1. Early supplementation may help offset early-life stress on the adult brain

    October 28, 2016 by Ashley

    From the Federation of American Societies for Experimental Biology media release:

    babies_cryingEarly-life stress has been shown to impair learning and memory in later life, but new research, published online in The FASEB Journal, suggests that improved nutrition may help offset the negative effects of this stress.

    Specifically, using mice, scientists focused on essential micronutrients, including methionine, vitamin B6 and vitamin B12, and folic acid, none of which are made by the body and need to be ingested through diet. They found that early-life stress reduces the levels of these nutrients in mouse pups, but supplementation prevented the reduction of methionine levels and even prevented some of the lasting negative effects of early-life stress on later learning and memory in adult offspring.

    “Today’s children are tomorrow’s future,” said Aniko Korosi, Ph.D., a researcher involved in the work from the Swammerdam Institute for Life Sciences and the Center for Neuroscience at the University of Amsterdam in Amsterdam, The Netherlands. “We hope that this study can contribute to novel nutritional strategies that help prevent lasting consequences of a stressful childhood on later mental health.”

    To make their discovery, Korosi and colleagues mimicked a stressful early-life environment during the first week after birth (postnatal days 2-9) for newborn mice and their mothers. Control mice and their mothers were housed in a normal environment. During the stress period, half of the mouse mothers (control and early-life stress) received a standard rodent diet, the other half received a diet that was supplemented with essential micronutrients. The lactating mouse mothers ate the diet and thereby developed elevated micronutrient levels in maternal milk and subsequently in the blood and the brains of their pups. After the initial stress period, all mice received a standard diet and environment. Once the mice became 4 months old, their learning and memory skills were tested in various cognitive/behavioral tasks. Mice that were previously exposed to early-life stress performed worse than control animals and demonstrated poor learning and memory skills. However, stress-exposed mice from mothers that received the supplemented diet performed equally well as the control mice did.

    “The field of postnatal nutrition has sometimes taken a back seat to research on the maternal-fetal axis, but of course we cannot ever ignore either,” said Thoru Pederson, Ph.D., Editor-in-Chief of The FASEB Journal. “Here we see strikingly beneficial cognitive effects of a sound postnatal diet. The nutrients tested were familiar ones, but the results speak for themselves.”

     


  2. Discrimination Based on Weight Doubles Health Risks

    October 21, 2016 by Ashley

    From the University of Rhode Island media release:

    obesityWe all know that carrying extra pounds can be bad for your health. Now a URI professor has found that how society treats overweight people makes matters worse.

    Maya Vadiveloo, assistant professor of nutrition and food sciences in the College of Health Sciences, and Josiemer Mattei, assistant professor of nutrition at Harvard University T.H. Chan School of Public Health, analyzed weight discrimination data from the long-term national study, Midlife Development in the United States.

    The researchers focused on respondents who reported regularly experiencing discrimination because of their weight. The study asked whether they were treated discourteously, called names, or made to feel inferior. Those who experienced weight discrimination over a 10-year period had twice the risk of high allostatic load, the cumulative dysfunction of bodily systems from chronic stress, they found. That stress can lead to heart disease, diabetes, inflammation and other disorders, increasing risk of death.

    “It is a pretty big effect,” Vadiveloo, of North Kingstown, says of the findings. “Even if we accounted for health effects attributed to being overweight, these people still experience double the risk of allostatic load because of weight discrimination.”

    The findings, published in the August issue of Annals of Behavioral Medicine, expose flaws in society’s approach to weight control, Vadiveloo says. “The main message is to be aware that the way we treat people may have more negative effects than we realize,” she says. “Our paper highlights the importance of including sensitivity and understanding when working with individuals with obesity and when developing public health campaigns.”

    People who experience weight discrimination often shun social interaction and skip doctor visits, she notes. “There is so much shaming around food and weight. We need to work together as a nation on improving public health and clinical support for individuals with obesity and targeting environmental risk factors,” she says. For example, Vadiveloo suggests developing strategies to make healthy foods affordable and creating safe places for people to be active.

    Vadiveloo hopes to address the topic in the classroom and revisit data from the nearly 1,000 respondents to explore whether having more social support or positive coping strategies reduces negative health effects of weight discrimination.


