Biological Psychology Links

Erin Allday, Chronicle Staff Writer We've all seen these people: the boss who blows her top when a meeting runs five minutes late, the man in the coffee shop who screams and rants when his latte isn't made with soy milk, the maniac driver who honks at every car in stop-and-go traffic. Maybe some of us actually are those people. Aside from being annoying, and sometimes even threatening, angry people aren't doing themselves any favors. A growing body of research suggests they may be setting themselves up for everything from heart disease and irritable bowel syndrome to headaches and maybe just the common cold. The latest research - a study of 5,600 Italians, published this month in the journal of the American Heart Association - found that individuals who are cynical, manipulative, arrogant or short-tempered have thicker carotid arteries, which means they're more vulnerable to heart attacks and strokes. What's doing the damage is stress and how angry people react to it - or overreact to it, mental health experts said. "It's sort of like idling the car too high on the traffic light - you're going to be racing your engine when you don't need to," said Dr. David Spiegel, associate chairman of psychiatry and behavioral sciences at Stanford University School of Medicine. "There are times when it's right to get angry. But if your characteristic response is anger, it's really a failure to deal with stress." © 2010 Hearst Communications Inc

By Jeremy Laurance, Health Editor If you want to tell whether your baby is in pain, looking at its face may not be enough, researchers have found. Generations of mothers have depended on their baby's facial expressions to tell them what they are feeling. But a study has found that giving a baby a spoonful of sugar before an injection or blood test may alter its expression without lessening its pain. The finding casts doubt on whether we can really know what a baby is feeling from observing its responses – and on the decade-old practice of using sugar as a pain reliever for infants. Until the 1950s, doctors thought babies did not suffer pain because their consciousness was not sufficiently developed. The normal pain responses – grimacing and crying – were dismissed as reflexes. Babies subjected to surgery were given anaesthetics to put them to sleep but not analgesic drugs for the pain, as children and adults were. In the 1970s, a definitive study showed babies did benefit from analgesia. But as it is difficult to test them on babies, few drugs are available. Giving a teaspoonful of sugar solution to babies was thought to relieve pain based on the way it reduced grimacing and crying after a painful procedure. It is believed to stimulate the production of "endogenous opiates" – the body's own natural pain-relieving drugs – and has become standard practice before blood tests and similar procedures. Some doctors maintain the evidence is now so strong that it may be unethical not to use it. ©independent.co.uk

by Catherine de Lange They might not win any Oscars, but orang-utans can act. They have been caught on camera performing "pantomimes", in which they express their intentions and desires by acting them out. The finding challenges the view that these behaviours are exclusive to humans. Non-human great apes such as orang-utans and chimpanzees were already known to display meaningful gestures. They might throw an object when angry, for example. But that is a far cry from displaying actions that are intentionally symbolic and referential – the behaviour known as pantomiming. "Pantomime is considered uniquely human," says Anne Russon from York University in Toronto, Canada. "It is based on imitation, recreating behaviours you have seen somewhere else, which can be considered complex and beyond the grasp of most non-human species." Yet over years she has worked with great apes, Russon has seen several cases that she thought could be considered pantomiming. So to gather more concrete evidence, she and colleague Kristin Andrews searched through 20 years of data on the behaviour of free-ranging, rehabilitated orang-utans. They found 18 cases of orang-utans clearly acting out a message. Sometimes it was a simple mime, such as body-scratching using a stick, probably to encourage another orang-utan to groom the actor. © Copyright Reed Business Information Ltd.

by Greg Miller In children, an anxious temperament can be a warning sign. Kids who are painfully shy and nervous are more prone to anxiety disorders and depression later in life, and they're more likely to self-medicate with alcohol and other drugs. But what causes a child to have an anxious temperament in the first place? A new study with monkeys finds that an anxious temperament is partly heritable and that it's tied to a particular brain region involved in emotion. Children with an anxious temperament often freeze up when they meet a stranger or encounter a social situation they perceive as threatening, says Ned Kalin, a psychiatrist and neuroscientist at the University of Wisconsin, Madison. Kalin and his colleagues have found that some young monkeys do much the same thing. When a human "intruder" enters the room and approaches their cage without making eye contact, these anxious youngsters freeze in place and grow quiet. Their stress hormone levels spike, too. In the new study, published in the 12 August issue of Nature, Kalin and colleagues studied 238 young rhesus monkeys from a family of more than 1500 lab-raised monkeys with well-documented pedigrees. By analyzing the family connections among the young monkeys, which ranged from siblings to distant cousins, the researchers found that an anxious temperament was partly heritable, accounting for about 36% of the variability in individual monkeys' responses on the human intruder test (as measured by the reduction in movement and vocalization and increase in stress hormone levels). © 2010 American Association for the Advancement of Science.

