Addiction Crisis

<p></p><p>Hear firsthand from individuals struggling with addiction and follow the cutting-edge work of doctors and scientists as they investigate why addiction is not a moral failing, but a chronic, treatable medical condition. Easy access to drugs like heroin, fentanyl, and even prescription medications like OxyContin has fueled an epidemic of addiction—the deadliest in U.S. history. Now, science is revealing how addiction affects the brain, and top experts are gathering evidence about how we should address our drug problem, from embracing evidence-based treatments, to rethinking public policies. (Premiered October 17, 2018)</p><p></p>

<p>Discover how opioid addiction affects the brain and how evidence-based treatments are saving lives.</p>

Addiction

swings-opioid-buffalo

<p>In Western New York, public health officials have organized a task force that’s giving people who suffer from opiate use disorder a new beginning.</p>

Restoring Hope: Fighting the Opioid Crisis in Buffalo

Could Cadaver Organs Save Your Life? Hero

<p>As the number of people who need organs goes up, the number of donors has plateaued, meaning we need to find new solutions. Dr. Doris Taylor and her team’s answer: custom-building organs from cadavers.</p>

<p>Custom-built lungs, livers, kidneys and hearts could someday save thousands of lives.</p>

Could Cadaver Organs Save Your Life?

topic-body-brain.jpg

Body & Brain

Koch Foundation

Draper





  
      <div class="rich-text"><p>There’s no two ways about it: From a young age, girls are <a href="https://psycnet.apa.org/doiLanding?doi=10.1037/a0021276">just as good at math</a> as boys. Even so, a <a href="https://www.nctm.org/Publications/Teaching-Children-Mathematics/Blog/Current-Research-on-Gender-Differences-in-Math/">gender gap</a> in math-focused fields persists, as women remain <a href="https://psycnet.apa.org/doiLanding?doi=10.1037%2Fa0027020">less likely</a> than men to pursue <a href="https://www.tandfonline.com/doi/abs/10.1080/00221546.2018.1486641?journalCode=uhej20">high-level studies</a> and careers in these areas.</p><p>Now, the findings of a <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.1905779116">new analysis</a> might help explain a crucial piece of this longstanding discrepancy. According to a study published today in the journal <i>PNAS,</i> many girls who do every bit as well as their male peers in mathematics may still decide on more humanities-centric careers—because their verbal skills outshine their already high marks in math.</p><p>The research, which drew on data from more than 300,000 high school students from 64 countries around the world, emphasizes the key distinction between absolute and relative performance in math and reading. Around the globe, students of all genders are proficient in both subjects. But because they’re socialized to view mathematical and verbal aptitude as <a href="https://psycnet.apa.org/record/2004-11358-005">mutually exclusive</a>, many students might believe they must choose one or the other, despite being well equipped to pursue both areas of study.</p></div>
  

  
      <div class="ad"></div>
  

  
      <div class="rich-text"><p>Because the paper examined data from only a single point in time, comparing students’ test scores to their future academic and career intentions, it can’t say anything definitive about cause and effect. Nonetheless, the authors argue that the girls’ comparative verbal advantage, measured by the difference between their scores in reading and math, could account for up to 80 percent of the gender gap in the inclination to go into math-related fields.</p><p>However, experts caution that the findings should <i>not</i> be interpreted as a reflection on innate differences in ability between the genders. It’s <a href="https://www.pnas.org/content/106/22/8801">well-established</a> that <a href="https://www.kellogg.northwestern.edu/faculty/sapienza/htm/science.pdf">social and cultural norms</a>, including the stereotypes and biases imposed on children from a very young age, account for a large part of the gender gap in the science, technology, engineering, and mathematics (STEM) fields. It’s likely that these norms are also the driving force behind this study’s results, the authors say, and social cues might still motivate young girls to prioritize verbal aptitude in a way that’s reflected in their high school performance.</p>
            <figure class="richtext-image full-width"><img alt="iStock-950614324.jpg" class="richtext-image full-width" height="531" width="800"
            src="/wgbh/nova/media/images/iStock-950614324.width-800.jpg"/><figcaption><p>Among different genders, there&#x27;s no inherent biological difference in math ability. But stereotypes and other social biases can make an enormous difference on who pursues math-related subjects professionally. Image Credit: Ridofranz, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>In the study, economists <a href="http://www.parisschoolofeconomics.com/breda-thomas/index_en.html">Thomas Breda</a> of the Paris School of Economics and <a href="https://sites.google.com/site/clotildenapp/home">Clotilde Napp</a> of Paris Dauphine University analyzed data from the <a href="https://www.oecd.org/pisa/data/">Programme of International Student Assessment (PISA)</a>, which conducts educational surveys in nearly 100 different countries every three years. All participating students were 15 years old—an age at which they were likely preparing to make major career decisions, Breda explains. The academic and professional intentions students report at this age tend to match up well with what they end up pursuing, he says.</p><p>Across the 64 countries analyzed in the study, students planning to pursue math-intensive studies and careers were more likely to identify as male than female, echoing trends that have been reported before. But while male students scored, on average, slightly higher in math than their female peers, the difference was small, and determines less than 10 percent of the observed gender gap in intentions.</p><p>In fact, almost none of the gap could be explained by how students were doing in relation to each <i>other</i>. Rather, it seemed to be more about how skills stacked up <i>within</i> each individual: While most girls excelled at reading over math, boys tended to show the opposite trend. Though there was no evidence to show that girls were doing poorly in math, their scores at age 15 seemed to reflect that they had a relative edge in the verbal department—one that had a big effect on their intentions for the future. And when the researchers adjusted for girls’ comparative verbal advantage in their data, the gender gap disappeared almost entirely.</p></div>
  

