ORLANDO, Fla. — Weight gain may depend on how an individual’s genes react to certain diets, a new study in mice suggests.
Four strains of mice fared differently on four different diets, William Barrington of North Carolina State University in Raleigh reported July 15 at the Allied Genetics Conference.
One strain, the A/J mouse, was nearly impervious to dietary changes. Those mice didn’t gain much weight or have changes in insulin or cholesterol no matter what they ate: a fat-and-carbohydrate-laden Western diet, traditional Mediterranean or Japanese diet (usually considered healthy) or very low-carbohydrate, fat-rich fare known as the ketogenic diet. In contrast, NOD/ShiLtJ mice gained weight on all but the Japanese diet. Those mice’s blood sugar shot up — a hallmark of diabetes — on a Mediterranean diet, but decreased on the Japanese diet.
FVB/NJ mice didn’t get fat on the Western diet, but became obese and developed high cholesterol and other health problems on the ketogenic diet. The opposite was true for C57BL/6J mice. They became obese and developed cholesterol and other problems linked to heart disease and diabetes in people on the Western diet, but not on the ketogenic diet. They also fattened up on the Mediterranean diet.
The results indicate that “there’s no universally healthy diet,” Barrington said. The findings echo results of a human study in which blood sugar rose in some people after eating some foods, even when the same food had no effect on other people (SN: 1/9/16, p. 8). Such individual reactions to food suggest that diets should be personalized.
Barrington and colleagues are working to find the genes that control the mouse strains’ varying responses to what they eat. There is still no way to predict how people will fare on a given diet, he said.
WASHINGTON — When bacteria lose genes needed to make enzymes for important chemical reactions, defeat isn’t inevitable. Sometimes other enzymes will take on new roles to patch together a work-around chain of reactions that does the job, biologist Shelley Copley reported August 4 at the 2nd American Society for Microbiology Conference on Experimental Microbial Evolution.
Bacteria that can adapt in this way are more likely to survive when living conditions change, passing along these new tricks to their descendants. So studying these biochemical gymnastics is helping scientists to understand how evolution works on a molecular level. Working with different strains of Escherichia coli bacteria, Copley and colleagues deleted genes responsible for making crucial enzymes. The team then watched the microbes replicate for many generations to see how they worked around those limitations.
Most enzymes are highly specialized: They only work well to speed up one type of reaction, the way a key fits only one lock. But some enzymes are more like master keys — they can boost multiple reactions, though they tend to specialize in one. These so-called “promiscuous” enzymes can switch away from their specialty if conditions change.
Copley’s team found that new enzymes would sub in to replace the missing ones. For instance, E. coli missing an enzyme needed to make vitamin B6 synthesized the vitamin using a different set of enzymes. But surprisingly, the promiscuous enzymes didn’t end up directly triggering the same reaction as the enzymes they replaced. Instead, the replacement enzymes cobbled together a different (often longer) work-around series of reactions that ultimately achieved the same function.
“We were rerouting metabolism,” said Copley, of the University of Colorado Boulder.
By modifying the bacteria’s genes and forcing the microbes to survive with a more limited chemical toolkit, Copley’s work gives a more detailed look at the biochemistry underlying evolution, says biologist Gavin Sherlock of Stanford University, who was not involved in the research. Betul Kacar, a synthetic biologist at Harvard University, says promiscuity could also be a window into the past, giving hints about enzymes’ previous roles earlier in evolutionary history. The role that an enzyme jumps in to play in a pinch could have once been its main job. “Trying to understand how novel pathways arise, what kind of mechanistic underlying forces shape those trajectories, is quite essential,” she says.
Bacteria can piece together all sorts of alternative routes in response to missing enzymes, depending on specific environmental conditions, Copley said. The ones that are most successful are more efficient —they have fewer steps, or they yield more of the desired reaction product.
Science’s human side In “The SN 10: Scientists to Watch” (SN: 10/1/16, p. 16), Science News recognized 10 up-and-coming scientists across a range of scientific fields who will be answering big questions in the decades to come.
