RealClearScience Journal Club

Science Figures Interpreted and Analyzed by RealClearScience

Study: More Guns Linked to More Mass Shootings

Ross Pomeroy - February 2, 2016

The United States now has more guns than people, according to estimates published last year in the Washington Post. But even before that disconcerting nugget of information entered the public realm, the U.S. still housed a rather obscene amount of firearms. Though nearly a decade old, the Small Arms Survey of 2007 still offers the most rigorous count of civilian gun ownership worldwide. The U.S. easily placed first, with approximately 88.8 guns per 100 individuals. Yemen came in a distant second with 54.8 firearms per 100 people.

The large number of guns in the United States has prompted a great deal of discussion. Is the rate of firearm ownership linked to homicide? What about crime in general? Owing to the often immeasurable variables that confound large societal studies, it's difficult to arrive at a clear answer. Even systematic reviews examining a wealth of research disagree.

Here's what we do know. After peaking in the 1980s and early 1990s, crime has plummeted in the United States. The rates of forcible rape, murder, violent crime, property crime, and aggravated assault are currently as low as they were in the 1960s.

While these statistics demonstrate that Americans are about as safe from crime as they have been in over a half-century, there is a particularly horrendous type of crime that has been alarmingly on the uptick: public mass shootings. In places like San Bernadino, California, Colorado Springs, Colorado, Roseburg, Oregon, Charleston, South Carolina, and Newtown, Connecticut, innocents have been mercilessly gunned down in great numbers.

Calls to reduce the availability of guns have followed in the wake of these tragic events. But yet to be determined empirically is whether or not gun ownership is even correlated to public mass shootings. Adam Lankford, an Associate Professor of Criminal Justice at University of Alabama, addresses that question with forthcoming research in the journal Violence and Victims.

In his study, Lankford combined data from the New York City Police Department’s (NYPD) 2012 Active Shooter report (PDF), the FBI’s 2014 active shooter report (PDF), as well as "data gathered on incidents from other countries" in an attempt to count all public mass shootings occurring between 1966 and 2012 in which at least four victims were killed. In total, Lankford tallied 292 incidents from 171 countries. 

Lankford then explored how the number of mass shootings per country were associated with each country's homicide rate, suicide rate (used a rough proxy for mental health), and firearm ownership rate. While he found no link between the number of shootings and suicide or homicide rates, he found a highly significant (p<.01) link between the number of shootings and firearm ownership rates. In countries with more guns, there were more public mass shootings. The association remained even when the United States -- a clear outlier with 90 mass public shootings -- was removed from the data set.

"Many of the nations in this study that ranked highest in firearm ownership rates also ranked highly in public mass shooters per capita," Lankford notes. "For example, the Small Arms Survey (2007) lists the United States, Yemen, Switzerland, Finland, and Serbia as the top five countries in civilian firearm ownership rates, and all five countries also ranked in the top 15 in public mass shooters per capita."

Lankford noted a number of limitations to his study. Older incidents occurring further in the past and in countries without streamlined reporting systems may have been missed. Moreover, since public mass shootings are rare, the sample size is small for the forty-six-year study period.

Lankford also made clear that he utilized the definition of public mass shooting from the NYPD's report. The attacks "must have (a) involved a firearm, (b) appeared to have struck random strangers or bystanders and not only specific targets, and (c) not occurred solely in domestic settings or have been primarily gang-related, drive-by shootings, hostage-taking incidents, or robberies."

For the most part, Lankford steered clear of speculation in his study, preferring to leave that to the political and policy arenas. "I don't want the findings or their implications to be misunderstood," he told RCS in an email.

He did however, state the natural conclusion from his findings.

"Perhaps the most obvious step the United States could take to reduce public mass shootings may also be the most politically challenging: reduce firearms availability."

Lankford noted that the approach seemed to work in Australia. After a public mass shooting in 1996 that left thirty-five people dead, the country's government passed comprehensive gun control legislation. Decades later, firearm homicide and suicide rates are way down, and there have been no more public mass shootings.

He ended his article with a plea for further research.

"Ultimately, more cross-national studies of public mass shooters could help ensure that future strategies for prevention are based on reliable scientific evidence. Some countries and cultures are clearly safer than others; it would be a shame not to learn from them."

Source: Lankford, Adam. "Public Mass Shooters and Firearms: A Cross-National Study of 171 Countries." 2016. Violence and Victims.