  
      <div class="related"></div>
  

  
      <div class="rich-text"><p>Part of this effect is probably attributable to the misconception that a student can be a math person or a verbal person, but not both, says <a href="https://www.awis.org/about-awis/staff/">Heather Metcalf</a>, Chief Research Officer at the Association for Women in Science, who was not involved in the study. Such a false binary could constrain the choices students make at a critical time in their education, she says.</p><p>What’s less clear, though, why girls score better in reading than math at age 15. Because the study didn’t track students over time, its results alone can’t definitively answer that question, Breda says. But he emphasizes that the study shouldn’t be misinterpreted as suggesting that women are inherently “worse” at math.</p><p>Years of research and <a href="https://journals.sagepub.com/doi/abs/10.1177/1529100614541236?rfr_dat=cr_pub%3Dpubmed&amp;url_ver=Z39.88-2003&amp;rfr_id=ori%3Arid%3Acrossref.org&amp;journalCode=psia">many</a> other <a href="https://www.pnas.org/content/106/22/8801">studies</a> have found <a href="https://pdfs.semanticscholar.org/98d3/dcfb67e27cca5c306ff7a09e8b3f14229f64.pdf">no evidence</a> for biology driving the <a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2015.00530/full">gender gap</a> in math. Instead, it seems <a href="https://www.pnas.org/content/106/22/8801">social and cultural forces</a> are to blame—a theory backed up by the fact that the gender gap (as well as girls’ comparative verbal advantage, according to the new study) <a href="https://science.sciencemag.org/content/359/6381/1219.summary">differs</a> quite a bit <a href="https://www.kellogg.northwestern.edu/faculty/sapienza/htm/science.pdf">between</a> <a href="https://www.researchgate.net/publication/5338649_Diversity_Culture_gender_and_math">countries</a>.</p><p>“Society still feels like girls are not as smart, or should not be in math,” says <a href="https://peabody.vanderbilt.edu/bio/nicole-joseph">Nicole Joseph</a>, a mathematics education expert at Vanderbilt University who was not involved in the study.</p><p>This, along with a bevy of other biases, may be seeding the gender gap as early as <a href="https://journals.sagepub.com/doi/full/10.1177/2332858416673617">kindergarten</a>. Teachers, parents, and peers may inadvertently favor students who fit stereotypical gender roles. Girls <a href="https://psycnet.apa.org/record/2011-13792-002">internalizing messages</a> from mentors and media sources alike may subconsciously shy away from “unfeminine” fields of study, or underestimate or discount their own skill level in STEM, despite doing <a href="https://www.nature.com/articles/s41467-018-06292-0">just as well as boys</a>.</p><p>As schooling continues, the gap <a href="https://www.jstor.org/stable/10.5951/jresematheduc.44.4.0634?seq=1#page_scan_tab_contents">only grows</a>—and discrimination clearly persists at even the highest levels, Metcalf says. “Even when women go into math-related fields, there are pay inequities, and inequities as they advance into leadership positions.” In other words, there are plenty of hurdles—not just to entry into STEM fields, but to retention and advancement.</p><p>As such, addressing the underrepresentation of women in math-related fields is no simple task. Effecting change will require boosting girls’ confidence early in their education, exposing them to a wealth of career options and role models, and generally increasing the visibility of women in STEM. And much of the battle will come down to debunking existing stereotypes—about not only gender and other aspects of identity, but also <a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2015.00189/full">math itself</a>.</p><p>For instance, women who are motivated to seek a career that will have a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843492/">positive impact</a> on the world may also be socialized to view math-focused fields of study as incompatible with this goal, Metcalf says. Bridging the gender gap, then, could require both sparking enthusiasm for math at an early age and <a href="https://journals.sagepub.com/doi/abs/10.1177/1088868316642141">making students aware</a> of the <a href="http://andromeda.rutgers.edu/~powellab/docs/gcedm-cmesg/gutstein2003.pdf">societal benefits math-heavy careers can have</a>.</p>
            <figure class="richtext-image full-width"><img alt="iStock-1000887536.jpg" class="richtext-image full-width" height="533" width="800"
            src="/wgbh/nova/media/images/iStock-1000887536.width-800.jpg"/><figcaption><p>Closing the gender gap in math will require fighting stereotypes on both gender and the study of math itself. Image Credit: skynesher, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>There also won’t be a one-size-fits-all approach to this issue, which ultimately encompasses far more than gender, says <a href="https://www.dapperstats.com/">Juniper Simonis</a>, a quantitative ecologist at DAPPER Stats and <a href="https://500womenscientists.org/who-we-are">500 Women Scientists</a> leadership team member who was not involved in the study. While the current research is ambitious, they add, the global- and country-level analyses presented present an oversimplified account of the gender gap, which, despite its name, involves more than gender-based discrimination.</p><p>That’s due in part to how PISA collects data, focusing primarily on country-wide statistics, Breda says. But that limitation, Simonis says, makes it difficult to disentangle the relative contributions of other aspects of identity, like race, ethnicity, LGBTQ status, socioeconomic variables, and more—all of which will inevitably affect the barriers individuals face in school, the workplace, and beyond.</p><p>“The reality is that people aren’t just their gender,” Simonis says. “It’s important to acknowledge and incorporate information about other factors that also significantly impact and intersect with gender-based opportunities.” What’s more, though gender continues to be portrayed as binary in many contexts, it’s important to point out that it’s not, they add.</p><p>Joseph agrees, highlighting the fact that girls and women who are also underrepresented minorities are <a href="http://www.vctm.org/The-Invisibility-of-Black-Girls-in-Mathematics">especially marginalized in math-related fields</a>. While more women overall have earned math doctorates in the United States in recent years, most of this increase is due to the advancement of white women. The numbers of Black, Latinx, and Native American women in these cohorts, on the other hand, have barely budged.</p><p>Acknowledging intersectional identities in the gender gap will be key to designing effective interventions, Joseph says. Such an approach could end up being a boon for those hoping to tackle the stubborn gender gap in math.</p><p>“When policies and changes are made without understanding who they’re for, we end up missing the mark,” she says. “Maybe that’s why we’re not seeing the needle move.”</p></div>
  

  
      <div class="newsletter"></div>
  



<p>Girls are great at math. But if they’re even better at reading, they might be more motivated to choose a humanities-focused career.</p>

Girls’ superb verbal skills may contribute to the gender gap in math





  
      <div class="related"></div>
  

  
      <div class="rich-text"><p>With a simple gesture, a magician can transform a playing card right in front of your eyes. But the illusion isn’t magic—it’s science.</p><p>A <a href="https://journals.sagepub.com/doi/abs/10.1177/0956797618822969">study published earlier this year</a> in the journal <i>Psychological Science</i> reveals that no matter how closely you watch a magic trick, you’ll probably miss the sleight of hand.</p><p>Imagine a magician waves a card back and forth, seemingly causing it to transform into another card. The small motion, swapping one playing card for another, is hidden by the larger motion happening at the same time, the wave of a hand (like in the video below). This illusion exploits a phenomenon called change blindness, which refers to a viewer not noticing a change in visual stimuli.</p></div>
  

  
      

<div class='cove-video'>
  <iframe allowfullscreen="" class="inline-cove-player" frameborder="0" height="100%" id="partnerPlayer" marginheight="0" marginwidth="0" scrolling="no" src="//player.pbs.org/partnerplayer/WV9mhtJzZiaRWX5X0DoLVQ==/?topbar=false&amp;end=0&amp;endscreen=true&amp;start=0&amp;autoplay=false" width="100%">
</iframe>
</div>


  

  
      <div class="rich-text"><p>The magician swaps the card at the moment their hand changes direction. That abrupt change in direction is all the misdirection they need to distract the audience from their sleight of hand, says Katherine Wood, an author of the recent study and PhD candidate in psychology at the University of Illinois.</p><p>This is possible because our brains don’t process everything our eyes see.</p><p>“The illusion that we’re always seeing everything all the time is such a powerful part of who we are,” says Stephen Goldinger, a psychologist at Arizona State University who was not involved in the study. Although we feel like we see everything, he says, we only see snapshots of the world around us. “Our brains are remarkably adept at filling in the background.”</p></div>
  