  3. New insights into how the mind influences the body

    October 20, 2016 by Ashley

    From the University of Pittsburgh Schools of the Health Sciences media release:

    airport zenNeuroscientists at the University of Pittsburgh have identified the neural networks that connect the cerebral cortex to the adrenal medulla, which is responsible for the body’s rapid response in stressful situations. These findings, reported in the online Early Edition of the journal Proceedings of the National Academy of Sciences (PNAS), provide evidence for the neural basis of a mind-body connection.

    Specifically, the findings shed new light on how stress, depression and other mental states can alter organ function, and show that there is a real anatomical basis for psychosomatic illness. The research also provides a concrete neural substrate that may help explain why meditation and certain exercises such as yoga and Pilates can be so helpful in modulating the body’s responses to physical, mental and emotional stress.

    “Our results turned out to be much more complex and interesting than we imagined before we began this study,” said senior author Peter L. Strick, Ph.D., Thomas Detre Chair of the Department of Neurobiology and scientific director of the University of Pittsburgh Brain Institute.

    In their experiments, the scientists traced the neural circuitry that links areas of the cerebral cortex to the adrenal medulla (the inner part of the adrenal gland, which is located above each kidney). The scientific team included lead author Richard P. Dum, Ph.D., research associate professor in the Department of Neurobiology; David J. Levinthal, M.D., Ph.D., assistant professor in the Department of Medicine; and Dr. Strick.

    The scientists were surprised by the sheer number of neural networks they uncovered. Other investigators had suspected that one or, perhaps, two cortical areas might be responsible for the control of the adrenal medulla. The actual number and location of the cortical areas were uncertain. In the PNAS study, the Strick laboratory used a unique tracing method that involves rabies virus. This approach is capable of revealing long chains of interconnected neurons. Using this approach, Dr. Strick and his colleagues demonstrated that the control of the adrenal medulla originates from multiple cortical areas. According to the new findings, the biggest influences arise from motor areas of the cerebral cortex and from other cortical areas involved in cognition and affect.

    Why does it matter which cortical areas influence the adrenal medulla? Acute responses to stress include a wide variety of changes such as a pounding heart, sweating and dilated pupils. These responses help prepare the body for action and often are characterized as “fight or flight responses.” Many situations in modern life call for a more thought-out reaction than simple “fight or flight,” and it is clear that we have some cognitive control (or what neuroscientists call “top-down” control) over our responses to stress.

    “Because we have a cortex, we have options,” said Dr. Strick. “If someone insults you, you don’t have to punch them or flee. You might have a more nuanced response and ignore the insult or make a witty comeback. These options are part of what the cerebral cortex provides.”

    Another surprising result was that motor areas in the cerebral cortex, involved in the planning and performance of movement, provide a substantial input to the adrenal medulla. One of these areas is a portion of the primary motor cortex that is concerned with the control of axial body movement and posture. This input to the adrenal medulla may explain why core body exercises are so helpful in modulating responses to stress. Calming practices such as Pilates, yoga, tai chi and even dancing in a small space all require proper skeletal alignment, coordination and flexibility.

    The PNAS study also revealed that the areas of the cortex that are active when we sense conflict, or are aware that we have made an error, are a source of influence over the adrenal medulla. “This observation,” said Dr. Strick, “raises the possibility that activity in these cortical areas when you re-imagine an error, or beat yourself up over a mistake, or think about a traumatic event, results in descending signals that influence the adrenal medulla in just the same way as the actual event.” These anatomical findings have relevance for therapies that deal with post-traumatic stress.

    Additional links with the adrenal medulla were discovered in cortical areas that are active during mindful awareness meditation and areas that show changes in bipolar familial depression. “One way of summarizing our results is that we may have uncovered the stress and depression connectome,” says Dr. Strick.

    Overall, these results indicate that circuits exist to link movement, cognition and affect to the function of the adrenal medulla and the control of stress. This circuitry may mediate the effects of internal states like chronic stress and depression on organ function and, thus, provide a concrete neural substrate for some psychosomatic illness.

     


  4. Online social media use does not impair our ability to concentrate

    October 19, 2016 by Ashley

    From the Inderscience Publishers media release:

    tablet computerUsing online social media does not lead to long-term problems with our ability to concentrate, according to new research published in the International Journal Social Media and Interactive Learning Environments.

    We are social animals, so it is really no surprise that billions of us now use online tools to communicate, educate and inform each other. The advent of social media and social networking has nevertheless been phenomenally rapid. “These networks have become an imprint of our everyday life and part of pop culture, revolutionizing the way people communicate and in the way organizations act, says Deborah Carstens of the Florida Institute of Technology.”With the abundance of technological devices, an increasing number of users of all ages rely on technology and specifically social media.”

