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Maybe sometimes it’s the questions that are biased, not the answers,” he said, flashing a friendly smile.

That question has been central to Ioannidis’s career. He’s what’s known as a meta-researcher, and he’s become one of the world’s foremost experts on the credibility of medical research.

He charges that as much as 90 percent of the published medical information that doctors rely on is flawed.

“I take all the researchers who visit me here, and almost every single one of them asks the tree the same question,” Ioannidis tells me, as we contemplate the tree the day after the team’s meeting. “‘Will my research grant be approved?’” He chuckles, but Ioannidis (pronounced yo-NEE-dees) tends to laugh not so much in mirth as to soften the sting of his attack. And sure enough, he goes on to suggest that an obsession with winning funding has gone a long way toward weakening the reliability of medical research.

“I assumed that everything we physicians did was basically right, but now I was going to help verify it,” he says. “All we’d have to do was systematically review the evidence, trust what it told us, and then everything would be perfect.” It didn’t turn out that way. In poring over medical journals, he was struck by how many findings of all types were refuted by later findings. Of course, medical-science “never minds” are hardly secret. And they sometimes make headlines, as when in recent years large studies or growing consensuses of researchers concluded that mammograms, colonoscopies, and PSA tests are far less useful cancer-detection tools than we had been told; or when widely prescribed antidepressants such as Prozac, Zoloft, and Paxil were revealed to be no more effective than a placebo for most cases of depression; or when we learned that staying out of the sun entirely can actually increase cancer risks; or when we were told that the advice to drink lots of water during intense exercise was potentially fatal; or when, last April, we were informed that taking fish oil, exercising, and doing puzzles doesn’t really help fend off Alzheimer’s disease, as long claimed. Peer-reviewed studies have come to opposite conclusions on whether using cell phones can cause brain cancer, whether sleeping more than eight hours a night is healthful or dangerous, whether taking aspirin every day is more likely to save your life or cut it short, and whether routine angioplasty works better than pills to unclog heart arteries.

“I realized even our gold-standard research had a lot of problems,” he says.

This array suggested a bigger, underlying dysfunction, and Ioannidis thought he knew what it was. “The studies were biased,” he says. “Sometimes they were overtly biased. Sometimes it was difficult to see the bias, but it was there.” Researchers headed into their studies wanting certain results—and, lo and behold, they were getting them. We think of the scientific process as being objective, rigorous, and even ruthless in separating out what is true from what we merely wish to be true, but in fact it’s easy to manipulate results, even unintentionally or unconsciously. “At every step in the process, there is room to distort results, a way to make a stronger claim or to select what is going to be concluded,” says Ioannidis. “There is an intellectual conflict of interest that pressures researchers to find whatever it is that is most likely to get them funded.”

He chose to publish one paper, fittingly, in the online journal PLoS Medicine, which is committed to running any methodologically sound article without regard to how “interesting” the results may be. In the paper, Ioannidis laid out a detailed mathematical proof that, assuming modest levels of researcher bias, typically imperfect research techniques, and the well-known tendency to focus on exciting rather than highly plausible theories, researchers will come up with wrong findings most of the time.

The article spelled out his belief that researchers were frequently manipulating data analyses, chasing career-advancing findings rather than good science, and even using the peer-review process—in which journals ask researchers to help decide which studies to publish—to suppress opposing views.

Ioannidis was putting his contentions to the test not against run-of-the-mill research, or even merely well-accepted research, but against the absolute tip of the research pyramid. Of the 49 articles, 45 claimed to have uncovered effective interventions. Thirty-four of these claims had been retested, and 14 of these, or 41 percent, had been convincingly shown to be wrong or significantly exaggerated. If between a third and a half of the most acclaimed research in medicine was proving untrustworthy, the scope and impact of the problem were undeniable. That article was published in the Journal of the American Medical Association.

When a five-year study of 10,000 people finds that those who take more vitamin X are less likely to get cancer Y, you’d think you have pretty good reason to take more vitamin X, and physicians routinely pass these recommendations on to patients. But these studies often sharply conflict with one another. Studies have gone back and forth on the cancer-preventing powers of vitamins A, D, and E; on the heart-health benefits of eating fat and carbs; and even on the question of whether being overweight is more likely to extend or shorten your life. How should we choose among these dueling, high-profile nutritional findings? Ioannidis suggests a simple approach: ignore them all.

the odds are that in any large database of many nutritional and health factors, there will be a few apparent connections that are in fact merely flukes, not real health effects—it’s a bit like combing through long, random strings of letters and claiming there’s an important message in any words that happen to turn up.

nd these problems are aside from ubiquitous measurement errors (for example, people habitually misreport their diets in studies), routine misanalysis (researchers rely on complex software capable of juggling results in ways they don’t always understand), and the less common, but serious, problem of outright fraud (which has been revealed, in confidential surveys, to be much more widespread than scientists like to acknowledge).