(Image: AP)

Overconfident Students Major in Political Science

Ross Pomeroy - January 26, 2016

Confidence, being certain that a prediction or a chosen course of action is correct, is widely considered a positive state of being. But when taken too far it can quickly turn negative. Overconfidence, having unrealistic certainty, has been linked to unemployment, market inefficiencies, and even the Great Recession.

In a study published Monday to the journal PLoS ONE, psychologists Jonathan Schulz and Christian Thöni, respectively of Yale University and the University of Lausanne, sought to examine whether a correlation exists between overconfidence and career choice, indicated by the student's chosen field of study.

To find out, Schulz and Thöni surveyed 711 first-year students from the University of St. Gallen and the University of Zurich in Switzerland. The students were brought into the lab in various group sizes and undertook numerous experiments during a session that lasted roughly an hour and a half. Amongst the experiments was a simple task. Subjects were presented with five historical events and were asked to guess the year each occurred. Examples included the reactor accident in Chernobyl and the first flight of the supersonic jet Concorde. Subjects scored more highly the closer their estimates were to the actual date of the events. Lastly, they were instructed to rank their performance amongst their peers. The difference between the ranks they gave themselves and their actual ranks (normalized to a 12-rank scale) served as the measure of overconfidence.

The most overconfident students were in the political sciences. On average, they overestimated their rankings by 1.4 places. Students majoring in law, administration, and economics also tended to over place themselves, but nowhere near the degree of political science majors. Students in the humanities significantly underestimated their rankings.

On average, subjects over placed themselves by 0.44 ranks, reproducing the above average effect, whereby individuals tend to overestimate their performance compared to others. Males students were far more overconfident that female students.

Since the study was conducted at universities in Switzerland, the sample likely consisted primarily of European-born students, so the results may not carry over to students in the United States or other parts of the world. Moreover, the study was correlational, so they authors urged caution in interpreting the data.

"We cannot rule out that subjects’ varying confidence levels are shaped by the experience they gained in their studies. However, our data stems from first year students, who only had limited exposure to an academic discipline."

It is interesting that politically minded students tended to display the most overconfidence. In a prior study, overconfidence was associated with increased voter turnout as well as ideological extremeness.

Moreover, in a USA Today column from 2011, Don Moore, a professor at UC-Berkeley who specializes in studying overconfidence, noted that "the process of political campaigning effectively selects the most confident — those who can go out day after thankless day, asking people for their votes and their money."

"Having elected the most confident candidate, who has won our votes by promising us glory and prosperity, we cannot help but be disappointed when this talented and idealistic politician’s plans run headlong into the realities of a political system that hamstrings him with checks, balances, and entrenched interests who put the brakes on those ambitious plans."

Source: Schulz JF, Thöni C (2016) Overconfidence and Career Choice. PLoS ONE 11(1): e0145126. doi:10.1371/journal.pone.0145126

(Image: Shutterstock)

Scientists Asked 2,799 People From 12 Countries to Define 'Happiness.' Here's What They Said.

Ross Pomeroy - January 12, 2016

You know when you're happy and you know when you aren't, but what really is happiness, and what exactly takes us to that joyous state? Psychologists from twelve different countries teamed up to discern a global perspective.

Their findings were just published to the journal Frontiers in Psychology.

The researchers comprehensively surveyed and queried 2,799 adults living in urban areas of Argentina, Brazil, Croatia, Hungary, India, Italy, Mexico, New Zealand, Norway, Portugal, South Africa, and the United States about their definitions of happiness. Between 200 and 220 adults aged thirty to sixty participated from each country, split evenly between men and women. Eight out of ten of the participants had children. Slightly over half were Christian, 12.4% were Hindu, and 27.6% didn't belong to a religion.

From the 7,551 definitions of happiness provided by the participants, the researchers distilled a number of findings. Overall, and in eleven of the twelve countries surveyed, subjects said that family and strong relationships contributed to happiness the most, followed by good health. People most often described family as a source of solidarity, cohesion, and mutual support, and reported contentment from watching their children grow into strong, positive individuals. Strong relationships were valued as a way of sharing life experiences, as well as giving and receiving support.

Worldwide, participants most often gave a psychological definition of happiness. Of these definitions, the notion of harmony dominated, including the components of inner peace, inner balance, contentment, and psychophysical well-being. This surprised the researchers somewhat, as the almost Zen-like idea of harmony is often neglected in psychological research on happiness, especially in the Western world. Harmony was regularly characterized by participants as achieving emotional stability, "being attuned with the universe," and attaining a balance between what is desired and what is achieved.