Barry Maletzky thought that highlighting 10 young scientists may have been unfair and detrimental to other researchers. “By drawing attention to just 10, I wonder if you are thereby discouraging others who may not make the headlines but whose basic research may lead the way toward important discoveries in the future,” Maletzky said. He also pointed out that scientific progress is made “through the tedious and often under-publicized work of a number of investigators working barely noticed through the years.” It’s true that in science journalism, as with all journalism, what you choose to cover can matter as much as how you choose to cover it, says Elizabeth Quill, Science News’ enterprise editor, who led the SN 10 project. Science News editors and writers take this responsibility seriously, which is why Science News avoided terms like “top,” “best” and other superlatives. Whenever possible, the names of mentors and collaborators were also included in the stories. “We recognize the dangers in calling out specific individuals, but we believe the rewards outweigh the risks,” Quill says. “The majority of Science News focuses on the data and the process. But here we see a different side. We are showing science as a human endeavor. We hope this list inspires all young scientists to follow their passion and their curiosity. But we also hope to do what we do best — inform our readers about new and interesting science.”
Kenneth Abate was disappointed by “The SN 10: Scientists to Watch” profiles and questioned how Science News chose the researchers. “The issue is probably a nice piece of advertising for the individuals to further their careers,” Abate said. However, it “is of little value to the scientific community nor does it contribute to the knowledge bank of those scientists or would-be scientist readers.” Choosing is never easy, but thankfully Science News staff didn’t do it alone. Every featured scientist was nominated by a Nobel laureate or recently elected member of the National Academy of Sciences on the basis of the scientist’s contributions to the field and promise for future contributions. As they do with any news or feature story, Science News editors and writers selected the final list of scientists by looking at who was doing novel, interesting and important work. As readers point out, the list could have easily been much, much longer.
Cool it The next big thing in high-tech clothing may be a plastic material similar to kitchen cling wrap that vents body heat, Meghan Rosen reported in “New fabric could make cool clothes” (SN: 10/1/16, p. 9).
Online reader Karl Chwe pointed out one potential drawback to the new material: “It is just a thin plastic film with tiny holes, and the holes aren’t big enough to allow water vapor to escape easily, so it doesn’t allow evaporative cooling,” he wrote. Chwe suggested that it might be better to wear fewer clothes.
Actually, the nanopores are permeable to water vapor, the authors reported. “In this regard, the new fabric is comparable to cotton,” Rosen says. “Without the nanopores, the fabric would be a literal sweat suit; it’s completely nonpermeable.” But even with pores, the fabric doesn’t quite feel like normal clothes just yet. Weaving the fibers into a textile could help. Still, when it comes to evaporative cooling, Rosen says, wearing fewer clothes might be the simplest solution of all.
Correction “A gut check gets personal” (SN: 10/1/16, p. 19) profiles Lawrence David, a computational biologist who studies the human gut microbiome at Duke University. David’s wife is a psychiatrist, not a psychologist as was incorrectly stated in the article.
Iridescent blue leaves on some begonias aren’t just for show — they help the plants harvest energy in low light.
The begonias’ chloroplasts, which use photosynthesis to convert light into fuel, have a repeating structure that allows the plants to efficiently soak up light. This comes in handy for a plant that lives on the shady forest floor. The structure acts as a “photonic crystal” that preferentially reflects blue wavelengths of light and helps the plant better absorb reds and greens for energy production, scientists report October 24 in Nature Plants. Colors in plants and animals typically come from pigments, chemicals that absorb certain wavelengths, or colors, of light. In rare cases, plants and animals derive their hues from microstructures. In begonias, such tiny, regular architectures can be found within certain chloroplasts, known as iridoplasts. As light bounces off these structures within an iridoplast, the reflected waves interfere at certain wavelengths (SN: 6/7/08, p. 26), creating a blue, iridescent shimmer. Those structured chloroplasts also offer a survival benefit, the new research shows: They help the plants collect light. In a hybrid of two species — Begonia grandis and Begonia pavonina — the structures enhance the absorption of green and red wavelengths by concentrating these rays on light-absorbing compartments within the iridoplasts. Importantly, the structures slow the light. The “group velocity,” or the speed of a packet of light waves, is decreased due to interference between incoming and reflected light. The slowdown gives the plant more time to absorb precious sunbeams.