And so it goes for all medical studies, he says. Indeed, nutritional studies aren’t the worst. Drug studies have the added corruptive force of financial conflict of interest. The exciting links between genes and various diseases and traits that are relentlessly hyped in the press for heralding miraculous around-the-corner treatments for everything from colon cancer to schizophrenia have in the past proved so vulnerable to error and distortion, Ioannidis has found, that in some cases you’d have done about as well by throwing darts at a chart of the genome.

Though scientists and science journalists are constantly talking up the value of the peer-review process, researchers admit among themselves that biased, erroneous, and even blatantly fraudulent studies easily slip through it.

Of those 45 super-cited studies that Ioannidis focused on, 11 had never been retested. Perhaps worse, Ioannidis found that even when a research error is outed, it typically persists for years or even decades. He looked at three prominent health studies from the 1980s and 1990s that were each later soundly refuted, and discovered that researchers continued to cite the original results as correct more often than as flawed—in one case for at least 12 years after the results were discredited.

Medical research is not especially plagued with wrongness. Other meta-research experts have confirmed that similar issues distort research in all fields of science, from physics to economics (where the highly regarded economists J. Bradford DeLong and Kevin Lang once showed how a remarkably consistent paucity of strong evidence in published economics studies made it unlikely that any of them were right).

Ioannidis initially thought the community might come out fighting. Instead, it seemed relieved, as if it had been guiltily waiting for someone to blow the whistle, and eager to hear more. David Gorski, a surgeon and researcher at Detroit’s Barbara Ann Karmanos Cancer Institute, noted in his prominent medical blog that when he presented Ioannidis’s paper on highly cited research at a professional meeting, “not a single one of my surgical colleagues was the least bit surprised or disturbed by its findings.” Ioannidis offers a theory for the relatively calm reception. “I think that people didn’t feel I was only trying to provoke them, because I showed that it was a community problem, instead of pointing fingers at individual examples of bad research,” he says. In a sense, he gave scientists an opportunity to cluck about the wrongness without having to acknowledge that they themselves succumb to it—it was something everyone else did.

The irony of his having achieved this sort of success by accusing the medical-research community of chasing after success is not lost on him, and he notes that it ought to raise the question of whether he himself might be pumping up his findings.

Tatsioni doesn’t so much fear that someone will carve out the man’s healthy appendix. Rather, she’s concerned that, like many patients, he’ll end up with prescriptions for multiple drugs that will do little to help him, and may well harm him. “Usually what happens is that the doctor will ask for a suite of biochemical tests—liver fat, pancreas function, and so on,” she tells me. “The tests could turn up something, but they’re probably irrelevant. Just having a good talk with the patient and getting a close history is much more likely to tell me what’s wrong.” Of course, the doctors have all been trained to order these tests, she notes, and doing so is a lot quicker than a long bedside chat. They’re also trained to ply the patient with whatever drugs might help whack any errant test numbers back into line.

patients often don’t even like it when they’re taken off their drugs, she explains; they find their prescriptions reassuring.

Already feeling that they’re fighting to keep patients from turning to alternative medical treatments such as homeopathy, or misdiagnosing themselves on the Internet, or simply neglecting medical treatment altogether, many researchers and physicians aren’t eager to provide even more reason to be skeptical of what doctors do—not to mention how public disenchantment with medicine could affect research funding.

being wrong in science is fine, and even necessary

“We were scared,” admitted Henrich. “We were warned that a lot of people were going to be upset.” “We were told we were going to get spit on,” interjected Norenzayan. “Yes,” Henrich said. “That we’d go to conferences and no one was going to sit next to us at lunchtime.”

The WEIRD mind also appears to be unique in terms of how it comes to understand and interact with the natural world. Studies show that Western urban children grow up so closed off in man-made environments that their brains never form a deep or complex connection to the natural world.

Children who grow up constantly interacting with the natural world are much less likely to anthropomorphize other living things into late childhood.

Despite these assurances, however, I found it hard not to read a message between the lines of their research. When they write, for example, that weird children develop their understanding of the natural world in a “culturally and experientially impoverished environment” and that they are in this way the equivalent of “malnourished children,” it’s difficult to see this as a good thing.

THE TURN THAT HENRICH, Heine, and Norenzayan are asking social scientists to make is not an easy one: accounting for the influence of culture on cognition will be a herculean task. Cultures are not monolithic; they can be endlessly parsed. Ethnic backgrounds, religious beliefs, economic status, parenting styles, rural upbringing versus urban or suburban—there are hundreds of cultural differences that individually and in endless combinations influence our conceptions of fairness, how we categorize things, our method of judging and decision making, and our deeply held beliefs about the nature of the self, among other aspects of our psychological makeup.

