Chapter 15. Emotions, Aggression, and Stress
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
Julie Beck When Paul Ekman was a grad student in the 1950s, psychologists were mostly ignoring emotions. Most psychology research at the time was focused on behaviorism—classical conditioning and the like. Silvan Tomkins was the one other person Ekman knew of who was studying emotions, and he’d done a little work on facial expressions that Ekman saw as extremely promising. “To me it was obvious,” Ekman says. “There’s gold in those hills; I have to find a way to mine it.” For his first cross-cultural studies in the 1960s, he traveled around the U.S., Chile, Argentina, and Brazil. In each location, he showed people photos of different facial expressions and asked them to match the images with six different emotions: happiness, sadness, anger, surprise, fear, and disgust. “There was very high agreement,” Ekman says. People tended to match smiling faces with “happiness,” furrow-browed, tight-lipped faces with “anger,” and so on. But these responses could have been influenced by culture. The best way to test whether emotions were truly universal, he thought, would be to repeat his experiment in a totally remote society that hadn’t been exposed to Western media. So he planned a trip to Papua New Guinea, his confidence bolstered by films he’d seen of the island’s isolated cultures: “I never saw an expression I wasn’t familiar with in our culture,” he says. Once there, he showed locals the same photos he’d shown his other research subjects. He gave them a choice between three photos and asked them to pick images that matched various stories (such as “this man’s child has just died”). Adult participants chose the expected emotion between 28 and 100 percent of the time, depending which photos they were choosing among. (The 28 percent was a bit of an outlier: That was when people had to choose between fear, surprise, and sadness. The next lowest rate was 48 percent.) © 2014 by The Atlantic Monthly Group.
Link ID: 20619 - Posted: 02.26.2015
By Sandhya Sekar It’s stressful being a low-ranking hyena—so stressful that even their chromosomes feel it. Researchers have discovered that the challenges of African savanna hyena society shorten underdogs’ telomeres, stretches of DNA that bookend chromosomes and protect them from wear and tear during cell replication. The stress may come from the top hyenas getting the best meat, whereas lower ranking individuals have to travel long distances—sometimes to the edges of the group territory—to fend for themselves. With increased stress, higher amounts of stress hormones and cellular byproducts like oxygen ions and peroxides are produced, both of which have been shown to shorten telomeres in other species. When telomeres fall below a certain length, cells go into damage-control mode and kick off biochemical pathways that can result in cell death. The study, the team reports online today in Biology Letters, is the first to show that the stress of social hierarchy can shorten telomeres in a wild species. © 2015 American Association for the Advancement of Science.
Link ID: 20611 - Posted: 02.25.2015
By Barron H. Lerner, M.D. I can’t stand it when someone behind me at a movie chews popcorn with his or her mouth open. I mean, I really can’t stand it. I have misophonia, a condition with which certain sounds can drive someone into a burst of rage or disgust. Although only identified and named in the last 20 years, misophonia has been enthusiastically embraced, with websites, Facebook pages and conferences drawing small armies of frustrated visitors. As a primary care physician, I find that misophonia can present some special challenges: At times, my patients can be the source of annoying sounds. At other times, the condition can be a source of special bonding if I realize that a patient is a fellow sufferer. But some experts question whether misophonia really exists. By naming it, are we giving too much credence to a series of symptoms that are no big deal? Coined by the married researchers Margaret and Pawel Jastreboff of Emory University in 2002, misophonia (“hatred of sound”) is sometimes referred to as selective sound sensitivity syndrome. Like me, those with the disorder identify a series of specific sounds that bother them. A2013 study by Arjan Schröder and his colleagues at the University of Amsterdam identified the most common irritants as eating sounds, including lip smacking and swallowing; breathing sounds, such as nostril noises and sneezing; and hand sounds, such as typing and pen clicking. The range of responses to these noises is broad, from irritation to disgust to anger. Some sufferers even respond with verbal or physical aggression to those making the noises. One woman reported wanting to strangle her boyfriend in response to his chewing. © 2015 The New York Times Company