  
      <div class="ad"></div>
  

  
      <div class="rich-text"><p>This concept of change blindness isn’t new. Studies like the famous <a href="https://www.youtube.com/watch?v=vJG698U2Mvo">selective attention test</a>, in which people watching one action or activity fail to notice a person in a gorilla suit walk through the background, have demonstrated change blindness in much more complex scenarios. But this is the first time change blindness has been studied in a scenario as simple as a single motion concealing a single change, says Richard Yao, lead author on the study.</p><p>In the study, the researchers had 21 undergraduate students <a href="https://osf.io/aucve/">watch a set of six dots</a> moving as a group across a screen. One of the dots would abruptly rotate 15 degrees while the other five stayed the same. The team asked the students to pick out the rotating dot.</p><p>Although it didn’t happen every time, the participants usually fell victim to change blindness and misidentified the rotating dot. The change blindness effect observed in this study was incredibly strong, says Anthony Barnhart, a psychologist at Carthage College who was not involved in the study.</p><p>Studies like this, Barnhart says, are important in helping understand how we’re able to perceive the world. “In many ways, magicians have a head start on psychologists when it comes to how the brain works,” he says.</p></div>
  

  
      <div class="newsletter"></div>
  



<p>How “change blindness” prevents you from seeing this 10 of clubs turn into an ace of spades.</p>

Poof! Science reveals how easily a magician can fool you





  
      <div class="rich-text"><p>Someday, in the very distant future, athletes might be able to boost their performance by tapping into a precious, albeit unconventional, resource: the poop of elite runners.</p><p>That possibility is still a long way off. But scientists may now have a few clues on which gut microbes give marathoners the runs (no, not that kind).</p></div>
  

  
      <div class="ad"></div>
  

  
      <div class="rich-text"><p>According to a <a href="https://www.nature.com/articles/s41591-019-0485-4">study</a> published today in the journal <i>Nature Medicine,</i> bacterial “probiotics” extracted from marathoners’ feces can boost the endurance of mice on tiny treadmills. The microbial magic appears to rely on the ability of these bacteria to do what mammalian cells can’t: convert a common byproduct of muscle metabolism into a performance-enhancing compound.</p><p>The treatment has yet to be tested in humans, and there’s nothing to suggest that bacteria alone could make or break an athletic career. But if the findings pan out, future studies of athletes’ fleet-footed feces might just contain a whiff of speedy success.</p><p>“This study presents a really fascinating hypothesis on the ways in which the microbiome can contribute to [human] physiology,” says <a href="http://fischbachgroup.org/people.html">Ariel Brumbaugh</a>, a microbiologist at Stanford University who was not involved in the study. “That said...this alone shouldn’t encourage people to immediately start a round of probiotics.”</p>
            <figure class="richtext-image full-width"><img alt="iStock-506979575.jpg" class="richtext-image full-width" height="430" width="800"
            src="/wgbh/nova/media/images/iStock-506979575.width-800.jpg"/><figcaption><p>Ready, set, poop! Image Credit: ZamoraA, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>Nowadays, there are few trendier topics in the world of biomedical research than the <a href="https://www.pbs.org/wgbh/nova/video/nova-wonders-whats-living-in-you/">gut microbiome</a>—the diverse, teeming population of single-celled organisms that inhabits the large intestine. Though they’re physically restricted to the colon, these industrious critters, which number in the trillions, are capable of performing a variety of functions that nourish and protect human cells, affecting just about every vital organ system in the body.</p><p>Years of research have shown that perturbing the gut microbiome can accelerate the onset of ailments ranging from <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4290017/">inflammatory bowel disease to certain types of cancer</a>. But in a departure from the disease-centric approach of many microbiome researchers, study author <a href="https://www.fitbiomics.com/">Jonathan Scheiman</a>, then a researcher at Harvard University, decided to test how gut microbes could <i>enhance</i> wellbeing in already healthy individuals—and, perhaps, push the limits of human performance.</p></div>
  