The job, experimental psychologists often assumed, was to push past the content of people’s thoughts and see the underlying universal hardware at work. “This is a deeply flawed way of studying human nature,” Norenzayan told me, “because the content of our thoughts and their process are intertwined.” In other words, if human cognition is shaped by cultural ideas and behavior, it can’t be studied without taking into account what those ideas and behaviors are and how they are different from place to place.

This new approach suggests the possibility of reverse-engineering psychological research: look at cultural content first; cognition and behavior second. Norenzayan’s recent work on religious belief is perhaps the best example of the intellectual landscape that is now open for study.

“I remember opening textbook after textbook and turning to the index and looking for the word ‘religion,’ ” he told me, “Again and again the very word wouldn’t be listed. This was shocking. How could psychology be the science of human behavior and have nothing to say about religion? Where I grew up you’d have to be in a coma not to notice the importance of religion on how people perceive themselves and the world around them.”

If religion was necessary in the development of large-scale societies, can large-scale societies survive without religion? Norenzayan points to parts of Scandinavia with atheist majorities that seem to be doing just fine. They may have climbed the ladder of religion and effectively kicked it away. Or perhaps, after a thousand years of religious belief, the idea of an unseen entity always watching your behavior remains in our culturally shaped thinking even after the belief in God dissipates or disappears.

almost every major theorist on human behavior in the last 100 years predicted that it was just a matter of time before religion was a vestige of the past. But the world persists in being a very religious place.

At its heart, the challenge of the WEIRD paper is not simply to the field of experimental human research (do more cross-cultural studies!); it is a challenge to our Western conception of human nature. For some time now, the most widely accepted answer to the question of why humans, among all animals, have so successfully adapted to environments across the globe is that we have big brains with the ability to learn, improvise, and problem-solve.

Henrich has challenged this “cognitive niche” hypothesis with the “cultural niche” hypothesis. He notes that the amount of knowledge in any culture is far greater than the capacity of individuals to learn or figure it all out on their own.

People are not “plug and play,” as he puts it, and you cannot expect to drop a Western court system or form of government into another culture and expect it to work as it does back home.

That we in the West develop brains that are wired to see ourselves as separate from others may also be connected to differences in how we reason, Heine argues. Unlike the vast majority of the world, Westerners (and Americans in particular) tend to reason analytically as opposed to holistically.

Heine and others suggest that such differences may be the echoes of cultural activities and trends going back thousands of years. Whether you think of yourself as interdependent or independent may depend on whether your distant ancestors farmed rice (which required a great deal of shared labor and group cooperation) or herded animals (which rewarded individualism and aggression).

These psychological trends and tendencies may echo down generations, hundreds of years after the activity or situation that brought them into existence has disappeared or fundamentally changed.

In the 1950s, when modern academic research took shape after its successes in the second world war, it was still a rarefied pastime.

Nowadays verification (the replication of other people’s results) does little to advance a researcher’s career. And without verification, dubious findings live on to mislead.

And as more research teams around the world work on a problem, the odds shorten that at least one will fall prey to an honest confusion between the sweet signal of a genuine discovery and a freak of the statistical noise.

The failure to report failures means that researchers waste money and effort exploring blind alleys already investigated by other scientists.

When a prominent medical journal ran research past other experts in the field, it found that most of the reviewers failed to spot mistakes it had deliberately inserted into papers, even after being told they were being tested.

One priority should be for all disciplines to follow the example of those that have done most to tighten standards. A start would be getting to grips with statistics, especially in the growing number of fields that sift through untold oodles of data looking for patterns.

Some government funding agencies, including America’s National Institutes of Health, which dish out $30 billion on research each year, are working out how best to encourage replication.

Stay Specific

Tinker Often, But Not Too Often

Seek Resistance

Revel in the Crafstmanship

“Great scientists tolerate ambiguity very well,” Hamming says. “They believe the theory enough to go ahead; [but] they doubt it enough to notice the errors and faults so they can step forward and create the new replacement theory.”

Many of us simply roll our eyes and click away when yet another medical study contradicts the last study—so what else is new? Coffee’s bad for you, until it’s good for you—and so is red wine. Antioxidants are essential, or they’re useless. And so on. Contradictory studies are an essential part of the science-news stream—and, in fact, an important part of science itself. But that doesn’t make it any less frustrating.

The fact that it didn’t, and that the two studies conflict, has unintentionally revealed a different truth about diet and aging. In both studies, the monkeys that ate less were healthier by a number of measures—and suffered far less from age-related disease. Even better, when taken together, both studies reveal a different path toward living a healthier life—one that doesn’t require self-starvation.