By Sonja Lyubomirsky Money can’t buy you love. Worshipping Mammon foments evil ways. Materialists are shallow and unhappy. The greenback finds itself in tough times these days. Whether it’s Wall Street bankers earning lavish multi-million-dollar bonuses or two-bit city managers in Los Angeles County bringing in higher salaries than President Obama the recessionary economic climate has helped spur outrage and revulsion at those of us collecting undeserved lucre. Wealthy people have a bad rep. Sure, there are philanthropists like Warren Buffet and Bill Gates, who have given billions of their net worth away and have made the world a better, healthier, safer place. But, sadly, they are an exception. American families who make over $300,000 a year donate to charity a mere 4 percent of their incomes. The statistic should not be surprising, as studies by University of Minnesota psychologist Kathleen Vohs and her collaborators have shown that merely glimpsing dollar bills makes people less generous and approachable, and more egocentric. Now come a new set of studies that reveal yet another toll that money takes. An international team of researchers led by Jordi Quoidbach report in the August 2010 issue of Psychological Science that, although wealth may grant us opportunities to purchase many things, it simultaneously impairs our ability to enjoy those things. Their first study, conducted with adult employees of the University of Liège in Belgium showed that the wealthier the workers were, the less likely they were to display a strong capacity to savor positive experiences in their lives. © 2010 Scientific American,

by Graham Lawton and Clare Wilson Why ask people what they think of a product when you can just scan their brains instead? New Scientist explores the brave new world of neuromarketing TAKE A look at the cover of this week's New Scientist magazine (right). Notice anything unusual? Thought not, but behind the scenes your brain is working overtime, focusing your attention on the words and images and cranking up your emotions and memory. How do we know? Because we tested it with a brain scanner. In what we suspect is a world first, this week's cover was created with the help of a technique called neuromarketing, a marriage of market research and neuroscience that uses brain-imaging technology to peek into people's heads and discover what they really want. You may find that sinister. What right does anyone have to try to read your mind? Or perhaps you are sceptical and consider the idea laughable. But neuromarketing, once dismissed as a fad, is becoming part and parcel of modern consumer society. So we decided to take a good look at it - and try it out ourselves. That is how several New Scientist readers ended up in a darkened room in London, wired up to an electroencephalograph (EEG) machine and being shown various magazine cover designs. Our aim - with the help of the European arm of neuromarketing company NeuroFocus, based in Berkeley, California - was to observe their reactions on a level that would not normally be possible. "I've been involved in market research for about 25 years," says Thom Noble, managing director of NeuroFocus Europe. "Every few years a new methodology comes out. Frankly, they're incrementally different. This is transformationally different." © Copyright Reed Business Information Ltd.

by Tyler Bancroft IN A classic Monty Python moment, a chirpy, long-haired man on a crucifix urges others around him in a similar predicament to cheer up. Now neurologists have discovered what might be described as a "Life of Brian" brain mechanism that encourages us to look on the bright side of life - even when confronted by thoughts of mortality. Shihui Han of Peking University, China, found activity in brain regions that normally deal with negative emotions and self-awareness are dampened when we process ideas about death. Han and colleagues placed 20 volunteers in functional MRI brain scanners while death-related words, such as graveyard, corpse, behead and slay, flashed up on a screen. Neutral and negative words were also displayed. Unsurprisingly, words related to death activated brain areas already known to process unpleasant or threatening notions. More interestingly, they were associated with comparatively lower activity in the insula and the mid-cingulate (Neuropsychologia, DOI: 10.1016/j.neuropsychologia.2010.07.026). The insula is associated with sense of self and awareness of sensations and movement. Further tests showed that the more participants associated specific words with death, the lower the activity in the insula. Damage to this region is associated with reduced emotional awareness and expression, sometimes resulting in socially inappropriate behaviour. © Copyright Reed Business Information Ltd.