“These iridoplasts can basically photosynthesize at low-light levels where normal chloroplasts just simply could not photosynthesize,” says study coauthor Heather Whitney, a plant biologist at the University of Bristol in England. Iridoplasts, however, can’t hold their own in bright light. So begonias also have standard chloroplasts, which provide energy in plentiful sunshine. Iridoplasts act like “a backup generator” in dim conditions, Whitney says.
Other plants have structured chloroplasts, too, so begonias might not be alone in their feats of light manipulation. “Plants can’t really run away from their problems,” Whitney says. Instead, they have to be crafty enough to survive where they stand.
When looking for love, some small-mouthed salamanders can really go the distance.
These intrepid amphibians (Ambystoma texanum) will risk death and dehydration to travel almost nine kilometers on average and as far as 14 to find a mate, researchers report December 20 in Functional Ecology. But all-female populations of a closely related group of salamanders that reproduce by cloning can’t go nearly as far.
Scientists tested the amphibians’ endurance on tiny treadmills. Then the team analyzed genetic differences between salamanders in patches of Ohio wetlands to see how far the amphibians might roam in the wild. Unisexual salamanders could only go a quarter of the treadmill distance that the small-mouthed salamanders could. And in the wild, they only dispersed about half as far from the pools where they were born. By making the treacherous trek to a different pool to mate, A. texanum salamanders can mix up their genes and keep healthy variation in each population. Unisexual salamanders may have less stamina because they don’t mate in the usual way. Instead of searching for the perfect partner, they steal sperm from nearby male salamanders of different species. The sperm kick-start egg production but rarely actually fertilize eggs; only occasionally does a male’s DNA sneak into a female’s offspring.
Ditching the guys can be efficient — every member of an all-female population can give birth, and that means more babies. But it seems that going it alone has drawbacks, too: These salamanders’ poorer endurance could be a disadvantage if environmental changes forced them to colonize new territory.
Scientists have produced a new form of hydrogen in the lab — negatively charged hydrogen clusters.
Each cluster consists of hydrogen molecules arranged around a negatively charged hydrogen ion — a single hydrogen atom with an extra electron — at temperatures near absolute zero, the researchers report in the Dec. 30 Physical Review Letters. Similar, positively charged ion clusters have previously been found, but this is the first time scientists have seen negative hydrogen cluster ions beyond the simplest possible pairing of one molecule and one ion. Physicist Michael Renzler of the University of Innsbruck in Austria and colleagues infused tiny droplets of liquid helium with hydrogen gas. Then, the scientists bombarded the droplets with a beam of electrons, which converted some hydrogen molecules into negatively charged hydrogen ions. Neighboring hydrogen molecules (two bonded hydrogen atoms) clustered around the ion, in groups of a few molecules to over 60.
The scientists also determined the geometric structures of the clusters. Hydrogen molecules organized into shells that surrounded the central ion. Clusters were most stable, and most common, when molecules filled shells to their capacity. In the first shell, for example, the cluster formed an icosahedron — a 3-D shape with 12 vertices — when 12 molecules filled this shell.
In space, hydrogen cluster ions might form naturally in cold, dense clouds of hydrogen or in atmospheres of gas giant planets.
The quantitative abilities of lizards may have their limits.
From horses to salamanders, lots of different species display some form of number sense, but the phenomenon hasn’t been investigated in reptiles. So a team of researchers in Italy set up two experiments for 27 ruin lizards (Podarcis sicula) collected from walls on the University of Ferrara’s campus. In the first test, the team served up two house fly larvae of varying sizes. Lizards consistently chose to scarf down bigger maggots.