There were a number of interesting cultural differences that arose in participants' definitions. Subjects from the U.S. described happiness as a state of "no negative feelings" and associated it with "optimism" more than residents of any other country, whereas residents of Norway particularly cared about "autonomy" and attaining "mastery" in certain skills or other aspects of life. In Croatia, participants focused less on psychological definitions of happiness and more on simply being healthy and satisfied in day-to-day life.

The study had a number of limitations. Participants were from urban areas, so perspectives from those living in rural areas are absent. Moreover, cultures from Asia, Africa, and Latin America were undersampled, and there were almost no viewpoints from Muslims.

The researchers hope their study will lead to more happiness across the globe.

"As most people now live in multi-cultural societies, a deeper understanding of cultural notions of happiness and well-being will be valuable to promote harmonious existence and well-being for all diverse groups within the same country."

Source: Delle Fave A, Brdar I, Wissing MP, Araujo U, Castro Solano A, Freire T, Hernández-Pozo M, Jose P, Martos T, Nafstad HE, Nakamura J, Singh K and Soosai-Nathan L (2016). Lay definitions of happiness across nations: The primacy of inner harmony and relational connectedness. Front. Psychol. 7:30. doi: 10.3389/fpsyg.2016.00030

Correction 1/13: A previous version of this article stated that Croatia was the poorest country on the list. It is not.

(Image: AP)

How Often Do Americans Shoot Themselves in the Foot?

Ross Pomeroy - January 11, 2016

If you didn't shoot yourself in the foot this holiday season, congratulations, you dodged a bullet! According to a study recently published to the Medical Journal of Australia, October, November, and December are the peak months when Americans shoot themselves in the feet.

Drs. Theodore Cosco and James Harmsworth King of the University of Cambridge undertook the study, which won the Medical Journal of Australia's annual Christmas competition, a contest traditionally reserved for "whacky research."

The duo examined seventeen years of data collected between 1993 and 2010 via the National Electronic Injury Surveillance System (NEISS) as part of the Firearm Injury Surveillance Study. They found that of the 69,111 firearm-related injuries that were reported, just 667 -- roughly one percent -- were self-inflicted gunshot wounds to the foot

"Contrary to popular belief, incidents of Americans shooting themselves in the foot are relatively rare," the Cosco and Harmsworth King cheekily reported.

Nine out of ten of the patients were men, and just over half of the patients were between the ages of 15 and 34. Most of the incidents occurred at home. Thankfully, the vast majority of injuries did not seem to be too serious, though a couple did lead to amputation. As mentioned earlier, October, November, and December were the peak months for self-inflicted gunshot wounds to the foot, likely because this is when most hunting seasons run, Cosco suggests.

The study was intended to be slightly humorous, but there is a serious angle to it, Cosco says. "I think the study highlights the importance of firearms safety and the potential for injury; a particularly salient issue in the US."

"On a lighter note, I think the study highlights the notion that academics can still demonstrate high calibre humour."

Cosco and Harmsworth King seem to be fond of puns. They concluded their paper with one so wonderfully awful you can't help but chuckle.

"Particular caution must be taken during the festive season if one is to avoid being caught under the missing toe."

How did that make it past peer review?

Source: Theodore D Cosco and James H King. Americans shooting themselves in the foot: the epidemiology of podiatric self-inflicted gunshot wounds in the United States. Med J Aust 2015; 203 (11): 458-461. doi: 10.5694/mja15.01031

(AP Photo)

A New Potential Replacement for Body Mass Index

Ross Pomeroy - December 30, 2015

Take your weight (in kilograms) and divide it by your height (in meters) squared. You've just calculated your body mass index (BMI), one of the most commonly used indicators of health. But though appealing for its simplicity, the measure is fundamentally flawed in many respects.

First off, BMI doesn't scale well. A tall man with the exact same build and body composition as a shorter man will have a higher BMI. Secondly, the measure ignores variation in body shape. Some people are slender; others are stocky. Moreover, people carry fat in different places. Subcutaneous fat just below the skin is generally not associated with a steep rise in mortality, while abdominal fat is. Finally, BMI does not differentiate between fat and muscle mass. This glaring drawback means that many muscular athletes are considered overweight or even obese.

Metric Body Mass Index Formula

While those athletes probably would laugh off the technicality, scientists and health experts should take it seriously. A great many epidemiological studies use BMI as a biomarker for health, and the CDC uses it to determine how many Americans are overweight or obese. It's high time that BMI be replaced with a more accurate and nuanced indicator.