By Lesley Richardson, Press Association A framework to understand the emotional lives of animals was revealed today. Animal choices can be assessed objectively as evidence of pessimistic or optimistic decision-making which indicates their long-term mood. Professor Mike Mendl and Dr Liz Paul, from the University of Bristol, and Dr Oliver Burman, from the University of Lincoln, looked through papers by experts from Charles Darwin to Paul Ekman and Jaak Panksepp to create the framework which can be used in the field of animal welfare and neuroscience. Professor Mike Mendl, head of the Animal Welfare and Behaviour research group at Bristol University's School of Clinical Veterinary Science, said: "Because we can measure animal choices objectively, we can use optimistic and pessimistic decision-making as an indicator of the animal's emotional state which itself is much more difficult to assess. "Recent studies by our group and others suggest that this may be a valuable new approach in a variety of animal species. Public interest in animal welfare remains high, with widespread implications for the way in which animals are treated, used and included in society. We believe our approach could help us to better understand and assess an animal's emotion." ©independent.co.uk

Q. I had migraine diagnosed when I was 24 years old (I’m now 30), but I remember having them since my teens. I usually get them during times when my hormone levels change (e.g., during periods, ovulation). There are also other triggers like stress, too little sleep, etc. If the migraines start during the day, they are often preceded and/or followed by major mood swings, the kind that make me want to go jump off the bridge. The associated depression often recedes with pain and then comes back again after the pain recedes. Afterward, I can feel on top of the world — loving, caring and full of joy. Is this normal? Espoo, Finland A. Dr. Dodick responds: What you are experiencing before and after the headache of a migraine attack is not unusual. I am glad you asked, because it speaks to why I emphasize that migraine is more than just a bad headache. Migraine is too often “bookmarked” by the start and stop of the headache, but migraine is frequently associated with symptoms other than headache before, during and after the onset of head pain. About 75 percent of migraine sufferers will experience non-headache premonitory symptoms prior to the headache pain. Patients experience a range of cognitive, emotional and physical symptoms in this phase; the most common include feeling tired and weary, difficulty concentrating, stiff neck, dizziness, light and noise sensitivity, yawning, and depression or irritability. Copyright 2010 The New York Times Company

By Jesse Bering Last week, while in a drowsy, altitude-induced delirium 35,000 feet somewhere over Iceland, I groped mindlessly for the cozy blue blanket poking out beneath my seat, only to realize—to my unutterable horror—that I was in fact tugging soundly on a wriggling, sock-covered big toe. Now with a temperament such as mine, life tends to be one awkward conversation after the next, so when I turned around, smiling, to apologize to the owner of this toe, my gaze was met by a very large man whose grunt suggested that he was having some difficulty in finding the humor in this incident. Unpleasant, yes. But I now call this event serendipitous. As I rested my head back against that sanitation paper-covered airline pillow, my mid-flight mind lighted away to a much happier memory, one involving another big toe, yet this one belonging to a noticeably more good-humored animal than the one sitting behind me. This other toe—which felt every bit as much as its overstuffed human equivalent did, I should add—was attached to a 450-pound Western Lowland gorilla, with calcified gums, named King. When I was 19, and he was 27, I spent much of the Summer of 1996 with my toothless friend King, listening to Frank Sinatra and the Three Tenors (my bizarre foray into science, which you can read about here), playing chase from one side of his exhibit to the other, and tickling his toes. He’d lean back in his night house, stick out one huge ashen grey foot through the bars of his cage and leave it dangling there in anticipation, erupting in shoulder-heaving guttural “laughter” as I’d grab hold of one of his toes and gently give it a palpable squeeze. He almost couldn’t control himself when, one day, I leaned down to act as though I was going to bite on that plump digit. If you’ve never seen a gorilla in a fit of laughter, I’d recommend searching out such a sight before you pass from this world. It’s something that would stir up cognitive dissonance in even the heartiest of creationists. © 2010 Scientific American