Then in the second experiment, the researchers gave lizards a choice between different numbers of larvae that were all the same size. The lizards didn’t show a preference. While the data suggest that the reptiles do discriminate between larger and smaller prey, they don’t distinguish between higher and lower numbers of maggots in a meal, the scientists report April 12 in Biology Letters.
The researchers cite two potential explanations for the discrepancy. Selecting larger prey rather than more prey might sometimes be advantageous for a predator. Or reptiles simply lack the numerical know-how seen in vertebrate relatives, such as fish.
Editor’s note: This story was updated April 17, 2017, to replace the previous image of a Podarcis muralis lizard with one that shows P. sicula, the species used in the study.
The rift in Antarctica’s Larsen C ice shelf continues to rip. Researchers from Project MIDAS, which tracks the effects of a warming climate on the ice shelf, report that the crack grew 17 kilometers between May 25 and May 31.
The crack has now turned toward the water and is within 13 kilometers of the edge of the shelf. Within days, the crack could reach the edge. When that happens, one of the largest icebergs ever recorded will fall into the ocean.
“There appears to be very little to prevent the iceberg from breaking away completely,” the researchers write.
After calving such a massive section, the shelf won’t be stable. It may experience the same fate as Larsen B, which disintegrated in 2002, after a crack there broke off a huge chunk of ice.
In pumped-up sequels for scary beach movies, each predator is bigger than the last. Turns out that predators in real-world oceans may have upsized over time, too.
Attack holes in nearly 7,000 fossil shells suggest that drilling predators have outpaced their prey in evolving ever larger bodies and weapons, says paleontologist Adiël Klompmaker of the University of California, Berkeley. The ability to drill through a seashell lets predatory snails, octopuses, one-celled amoeba-like forams and other hungry beasts reach the soft meat despite prey armor. Millions of years later, CSI Paleontology can use these drill holes to test big evolutionary ideas about the power of predators. “Predators got bigger — three words!” is Klompmaker’s bullet point for the work. Over the last 450 million years or so, drill holes have grown in average size from 0.35 millimeters to 3.25 millimeters, Klompmaker and an international team report June 16 in Science. Larger holes generally mean larger attackers, the researchers say, after looking at 556 modern drillers and the size of their attack holes.
Prey changed over millennia, too, but there’s no evidence for a shift in body size. The ratio of drill-hole size to prey size became 67 times greater over time, the researchers conclude.
It’s “the rise of the bullies,” says coauthor Michal Kowalewski of the University of Florida in Gainesville.
All these data on shell holes allow researchers to test a key part of what’s called the escalation hypothesis. In 1987, Geerat Vermeij proposed a top-down view of evolutionary change, where predators, competitors and other enemies growing ever more powerful drive the biggest changes in their victims. This wasn’t so much an arms race between predators trading tit for tat with their prey as a long domination of underdogs repeatedly stomped by disproportionate menace. (Unless the prey somehow flips the relationship and can do deadly harm in return.) Vermeij, now at the University of California, Davis, and others have drawn on escalating threats to explain prey evolutionary innovations in thick shells, spines and spikes, mobility, burrowing lifestyles and toxins. One aspect of escalation scenarios has been especially hard to test: the idea that predators can become more dangerous and a stronger evolutionary force over time. Drill holes suggesting bigger, more powerful attackers allowed a rare way of exploring the idea, Klompmaker says. He now reads the deep history as showing predators escalated in size, but prey didn’t.
The energetics worked out, in large part, because early hard-shelled prey called brachiopods — a bit like clams but with one shell-half larger than the other — became scarcer over time, while clams and their fellow mollusks grew abundant. Mollusks typically have more flesh inside their shells than brachiopods, and prey overall grew denser on the ocean bottom. Killer drillers, able to dine at this buffet, could thus support bigger bodies even when prey size wasn’t rising, too.