Over the years, various researchers have shown that caloric restriction can extend life in bats, dogs, and even spiders, and on down to nematode worms and single-celled organisms like yeast. After decades of work, it remains the only way known to increase maximum lifespan. So a lot is riding on the concept, scientifically speaking.

In the 1990s, Leonard Guarente of MIT discovered a class of longevity genes in yeast called sirtuins that appear to be activated by a lack of food. Sirtuins appeared to be “conserved” in evolution, meaning that they appear in nearly all species, on up to humans. Sirtuins are thought to have evolved as a way to enable animals to survive periods of famine. They seem to work by regulating certain metabolic pathways and reduce the amount of damage cells endure.

If researchers could somehow identify and isolate that mechanism, they’d be that much closer to some kind of longevity pill. Except for one inconvenient fact: Caloric restriction itself does not always work.

While 80 percent of the monkeys were still alive, the restricted animals had better measures of cardiovascular health, hormone levels, and blood-sugar management, an early indicator of diabetes risk. So it came as a bit of a surprise, eight years later, to find that the hungry monkeys are not actually living longer.

In fact, caloric restriction really seemed to work best in standard laboratory mice. This may be because they are predisposed to eat a lot, gain weight, and reproduce early—and thus are more sensitive to reduced food intake. (Slate’s Daniel Engber has written about how overfed lab mice have distorted scientific research.)

But in a long-awaited, well-funded monkey study like this, an “odd” result could not be ignored. Still stranger was the fact that even though the underfed monkeys were healthier than the others, they still didn’t live longer. They had lower incidence of cardiovascular disease, as well as diabetes and cancer—and when these diseases did appear, they did so later

At first, it seemed like a scientist’s nightmare: The control group is indistinguishable from the test group. In clinical trials, a result like this would kill any drug candidate. Then de Cabo took a closer look at a seemingly minor difference between the Wisconsin and NIA studies: the animals’ diets.

Furthermore, the NIA diet consisted of 4 percent sucrose—while in the Wisconsin diet, sucrose accounted for some 28 percent of the total calories.

“In physics, a calorie is a calorie,” says de Cabo. “In nutrition and animal physiology, there is more and more data coming out that says that the state of the animal is going to depend more on where the calories are coming from.”

In his study based on the two-year experience, Walford reported that the main effect of caloric restriction was to drastically lower his fellow crew members’ cholesterol levels, to 140 and below—well below the average for people in the industrialized world. Walford concluded that a calorie-restricted diet would have the same beneficial effects that he and other scientists had observed in mice.

Several studies have shown that excessive leanness—seen often in calorie-restricting humans—can be as risky as obesity. Taken together, these studies suggest that the optimal body-mass index is about 25, which is on the verge of being overweight.

But if it’s OK to be almost overweight, it might not pay to go beyond that. Another key difference between the two monkey studies has to do with the definition of “ad libitum.” While the Wisconsin control-group monkeys were allowed to stuff themselves, with the equivalent of an all-you-can-eat buffet for several hours at feeding times, the NIA monkeys were given a fixed amount of food. “You could view it as the Wisconsin monkeys were overindulging, like the rest of the American population,” says Rozalyn Anderson, a member of the Wisconsin team. Compared with           their Wisconsin brothers, then, the NIA monkeys in the non-calorie-restricted control group were arguably practicing a mild form of calorie restriction—and that, Anderson suggests, might have made a difference.

Higher levels of female obesity correlated with higher levels of gender inequality in each nation Of course, that’s not the impression you will get from the admonishments of public-health agencies and wellness businesses.

Yet the scientists who study the biochemistry of fat and the epidemiologists who track weight trends are not nearly as unanimous as Bloomberg makes out. In fact, many researchers believe that personal gluttony and laziness cannot be the entire explanation for humanity’s global weight gain.

Consider, for example, this troublesome fact, reported in 2010 by the biostatistician David B Allison and his co-authors at the University of Alabama in Birmingham: over the past 20 years or more, as the American people were getting fatter, so were America’s marmosets.

‘Virtually in every population of animals we looked at, that met our criteria, there was the same upward trend,’ he told me.

It isn’t hard to imagine that people who are eating more themselves are giving more to their spoiled pets, or leaving sweeter, fattier garbage for street cats and rodents. But such results don’t explain why the weight gain is also occurring in species that human beings don’t pamper, such as animals in labs, whose diets are strictly controlled. In fact, lab animals’ lives are so precisely watched and measured that the researchers can rule out accidental human influence

In rich nations, obesity is more prevalent in people with less money, education and status. Even in some poor countries, according to a survey published last year in the International Journal of Obesity, increases in weight over time have been concentrated among the least well-off. And the extra weight is unevenly distributed among the sexes, too.