  
      <div class="related"></div>
  

  
      <div class="rich-text"><p>Scheiman and his colleagues began their study by investigating how the gut microbiome responded to intense exercise. For this team of Boston-based scientists, that meant leveraging the city’s low-hanging fitness fruit: long-distance runners, competing in the <a href="https://www.pbs.org/wgbh/nova/video/marathon-challenge">annual marathon</a>.</p><p>It was a task that required a lot of poop—and a lot of patience. In weeks bookending the 2015 Boston Marathon, Scheiman spent close to 90 hours battling Boston traffic, ferrying samples on dry ice after 15 elite runners and 10 more-sedentary controls dropped their daily deuce.</p><p>But the work paid off. An analysis of the runners’ pre- and post-marathon feces suggested the event had spurred an uptick in a bacterial genus called <i>Veillonella—</i>a group that also seemed to be more prevalent in the average runner than in their non-racing counterparts.</p><p>It’s hard to know which came first, the microbes or the athleticism, says study author <a href="http://www.kosticlab.org/team/#">Aleksander Kostic</a>, a microbiologist and immunologist at Harvard University’s Joslin Diabetes Center. But these associations hinted that something about the runners’ bodies might make them especially good homes for these bacteria.</p><p>That something turns out to be lactate, one of the major byproducts of the reactions that take place in hardworking muscles—and a main source of energy for <i>Veillonella</i>.</p><p>A quick aside: The word “lactate” (often erroneously referred to as “lactic acid”) may sound familiar, as it’s still commonly cited as the culprit behind sore, fatigued muscles. But <a href="https://www.nytimes.com/2006/05/16/health/nutrition/16run.html">that myth was busted long ago</a>, explains <a href="http://nep.missouri.edu/faculty_vieira.html">Victoria Vieira-Potter</a>, an exercise physiologist at the University of Missouri who was not involved in the study. Instead of <i>causing</i> aches, this molecular scapegoat is actually an important source of fuel that cells can use to push <i>through</i> the pain.</p><p>What lactate <i>does</i> do is build up as muscles tire out. And if that’s a common occurrence, that’s probably good news for lactate-loving <i>Veillonella</i>. In return, <i>Veillonella</i> pumps out a molecule called propionate—a compound thought to have a bevy of beneficial effects on the mammalian body, including <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4063845/">regulating</a> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3600440/">blood pressure</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5873405/">revving up metabolism</a>.</p><p>To see if this microbial pathway had any performance-enhancing effects, the researchers orally injected two groups of 16 mice with either a strain of <i>Veillonella</i> isolated from one of the marathoners’ fecal samples, or <i>Lactobacillus,</i> another innocuous microbe that’s commonly found in yogurt. Five hours later, the researchers had the rodents hop onto a set of miniature treadmills and run until they were too exhausted to keep going.</p><p>It took around 16 or 17 minutes for the <i>Lactobacillus</i> mice to crap out. The <i>Veillonella</i> mice, on the other hand, lasted closer to 19 minutes—a 13 percent increase in endurance. Even when the researchers leapfrogged the <i>Veillonella</i> and administered propionate directly, the mice maintained a comparable edge over others who received only squirts of salt water.</p><p>Thirteen percent might not sound like much, Kostic says. But for an athlete in the midst of training, even the smallest gains in performance can make an enormous difference. Besides, he adds, this whole pathway constitutes a metabolic bonus: During exercise, there’s often lactate to spare—but if there’s <i>Veillonella</i> around, it might just get recycled into something more useful.</p><p>This symbiotic feedback loop, in which human and microbe alike benefit from repurposing each other’s byproducts, is “the coolest thing about this paper,” says <a href="https://carolina.tropini.org/">Carolina Tropini</a>, a microbiologist at the University of British Columbia who was not involved in the study. It’s also an outside-of-the-box way to think about what these bacteria are sensitive to, she adds. “We always think about <a href="https://www.pbs.org/wgbh/nova/article/gut-microbiome-nutrition-food-groups/">influencing our gut microbes</a> <a href="https://www.pbs.org/wgbh/nova/article/sugar-keeps-good-microbes-at-bay/">through diet</a>,” she says. “But this is a way of shaping the microbiome that has nothing to do with what we’re eating.”</p><p>Figuring out how propionate improves performance is the clear next step, but Kostic’s gut feeling is that the perks of harboring <i>Veillonella</i> go beyond having an in-house propionate factory. Scheiman, who has since left Harvard, and several of the paper’s other authors now run the sports biotechnology company FitBiomics, which they hope will eventually pioneer a line of fitness-enhancing probiotics (this time for humans) that may include <i>Veillonella</i> and similar strains.</p>
            <figure class="richtext-image full-width"><img alt="shutterstock_240595447.jpg" class="richtext-image full-width" height="332" width="800"
            src="/wgbh/nova/media/images/shutterstock_240595447.width-800.jpg"/><figcaption><p>Gut microbes can make a world of difference. But even the best probiotic won’t turn a couch potato into an Olympic runner—and, conversely, a dose of microbiome-altering antibiotics isn’t necessarily going to bench a top-performing athlete. Image Credit: lzf, Shutterstock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>A lot will need to happen before then, Brumbaugh says. The data so far is intriguing, she adds, but because several of the findings rely on behavioral data in mice, they may be difficult to reproduce in humans. Additionally, larger studies in more diverse populations are needed to figure out how generalizable these results are to other types of exercise, as well as people with different levels of fitness, Vieira-Potter says. Tropini advises caution as well, noting that a human probiotic could have unexpected side effects, or simply no effect at all—especially in the long term.</p><p>Even if a human probiotic passes muster, things could easily get murky if microbes begin to venture into the realm of performance-enhancing drugs. Bacterial “doping” may eventually become something humankind has to grapple with, and “this is an area in which we should tread with caution,” Vieira-Potter says.</p><p>For now, it’s worth keeping in mind that plenty more goes into athleticism than what’s living in your gut. Even in the study, <i>Veillonella</i> was by no means universal among athletes, and not every mouse that received it responded to its effects.</p><p>But we humans still have a lot to learn about the bacterial cells that share our bodies. If the past several decades of research have taught us anything, it’s that our gut microbes are full of surprises.</p><p>Who knows? Someday, going that extra mile may truly come down to going with your gut.</p></div>
  

  
      <div class="newsletter"></div>
  



<p>A bacterial “probiotic” may enhance athletic performance. But it’s a long way from being ready for use in humans.</p>

Microbes from marathoner poop boost endurance in mice





  
      <div class="rich-text"><p>Ah, the lost wallet. Few inanimate objects are capable of sowing more internal conflict.</p><p>Stumble upon a forsaken folio, and your brain will quickly find itself on an ethical seesaw: While keeping the wallet comes with a clear payoff, there’s also a serious moral cost to pocketing the prize.</p><p>It’s hard to predict what someone will do when these two impulses clash, and countless extenuating circumstances can sway the outcome. But what happens when the amount of money in the wallet increases? You might think that the average human would be more tempted to keep a fatter pocketbook.</p><p>If that’s what your gut is telling you, congratulations: You’d be in agreement with the majority of people, including most professional economists.</p><p>You’d also be wrong.</p><p>At least, that’s what a new <a href="https://science.sciencemag.org/lookup/doi/10.1126/science.aau8712">study</a> suggests. In an unprecedented global experiment, a team of international researchers has discovered that as the amount of cash in a lost wallet increases, so does a person’s likelihood of contacting the owner. The findings, published today in the journal <i>Science</i>, fly in the face of economic theories that predict the predominance of self-interest, and contradict the assumptions of researchers and non-researchers alike. Nonetheless, they hold true in 38 out of 40 countries tested around the world, capturing what appears to be a nearly universal, albeit unexpected, trend.</p><p>“What this study [found]...is delightfully counterintuitive,” says <a href="https://www.human.cornell.edu/people/vr53">Valerie Reyna</a>, a psychologist and expert in human decision making at Cornell University who was not involved in the study. “It goes against what many would assume, and the logic of...many powerful economic theories. Whenever you have something like that, it’s exciting for science.”</p></div>
  

  
      <div class="ad"></div>
  

  
      <div class="rich-text"><p>In the study, a globetrotting team of economists, psychologists, and 13 very intrepid research assistants planted 17,303 “lost” wallets in 355 metropolitan hubs around the world. In each case, an undercover scientist approached an employee at a bank, theatre, police station, post office, hotel, or other public institution and hurriedly handed over a wallet, claiming to have found it on the street. The researcher then hastily exited stage left, saddling their unwitting study subject with a difficult choice.</p><p>Every wallet in the study was transparent, and was stuffed with a key, a grocery list, and three business cards with a (fictitious) male name and email address, giving the employee ample opportunity to return the wallet. Some wallets came with each country’s equivalent of $13.45 in United States currency, while others had no money at all. In the United States, United Kingdom, and Poland, the researchers also distributed a third set of wallets containing $94.15—a hefty sum they nicknamed “Big Money.”</p>
            <figure class="richtext-image full-width"><img alt="wallet_all.jpg" class="richtext-image full-width" height="568" width="800"
            src="/wgbh/nova/media/images/wallet_all.width-800.jpg"/><figcaption><p>An example wallet. Each wallet belonged to a (fictitious) male software developer with a country-specific name (in this case, the United States), listed on a business card with an email address. Also in the wallet were a key, a grocery list, and cash and coins. Image Credit: Courtesy of Alain Cohn, University of Michigan</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>When the team looked at how often people in each country tried to reach out to the wallets’ rightful “owners” over email, stark differences emerged: While only 10 or 15 percent of wallet recipients came clean in China and Morocco, for instance, the numbers jumped close to 70 percent in Switzerland and several Nordic countries. (In the United States, citizens landed in the absolute middle of the pack, contacting the researchers about 50 percent of the time.)</p><p>While it’s not completely clear what underlies these differences, there were a few hints of what kinds of societies might encourage or discourage financial integrity. A country’s tendency to keep mum about a lost wallet is actually a decent proxy for other measures of nationwide “dishonesty,” like public corruption, smuggling, and even filing inaccurate tax forms, says study author <a href="https://michelmarechal.com/">Michel Maréchal</a>, an economist at the University of Zürich in Switzerland.</p><p>On the other hand, people in countries that were wealthier, educated, and more politically egalitarian—as well as those that placed more cultural emphasis on individual culpability—were more likely to speak up about the wallet.</p><p>From the outset, however, the researchers were more interested in a related, but separate, question probing the data <i>within</i> each country: whether or not a larger sum of cash would deter people from emailing the wallet’s owner.</p></div>
  