By Nathan Seppa Ask anybody — stress is bad news. The negative view of stress has been expressed so consistently that the concept is now built into our vernacular, which is spiced with advice on avoiding it: Take it easy. Calm down. Chill. Of course, a good case of stress comes in handy during an encounter with a grizzly bear on a hiking trail. In that situation, a stress reaction delivers a burst of hormones that revs up the heart and sharpens attention. This automatic response has served humans well throughout evolution, improving our odds of seeing another day. Problems arise, however, when stress becomes a feature of daily life. Chronic stress is the kind that comes from recurring pain, post-traumatic memories, unemployment, family tension, poverty, childhood abuse, caring for a sick spouse or just living in a sketchy neighborhood. Nonstop, low-grade stress contributes directly to physical deterioration, adding to the risk of heart attack, stroke, infection and asthma. Even recovery from cancer becomes harder. Scientists have now identified many of the biological factors linking stress to these medical problems. The evidence centers on nagging inflammation and genetic twists that steer cells off a healthy course, resulting in immune changes that allow ailments to take hold or worsen. Despite the bad rap stress has acquired throughout history, researchers have only recently been able to convince others that it’s dangerous. “It’s taken much more seriously now,” says Janice Kiecolt-Glaser, a clinical psychologist at Ohio State University in Columbus. “In the 1980s, we were still in the dark ages on this stuff.” © Society for Science & the Public 2000 - 2015
By Christie Aschwanden Paul Offit likes to tell a story about how his wife, pediatrician Bonnie Offit, was about to give a child a vaccination when the kid was struck by a seizure. Had she given the injection a minute sooner, Paul Offit says, it would surely have appeared as though the vaccine had caused the seizure and probably no study in the world would have convinced the parent otherwise. (The Offits have such studies at the ready — Paul is the director of the Vaccine Education Center at the Children’s Hospital of Philadelphia and author of “Deadly Choices: How the Anti-Vaccine Movement Threatens Us All.”) Indeed, famous anti-vaxxer Jenny McCarthy has said her son’s autism and seizures are linked to “so many shots” because vaccinations preceded his symptoms. But, as Offit’s story suggests, the fact that a child became sick after a vaccine is not strong evidence that the immunization was to blame. Psychologists have a name for the cognitive bias that makes us prone to assigning a causal relationship to two events simply because they happened one after the other: the “illusion of causality.” A study recently published in the British Journal of Psychology investigates how this illusion influences the way we process new information. Its finding: Causal illusions don’t just cement erroneous ideas in the mind; they can also prevent new information from correcting them. Helena Matute, a psychologist at Deusto University in Bilbao, Spain, and her colleagues enlisted 147 college students to take part in a computer-based task in which they each played a doctor who specializes in a fictitious rare disease and assessed whether new medications could cure it. ©2015 ESPN Internet Ventures.
Berit Brogaard On popular websites, we read headlines such as “Scientists are finding that love really is a chemical addiction between people.” Love, of course, is not literally a chemical addiction. It’s a drive perhaps, or a feeling or an emotion, but not a chemical addiction or even a chemical state. Nonetheless, romantic love, no doubt, often has a distinct physiological, bodily, and chemical profile. When you fall in love, your body chemicals go haywire. The exciting, scary, almost paranormal and unpredictable elements of love stem, in part, from hyper-stimulation of the limbic brain’s fear center known as the amygdala. It’s a tiny, almond-shaped brain region in the temporal lobe on the side of your head. In terms of evolutionary history, this brain region is old. It developed millions of years before the neocortex, the part of the brain responsible for logical thought and reasoning. While it has numerous biological functions, the prime role of the amagdala is to process negative emotional stimuli. Significant changes to normal amygdala activation are associated with serious psychological disorders. For example, human schizophrenics have significantly less activation in the amygdala and the memory system (the hippocampus), which is due to a substantial reduction in the size of these areas. People with depression, anxiety, and attachment insecurity, on the other hand, have significantly increased blood flow in the amygdala and memory system. Neuroscientist Justin Feinstein and his colleagues (2010) studied a woman whose amygdala was destroyed after a rare brain condition. They exposed her to pictures of spiders and snakes, took her on a tour of the world’s scariest haunted house, and had her take notes about her emotional state when she heard a beep from a random beeper that had been attached to her. After three months of investigation, the researchers concluded that the woman could not experience fear. This is very good evidence for the idea that the amygdala is the main center for fear processing. (The chief competing hypothesis is that fear is processed in a brain region that receives its main information from the amygdala.) © 2015 Salon Media Group, Inc.