In Monday's release of PLoS ONE, West Virginia University computer scientists Syed Ashiqur Rahman and Donald Adjeroh proposed a new alternative: the Surface-based Body Shape Index (SBSI). Though decidedly more of a mouthful to say, the indicator is far more rigorous, based upon four key measurements: the body surface area (BSA), vertical trunk circumference (VTC), height (H), and waist circumference (WC).

After expounding on the details of their formula, Rahman and Adjeroh put it to the test, seeking to find how well it predicts all-cause mortality. They examined data on 11,808 subjects from the National Health and Human Nutrition Examination Surveys (NHANES) 1999–2004, in which the average SBSI was roughly 0.107 for women (standard deviation of .007) and 0.108 for men (standard deviation of .006). The duo found that SBSI outperformed BMI, waist circumference, and A Body Shape Index (ABSI), an alternative to BMI that garnered a lot of attention when it was proposed back in 2012.

Unfortunately, ABSI seems to have mostly fizzled out, earning only 83 mentions in PubMed, the international database for biomedical science, since its inception. Over the same period, BMI has been mentioned more than 34,000 times! The new indicator, SBSI, is probably doomed to the same fate. Thus far, it seems that simplicity trumps accuracy in health research, at least as far as BMI is concerned.

Source: Rahman SA, Adjeroh D (2015) Surface-Based Body Shape Index and Its Relationship with All-Cause Mortality. PLoS ONE 10(12): e0144639. doi:10.1371/journal.pone.0144639

(Images: AP, BruceBlaus)

Update 12/30: An earlier version of this article mistated the equation for BMI. That has been fixed.

When Americans Are Inactive, This Is What They Do

Ross Pomeroy - December 10, 2015

The average American man and woman are considered overweight. He and she also spend about eight hours a day (roughly 55% of their waking time) being physically inactive, or sedentary. For a species that, for most of its existence, spent its time on the move, modern humans residing in the developed world are spending an awful lot of time not moving at all.

In a new study published to the journal BMC Public Health, Iowa State kinesiologists Youngwon Kim and Gregory J. Welk sought to find out how Americans spend their inactive time.

Over 1400 adults were recruited via random selection from four different Iowa communities. The sample was roughly divided fifty-fifty between men and women and participants' average age was 46. 

Once recruited, sets of subjects wore an armband monitor on one randomly selected day and then completed an in-depth interview the following day to recall the specific activities they performed. These methods were repeated for a new set of participants at least three weeks later. The process continued until all of the participants had been assessed, which ended up taking more than two years.

Participants reported an average of 7.7 sedentary hours per day, not including sleep -- very close to the national average -- with men spending slightly more time being inactive than women. The most commonly reported physical activities by frequency were eating while sitting, watching television, talking on the phone, and using a computer. Unsurprisingly, computers and televisions took up the most sedentary time in people's days. Those who reported using the computer spent an average of 138 minutes doing so, and those who reported watching television spent 129 minutes doing so.

The researchers compiled their data into a neat figure, shown below.

As all of the subjects were from Iowa, the findings of the study may not be generalizable to the rest of the U.S. population. The data was also self-reported, which is subject to the fallibilities of human memory. However, the authors reinforced their data with a sizable sample. Armband monitors were also utilized to ensure the reported data wasn't unreasonable. The authors actually eliminated 111 subjects from the final analysis because of conflicting, "problematic," data, which may have biased the results.

"These findings may have value for understanding disparities of sedentary behavior and health in the population," the researchers say.

Most notable is the immense amount of computer use. Just thirty-five years ago, spending more than two hours a day sitting in front of a computer would have been a challenge for the average American. Today, it's the norm.

Source: Youngwon Kim and Gregory J. Welk. "Characterizing the context of sedentary lifestyles in a representative sample of adults: a cross-sectional study from the physical activity measurement study project." BMC Public Health 2015 15:1218  DOI: 10.1186/s12889-015-2558-8

(Image: AP Photo/Kathy Willens)

Deaths from Law Enforcement Rose 45% Between 1999 and 2013

Ross Pomeroy - December 3, 2015

The number of people killed by law enforcement officials rose 45% between 1999 and 2013, a new study finds.

Researchers based out of Florida Atlantic and Baylor Universities obtained the finding by examining the Compressed Mortality File maintained by the National Center for Health Statistics Centers. They announced their discovery in the December issue of the journal Preventive Medicine.