  
      <div class="related"></div>
  

  
      <div class="rich-text"><p>In situations like these, economic dogma dictates that there’s a certain point at which greed wins out. In other words, guilt has a probable price tag—and from a self-interested perspective, the more money the wallet contains, the less likely someone should be to speak up.</p><p>That’s what Cohn and his economist colleagues went in thinking. And when surveyed, most people in a pool of 279 experts and 299 members of the general public predicted the same.</p><p>But the exact opposite turned out to be true. The sweeter the pot, the <i>more</i> likely recipients were to try to contact the owner, topping out at an attempted return rate of 72 percent in the “Big Money” condition. This trend, which bucked economic expectation, was observed in 38 out of 40 countries tested.</p><p>“We were really surprised by how robust the effect was across countries,” says study author <a href="https://www.si.umich.edu/people/alain-cohn">Alain Cohn</a>, an economist at the University of Michigan. “It’s remarkable to observe such a consistent result.”</p><p>Of course, not all wallets were homeward bound. Post office employees, for instance, were particularly unlikely to reach out, possibly because of the demands of their hectic schedules, says study author <a href="https://davetannenbaum.github.io/">David Tannenbaum</a>, a behavioral scientist at the University of Utah. Wallets turned into the Vatican and a couple anti-corruption bureaus also mysteriously went off the grid.</p><p>There were also two countries—Mexico and Peru—in which cash didn’t boost wallet reporting. But even here, the patterns didn’t completely reverse: Money or no, people attempted to return the wallets at roughly the same rate.</p><p>Explaining the trend was another matter entirely. The trend couldn’t be chalked up to self-consciousness, fear of penalty, or even the expectation of a bigger finder’s fee. It was even clear that participants weren’t returning the wallets after skimming off some of the cash: In the Czech Republic and Switzerland, research assistants kept up the ruse long enough to reunite with nearly 200 wallets, and found 98 to 99 percent of the money intact. (In all other cases, after being contacted over email, the researchers—still impersonating the wallet’s owner—thanked the study’s good Samaritans and told them they didn’t need the contents.)</p>
            <figure class="richtext-image full-width"><img alt="aau8712_Figure_fig1_seq7_v2.jpg" class="richtext-image full-width" height="566" width="800"
            src="/wgbh/nova/media/images/aau8712_Figure_fig1_seq7_v2.width-800.jpg"/><figcaption><p>The share of wallets in each country reported to their &quot;owners&quot; in each of two conditions: US $0 (No Money, orange) and US $13.45 (Money, red). Image Credit: Cohn <i>et al. Science, </i>2019</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>One thing that <i>did</i> seem to make a difference, however, was pure and simple altruism. When the researchers repeated their experiment in a subset of countries with some of the wallets’ contents removed, they noticed that the presence of a key upped the number of concerned emails they received. Taking a key from a lost wallet is pointless. Returning it to the owner, however, benefits the other party exclusively—a hint that the bump in reporting reflected magnanimity.</p><p>“People are surprisingly caring about others,” Reyna says. “More caring than you would think when there’s nothing in it for them.”</p><p>It’s also noteworthy, Tannenbaum says, that this tendency toward benevolence transcended so many cultural and geographical boundaries. “This might suggest that this [impulse] is just a very basic human motivation,” he says. “We may come into this world with a prepackaged moral psychology.”</p><p>The inclination to rehome a lost wallet, however, wasn’t entirely charitable. Through a series of follow-up surveys, the team discovered another major motivation behind this seemingly selfless act: a strong aversion to coming off as a thief—one that increased with the amount of money packed into the wallet.</p><p>There’s a little bit of irony in this, Reyna points out. Strictly speaking, she says, “a thief is a thief for $10, and a thief for $1000.” Nonetheless, the more money the wallet contained, the more crooked people felt about pocketing it.</p>
            <figure class="richtext-image full-width"><img alt="iStock-843522736.jpg" class="richtext-image full-width" height="600" width="800"
            src="/wgbh/nova/media/images/iStock-843522736.width-800.jpg"/><figcaption><p>To test the limits of human integrity, researchers planted more than 17,000 &quot;lost&quot; wallets in 40 countries around the world. Image Credit: spukkato, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>Compared to altruism, preserving a positive self-image is probably a more subtle driving force—one that might not often occur to people when they’re attributing intention to others, explains <a href="https://sites.google.com/view/ukarma">Uma Karmarkar</a>, a decision neuroscientist at the University of California San Diego who was not involved in the study. “It’s easier to focus on other people’s desires...and more difficult to imagine the social pressures they might face,” she says. This, she adds, could help explain why the predictions made by study participants were so off base.</p><p>Not wanting to sully your identity doesn’t sound quite as noble as worrying about someone else’s wellbeing. But the study’s findings aren’t necessarily cynical, Tannenbaum says. “It feels more positive if it’s all driven by altruism...But if we still have these concerns where we don’t want to see ourselves as bad people, that’s still a positive. We’re better off with people having those motivations than not.”</p><p>There’s no guarantee the implications of these results will translate into other ethically fraught scenarios—or even to a slightly altered (and more experimentally challenging) situation in which wallets were dropped on sidewalks, rather than entrusted to employees in a professional setting, Karmarkar points out. But there’s no denying the importance of a field study, conducted outside the artificial environment of a research laboratory. It is, after all, a unique opportunity to observe humans in the wild, behaving as they otherwise would. Even if vanity sneaks its way in, when push comes to shove, people often <i>will</i> do the right thing. And sometimes, that’s enough.</p><p>“I think there’s a lot of room for optimism,” Karmarkar says. “The study shows that the social norms we have decided are important for our society hold up reasonably well under duress. And that’s reassuring.”</p></div>
  