By Jane E. Brody Bereavement — how one responds and adjusts to the death of a loved one — is a very individual matter. It is natural to experience a host of negative reactions in the weeks and months following the loss of a loved one: among them, sadness, difficulty sleeping, painful reminders of the person, difficulty enjoying activities once shared, even anger. Grief is a normal human reaction, not a disease, and there is no one right way to get through it. Most often, within six months of a death, survivors adjust and are more or less able to resume usual activities, experience joy, and remember their loved ones without intense pain. But sometimes, even when the loss is neither sudden nor unexpected, as is true in the majority of deaths in the United States, survivors close to the deceased can experience extremely disruptive grief reactions that persist far longer. In a report last month in The New England Journal of Medicine, Dr. M. Katherine Shear presents a composite portrait of what is known as complicated grief, an extreme, unrelenting reaction to loss that persists for more than six months and can result in a serious risk to health. She describes a 68-year-old widow who continued to be seriously impaired by grief four years after her husband died. The woman slept on the couch because she could not bear to sleep in the bed she had shared with him. She found it too painful to engage in activities they used to do together. She no longer ate regular meals because preparing them was a too-distressing reminder of her loss. And she remained alternately angry with the medical staff who cared for him and with herself for not recognizing his illness earlier. Symptoms of complicated grief commonly include intense yearning, longing or emotional pain; frequent preoccupying, intrusive thoughts and memories of the person lost; a feeling of disbelief or inability to accept the loss; and difficulty imagining a meaningful life without that person. © 2015 The New York Times Company
By PAULA SPAN The word “benzodiazepines” and the phrase “widely prescribed for anxiety and insomnia” appear together so frequently that they may remind you of the apparently unbreakable connection between “powerful” and “House Ways and Means Committee.” But now we have a better sense of just how widely prescribed these medications are. A study in this month’s JAMA Psychiatry reports that among 65- to 80-year-old Americans, close to 9 percent use one of these sedative-hypnotics, drugs like Valium, Xanax, Ativan and Klonopin. Among older women, nearly 11 percent take them. “That’s an extraordinarily high rate of use for any class of medications,” said Michael Schoenbaum, a senior adviser at the National Institutes of Mental Health and a co-author of the new report. “It seemed particularly striking given the identified clinical concerns associated with benzodiazepine use in anybody, but especially in older adults.” He was referring to decades of warnings about the potentially unhappy consequences of benzodiazepines for older users. The drugs still are recommended for a handful of specific disorders, including acute alcohol withdrawal and, sometimes, seizures and panic attacks. But concerns about the overuse of benzodiazepines have been aired again and again: in the landmark nursing home reform law of 1987, in the American Geriatrics Society’s Choosing Wisely list of questionable practices in 2013, in last year’s study in the journal BMJ suggesting an association with Alzheimer’s disease. Benzodiazepine users face increased risks of falls and fractures, of auto accidents, of reduced cognition. “Even after one or two doses, you have impaired cognitive performance on memory and other neuropsychological tests, compared to a placebo,” said Dr. D.P. Devanand, director of geriatric psychiatry at Columbia University Medical Center. © 2015 The New York Times Company
By Devin Powell Dog owners may think their pets can tell a smile from a frown, but scientific evidence has been lacking. Now, researchers have trained dogs from a variety of breeds to look at a pair of photos arranged side by side—one showing the upper half of a woman’s face looking happy and the other showing the upper half of the same woman’s face looking angry—and pick out the happy expression by touching their snouts to it (pictured). When then shown the lower halves of the faces or pieces of other people’s faces, the perceptive pooches could still easily discern happy from angry. Another group of canines similarly learned to identify angry faces. Dogs in a previous study that distinguished expressions on whole faces could have done so using simple visual clues that reappeared in every face: the white of teeth in a smile, for instance, or creases in angry skin. Identifying emotions from photos of different parts of the face requires a more holistic understanding of expression, argue the authors of the new study, published online today in Current Biology. While primates are known to recognize faces, dogs may have been especially adapted for emotional sensitivity to humans during their domestication. The researchers plan to investigate how common this ability is by testing pigs and other animals. © 2015 American Association for the Advancement of Science.
by Sandrine Ceurstemont Malte Andersson from the University of Gothenburg in Sweden has been testing whether Norwegian lemmings (Lemmus lemmus), like the one in the video above, deter predators by warning them of their aggressive nature with their shrieks. The vivid markings on the fur also indicate to predators that this critter isn't for eating. Having such warning colours – a phenomenon known as aposematism – is common in insects, snakes and frogs, but unusual in herbivorous mammals. This combination of hues made the lemmings easier to spot than their plain-looking neighbours, grey-sided voles. When a predator, played by humans in Andersson's test, is far away, these lemmings prefer to go unnoticed, he found. But when predators get closer, to within a few metres, these lemmings were much more likely to give out a warning call than their browner relatives. The conspicuous colours, aggressive calls and threatening postures together let predators know to expect a fight, and potentially damage, if they attempt to eat a Norwegian lemming. In contrast with the voles, these lemmings aggressively resist attacks by predatory birds. © Copyright Reed Business Information Ltd.