The story might go like this: being poor is stressful, and stress makes you eat, and the cheapest food available is the stuff with a lot of ‘empty calories’, therefore poorer people are fatter than the better-off. These wheels-within-wheels are required because the mantra of the thermodynamic model is that ‘a calorie is a calorie is a calorie’: who you are and what you eat are irrelevant to whether you will add fat to your frame. The badness of a ‘bad’ food such as a Cheeto is that it makes calorie intake easier than it would be with broccoli or an apple.

More importantly, ‘things that alter the body’s fat metabolism’ is a much wider category than food. Sleeplessness and stress, for instance, have been linked to disturbances in the effects of leptin, the hormone that tells the brain that the body has had enough to eat.

If some or all of these factors are indeed contributing to the worldwide fattening trend, then the thermodynamic model is wrong.

According to Frederick vom Saal, professor of biological sciences at the University of Missouri, an organic compound called bisphenol-A (or BPA) that is used in many household plastics has the property of altering fat regulation in lab animals.

BPA has been used so widely — in everything from children’s sippy cups to the aluminium in fizzy drink cans — that almost all residents of developed nations have traces of it in their pee. This is not to say that BPA is unique.

Contrary to its popular image of serene imperturbability, a developing foetus is in fact acutely sensitive to the environment into which it will be born, and a key source of information about that environment is the nutrition it gets via the umbilical cord.

It’s possible that widespread electrification is promoting obesity by making humans eat at night, when our ancestors were asleep

consider the increased control civilisation gives people over the temperature of their surroundings.

Temperatures above and below the neutral zone have been shown to cause both humans and animals to burn fat, and hotter conditions also have an indirect effect: they make people eat less.

A study by Laura Fonken and colleagues at the Ohio State University in Columbus, published in 2010 in the Proceedings of the National Academy of Sciences, reported that mice exposed to extra light (experiencing either no dark at all or a sort of semidarkness instead of total night) put on nearly 50 per cent more weight than mice fed the same diet who lived on a normal night-day cycle of alternating light and dark.

A virus called Ad-36, known for causing eye and respiratory infections in people, also has the curious property of causing weight gain in chickens, rats, mice and monkeys.

xperiments by Lee Kaplan and colleagues at Massachusetts General Hospital in Boston earlier this year found that bacteria from mice that have lost weight will, when placed in other mice, apparently cause those mice to lose weight, too.

It might be that every one of the ‘roads less travelled’ contributes to global obesity; it might be that some do in some places and not in others. The openness of the issue makes it clear that obesity isn’t a simple school physics experiment.

In a capitalistic quest for new markets and cheap materials and labour, Europeans take control of the economy in the late 18th or early 19th century. With taxes, fees and sometimes violent repression, their new system strongly ‘encourages’ the farmer and his neighbours to stop growing their own food and start cultivating some more marketable commodity instead – coffee for export, perhaps. Now that they aren’t growing food, the farmers must buy it. But since everyone is out to maximise profit, those who purchase the coffee crop strive to pay as little as possible, and so the farmers go hungry. Years later, when the farmer’s children go to work in factories, they confront the same logic: they too are paid as little as possible for their labour. By changing the farming system, capitalism first removes traditional protections against starvation, and then pushes many previously self-sufficient people into an economic niche where they aren't paid enough to eat well.

Eighty years later, the farmer’s descendants have risen out of the ranks of the poor and joined the fast-growing ranks of the world’s 21st-century middle-class consumers, thanks to globalisation and outsourcing. Capitalism welcomes them: these descendants are now prime targets to live the obesogenic life (the chemicals, the stress, the air conditioning, the elevators-instead-of-stairs) and to buy the kinds of foods and beverages that are ‘metabolic disturbers’.

Wells memorably calls this double-bind the ‘metabolic ghetto’, and you can’t escape it just by turning poor people into middle-class consumers: that turn to prosperity is precisely what triggers the trap.

The ‘unifying logic of capitalism’, Wells continues, requires that food companies seek immediate profit and long-term success, and their optimal strategy for that involves encouraging people to choose foods that are most profitable to produce and sell — ‘both at the behavioural level, through advertising, price manipulations and restriction of choice, and at the physiological level through the enhancement of addictive properties of foods’ (by which he means those sugars and fats that make ‘metabolic disturber’ foods so habit-forming).

One possible response, of course, is to decide that no obesity policy is possible, because ‘science is undecided’. But this is a moron’s answer: science is never completely decided; it is always in a state of change and self-questioning, and it offers no final answers. There is never a moment in science when all doubts are gone and all questions settled,

Faced with signs of a massive public-health crisis in the making, governments are right to seek to do something, using the best information that science can render, in the full knowledge that science will have different information to offer in 10 or 20 years.