  
      <div class="newsletter"></div>
  



<p>Altruism is alive and well. So is the desire to protect one’s self-image.</p>

Humans are surprisingly honest when it comes to returning lost wallets





  
      <div class="rich-text"><p>Several decades ago, a <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1398-9995.1989.tb04202.x?sid=nlm%3Apubmed">handful</a> of <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1398-9995.1994.tb00831.x?sid=nlm%3Apubmed">researchers</a> <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1399-3038.1991.tb00174.x">picked</a> up on an unusual epidemiological trend: Children who grow up on farms rarely develop asthma.</p><p>Some chalked it up to the effects of exercise, or cleaner air. But over time, it became clear that microbes, ferried into agrarian homes on a conveyor belt of grime, were the real heroes. Early exposures to these farm microbes, scientists reasoned, might teach kids’ immune systems not to overreact to foreign substances—like the ones that trigger asthma attacks—later in life.</p><p>This rural revelation was compelling, but acting on it seemed impractical. Most of the initial observations had been made exclusively in the countryside, and, barring a mass metropolitan exodus, researchers worried the forecast for urban children looked bleak.</p></div>
  

  
      <div class="ad"></div>
  

  
      <div class="rich-text"><p>Now, the findings of an international team of scientists may offer a glimmer of hope for city-dwelling families. According to <a href="https://www.nature.com/articles/s41591-019-0469-4">new research</a> published today in the journal <i>Nature Medicine</i>, microbes in urban schmutz also have the potential to ward off asthma in children—as long as they resemble those found on farms.</p><p>The study wasn’t designed to show cause and effect, but it strongly suggests that, while farms are a common backdrop for asthma avoidance, the microbes themselves matter more than the local environment. The findings may even have the potential to inform the development of asthma-preventive treatments, and could someday help safeguard children in rural and urban homes alike.</p><p>“This is a very cool, informative study that really advances what we know about the connections between asthma risk and farm living,” says <a href="https://www.arrietalab.com/">Marie-Claire Arrieta</a>, a microbiologist at the University of Calgary who was not involved in the study. “It shows it’s not the farm, per se, but the bacteria that are behind this...and gives us hope that someday, we may even be able to take farm bugs to the city.”</p>
            <figure class="richtext-image full-width"><img alt="iStock-1094974240.jpg" class="richtext-image full-width" height="534" width="800"
            src="/wgbh/nova/media/images/iStock-1094974240.width-800.jpg"/><figcaption><p>Farm kids rarely get asthma, thanks to the rural microbes they mingle with in their homes. But the same could be true for city-dwelling kids with similar species in their living rooms. Image Credit: Katie Ellement, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>Rural and urban environments typically harbor different microbial species. While farms run thick with single-celled critters that hail from soil and animals, city living rooms tend to be dominated by bacteria that associate with human bodies.</p><p>But within these broad categories, there’s still plenty of variation. To see if metropolitan microbes could mimic those found on a farm, a team of researchers led by <a href="https://www.researchgate.net/profile/Pirkka_Kirjavainen">Pirkka Kirjavainen</a>, a microbiologist at Finland’s National Institute for Health and Welfare, sampled living rooms in nearly 400 rural and suburban residences around Finland. Each was home to at least one young child whom the researchers monitored through early development. </p></div>
  

  
      <div class="related"></div>
  

  
      <div class="rich-text"><p>When the infants were two months old—an age, Kirjavainan explains, when babies are still developing their immune systems and are likely inhaling and ingesting a lot of microscopic household debris—the researchers visited their homes and collected samples of living room dust. By genetically analyzing the single-celled life within, the team was able to identify a microbial signature unique to farms. They then used their model as an index to measure how “farmlike” the collective microbes in each residence were. The higher a home scored, the less likely its resident infant was to receive a diagnosis of asthma by the age of six.</p><p>Without an explicit intervention, these kinds of studies can’t show definitive proof that farmlike microbes are actually armoring kids against asthma, Kirjavainan says. But a pattern that manifests over the course of six years, he says, “supports [the notion of] causal effects.”</p><p>To see if the findings held true in another population, Kirjavainen and his colleagues repeated their analysis in a cohort of more than 1,000 children in Germany. This second dataset, compiled by a different group of researchers, was composed of dust samples from mattresses in the homes of kids who had already developed asthma.</p><p>In spite of these differences, however, the researchers were able to use the Finnish farm microbe template to zero in on residences with high and low asthma risk. This, Kirjavainen says, shows the model can be applied to multiple geographical locations and groups of people, and can even accommodate different types of residential grit.</p><p>“At this early stage [of research], it’s important that the phenomenon isn’t necessarily limited to just one environment or population,” says <a href="https://medicine.umich.edu/dept/intmed/divisions/pulmonary-critical-care-medicine/education-training/multidisciplinary-t32-research-training-program-lung-disease/our-fellows">Ariangela Kozik</a>, a microbiologist at the University of Michigan who was not involved in the study. However, she adds, microbial differences between Finland and Germany did exist, and adjustments will need to be made to accommodate other environments on a more global scale.</p><p>On the whole, the research isn’t ready to be deployed as a diagnostic. But in the future, these kinds of microbial headcounts could come in handy for identifying homes that are more protective, says <a href="https://finlaylab.msl.ubc.ca/current-personnel/postdoctoral-scientists/charisse-petersen/">Charisse Petersen</a>, a microbiologist at the University of British Columbia who was not involved in the study. </p>
            <figure class="richtext-image full-width"><img alt="iStock-1062906906.jpg" class="richtext-image full-width" height="533" width="800"
            src="/wgbh/nova/media/images/iStock-1062906906.width-800.jpg"/><figcaption><p>Did someone track mud into your house? Relax—it might not be such a bad thing. Image Credit: AndreyPopov, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>The findings also lend support to a longstanding theory called the hygiene hypothesis, which posits that humankind’s zeal for cleanliness has stripped us of the microbes that help shape and rein in immune responses in early childhood. In recent years, however, many researchers have begun to put a finer point on the idea: Health isn’t just a question of dirty or clean—and not just any microbes will do. Rather, <i>which </i>species are present may make all the difference. Studies like this get us a little closer to identifying <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1774411/">our most important microbial allies</a>, Arrieta says.</p><p>Such developments are particularly timely as asthma rates <a href="https://www.cdc.gov/vitalsigns/asthma/index.html">continue to increase</a> worldwide. A cure for the condition remains elusive, and many available therapies remain imperfect, Petersen says. “At this point, the future is all about prevention.” </p><p>To this end, researchers may someday be able to leverage farm microbes to manufacture something akin to a dust probiotic, possibly in the form of nasal spray, or a treatment to coat urban living rooms in common rural species. </p>
            <figure class="richtext-image full-width"><img alt="iStock-1069463010.jpg" class="richtext-image full-width" height="533" width="800"
            src="/wgbh/nova/media/images/iStock-1069463010.width-800.jpg"/><figcaption><p>Small steps to recreate a farm environment, like regular gardening, exercise, and owning pets might be beneficial for kids&#x27; developing immune systems. Image Credit: kokouu, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>Before that happens, though, researchers will need a better understanding of what’s going on at the molecular level, Kozik says. Once the microbes enter the human body, it’s not entirely clear how they work their magic—and though <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa1508749">several</a> <a href="https://science.sciencemag.org/content/349/6252/1106">studies</a> in mice have provided some hints, many questions remain about how effective interventions would be in people.</p><p>In the meantime, there may still be a few actions urbanites can take to recreate protection in their daily lives, Petersen says. For instance, in the study, urban dwellings where people wore shoes indoors were more likely to harbor farmlike microbes. Gardening or owning pets might not hurt either, she adds. More work is needed to understand these connections, she says, but these findings and others suggest it can’t hurt to loosen our standards about letting the outdoors in.</p><p>“It’s not just, ‘You don’t live on a farm, you’re out of luck,’” she says. “If you take small steps to replicate a farm environment, you might get protection later in life. It gives us hope that we can take small steps to protect our kids.”</p></div>
  