By Laura Sanders As people grow older, sad films seem sadder. In a recent study, people in their sixties felt sadder than people in their twenties did after viewing an emotionally distressing scene from a movie. This heightened emotional response to sorrow may reflect a greater compassion for other people and may strengthen social bonds, researchers propose. The finding is an important contribution to emotion studies because it adds to a growing body of work showing that emotions don’t deteriorate, says Stanford University psychologist Laura Carstensen, who was not involved in the research. “One of the important findings of this is that the emotion system is in no way broken in old age,” she says. To explore how feelings of sadness change with age, researchers led by Robert Levenson of the University of California, Berkeley brought 222 study participants into the laboratory to watch neutral, disgusting or sad movie clips. The volunteers made up three age groups: young people in their twenties, middle-aged people in their forties, and older people in their sixties. Before watching the movies, participants were hooked up to monitors that recorded physiological responses such as blood pressure, heart rate and breathing patterns. Levenson and his team chose two gut-wrenchingly sad scenes to elicit responses: In the first clip, from the movie 21 Grams, a mother is told of the deaths of her two young daughters. The second scene, from The Champ, depicts a young boy watching his father die after a boxing match. © Society for Science & the Public 2000 - 2010

By Susan Gaidos Anyone who has felt the sting of tears while listening to a bugler play “Taps,” swooned to a love song or cringed with irritation as a neighbor cranked the heavy metal knows that music can exert a powerful emotive effect. And you don’t need a neuroscientist to tell you that manipulating a melody’s pace, tone and intensity can stir the emotions. Composers of symphonies, pop tunes, movie sound tracks and TV ads all know how to tune an audience’s mood along a dial ranging from sad and glum to cheerful and chipper. But neuroscientists might have something to say about how music orchestrates such profound emotional effects on the brain. And understanding the how may offer a hint as to why music affects humans so powerfully. Over the past decade or so, studies have shown that music stimulates numerous regions of the brain all at once, including those responsible for emotion, memory, motor control, timing and language. While the lyrics of a song activate language centers, such as Broca’s area, other parts of the brain may connect the tune to a long-ago association — a first kiss or a road trip down the coast, perhaps. “It’s like the brain is on fire when you’re listening to music,” says Istvan Molnar-Szakacs, a neuroscientist at the University of California, Los Angeles. “In terms of brain imaging, studies have shown listening to music lights up, or activates, more of the brain than any other stimulus we know.” © Society for Science & the Public 2000 - 2010

By Tom Wilkinson, Press Association Pigs can feel optimistic and pessimistic according to how they are being treated, scientists revealed today. Experts from Newcastle University's School of Agriculture, Food and Rural Development found they were just as likely as humans to feel the glass was half empty or half full, depending on their living conditions, as hogs kept in piggy luxury were more likely to respond positively to a new experience than those in less stimulating pens. The scientists hoped the research, which shows pigs are capable of feeling complex emotions, will have an impact on animal welfare. Led by Dr Catherine Douglas, the team employed a technique to "ask" pigs if they are feeling optimistic or pessimistic about life as a result of the way in which they live. In an experiment reminiscent of Pavlov's dogs, pigs were taught to associate a note on a glockenspiel with a treat - an apple - and a dog training "clicker" with something mildly unpleasant - in this case rustling a plastic bag. Then they placed half the pigs in an enriched environment - with more space, freedom to roam in straw and play with toys - while the other half were placed in a smaller, boring environment with no straw and only one non-interactive toy. The team then played an ambiguous noise - a squeak - and studied how the pigs responded. ©independent.co.uk

By Daniela Schiller You are on a plane, thirty thousand feet above ground. Four hundred and fifty snakes crawl into the passenger cabin. You think this is terrifying? Hollywood producers certainly gambled on that when they released the 2006 summer blockbuster “Snakes on a Plane.” Israeli scientists, however, have come up with an even creepier scenario. You are in an MRI machine. Your head is fixed in a round cage. Your body is rolled into a narrow tube. Magnetic pulses are beamed into your brain. A meter-and-a-half-long snake is strapped with Velcro atop a small box on a conveyor belt just inches behind your head. Your eyes meet the snake’s beady gaze through a tiny mirror above your head. You can’t move. Why would Uri Nili and Yadin Dudai, two scientists from the Weizmann Institute of Science in Rehovot, Israel, want to put a snake in the MRI scanner with you? Obviously, not to scan the snake’s brain (although this might be an interesting possibility). They wanted to scan your brain while you perform an act of courage. They wanted to push research on fear one step further – from understanding how we passively react to fear, through actively avoiding it, to actually confronting it. FBI agent Neville Flynn (Samuel L. Jackson) could have been an ideal candidate for the experiment. Grabbing and fighting the snakes on the plane with his bare hands, Flynn came to the rescue of the passengers on red-eye flight 121. But there was no FBI or Mossad agent at the Weizmann Institute. The participants in the experiment had to face the snake on their own. All they had were two buttons. Pressing one would roll the snake closer. Pressing the other would slide it away. ‘Advance’ or ‘Retreat’, were their two options. They could choose either one, instructed only to do their best in pulling the snake toward their heads. (See the video here.) © 2010 Scientific American,