Prey don’t make drilling easy, Klompmaker says. An hour’s work gets a typical modern predatory snail only about 0.01 to 0.02 millimeters deeper into a mollusk shell. So finally striking lunch could take days of effort with the thickest shells. And that’s with specialty equipment: A snail alternates grinding away using a hard, rasplike driller and then switching to its accessory boring organ that releases acids and enzymes, weakening the drilling spot for the next bout.
The role of such animal clashes in evolution has been notoriously difficult to study, says marine ecologist Nick Dulvy of Simon Fraser University in Burnaby, Canada. Nutrients, climate and other factors that don’t swim away into the blue are much easier to measure. Even after a robust century of ecological study, “the discoveries that otters propped up kelp forests, triggerfishes garden coral reefs, and wolves and cougars create lush diverse watersheds are comparatively recent,” Dulvy says. Until the new drill-hole study, he could think of only one earlier batch of evidence (crabs preying on mollusks) for the long rise of predators as an evolutionary force.
The story from drill holes, says Vermeij, is “very convincing.”
A string of state-directed, targeted mass killings left a bloody stain on the 20th century. A genocide more recent than the Holocaust is providing new insights into why some people join in such atrocities.
Adolf Hitler’s many accomplices in his campaign to exterminate Jews throughout Europe have justifiably attracted the attention of historians and social scientists. But a 100-day spasm of unprecedented violence in 1994 that wiped out about three-quarters of the ethnic Tutsi population in the African nation of Rwanda has the potential to reveal much about how mass killings unfold at ground level. There is no guarantee that a better, although inevitably incomplete, understanding of why certain members of Rwanda’s majority Hutu population nearly eliminated a Tutsi minority will prevent future large-scale slaughters. The research is worth the effort, though, especially in a 21st century already marked by massacres of hundreds of thousands of people in western Sudan’s Darfur region and in Syria.
Researchers have an advantage in Rwanda. When hostilities ended, Rwanda’s government gathered extensive data on genocide victims and suspected perpetrators through a national survey. And local courts tried more than 1 million cases of alleged involvement in the violence, making the case documents available to researchers.
Genocide studies have often split offenders into organizers — mainly political and community leaders — and “ordinary men” who kill out of blind obedience to central or local authorities and hatred of those deemed enemies. But the extensive data from Rwanda tell a different story: An individual’s willingness to take part in genocidal violence depends on many personal and social factors that influence whether and how deeply a person participates, says sociologist and Rwanda genocide researcher Hollie Nyseth Brehm of Ohio State University in Columbus.
Nyseth Brehm’s findings may not apply to some of Rwanda’s most avid killers, who eluded capture and fled the country as soon as hostilities stopped. But when it comes to the ordinary citizens swept up in the deadly campaign, involvement was not primarily about following political leaders’ orders to eliminate Tutsis.
New reports by Nyseth Brehm and others fuel skepticism about the popular idea that regular folks tend to do as they’re told by authorities. And a fresh look at a famous 1960s psychology study adds further doubt that people will blindly follow orders to harm or kill others. In reality, only about 20 percent of Hutu men, an estimated 200,000, seriously injured or killed at least one person during the genocidal outbreak, estimates Rwanda genocide researcher Omar McDoom of the London School of Economics and Political Science.
“Why did four in five Hutu men not engage in the killing?” McDoom asks. That puzzle goes against the ordinary man thesis that “implies there are no individual differences in genocide participation,” he says. He suspects participation hinged on personal motivations, such as wanting to defend Rwanda from enemies or make off with a Tutsi neighbor’s possessions. Social circumstances, such as living in high-violence areas or having friends or family members who had already murdered Tutsis, probably played a role too. Nyseth Brehm agrees.
Local triggers Genocides often fester before exploding. In Rwanda, Tutsi rebels attacked the Hutu-led government and set off a civil war several years before mass killings started. A turning point came when unidentified forces killed Rwanda’s president, shooting down his plane on April 6, 1994. Over the next three months, the government orchestrated a massacre of Tutsis and any Hutus deemed friendly or helpful to Tutsis. Most scholars place the death toll at around 800,000, although estimates range from 500,000 to 1.2 million. Bands of Hutus scoured the countryside for their sworn enemies. Killings took place at roadblocks and in raids on churches, schools and other community facilities. Hutu women killed on a much smaller scale than men did, although they often aided those involved in the carnage.