  
      <div class="newsletter"></div>
  



<p>Urban infants who spend their first year of life around microbes like those found on farms are less likely to develop asthma.</p>

‘Farm-like’ dust microbes may protect kids from asthma, even in the city





  
      <div class="rich-text"><p>When it comes to nutrition, human and microbe don’t quite see eye to eye.</p><p>According to <a href="https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(19)30250-1">new research</a> published today in the journal <i>Cell Host &amp; Microbe</i>, nutrition labels aren’t enough to predict diet’s effects on the gut microbiome, the bustling population of friendly microbes that colonize the human colon. A food’s influence on our resident microbes seems to have more to do with where it falls in subgroups of categories like dairy, meats, and vegetables, than what its overall carbohydrate or fat content is.</p><p>On the whole, the study, which closely tracked dietary records and stool samples from 34 individuals over a period of two weeks, also shows that food isn’t the only thing that governs how the gut microbiome changes over time. Although diet helps predict the composition of these communities from day to day in an individual, microbes generally don’t respond to foods in the same way from person to person.</p></div>
  

  
      <div class="ad"></div>
  

  
      <div class="rich-text"><p>The findings reinforce the idea that there’s no one-size-fits-all protocol for establishing and maintaining a healthy microbiome—and suggest that dietary interventions targeted at gut microbes may need to be tailored to individual patients.</p><p>“For a long time, we’ve been trying to move toward prescribing diets for the microbiome,” says <a href="http://www.biology.howard.edu/faculty/robinson/robinson.html">Courtney Robinson</a>, a microbiologist at Howard University who was not involved in the study. “We still don’t really know how to make a ‘healthy’ microbiome...but [this study] offers a more granular assessment on this process that we haven’t had before.”</p><p>Researchers have long known that <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3957428/">diet can shape and reshape</a> the gut microbiome, which plays a role in essential functions from synthesizing vitamins to guarding against infection. But the ways in which specific foods and nutrients affect the hundreds or thousands of microbial species that colonize the human digestive tract remain mostly mysterious. Both diet and microbiome vary enormously from person to person, and tend to change from day to day, even within the same individual.</p>
            <figure class="richtext-image full-width"><img alt="iStock-854725372.jpg" class="richtext-image full-width" height="355" width="800"
            src="/wgbh/nova/media/images/iStock-854725372.width-800.jpg"/><figcaption><p>Just like there&#x27;s not one healthy diet, there&#x27;s not one healthy microbiome—and different sets of gut microbes can react differently to identical foods. Image Credit: Lisovskaya, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>To disentangle some of this complexity, a team of researchers led by <a href="https://www.knightslab.org/people">Abigail Johnson</a> and <a href="https://www.knightslab.org/">Dan Knights</a> at the University of Minnesota put 34 humans and their microbes under the figurative microscope.</p><p>For the duration of the 17-day study, participants recorded everything they ate and provided daily fecal samples. But when the researchers tried to match shifts in diet to changes in the gut, they realized they needed a new way to categorize foods. Broadly speaking, most of the people enrolled in the study were eating nutritionally similar diets, with about the same proportions of carbohydrates, fats, and proteins, making these categories too vague to yield much insight. Going food item by food item, however, was a pointless extreme at the other end of the spectrum. “That was one of the biggest limitations we hit,” Johnson says. “Nobody eats the same things.”</p><p>Instead, Johnson, who is both a microbiologist and registered dietician, and her team decided to sort the dietary data in a manner based loosely on <a href="https://www.choosemyplate.gov/">USDA nutrition guidelines</a>. The approach, Johnson explains, is comparable to an extremely detailed version of the food groups most American kids are taught in school. For instance, a category like dairy might be further broken down into milks, creams, milk desserts, and cheeses. In this new system, nutritionally similar foods like rice and potatoes—which are known to be <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5915309/">interpreted differently</a> by gut microbes—ended up in different subgroups.</p></div>
  