Link ID: 20558 - Posted: 02.07.2015
By Nicholas Weiler When you spend your days battling giant squid, it’s good to have friends you can rely on. New research from the Caribbean suggests that female sperm whales (Physeter macrocephalus, pictured) swim with favored companions and form long-term family allegiances. Sperm whales raise their young in communal family groups of about a dozen related females, but mapping out the giant animals' social lives in much detail has been a challenge for scientists. The whales spend 60% of their lives hunting squid hundreds of meters below the waves, and researchers can watch them interact for only a few minutes at a time when they surface to breathe. But a new multiyear study has created the most detailed map yet of sperm whales’ social networks. Between 2005 and 2010, scientists followed nine whale families along the west coast of the Caribbean island of Dominica and mapped their social relationships by counting which females spent the most time together at the surface between dives. As expected, whales mostly preferred to relax with family members, but within families they played favorites, frequently swimming with the same sister, auntie, or aged granny, the researchers report online this week in Animal Behaviour. The network diagram also revealed three pairs of families that mingled frequently over the years to socialize and share babysitting duty. One of these pairs has been fraternizing since 1995, according to data from other researchers, suggesting that such allegiances can last more than a decade. These observations suggest sperm whale families may be similar to the matriarchal clans of elephants, which also form long-lasting family bonds, the researchers say. Further research may determine whether allied families are actually distant cousins and investigate whether whales use signature songs to find their best friends. © 2015 American Association for the Advancement of Science
By Pam Belluck A large new study has documented unexpected links in the timing and severity of symptoms of maternal depression, which could help mothers and doctors better anticipate and treat the condition. The study of more than 8,200 women from 19 centers in seven countries, published last month in Lancet Psychiatry, found that in those with the severest symptoms — suicidal thoughts, panic, frequent crying — depression most often began during pregnancy, not after giving birth, as is often assumed. Moderately depressed women often developed their symptoms postpartum, and were more likely than severely depressed women to have experienced complications during pregnancy like pre-eclampsia, gestational diabetes or hypertension. Severely depressed women, however, more often reported complications during delivery. “This is the largest study to date on postpartum depressive symptoms,” said Leah Rubin, an assistant professor in the Women’s Mental Health Research Program at University of Illinois at Chicago, a co-author of a commentary about the study. “This is definitely a first step in the right direction, knowing that depression isn’t one-size-fits-all.” Ten to 20 percent of mothers experience depression, anxiety, bipolar disorder or other symptoms at some point from pregnancy to a year after giving birth. The study could aid efforts to find causes and treatments. The study participants were all mothers. Some had been found to have postpartum depression by clinicians, while others were assessed via a widely used questionnaire. (Some participants fell into both groups.) © 2015 The New York Times Company
Link ID: 20546 - Posted: 02.03.2015
by Penny Sarchet It's a familiar sight: a flock of birds flying overhead in a classic V-formation, each saving energy by stealing lift from the bird flying ahead. But what's in it for the bird out front? For northern bald ibises, it's all about taking turns. The leading bird soon swaps places with the bird immediately behind it, in a rare example of a phenomenon called reciprocal altruism. To understand how birds cooperate in flight, Bernhard Voelkl at the University of Oxford and his team tagged every ibis in a group of 14 with high-precision GPS data loggers, allowing them to measure each individual's position in relation to the rest of the flock. They found that individual birds changed positions frequently, and were only in an aerodynamically helpful position about a third of the time. Most of these formations comprised just two birds sharing duties equally. "For whichever combination of two birds we looked at, we saw that the time bird A was flying in front of bird B matched closely the time bird B was flying in front of bird A," says Voelkl. And this wasn't just an average over the 39 kilometres that the flock flew – Voelkl's team frequently observed swaps within a pair happening within seconds, with the leader moving back behind the same bird for a similarly timed spell of following. "This immediacy of the reciprocation reduces the opportunity for cheating," says Voelkl. "Direct swaps also mean that you do not have to memorise who is 'owing' you leading time, so doesn't require a lot of memory." © Copyright Reed Business Information Ltd.