    There are, however, worries about the impact such tools have on our psyche and our ability to concentrate, for instance. Now research from Carstens’ team and their colleagues at Barry University also in Florida, demonstrates that despite the often skittish and transient nature of online social interactions there is no difference to be seen in the attention span or “offline” sociability of occasional users and frequent users of online social media. These modern communication tools do not, it seems, interfere with our primal instincts, such as long-term attitudes, time appreciation, and concentration, in the way that many critics have suggested in recent years.

    “Social media is not a fad as it continues to play an increasing role in the individuals’ lives. Understanding how to utilize this social media epidemic to enhance learning, relationships and business knowledge is essential as individuals are spending an increasing amount of time on these networks,” the researchers conclude.


  5. Study supports do not sell voluntary waiting period for gun sales to reduce suicide

    October 11, 2016 by Ashley

    From the University of Alabama at Birmingham media release:

    Depressed seniorA new study suggests many patients at risk for suicide would voluntarily place their name on a Do Not Sell list, prohibiting gun shops from immediately selling them a firearm.

    The study, published in Suicide and Life-Threatening Behavior, says nearly half of the 200 people surveyed would willingly place their name on such a list.

    “There is evidence that suicide, in particular suicide-by-gun, is often impulsive — that once an individual decides to take their own life they are, in many cases, able to quickly obtain a firearm and use it,” said lead author Fredrick Vars, J.D., a professor in the School of Law at the University of Alabama. “The concept of a Do Not Sell list, similar to the national Do Not Call list, would be to eliminate such impulsive transactions. Restricting access to firearms, even temporarily, could save many lives.”

    The authors report that previous studies of survivors of firearm suicide attempts found a majority had suicidal thoughts for less than a day, while another found that, of nearly lethal suicide attempts among people 13-34 years of age, about one-fourth of attempters spent less than five minutes between the decision to attempt suicide and the actual attempt.

    Vars conducted the survey with investigators in the University of Alabama at Birmingham Department of Psychiatry in the School of Medicine.

    “People with mental illness are more likely to commit suicide,” said Richard Shelton, M.D., vice chair of Research for the UAB Department of Psychiatry and a study co-author. “Studies indicate the vast majority of suicide attempt survivors end up eventually dying of something other than suicide, so a means of preventing someone from making future gun purchases during a suicidal crisis might reduce suicide rates.”

    The researchers surveyed 200 patients at an inpatient psychiatric unit and two outpatient psychiatry clinics at UAB. The most commonly reported conditions of those surveyed were mood disorders, anxiety disorders, psychotic disorders or substance abuse.

    The survey presented two options to study participants. In the first, respondents would voluntarily place their name on the Do Not Sell list, which would feature a seven-day waiting period following a request for removal from the list to avoid an impulse buy. The second option would require a judicial hearing to remove a name from the list and allow a gun sale. A total of 46 percent of respondents indicated willingness to participate in one of the two methods, with a slight preference for the seven-day waiting period.

    “Nearly one-half of participants indicated they would like to be able to restrict their own future gun purchases,” Vars said. “This approach wouldn’t stop all suicides, but any dent we could make in the estimated 20,000 people who use a gun to commit suicide every year in the United States would be significant.

    “Waiting periods to purchase firearms have been shown to reduce gun suicide, most likely due to the impulsive nature of suicide attempts,” said Karen L. Cropsey, Psy.D., associate professor of psychiatry at UAB and a study co-author. “The Do Not Sell list is a new type of means restriction, and means restriction generally has been shown to be one of the most effective suicide prevention strategies.”

    Cropsey says a Do Not Sell list would be a natural extension of current counseling practice.

    “We regularly have conversations with patients who are having or have had suicidal thoughts about removing access to firearms in the home,” she said. “Taking a gun out of the home or, as in this case, creating a delay period that removes the ability to impulsively purchase a firearm are good strategies for suicide prevention.”

    Vars, who has studied mental health and gun ownership for years, believes the concept of the Do Not Sell list is unique but could be implemented fairly easily.

    A waiting period — say seven, 10 or perhaps 15 days — would be fairly easy to establish and would involve primarily one-time set up costs rather than an ongoing expense,” Vars said. “The judicial review option would be more expensive. The largest hurdle would be in educating health care providers and the public that an option such as a Do Not Sell list exists.”