What The Spirit Level shows is that more equal societies enjoy better physical and mental health, lower homicide rates, fewer drug problems, fewer teenage births, higher maths and literacy scores, higher standards of child wellbeing, less bullying in schools, lower obesity rates, and fewer people in prison.

This left us with 23 rich market societies. We took our data from the best sources, such as the World Health Organisation, the United Nations and the World Bank. To double-check our findings, we then repeated our analyses for the 50 US states, to see if more unequal states showed the same consistent tendency to have more of these health and social problems. In almost 30 different cross-national analyses, we show the same tendency for one problem after another to be significantly worse in societies with bigger income differences.

Our critics also ignore the fact that these relationships have been widely demonstrated by other researchers. For example, as early as 1993 in the Criminal Justice Review, Hsieh and Pugh reviewed 34 studies of income inequality and violent crime and found a consistent correlation between the two—the authors estimated that it would need 58 new studies which found no effect in order to overturn this result. But studies since then have continued to confirm the link.

For the purposes of this article, we’ll focus on the fundamental difference between two major types of life-forms: those that have a cell wall but few or no internal subdivisions, and those that possess cells containing a nucleus, mitochondria, chloroplasts and other smaller substructures, or organelles.

Even before quorum sensing was discovered in V. fischeri, scientists had noted many examples of coordinated action, such as “swarming,” in which a colony of bacteria moves as a unit across a surface, and the development of “fruiting bodies,” in which bacteria glom together to form inert spores as a means of surviving severe environmental conditions.

Bacteria can live solitary lives, of course, but they prefer to aggregate in biofilms, also known as “slime cities.” Biofilms usually form on a surface, whether it’s the inner lining of the intestines or inside water pipes or on your teeth. In these close-knit colonies, bacteria coordinate group production of a slimy translucent coating and fibers called “curli” and “pili” that attach the colony to something else. Biofilms can harbor multiple types of bacteria as well as fungi and protists (microscopic eukaryotes). A complex vascular system for transporting nutrients and chemical signals through a biofilm may also develop. As Tim Friend described in his book The Third Domain, explorers diving to the wreck of the Titanic found these features in “rusticles” — draped colonies of microbes — feeding on the iron in the Titanic‘s hull and skeleton, more than 2 miles under the surface.

in practice, the medical notion of friendly microbes has yet to extend much past the idea that eating yogurt is good for you. For most doctors and medical microbiologists, microbes are enemies in a permanent war. Medicine certainly has good reason to view microbes as dangerous, since the germ theory of disease and the subsequent development of antibiotics are two of medical science’s greatest accomplishments.

When threatened, bacteria become defensive, often producing toxins that make the host even sicker. They also tend to speed up their acquisition of and purging of genes when under external selection pressure, of which antibiotics are an obvious and powerful example.

Gut bacteria play a role in obesity, which affects about a third of American adults.

Research in animals supports the idea that gut bacteria play a role in weight regulation.

bacteria produce some of the same types of neurotransmitters that regulate the function of the human brain.

it’s been known for a while that sick people get depressed and anxious. This seems so obvious as to be a no-brainer, but research suggests that some of the fear and fatigue associated with infections stems from immune responses affecting the brain.

As it turns out, however, very few bacteria can be grown in the relatively austere conditions of laboratories. In fact, only about 0.1 percent of all bacteria are currently culturable. Many bacteria don’t do well in monoculture, preferring to live in mixed communities of microorganisms. Those living in extreme temperatures and pressures require very specialized equipment to grow in a typical lab.

In fact, they wrote, the genes that enable these processes today “may have been distributed across a common global gene pool, before cellular differentiation and vertical genetic transmission evolved as we know it today.”

The grand story of human exceptionalism — the idea that humans are separate from and superior to everything else in the biosphere — has taken a terminal blow from the new knowledge about bacteria. Whether humanity decides to sanctify them in some way or merely admire them and learn what they’re really doing, there’s no going back.

15 of the 25 worst mass shootings in the last 50 years took place in the United States. Time has the full list here. In second place is Finland, with two entries.

Lots of guns don’t necessarily mean lots of shootings, as you can see in Israel and Switzerland.*

*Correction: The info is out-of-date, if not completely wrong. Israel and Switzerland have tightened their gun laws substantially, and now pursue an entirely different approach than the United States. More details here. I apologize for the error.

Of the 11 deadliest shootings in the US, five have happened from 2007 onward.

Kieran Healy, a sociologist at Duke University, made this graph of “deaths due to assault” in the United States and other developed countries. We are a clear outlier.