Link ID: 20545 - Posted: 02.03.2015
by Jessica Hamzelou WHAT doesn't kill you makes you stronger, at least when it comes to stress and immune cells. Mice that received a cocktail of immune cells from bullied mice appeared to experience a mood boost. The unexpected discovery may have implications for treating depression. We know that prolonged bouts of stress take their toll on the immune system. That leaves us susceptible to illness, which in some cases can lead to depression. Most research on the link between immune health and mood has focused on the innate branch of the immune system – the cells that mount the first response to pathogens, says Miles Herkenham at the National Institutes of Health in Bethesda, Maryland. His team wondered if there might also be a role for the adaptive branch of the immune system, which "learns" about a pathogen in order to respond rapidly the next time it appears. To find out, the team introduced an aggressive competitor mouse into the cages of male mice. "These mice are like bullies," says Herkenham. Two weeks later, the bullied mice seemed depressed: they cowered in dark corners and seemed uninterested in the scent of a female. The team extracted their adaptive immune cells and injected them into another set of mice bred to lack these cells. This meant that the recipient mice essentially acquired the adaptive immune system of the bullied ones. © Copyright Reed Business Information Ltd.
Criminal psychopaths learn to respond differently to punishment cues than others in jail and may need more reward-focused treatments, new research suggests. Criminals such as Paul Bernardo, Ted Bundy and Clifford Olson, who scored high on psychopathy checklists, were known to be callous and unemotional. Psychopaths derive pleasure from being manipulative and use premeditated aggression to get what they want with no regard for those who are hurt. The search for what makes them tick has shown some physical differences in their brains such as reductions in grey matter. Now researchers in London, Montreal and Bethseda, Md., have used functional MRI imaging to assess how the brains of 12 violent criminals with psychopathy, 20 violent criminals with antisocial personality disorder but not psychopathy (such as those with a history of impulsivity and risk-taking), and 18 healthy people who were not criminals responded differently to rewards and punishment. "In the room with them, there's the sense that the weight of what they've done and the deleterious effect this is having on their lives doesn't really hold for them," said Dr. Nigel Blackwood of King's College London, a senior author of the paper in Wednesday's issue of Lancet Psychiatry. It's only at the moment in the scanner when the sanction of lost points cues them to change their behaviour that the differences between violent psychopaths and those with antisocial personality disorder appear. ©2015 CBC/Radio-Canada
Sara Reardon The US National Institutes of Health (NIH) has modified the way a controversial lab studies stress in monkeys in response to criticism by animal-rights activists and members of Congress who say that the research is inhumane. At issue are experiments led by Stephen Suomi, a psychologist at the US National Institute of Child Health and Human Development (NICHD) in Poolesville, Maryland. Suomi’s lab studies how removing newborn rhesus macaques from their mothers affects biological processes such as brain activity and gene expression, and behaviours such as alcohol consumption in the infants. He has performed similar experiments for about three decades, and has received roughly US$30 million over the past seven years for the work, according to the activist group People for the Ethical Treatment of Animals (PETA), which obtained documents and videos from the lab through a freedom-of-information request. In September, PETA began posting ads in the subway station near NIH’s Bethesda, Maryland, campus, and in newspapers condemning the experiments as “cruel and archaic”, and arguing that they yielded results that were not relevant to human health. The group also posted video of NIH monkey experiments on its website. PETA’s campaign drew the attention of Congress. In December, four Democratic members of the House of Representatives wrote to the NIH, demanding that the agency’s Bioethics Commission investigate the Suomi lab’s practices and the justification for the experiments. “We know what the impact is when children are taken from their parents,” says one of the lawmakers, Lucille Roybal-Allard (Democrat, California). “While [animal] research is necessary in many cases, we can’t just do it without evaluation and having a clear purpose.” © 2015 Nature Publishing Group