  
      <div class="related"></div>
  

  
      <div class="rich-text"><p>Using these patterns, the researchers were then able to predict what a person’s gut microbiome might look like based on what they’d eaten over the past several days. Diet, however, is just one of a constellation of factors that influence which microbes will and won’t thrive in a given individual’s gut. These food-based forecasts also required prior knowledge about what each individual’s microbiome looked like at baseline. As a result, the predictions were completely personalized, and couldn’t be generalized among participants.</p><p>But a lack of uniformity isn’t cause for concern: Just like there isn’t one healthy diet, there isn’t one healthy microbiome. Even though the study’s participants were eating different foods, and harbored substantially different communities in their guts, all were in relatively good health, Johnson says. (Two of the participants subsisted almost entirely on the dietary replacement beverage Soylent for the duration of the study, and their microbiomes didn’t seem to suffer.)</p><p>“There’s a tendency to want to categorize things as good or bad,” says <a href="https://profiles.stanford.edu/amy-jacobson">Amy Jacobson</a>, a microbiologist at Stanford University who was not involved in the study. “But those types of black and white categorizations are difficult to make [for the gut microbiome]. What could be ‘good’ for one person may not be good for another.”</p><p>With that in mind, a personalized medicine approach makes sense, says <a href="https://gilbertoflores.weebly.com/">Gilberto Flores</a>, a microbial ecologist at California State University, Northridge who was not involved in the study. More work is needed to figure out if these predictions pan out long term, and with a larger, more diverse population of individuals. As research like this continues, however, similar models “could be a powerful tool in the future,” he says.</p><p>For now, these results underscore the fact that people still have a lot to learn about the food on their plates, Knights says. The nutrients human cells extract and absorb from the things we eat are the same ones that end up on labels, but a good portion of food matter is accessible only to the microbes in our colon. Deep in the large intestine, one organism’s trash can quickly become another’s treasure—and it’s here that this undigested “junk” starts to make a difference. Microbes simply don’t interpret foods in the same ways we do, and it may be time to start acknowledging their point of view.</p>
            <figure class="richtext-image full-width"><img alt="iStock-1091215168.jpg" class="richtext-image full-width" height="533" width="800"
            src="/wgbh/nova/media/images/iStock-1091215168.width-800.jpg"/><figcaption><p>Nutrition Facts labels track broad categories like carbohydrates and protein. But within these groups are a variety of chemicals, compounds, and molecules that are all interpreted differently by the microbes that live in our guts. Image Credit: zoranm, iStock</p><div class="credit"><p></p></div></figcaption>
            </figure>
            <p>What’s not yet clear is what exactly comprises the dietary dark matter that <a href="https://www.pbs.org/wgbh/nova/article/ultra-processed-foods-weight-gain/">nutrition labels leave off</a>. One likely culprit is fiber, which is a single word that actually encompasses many, many different subtypes. “Microbes care intensely about the exact chemical structures of fibers, which can be different even between two different types of rice,” Knights says. “It’s going to take a long time for humans to build that knowledge base.” And the intricacies of fiber are likely just the tip of the nutritional iceberg, he adds. There are probably many more molecular nuances to food that humans haven’t even begun to uncover.</p><p>If all this sounds frustratingly complicated, that’s because it is. How, and to what extent, diet alters the microbiome are still open questions, says <a href="http://web.stanford.edu/~gabif/about.html">Gabriela Fragiadakis</a>, a microbiologist and immunologist at Stanford University who was not involved in the study.</p><p>That being said, years of research have shown that the foods thought to be beneficial for the gut microbiome tend to overlap with dietary recommendations for people, she says. For all our differences, humans and microbes still have <a href="https://www.pbs.org/wgbh/nova/article/sugar-keeps-good-microbes-at-bay/">plenty in common</a>. Stick to that rule of thumb, she says, “and at worst, you’ll still be consuming a healthy diet.”</p></div>
  

  
      <div class="newsletter"></div>
  



<p>To predict how diet shapes a person’s gut microbiome, researchers came up with a new way to categorize foods.</p>

Nutrition labels aren’t enough to predict diet’s effects on gut microbes





  
      <div class="rich-text"><p>Five years ago, a team of researchers rifling through death certificate data uncovered <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4392651/">an unexpected trend</a>: Opioid-related deaths were a whopping 25 percent lower in the 13 states that had legalized medical marijuana, compared to those that hadn’t.</p><p>There was nothing in the study that demonstrated a causal link between the two statistics, and the authors cautioned against overinterpreting the findings. Regardless, advocates for legal cannabis quickly began to leverage the study as evidence that medical marijuana, which could offer an alternative to prescription painkillers for patients with chronic pain, could become the next big thing in the fight against the opioid epidemic.</p><p>Now, <a href="https://www.pnas.org/cgi/doi/10.1073/pnas.1903434116">new research</a> published today in the journal <i>PNAS</i> suggests the story is far more complicated, <a href="https://www.theatlantic.com/health/archive/2019/06/medical-marijuana-probably-wont-stop-opioid-crisis/591355/">Olga Khazan reports for <i>The Atlantic</i></a>. The study, which used methods identical to its 2014 predecessor, also found that, between 1999 and 2010, opioid-related deaths declined in states that had introduced medical marijuana. But in the years following, the trend began to <i>reverse—</i>and by 2017, the overall picture was looking bleak: Over the past two decades, states with cannabis-related legislation have actually seen a 23 percent <i>increase</i> in deaths from opioid overdoses.</p><p>“If you think opening a bunch of dispensaries is going to reduce opioid deaths, you&#x27;ll be disappointed,” study author Keith Humphreys, a psychiatrist and behavioral scientist at Stanford University, <a href="https://www.eurekalert.org/pub_releases/2019-06/sm-m060619.php">said in a statement</a>. “We don&#x27;t think cannabis is killing people, but we don&#x27;t think it&#x27;s saving people.”</p></div>
  

  
      <div class="ad"></div>
  

  
      <div class="rich-text"><p>Since California legalized medical marijuana in 1996, 46 additional states have passed legislation permitting some version of cannabis in clinical settings. But in the same timespan, the United States’ opioid epidemic has ballooned, with <a href="https://www.hhs.gov/opioids/about-the-epidemic/index.html">close to 50,000 Americans</a> dying from opioid overdoses each year.</p><p>That certainly doesn’t imply that marijuana use is <i>enabling</i> opioid use. But the new study’s sobering finds do indicate that cannabis legislation probably won’t provide the panacea many hoped for.</p></div>
  

  
      <div class="related"></div>
  

  
      <div class="rich-text"><p>In the study, state death statistics didn’t show a lasting dip in opioid-related deaths after the passage of medical marijuana laws. These findings didn’t change when the researchers considered the differences between states that allowed recreational cannabis use—thus giving its residents more access to marijuana—and those with more restrictive laws.</p><p>It’s still not clear why the two studies yielded such different results. One possible explanation, however, could be cultural. The 13 states in the 2014 study were, on average, wealthier and more politically liberal, Humpheys said in the statement. In these regions, patients also had more access to treatments for addiction and naloxone, which can prevent overdose fatalities. Geographically, these 13 states also fell mostly in the American West, where the opioid epidemic arrived later, study author Chelsea Shover <a href="https://www.theatlantic.com/health/archive/2019/06/medical-marijuana-probably-wont-stop-opioid-crisis/591355/">told Khazan at <i>The Atlantic</i></a><i>.</i></p><p>The trajectories of marijuana and opioids may not be as entangled as once thought. Chinazo Cunningham, a physician at the Albert Einstein College of Medicine and author of the original study, told Khazan that she agrees that marijuana should not be considered a “silver bullet” for the opioid epidemic. But, she adds, cannabis can still play a role in pain management in general.</p><p>More work is needed to figure out how—or even if—marijuana’s palliative effects can be put to good use in avoiding addictive painkillers. Either way, cannabis legislation alone won’t be enough to solve the opioid epidemic.</p><p>“I wish it were true. I wish that passing medical cannabis [laws] would solve the opioid crisis,” Shover <a href="https://www.washingtonpost.com/health/a-cautionary-tale-about-medical-marijuana-and-opioid-deaths/2019/06/10/b8e1c924-8b97-11e9-adf3-f70f78c156e8_story.html?utm_term=.dd61967db30a">told Lenny Bernstein at <i>The Washington Post</i></a>. “But the evidence doesn’t support that.”</p></div>
  

  
      <div class="newsletter"></div>
  



<p>A new study shows casts doubt on the idea that medical marijuana might help patients avoid an addiction to prescription painkillers.</p>

Topic: Body & Brain

Hero Feature