    Vars would like to see the survey administered in other regions of the country to see if the results are similar.

    “Alabama has a high rate of gun ownership and a strong consensus against gun regulation,” Vars said. “Sign-up rates could be different and possibly higher in regions with lower gun ownership rates.”


  6. Metaphors bias perceptions of scientific discovery

    by Ashley

    From the Society for Personality and Social Psychology media release:

    woman contemplatingWhether ideas are “like a light bulb” or come forth as “nurtured seeds,” how we describe discovery shapes people’s perceptions of both inventions and inventors.

    Notably, Kristen Elmore (Bronfenbrenner Center for Translational Research at Cornell University) and Myra Luna-Lucero (Teachers College, Columbia University) have shown that discovery metaphors influence our perceptions of the quality of an idea and of the ability of the idea’s creator. The research appears in the journal Social Psychological and Personality Science.

    While those involved in research know there are many trials and errors and years of work before something is understood, discovered or invented, our use of words for inspiration may have an unintended and underappreciated effect of portraying good ideas as a sudden and exceptional occurrence.

    In a series of experiments, Elmore and Luna-Lucero tested how people responded to ideas that were described as being “like a light bulb,” “nurtured like a seed,” or a neutral description.

    According the authors, the “light bulb metaphor implies that ‘brilliant’ ideas result from sudden and spontaneous inspiration, bestowed upon a chosen few (geniuses) while the seed metaphor implies that ideas are nurtured over time, ‘cultivated’ by anyone willing to invest effort.”

    The first study looked at how people reacted to a description of Alan Turing’s invention of a precursor to the modern computer. It turns out light bulbs are more remarkable than seeds.

    We found that an idea was seen as more exceptional when described as appearing like a light bulb rather than nurtured like a seed,” said Elmore.

    But this pattern changed when they used these metaphors to describe a female inventor’s ideas. When using the “like a light bulb” and “nurtured seed” metaphors, the researchers found “women were judged as better idea creators than men when ideas were described as nurtured over time like seeds.”

    The results suggest gender stereotypes play a role in how people perceived the inventors.

    In the third study, the researchers presented participants with descriptions of the work of either a female (Hedy Lamarr) or a male (George Antheil) inventor, who together created the idea for spread-spectrum technology (a precursor to modern wireless communications). Indeed, the seed metaphor “increased perceptions that a female inventor was a genius, while the light bulb metaphor was more consistent with stereotypical views of male genius,” stated Elmore.

    Elmore plans to expand upon their research on metaphors by examining the interactions of teachers and students in real world classroom settings.

    The ways that teachers and students talk about ideas may impact students’ beliefs about how good ideas are created and who is likely to have them,” said Elmore. “Having good ideas is relevant across subjects — whether students are creating a hypothesis in science or generating a thesis for their English paper — and language that stresses the role of effort rather than inspiration in creating ideas may have real benefits for students’ motivation.”


  7. What’s really going on in PTSD brains? Experts suggest new theory

    by Ashley

    From the University of Michigan Health System media release:

    brain scanFor decades, neuroscientists and physicians have tried to get to the bottom of the age-old mystery of post-traumatic stress disorder, to explain why only some people are vulnerable and why they experience so many symptoms and so much disability.

    All experts in the field now agree that PTSD indeed has its roots in very real, physical processes within the brain — and not in some sort of psychological “weakness.” But no clear consensus has emerged about what exactly has gone “wrong” in the brain.

    In a Perspective article published this week in Neuron, a pair of University of Michigan Medical School professors — who have studied PTSD from many angles for many years — put forth a theory of PTSD that draws from and integrates decades of prior research. They hope to stimulate interest in the theory and invite others in the field to test it.

    The bottom line, they say, is that people with PTSD appear to suffer from disrupted context processing. That’s a core brain function that allows people and animals to recognize that a particular stimulus may require different responses depending on the context in which it is encountered. It’s what allows us to call upon the “right” emotional or physical response to the current encounter.

    A simple example, they write, is recognizing that a mountain lion seen in the zoo does not require a fear or “flight” response, while the same lion unexpectedly encountered in the backyard probably does.

    For someone with PTSD, a stimulus associated with the trauma they previously experienced — such as a loud noise or a particular smell — triggers a fear response even when the context is very safe. That’s why they react even if the noise came from the front door being slammed, or the smell comes from dinner being accidentally burned on the stove.