By Nicholas Weiler If you find people watching oddly compelling, you’re not alone. A new study suggests that gregarious European starlings (Sturnus vulgaris) get a kick out of looking at their fellow birds, even if it’s just on a computer screen. Researchers took 10 captive starlings from their flock and isolated them for 4 days in a cage with plenty of food and water and a large flat-screen monitor. Most of the birds quickly discovered that poking their beaks into one sensor in the cage flashed a life-size photograph of an unknown starling onto the screen, while a second sensor produced a picture of a suburban landscape. The lonely birds seemed to enjoy looking at other starlings, the researchers found. On average, they triggered a new starling photo every 6 minutes, 7 hours a day, for 4 days. They only threw in a landscape every 20 minutes or so. It wasn’t just that the landscapes were boring. Given the choice between photos of starlings and photos of monkeys, a second group of five birds also pecked to view their own kind three times more often. The results suggest starlings have a natural yearning for social stimulation, the authors report online this month in Animal Cognition. In the future, starlings’ drive to view photos of one another could be used to study the social rewards that knit communities together. © 2015 American Association for the Advancement of Science
|By Daniel Yudkin Imagine you are with some friends at a concert, and the bouncer approaches the group and says that, because you are all looking so ravishing tonight, he’s been instructed to offer one of you—just one!—a backstage pass to meet the artist. Do you raise your hand? For most people, this would be a no-brainer: who wouldn’t leap at the chance to meet a famous singer or secure a long-sought autograph? The results of a recent study, published in Psychological Science by Gus Cooney, Daniel Gilbert, and Timothy Wilson, however, suggest taking a second’s pause before snapping up that backstage pass. Cooney, Gilbert, and Wilson suspected that extraordinary experiences—like meeting a musical idol—carry hidden costs. They hypothesized that, while such occurrences undoubtedly make us happier in the moment, they also risk separating us from our peers, leading to a sense of isolation so unpleasant as to outweigh whatever enjoyment they initially confer. To test this idea, the researchers recruited subjects in groups of four and had them watch a video clip. Of the group, three were told that they would watch a clip that previous viewers had given a 2-star rating; the remaining subject, by contrast, was granted the opportunity to view a special 4-star clip. After watching the videos, all four subjects were given some time to talk amongst themselves, and then each reported on their general happiness. © 2015 Scientific American
Link ID: 20527 - Posted: 01.28.2015
/ by Tanya Lewis, LiveScience You know the feeling: the dryness in the mouth, the stickiness in the throat and the creeping salivation — thirst. But what causes feelings of thirst in the brain? In a new study, scientists used laser light to activate groups of neurons in the brains of mice. By targeting specific neuron groups, the scientists could make the animals drink even if they weren't thirsty, and stop drinking even if they were thirsty. Understanding how the brain causes feelings of thirst could help scientists learn what goes awry in disorders that make people drink too much or too little fluid, researchers say. "Thirst has attracted a lot of interest because it is such a basic function for all organisms," said Yuki Oka, a neuroscientist currently at the California Institute of Technology and co-author of the study published today (Jan. 26) in the journal Nature. Before this study, scientists knew which brain regions were activated by dehydration and hydration. "But key information was missing as to which were controlling thirst," Oka told Live Science. In the new study, Oka and a team of colleagues at Columbia University used a technique called optogenetics to pinpoint the origin of thirst impulses in the brains of mice. The researchers injected the mouse brains with a virus that made certain cells sensitive to laser light, and when scientists shone the laser on those cells, it caused them to turn nerve impulses "on" or "off." © 2015 Discovery Communications, LLC.
Link ID: 20525 - Posted: 01.28.2015
David Cox Bernd Heinrich was on a hike through the woods of New England when he observed something which would go on to change our perception of animal psychology. A group of ravens had gathered to feed on a dead moose. But rather than choosing to keep the bounty for themselves, they were making a strange call, one which seemed to be deliberately attracting more ravens to the feast. A biologist at the University of Vermont, Heinrich was initially confused. By helping their competitors, the ravens appeared to be defying all natural biological instinct. But as it transpired, their motivation was actually deeply selfish. The birds were juveniles who had discovered the moose in an adult raven’s territory. By inviting other ravens to join them, their intrusion was more likely to go unchallenged. Last month, an astonishing video emerged of a rhesus macaque successfully resuscitating another of its species which had been electrocuted at a train station in India. It is tempting to describe the sustained display of persistence and apparent concern as almost human. But there is a danger in viewing animal behaviour through the misty lens of human emotion. What both Heinrich’s “sharing ravens’ and the macaques of Kampur do provide is a window into the gradual evolution of one of the most human of traits – altruism. Altruism in its purest form should be an entirely selfless action. “If there’s any kind of selfish interest at stake, like secretly hoping for a return favour or even doing it deliberately because you know it will make you feel good, then that doesn’t really count at all,” says psychologist Michael Platt of the Center for Cognitive Neuroscience at Duke University, North Carolina.