by Kate Douglas "What are you laughing at?" Ignoring any aggressive intent, the answer is obvious: I am laughing because something you said amused me. Right? Wrong. According to a classic study of laughter by Robert Provine of the University of Maryland, Baltimore County, and his colleagues, laughter is an unexpectedly serious business. Observing the human animal in its natural habitat - the shopping mall - they documented 1200 instances of laughter, and found that only 10 to 20 per cent of them were responses to anything remotely resembling a joke. Most laughter was in fact either triggered by a banal comment or used to punctuate everyday speech. Furthermore, says Provine in his book Laughter: A scientific investigation, we are 50 per cent more likely to laugh when speaking than when listening, and 30 times gigglier in a social setting than when alone without a social surrogate such as a television. Provine's conclusion was that the essential ingredient for laughter is not a joke but another person. Laughter is far more general than just a response to humour: it is a social glue that we use in all sorts of ways to bind ourselves together. As such, it comes in many guises. Our first laughs occur at between 2 and 6 months of age - even in deaf babies. They are triggered by surprise in a safe situation (think peek-a-boo), and don't just endear babies to their parents. Since laughter is associated with activity in the brain's dopamine reward circuitry, it encourages babies to explore the world by making them feel happy and safe. When infants begin to engage in rough-and-tumble play, laughter signals that the intentions are not serious, allowing children to test physical and social boundaries without serious jeopardy. © Copyright Reed Business Information Ltd.

by Linda Geddes NEXT time a sentimental movie makes you cry, blame your serotonin levels. Differences in the neurotransmitter might explain why some people are more prone to crying in emotional situations than others. Frederick van der Veen's team at the Erasmus Medical Centre in Rotterdam, the Netherlands, gave 25 female volunteers a single dose of either paroxetine - a selective serotonin reuptake inhibitor (SSRI) which briefly increases serotonin levels - or a placebo. Four hours later they were asked to watch one of two emotional movies: Brian's Song, in which the hero dies of cancer, or Once Were Warriors, about domestic violence, and to indicate if, and to what extent certain scenes had made them cry. On another day, the women watched the second film with their treatments swapped over. "It didn't matter which movie they saw, we saw a strong and consistent effect of paroxetine," says van der Veen, who presented the results at the Forum of European Neuroscience in Amsterdam last week. "Higher serotonin levels lead to less crying." Although SSRIs are used to treat depression, their mood-boosting effects do not normally show up for around six weeks. The women reported no change in mood in the current study. "We're looking at the direct effect of a single dose of paroxetine," says van der Veen, who adds that the findings might help explain why some people report blunted emotions when taking SSRIs. © Copyright Reed Business Information Ltd

By Patrick House What if I told you that last week I predicted all eight winners of a round of the World Cup? And that instead of rankings or divination all I did was look up how many people in each team's home country had a tiny parasite lurking in their amygdalas? Would you believe me? A decade ago, Discover Magazine concluded that parasites ruled the world, and now I'm going to try to tell you that, at the very least, parasites rule the World Cup. Toxo is one of the most successful parasites in the world and is found in almost every type of mammal. Goats, cows, pigs, sheep, humans. But it spends its time trying to get into the stomach of a cat, the only place where it can successfully reproduce. Thus the organism has evolved an unusual lifecycle relating to the brains of rats and mice. Rodents ingest little bits of Toxo from cat feces and Toxo goes straight to their heads. Once there, it scrambles the neurons around and reverses the animals' natural aversion to cat urine. Soon after, a recently relieved cat returns to the scene and takes its supper. In other words, the rat plays taxi to the parasite, finding it a new feline host and completing the Toxo lifecycle. Livestock fields are full of fertilizer made from, you guessed it, bits of cat feces. When the cows and goats graze, they ingest Toxo, and it sneaks its way into their brains. Eat one of these livestock uncooked and you'll get Toxo in your brain, too. Thanks to the urbanization of cats (and their feces), almost a third of the human population now has a chronic, latent, and seemingly innocuous Toxo infection. This is, of course, an average: Rates vary a great deal from one country to another, from 6 percent in South Korea to 92 percent in Ghana. © Copyright 2010 Washington Post.Newsweek Interactive Co. LLC

