs and eyes were scorched. While I knew that Delhi’s air quality was bad, I had no idea it’s the 12th worst in the world—nor was I aware of precisely how damaging air pollution can be to the body.
As we’ve written about recently, researchers have discovered that smog can cause lung cancer and that nano-particles in the air burrow through cell membranes, possibly damaging the lungs and the circulatory system. But a new study published today in the journal PLOS Medicine shows that exposure to fine particulate matter in the air may be linked to a faster hardening of the arteries in otherwise healthy people, which can lead to increases in stroke and heart attack.
The study, conducted by researchers from University of Michigan and University of Washington, followed nearly 5,500 people—all heart-disease-free—from six American metro areas (Baltimore; Chicago; Los Angeles; New York City; Winston Salem, North Carolina and St. Paul, Minnesota). Scientists began the study by conducting ultrasound tests to measure the thickness of each participant’s right common carotid artery, which supplies blood to the head, neck, and brain.
The participants’ home addresses were then recorded, and the researchers tapped the Environmental Protection Agency’s Air Quality System, a database of air quality levels gathered by monitors throughout the country, to gauge the amount of fine particulate matter in their neighborhoods. The scientists were able to factor in variables including proximity to major streets and highways, which allowed for a great deal of precision–air pollution concentrations varied, as it turned out, even within specific neighborhoods. Within the next five years, the thickness of each participant’s artery was tested once more. The scientists estimated their exposure to fine particulate matter during the period between the exams.
What they found was that exposure to higher concentrations of fine particulate air pollution correlated with an accelerated thickening of the arteries. Conversely, reductions in air pollution were linked with a slower progression of arterial thickening. Such a thickening or hardening of the arteries can eventually block the flow of blood to the head, resulting in stroke, or to the heart, causing heart attack.
“Linking these findings with other results from the same population suggests that persons living in a more polluted part of town may have a 2 percent higher risk of stroke as compared to people in a less polluted part of the same metropolitan area,” study author Sara Adar said in a statement.
The findings may also help shed light on previous studies that have linked chronic air pollution exposure and death, and may encourage lawmakers to support clean air standards. “Our findings furthermore bolster recent reports that falling pollution levels in the United States after the adoption of the Clean Air Act are associated with reduced mortality and increased life expectancy,” the study authors wrote.
Air quality in the United States is far superior to that in many parts of the world. But where is air quality the worst? The World Health Organization’s database of global air pollution statistics reveals that low- and middle-income regions of the Eastern Mediterranean have the worst air quality overall. Among cities, Ahwaz in Iran is the world’s most polluted. Mongolia’s Ulan Bataar ranks second in air pollution and Delhi comes in 12th.
The W.H.O. rankings are based on the number of parts per million of particles smaller than 10 micrometers (PM10) floating around in the air. Even the filthiest air in the U.S., in California’s San Joaquin Valley, pales in comparison to these other cities. Ahwaz has 372 PM10, while Delhi has 198. Bakersfield, the most polluted city in the U.S., has 38.
The best cities in the U.S. for keeping your arteries free and clear? Santa Fe, New Mexico and Clearlake, California–each with a PM10 of just six. Much healthier choices for a jog the next time around.
April 22, 2013
Anyone who has read a Richard Preston book, such as The Hot Zone or Panic in Level 4, knows the danger of tampering with wildlife. The story usually goes something like this: Intrepid explorers venture into a dark, bat infested cave in the heart of East Africa, only to encounter something unseen and living, which takes up residence in their bodies. Unknowingly infected, the happy travelers jump on a plane back to Europe or the States, spreading their deadly pathogen willy-nilly to every human they encounter upon the way. Those people, in turn, bring the novel virus or bacterium back home to strangers and loved ones alike. Before the world knows it, a pandemic has arrived.
This scenario may sound like fiction, but it’s exactly what infectious disease experts fear most. Most emerging infectious diseases in humans have indeed arisen from animals–think swine and bird flu (poultry and wild birds), SARS (unknown animals in Chinese markets), Ebola (probably bats) and HIV (non-human primates). Therefore, experts prioritize the task of figuring out which animals in which regions of the world are most prone to delivering the latest novel pathogen to hapless humanity.
With this in mind, researchers at Harvard University, the University of Granada and the University of Valencia set out to develop a new strategy for predicting the risk and rise of new diseases transmitted from animals before they happen, describing their efforts in the journal Proceedings of the National Academy of Sciences.
To narrow the hypothetical disease search down, the team chose to focus on non-human primates. Because monkeys and great apes are so closely related to us, their potential for developing and transmitting a pathogen suited to the human body is greater than the equivalent risk from animals such as birds or pigs. As a general rule, the more related species are, the greater the chances they can share a disease. The researchers gathered data from 140 species of primates. They overlaid that information with more than 6,000 infection records from those various primate species, representing 300 different pathogens, including viruses, bacteria, parasitic worms, protozoa, insects and fungus. This way, they could visualize which pathogens infect which species and where.
Like mapping links between who-knows-who in a social network, primates that shared pathogens were connected. This meant that the more pathogens an animal shared with other species, the more centrally located it was on the tangled web of the disease diagram.
From studying these charts, a few commonalities emerged. Animals at the center of the diagram tended to be those that lived in dense social groups and also covered a wide geographic range (yes, similar to humans). These species also tended to harbor parasites that are known to infect humans, including more pathogens identified as emerging infectious diseases. In other words, those species that occurred in the center of the diagram are the best positioned to kick off the next pandemic or horrific infectious disease, and thus should be the ones that experts should keep the closest watch on.
Such animals could qualify as “superspreaders,” or those that receive and transmit pathogens very often to other species.”The identification of species that behave as superspreaders is crucial for developing surveillance protocols and interventions aimed at preventing future disease emergence in human populations,” the authors write.
Apes appeared in the heart of the disease diagram and are among the species we should be most worried about, which is not surprising considering that diseases such as malaria and HIV first emerged from these animals. On the other hand, some non-ape primates, including baboons and vervet monkeys, also popped up in the center of the diagram and turn out to harbor many human emerging disease parasites.
Currently, our ability to predict where, when and how new emerging infectious diseases might arise is “remarkably weak,” they continue, but if we can identify those sources before they become a problem we could prevent a potential health disaster on a regional or even global scale. This new approach for identifying animal risks, the authors write, could also be applied to other wildlife groups, such as rodents, bats, livestock and carnivores. “Our findings suggest that centrality may help to detect risks that might otherwise go unnoticed, and thus to predict disease emergence in advance of outbreaks—an important goal for stemming future zoonotic disease risks,” they conclude.