In many parts of Rwanda, local authorities appointed by the national government recruited Hutu men into groups that burned and looted homes of their Tutsi neighbors, killing everyone they encountered, says political scientist Scott Straus of the University of Wisconsin–Madison. In his 2016 book Fundamentals of Genocide and Mass Atrocity Prevention, Straus describes how Rwandan recruitment efforts coalesced into a killing machine. Politicians, business people, soldiers and others encouraged Hutu farmers to kill an enemy described as “cockroaches” in need of extermination. Similarly, Nazis portrayed Jews as cockroaches and vermin.
Despite the Rwandan state’s best efforts to encourage nationwide Tutsi annihilation, local conditions shaped how the 1994 genocide unfolded, Nyseth Brehm reported in February in Criminology. She looked at 142 of the nation’s 145 municipalities, known as communes. Some experienced as few as 71 killings, while in others, as many as 54,700 people were murdered, she found.
Communes with the fewest killings were those that had the highest marriage and employment rates, Nyseth Brehm says. In those settings, mainly farming communities where people knew and trusted each other, most citizens valued a peaceful status quo and discouraged a descent into mass killing, she suspects. Curiously, violence was worse in areas with the largest numbers of educated people. That points to the effectiveness of anti-Tutsi teachings in Rwandan schools, Nyseth Brehm suggests.
Her study relied on data from a postgenocide survey, published in 2004 by Rwanda’s government, intended to document every person killed during the atrocity. Citizens throughout Rwanda told interviewers about individuals in their communities who had been killed during the outburst of slaughter. Reported and confirmed deaths were checked against records of human remains linked to the 1994 genocide. Comparisons were also made to Rwanda’s 1991 census.
However, any data on killings during mass violence, including from the Rwandan survey, will be incomplete, Nyseth Brehm cautions. So she also analyzed data from 1,068,192 genocide-related cases tried in local Rwandan courts from 2002 to 2012. Of particular note, although most nongenocidal murders in Rwanda are carried out by men in their 20s, the average age of accused genocide perpetrators was 34.7 years old, Nyseth Brehm reported in the November 2016 Criminology.
Hutu men in their 30s joined the genocidal fray as a way to fulfill adult duties by defending their communities against an outside threat, she suggests. Preliminary analyses show that perpetrators tended to cluster in families; if one of several brothers killed Tutsis, the others were far more likely to follow suit.
Additional scouring of court data indicated that Rwandans who had siblings convicted of genocide killings were especially likely to have murdered Tutsis themselves. In earlier interviews of 130 Rwandans, some who had killed Tutsis and others who hadn’t, McDoom similarly found that perpetrators tended to cluster in families.
Missing murderers Unfortunately, the Rwandan genocide’s most prolific players have eluded both the law and science, says political scientist Cyanne Loyle of Indiana University Bloomington. Investigators have so far interviewed only a handful of the powerful “big fish” who orchestrated the genocide, plus several hundred people tried and imprisoned for genocide participation. Survey and court data are limited to killers who either stayed in Rwanda after atrocities ended or were caught trying to flee the country.
But perpetrators with the most blood on their hands traveled in bands, wiping out tens of thousands of people at a time before hiding abroad, Loyle says. For instance, local officials lured large numbers of Tutsis to a school near the town of Murambi, where Hutu militias used machine guns, explosives and other weapons to kill more than 40,000 people in just three days.
“Scholars have studied Rwandans who killed on the sidelines while a larger and deadlier campaign was under way,” Loyle says. “They have mistaken a sideshow for the main event.”
Perpetrators of colossal atrocities at Murambi and elsewhere were less powerful than the government’s genocide masterminds, Loyle says. These “murderers in the middle,” however, were better equipped and far more effective at killing than common folk who got caught up in events, she contends.