By Bruce Bower Botox treatment to erase unsightly frown lines may cause unforeseen emotional wrinkles. First-time Botox patients become slower at evaluating descriptions of negative emotions, possibly putting the patients at a social disadvantage, a new study indicates. For more than a century, scientists have posited that facial expressions trigger and intensify relevant feelings, rather than simply advertise what an individual already feels. Botox patients provide a novel line of support for this idea, as well as for the notion that facial expressions activate links between brain regions responsible for emotions and language, says psychology graduate student David Havas of the University of Wisconsin–Madison. Botox is short for botulinum toxin-A, a neurotoxic protein that causes temporary muscle paralysis beginning one to three days after an injection and lasting for three to four months. Two weeks after their first Botox injections, 40 women took an average of about one-third of a second longer to read sentences describing angry and sad situations than they did immediately before the procedure, Havas and his colleagues found. Critically, Botox patients show no decline in the speed with which they read sentences about happy situations, Havas’ team reports in an upcoming Psychological Science. © Society for Science & the Public 2000 - 2010

by Barbara Bradley Hagerty Kent Kiehl has studied hundreds of psychopaths. Kiehl is one of the world's leading investigators of psychopathy and a professor at the University of New Mexico. He says he can often see it in their eyes: There's an intensity in their stare, as if they're trying to pick up signals on how to respond. But the eyes are not an element of psychopathy, just a clue. Officially, Kiehl scores their pathology on the Hare Psychopathy Checklist, which measures traits such as the inability to feel empathy or remorse, pathological lying, or impulsivity. "The scores range from zero to 40," Kiehl explains in his sunny office overlooking a golf course. "The average person in the community, a male, will score about 4 or 5. Your average inmate will score about 22. An individual with psychopathy is typically described as 30 or above. Brian scored 38.5 basically. He was in the 99th percentile." "Brian" is Brian Dugan, a man who is serving two life sentences for rape and murder in Chicago. Last July, Dugan pleaded guilty to raping and murdering 10-year-old Jeanine Nicarico in 1983, and he was put on trial to determine whether he should be executed. Kiehl was hired by the defense to do a psychiatric evaluation. On screen, Dugan is dressed in an orange jumpsuit. He seems calm, even normal — until he lifts his hands to take a sip of water and you see the handcuffs. Dugan is smart — his IQ is over 140 — but he admits he has always had shallow emotions. He tells Kiehl that in his quarter century in prison, he believes he's developed a sense of remorse. Copyright 2010 NPR

by Michael Balter Want to live a long life? Have lots of friends. Studies in humans have made clear that people with stronger social networks have greater longevity. Now a new analysis shows the same is true for baboons. The research adds to growing evidence that friendship is an adaptation with deep evolutionary roots. Little is known about how social bonds influence longevity in nonhuman animals, in part because tracking animal relationships over many years is very difficult. Nevertheless, recent evidence shows that social bonding enhances reproductive success, an important indicator of evolutionary fitness. A study last year of female horses, led by Elissa Cameron, a zoologist at the University of Pretoria, showed that mares with the weakest social ties had about half as many surviving foals as those who were most sociable. And in 2006, a team led by University of California, Los Angeles, anthropologist Joan Silk reported that the infants of female baboons with close social ties to unrelated females survive longer than those that do not have such ties. In the new work, a team led by Silk looked at the correlation between social bonding and longevity, another important indicator of fitness. Silk studied wild baboons in Botswana's Moremi Game Reserve, teaming up with a long-term project led by University of Pennsylvania biologist Dorothy Cheney and psychologist Robert Seyfarth. From 2001 to 2007, the researchers closely watched 44 female baboons, recording how often they approached each other, how long they groomed each other, and other measures of social interaction. (The researchers looked at females because, in many species, only females form these kinds of social bonds, whereas males are off doing other things and are competitive with each other rather than cooperative.) From these data, the researchers determined each baboon's top three partners in any given year. Thus the team could estimate the strength of each baboon's relationships with its closest partners over the years and the extent to which each baboon stuck to her best buddies. © 2010 American Association for the Advancement of Science.

Links for keyword: Emotions