“The most striking features of the data are (1) how much more violent the U.S. is than other OECD countries (except possibly Estonia and Mexico, not shown here), and (2) the degree of change—and recently, decline—there has been in the U.S. time series considered by itself.”

In a subsequent post, Healy drilled further into the numbers and looked at deaths due to assault in different regions of the country. Just as the United States is a clear outlier in the international context, the South is a clear outlier in the national context:

“For all the attention given to America’s culture of guns, ownership of firearms is at or near all-time lows,” writes political scientist Patrick Egan. The decline is most evident on the General Social Survey, though it also shows up on polling from Gallup, as you can see on this graph:

The Harvard Injury Control Research Center assessed the literature on guns and homicide and found that there’s substantial evidence that indicates more guns means more murders. This holds true whether you’re looking at different countries or different states. Citations here.

Higher populations, more stress, more immigrants, and more mental illness were not correlated with more deaths from gun violence. But one thing he found was, perhaps, perfectly predictable: States with tighter gun control laws appear to have fewer gun-related deaths. The disclaimer here is that correlation is not causation. But correlations can be suggestive:

Since 1990, Gallup has been asking Americans whether they think gun control laws should be stricter. The answer, increasingly, is that they don’t. “The percentage in favor of making the laws governing the sale of firearms ‘more strict’ fell from 78% in 1990 to 62% in 1995, and 51% in 2007,” reports Gallup. “In the most recent reading, Gallup in 2010 found 44% in favor of stricter laws. In fact, in 2009 and again last year, the slight majority said gun laws should either remain the same or be made less strict.”

An August CNN/ORC poll asked respondents whether they favor or oppose a number of specific policies to restrict gun ownership. And when you drill down to that level, many policies, including banning the manufacture and possession of semi-automatic rifles, are popular.

Shootings don’t tend to substantially affect views on gun control. That, at least, is what the Pew Research Center found:

The research team of Raj Chetty, Nathaniel Herndon, Patrick Kline, and Emmanuel Saez looked at each "commuting zone" (CZ) within the U.S., and found that the American Dream is still alive in some parts of the country.

You can see what my colleague Derek Thompson calls the geography of the American Dream in the map below. It shows where kids have the best and worst chances of moving up from the bottom to the top quintile—and that the South looks more like a banana republic. (Note: darker colors mean there is less mobility, and lighter colors mean that there's more).

The researchers found that local tax and spending decisions explain some, but not too much, of this regional mobility gap. Neither does local school quality, at least judged by class size. Local area colleges and tuition were also non-factors. And so were local labor markets

1. Race. The researchers found that the larger the black population, the lower the upward mobility. But this isn't actually a black-white issue. It's a rich-poor one.

2. Segregation. Something like the poor being isolated—isolated from good jobs and good schools. See, the more black people a place has, the more divided it tends to be along racial and economic lines.

That leaves the poor in the ghetto

So it should be no surprise that the researchers found that racial segregation, income segregation, and sprawl are all strongly negatively correlated with upward mobility.

3. Social Capital. Living around the middle class doesn't just bring better jobs and schools (which help, but probably aren't enough). It brings better institutions too.

4. Inequality. The 1 percent are different from you and me—they have so much more money that they live in a different world.

it doesn't hurt your chances of making it into the top 80 to 99 percent if the super-rich get even richer.

But inequality does matter within the bottom 99 percent.

5. Family Structure. Forget race, forget jobs, forget schools, forget churches, forget neighborhoods, and forget the top 1—or maybe 10—percent. Nothing matters more for moving up than who raises you.

we don't really have any idea how to promote marriage.

Flat mobility is the defining Rorschach test of our time. Conservatives look at it, and say, see, we shouldn't worry about the top 1 percent, because they're not making the American Dream any harder to achieve. But liberals look at it, and say see, we should care about inequality, because it can make the American Dream harder to achieve—and it raises the stakes if you don't.

The American Dream is alive in Denmark and Finland and Sweden. And in San Jose and Salt Lake City and Pittsburgh.

But that raises another question: Could unusual environmental conditions be triggering intergroup chimpanzee killing?

When we first offered the chimps bananas the males seldom fought over their food; …now…there was a great deal more fighting than ever before." (This quote appears in Sussman and Marshack's paper.)

Ian Tattersall, an anthropologist at the American Museum of Natural History, told me that chimpanzee violence is "plausibly related to population stress occasioned by human encroachment."

Researchers have never observed coalitionary killing among bonobos. Noting that bonobos are just as genetically related to us as chimpanzees, Frans de Waal, a primatologist at Emory University, suggested last year in The Wall Street Journal that bonobos may be "more representative of our primate background" than are chimpanzees.

One author, anthropologist Owen Lovejoy of Kent State University, told me that Ardi has triggered a "tectonic shift" in views of human evolution.