"Between 1999 and 2013 in the US, there were 5,551 deaths by legal intervention," the authors reported. Nationwide, mortality rates by legal intervention now stand at 0.24 per 100,000 individuals among Blacks, 0.11 among Whites, and 0.05 among Asians.

Rates are higher in certain states. In Nevada, California, and Maryland, mortality rates among blacks eclipse 1 per 100,000 individuals, making them comparable to the death rates for malnutrition, asthma, and accidental drowning.

The two districts with the highest mortality rates from police intervention are Riverside County, California and Baltimore Maryland. Respectively, 2.4 and 1.82 out of every 100,000 blacks are killed by law enforcement in those areas.

Police killings increased between 1999 and 2013 despite a 29.4% drop in violent crime over the same period.

It's possible that the large increase in deaths by law enforcement could be attributed to a rise in reporting. Police killings have been widely covered in the media of late, and this may prompt officials to take greater care in reporting these deadly incidents.

Overall, the authors say the data may actually underestimate the deaths due to law enforcement, as the statistics don't pertain to illegal immigrants.

The authors also stress that deaths from law enforcement are still exceedingly rare, and this may make the mortality rates unreliable.

The authors offered no policy solutions for the situation, simply concluding, "The demographic and geographic variations in these data likely reflect deep-rooted social issues requiring broad-based national and local solutions."

Source: Joanna Drowosa, Charles H. Hennekens, Robert S. Levine. "Variations in mortality from legal intervention in the United States—1999 to 2013." Preventive Medicine Volume 81, December 2015, Pages 290–293

(Image: Associated Press)

The Bacteria that Live in Your Coffee Maker

Alex B. Berezow - November 30, 2015

Wherever you live, bacteria live. Wherever you can't live, bacteria live. From hydrothermal vents to acid mines, microbes have the planet covered. They also have your Nespresso machine covered. Recently, Spanish researchers decided to inventory the microbial community that dwells inside George Clooney's favorite coffee maker.

The team analyzed several Nespresso machines that had been operated for at least one year. They sampled the drip tray and subjected the microbes to high-throughput DNA sequencing. They found a wide diversity of bacteria, with Enterococcus and Pseudomonas appearing most frequently. The latter genus is particularly notable because certain species are known to degrade caffeine. Enterococcus and many of the other bacteria present probably cannot degrade caffeine, but simply tolerate an environment that many other species find unpleasant.

The authors then decided to observe the microbial colonization of a brand new Krups coffee maker over a two-month period. Their results are depicted below:

The figure shows an unstable and rapidly shifting community. A particular group of bacteria dominates for a few days and is then gradually replaced by another group. By the end of the two-month period, however, Enterococcus and Pseudomonas showed up. Combined with the results from the Nespresso machines, this suggests that these two genera are particularly suited to life inside a coffee maker.

This sort of "ecological succession" is not unusual. Indeed, scientists have observed elsewhere that "generalist" bacteria are often the first colonizers but are eventually replaced by more "specialist" bacteria. Something similar could be happening here.

From a more practical standpoint, the authors may have begun to uncover the sort of microbes that could be useful in wastewater treatment. Caffeine has been detected off the coast of the Pacific Northwest, and its impact on the environment is unknown. Perhaps one day, wastewater treatment facilities could employ a community of microbes to decaffeinate our pee.

Source: Cristina Vilanova, Alba Iglesias & Manuel Porcar. "The coffee-machine bacteriome: biodiversity and colonisation of the wasted coffee tray leach." Scientific Reports 5, Article number: 17163. Published online: 23-November-2015. doi: 10.1038/srep17163

(AP photo)

Cachexia: Why Cancer Patients Waste Away

Alex B. Berezow - November 24, 2015

One of the most pernicious conditions that arises as a consequence of cancer is a sort of wasting syndrome. More formally known as cachexia, it causes patients to lose body mass (including both muscle and fat) and to grow weak and fatigued. Whether or not a patient develops cachexia largely depends on the type of cancer he has. Those with pancreatic cancer, for instance, have an 80% chance of suffering from it, while those with breast cancer have a 40% chance. The syndrome takes such a physical toll on the patient that it is largely to blame for a fifth of all cancer deaths. Cachexia, therefore, remains one of the most heartbreaking and puzzling aspects of cancer.