There are no good estimates of how many members of large-scale killing squads escaped Rwanda and now live elsewhere. From 15,000 to 22,000 members of the Rwandan army and local militia groups were at large in the Democratic Republic of the Congo, near Rwanda’s border, in January 2003, according to a report by the International Crisis Group, a nonprofit organization.
Nyseth Brehm acknowledges the difficulty of accounting for genocide perpetrators who eluded justice. She and others, including Straus, have interviewed genocide offenders who stayed in Rwanda, often imprisoned for their crimes. Many of those who fled must have traveled in groups that murdered on a grand scale, she says. Those mass killers represent crucial missing data on who participates in genocide, and for what reasons. Vicious virtue In interviews by Nyseth Brehm, McDoom and others, perpetrators listed many reasons for joining the 1994 killing spree — hatred of Tutsis, a perceived need to protect nation and family, a desire to claim a neighbor’s property or a decision to join a suddenly popular cause, to name a few. Blind obedience to brutal leaders was far from the only reason cited.
That finding conflicts with the late psychologist Stanley Milgram’s interpretation of his famous “obedience to authority” experiments. Milgram described those trials, in which volunteers were told to administer increasingly intense shocks to another person, as a demonstration of people’s frequent willingness to follow heinous commands. He saw the experiments as approximating the more extreme situations in which Germans had participated in the Holocaust. On closer inspection, though, Milgram’s study aligns closely with what’s known about Rwandan genocide perpetrators, says S. Alexander Haslam, a psychologist at the University of Queensland in Australia. In Milgram’s experiments, as in Rwanda and Nazi Germany, “those willing to harm others were not so much passive ciphers as motivated instruments of a collective cause,” Haslam says. “They perceived themselves as acting virtuously and doing good things.”
Although Milgram’s tests upset some volunteers, most participants identified with his scientific mission to understand human behavior and wanted to prove themselves as worthy of the project, Haslam and psychologist Stephen Reicher of the University of St. Andrews in Fife, Scotland, conclude in a research review scheduled to appear in the 2017 Annual Review of Law and Social Science.
Milgram conducted 23 obedience experiments with New Haven, Conn., residents in 1961 and 1962 (SN: 9/21/13, p. 30). Most attention has focused on only one of those experiments. Volunteers designated as “teachers” were asked by an experimenter to continue upping the intensity of what they thought were electric shocks to a “learner” — who was actually in league with Milgram — who erred time and again on a word-recall test. Through screams, shouts and eventually dead silence from the learner, 26 of 40 volunteers, or 65 percent, administered shocks all the way to a maximum of 450 volts.
But experiments that undermined participants’ identification with the scientific mission lowered their willingness to deliver the harshest shocks, Haslam and Reicher say. Fewer volunteers shocked to the bitter end if, for instance, the study was conducted in an office building rather than a university laboratory or if the experimenter was not physically present. An analysis of data available from 21 of the 23 experiments finds that 43.6 percent of 740 volunteers shocked learners to the limit. Participants were most compliant when an experimenter encouraged them to continue shocking for the sake of the experiment (by saying, “The experiment requires that you continue”), the psychologists add. Participants never followed the order: “You have no choice, you must continue.”
Milgram’s archives at Yale University contain letters and survey responses from former participants reporting high levels of support for Milgram’s project and for science in general. Many former volunteers told Milgram that they administered shocks out of a duty to collaborate on what they viewed as important research, even if it caused them distress at the time. Still, Milgram’s recruits often admitted having had suspicions during the experiments that learners were not really being zapped.
Milgram was right that his experiments applied to real-world genocides, Haslam concludes, but erred in assuming that obedience to authority explained his results. From Milgram’s laboratory to Rwanda’s killing squads and Nazi concentration camps, orders to harm others are carried out by motivated followers, not passive conformists, he asserts.
If anything, that makes genocide all the more horrifying.