There is also no fossil or archaeological evidence that our ancestors fought millions or even hundreds of thousands of years ago. Yes, archaeological digs and modern ethnography have established that warfare was common among pre-state societies, notably hunter–gatherers; our ancestors are thought to have lived as hunter–gatherers since the emergence of the Homo genus two million years ago.

But as the anthropologist Douglas Fry of Åbo Akademi University in Finland pointed out in his book Beyond War: The Human Potential for Peace (Oxford University Press, 2009), the oldest clear-cut relic of group violence is a 13,000-year-old grave along the Nile River in the Jebel Sahaba region of Sudan.

Evidence of earlier lethal human violence is ambiguous, at best.

But most Paleolithic injuries probably resulted from "hunting large animals who object to being speared," Trinkaus told me. "You find a lot of evidence of bumps and bruises and broken bones" among Neandertals and other early humans. "There is absolutely no evidence," Trinkaus says, that "war is continuous back to the common ancestor with chimps."

But reasoning comes later, works slower—and even then, it doesn't take place in an emotional vacuum.

In other words, when we think we're reasoning, we may instead be rationalizing.

Ironically, in part because researchers employ so much nuance and strive to disclose all remaining sources of uncertainty, scientific evidence is highly susceptible to selective reading and misinterpretation.

people's deep-seated views about morality, and about the way society should be ordered, strongly predict whom they consider to be a legitimate scientific expert in the first place—and thus where they consider "scientific consensus" to lie on contested issues.

In Kahan's research [13] (PDF), individuals are classified, based on their cultural values, as either "individualists" or "communitarians," and as either "hierarchical" or "egalitarian" in outlook.

The results were stark: When the scientist's position stated that global warming is real and human-caused, for instance, only 23 percent of hierarchical individualists agreed the person was a "trustworthy and knowledgeable expert." Yet 88 percent of egalitarian communitarians accepted the same scientist's expertise.

A key question—and one that's difficult to answer—is how "irrational" all this is. On the one hand, it doesn't make sense to discard an entire belief system, built up over a lifetime, because of some new snippet of information. "It is quite possible to say, 'I reached this pro-capital-punishment decision based on real information that I arrived at over my life,'" explains Stanford social psychologist Jon Krosnick [21]. Indeed, there's a sense in which science denial could be considered keenly "rational." In certain conservative communities, explains Yale's Kahan, "People who say, 'I think there's something to climate change,' that's going to mark them out as a certain kind of person, and their life is going to go less well."

people gravitate toward information that confirms what they believe, and they select sources that deliver it. Same as it ever was, right? Maybe, but the problem is arguably growing more acute, given the way we now consume information

a higher education correlated with an increased likelihood of denying the science on the issue.

one insidious aspect of motivated reasoning is that political sophisticates are prone to be more biased than those who know less about the issues.

It all raises the question: Do left and right differ in any meaningful way when it comes to biases in processing information, or are we all equally susceptible?

In a study of nearly 400 employees, published last year, researchers found that sleeping too little — defined as less than six hours each night — was one of the best predictors of on-the-job burn-out. A recent Harvard study estimated that sleep deprivation costs American companies $63.2 billion a year in lost productivity.

Daytime naps have a similar effect on performance. When night shift air traffic controllers were given 40 minutes to nap — and slept an average of 19 minutes — they performed much better on tests that measured vigilance and reaction time.

Longer naps have an even more profound impact than shorter ones. Sara C. Mednick, a sleep researcher at the University of California, Riverside, found that a 60- to 90-minute nap improved memory test results as fully as did eight hours of sleep.

The importance of restoration is rooted in our physiology. Human beings aren’t designed to expend energy continuously. Rather, we’re meant to pulse between spending and recovering energy.

we sleep in cycles of roughly 90 minutes, moving from light to deep sleep and back out again. They named this pattern the Basic-Rest Activity Cycle or BRAC. A decade later, Professor Kleitman discovered that this cycle recapitulates itself during our waking lives.

Along the way, I learned that it’s not how long, but how well, you renew that matters most in terms of performance. Even renewal requires practice. The more rapidly and deeply I learned to quiet my mind and relax my body, the more restored I felt afterward. For one of the breaks, I ran. This generated mental and emotional renewal, but also turned out to be a time in which some of my best ideas came to me, unbidden. Writing just four and half hours a day, I completed both books in less than six months and spent my afternoons on less demanding work.

Our basic idea is that the energy employees bring to their jobs is far more important in terms of the value of their work than is the number of hours they work. By managing energy more skillfully, it’s possible to get more done, in less time, more sustainably. In a decade, no one has ever chosen to leave the company. Our secret is simple — and generally applicable. When we’re renewing, we’re truly renewing, so when we’re working, we can really work.