An article published last year in the journal Nature Reviews Cancer attempts to shed light on the molecular mechanisms underlying the condition. The authors believe that the existing evidence points to cachexia being a multi-organ syndrome that results from metabolic inefficiency, wasting of muscle and fat tissue, and systemic inflammation.

An example of metabolic inefficiency is a futile cycle; that is, a vicious cycle that does nothing productive and wastes energy in the form of heat. Tumors tend to gobble up glucose, a valuable source of energy, and convert it to pyruvate, a waste product. The liver accepts the pyruvate and, in cachexic patients, converts it back to glucose (which uses up energy), before shipping it back to the tumor. Simultaneously, the energy-producing structures, called mitochondria, inside muscle cells start to malfunction.

Worsening the problem for muscle cells is a total disruption of normal metabolism. Muscles begin exporting glutamine, an amino acid, into the bloodstream, after which it is imported by the tumor. This results in nitrogen starvation in the muscle cells. Furthermore, inflammatory molecules induced by the tumor tell muscle cells to destroy proteins and commit suicide. The ultimate result is muscle wasting. Similarly, metabolic changes inside fat tissue causes it to atrophy, as well. One such change is the diversion of mitochrondia from the production of energy "currency" (molecules called ATP) to the production of waste heat.

Underlying all of these perturbations is systemic inflammation. Tumors activate the immune system, which in turn releases messenger molecules that severely disrupt normal physiology by triggering the dysfunction described above. Besides muscles and fat tissue, cachexia also disturbs the brain, liver, gut, and heart. The brain, for example, begins to suppress appetite. (See figure.)

Source: JM Argilés et al. Nat Rev Cancer 14 (11): 754-62.

As if all of this weren't bad enough, the side effects of chemotherapy and radiation therapy tend to aggravate cachexia.

Can anything be done to stop cachexia? Perhaps, but it must be addressed before it becomes late-stage, which is untreatable. One potential therapy, described by Cosmos Magazine, involves using antibodies against a protein produced by cancer cells called Fn14. In mice, these antibodies effectively blocked cachexia. Human clinical trials may be on the way.

The other good news is, though it certainly doesn't feel like it, we are slowly winning the war on cancer.

Source: Josep M. Argilés, Sílvia Busquets, Britta Stemmler and Francisco J. López-Soriano. "Cancer cachexia: understanding the molecular basis." Nat Rev Cancer 14 (11):754-62. Published online: 9-Oct-2014. doi: 10.1038/nrc3829.

(AP photo)

Pigeons Can Be Taught Pathology and Radiology

Ross Pomeroy - November 19, 2015

A new study shows that pigeons can be trained to recognize breast cancer with surprising accuracy.

The research was published yesterday to PLoS ONE.

In the past, pigeons have been trained to recognize letters of the alphabet, identify human emotions, and even differentiate paintings by Monet and Picasso, but evaluating medical imagery was an entirely novel foray.

Researchers primarily based out of the University of Iowa trained eight pigeons to differentiate between images of benign and malignant breast cancer slides at varying levels of magnification. In just a couple of weeks, the birds' accuracy rose from 50% to 85%.

At the conclusion of the training phase, the researchers challenged the birds with images they'd never seen before, and incredibly, the birds correctly identified 85% of the new images, indicating that they had somehow learned to detect the defining features of breast cancer.

In a second experiment, the researchers trained four different birds to detect microcalcifications from mammograms (seen below), an early sign of cancer. Again, the pigeons attained an average 85% accuracy after two weeks. When presented with novel images, they correctly identified 69% percent of the images with microcalcifications, which was significantly better than chance, but not nearly as good as their earlier performance with breast tissue. Human radiologists and radiology residents given the same cases to review averaged 97% accuracy for images without calcifications and 70% for images with them.

Lastly, the researchers challenged four pigeons to discern between benign and malignant masses on mammograms (shown below). This time the birds never really got the hang of it. After twelve weeks of training, just two pigeons were able to differentiate the images at accuracies approaching 80%, and when presented with novel images, they performed no better than chance. A panel of radiologists achieved an accuracy rate of about 80% when viewing the same images, much better than the pigeons.

While the results of the study are fairly remarkable, especially for animals with brains no bigger than the tip of an index finger, it doesn't seem that pigeons are ready for white coats just yet.

Source: Levenson RM, Krupinski EA, Navarro VM, Wasserman EA (2015) Pigeons (Columba livia) as Trainable Observers of Pathology and Radiology Breast Cancer Images. PLoS ONE 10(11): e0141357. doi:10.1371/journal.pone.0141357

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