    Context processing involves a brain region called the hippocampus, and its connections to two other regions called the prefrontal cortex and the amygdala. Research has shown that activity in these brain areas is disrupted in PTSD patients. The U-M team thinks their theory can unify wide-ranging evidence by showing how a disruption in this circuit can interfere with context processing and can explain most of the symptoms and much of the biology of PTSD.

    “We hope to put some order to all the information that’s been gathered about PTSD from studies of human patients, and of animal models of the condition,” says Israel Liberzon, M.D., a professor of psychiatry at U-M and a researcher at the VA Ann Arbor Healthcare System who also treats veterans with PTSD. “We hope to create a testable hypothesis, which isn’t as common in mental health research as it should be. If this hypothesis proves true, maybe we can unravel some of the underlying pathophysiological processes, and offer better treatments.”

    Liberzon and his colleague, James Abelson, M.D., Ph.D., describe in their piece models of PTSD that have emerged in recent years, and lay out the evidence for each. The problem, they say, is that none of these models sufficiently explains the various symptoms seen in patients, nor all of the complex neurobiological changes seen in PTSD and in animal models of this disorder.

    The first model, abnormal fear learning, is rooted in the amygdala — the brain’s ‘fight or flight’ center that focuses on response to threats or safe environments. This model emerged from work on fear conditioning, fear extinction and fear generalization.

    The second, exaggerated threat detection, is rooted in the brain regions that figure out what signals from the environment are “salient,” or important to take note of and react to. This model focuses on vigilance and disproportionate responses to perceived threats.

    The third, involving executive function and regulation of emotions, is mainly rooted in the prefrontal cortex — the brain’s center for keeping emotions in check and planning or switching between tasks.

    By focusing only on the evidence bolstering one of these theories, researchers may be “searching under the streetlight,” says Liberzon. “But if we look at all of it in the light of context processing disruption, we can explain why different teams have seen different things. They’re not mutually exclusive.”

    The main thing, says Liberzon, is that “context is not only information about your surroundings — it’s pulling out the correct emotion and memories for the context you are in.”

    A deficit in context processing would lead PTSD patients to feel “unmoored” from the world around them, unable to shape their responses to fit their current contexts. Instead, their brains would impose an “internalized context” — one that always expects danger — on every situation.

    This type of deficit, arising in the brain from a combination of genetics and life experiences, may create vulnerability to PTSD in the first place, they say. After trauma, this would generate symptoms of hypervigilance, sleeplessness, intrusive thoughts and dreams, and inappropriate emotional and physical outbursts.

    Liberzon and Abelson think that testing the context processing theory will enhance understanding of PTSD, even if all of its details are not verified. They hope the PTSD community will help them pursue the needed research, in PTSD patients and in animal models. They put forth specific ideas in the Neuron paper to encourage that, and are embarking on such research themselves.

    The U-M/VA team is currently recruiting people with PTSD — whether veterans or not — for studies involving brain imaging and other tests.

    In the meantime, they note that there is a growing set of therapeutic tools that can help patients with PTSD, such as cognitive behavioral therapy mindfulness training and pharmacological approaches. These may work by helping to anchor PTSD patients in their current environment, and may prove more effective as researchers learn how to specifically strengthen context processing capacities in the brain.


  8. Stress and obesity biologically linked

    by Ashley

    From the Hebrew University of Jerusalem media release:

    obesityMetabolic and anxiety-related disorders both pose a significant healthcare burden, and are in the spotlight of contemporary research and therapeutic efforts. Although intuitively we assume that these two phenomena overlap, the link has not been proven scientifically.

    Now, a team of researchers from the Hebrew University of Jerusalem, headed by Prof. Hermona Soreq from the Edmond and Lily Safra Center for Brain Sciences and the Department of Biological Chemistry at the Faculty of Mathematics and Sciences, revealed the molecular elements that bridge anxiety and metabolism — a type of microRNA that influences shared biological mechanisms.

    “We already know that there is a connection between body and mind, between the physical and the emotional, and studies show that psychological trauma affects the activity of many genes. Our previous research found a link between microRNA and stressful situations — stress and anxiety generate an inflammatory response and dramatically increase the expression levels of microRNA regulators of inflammation in both the brain and the gut, for example the situation of patients with Crohn’s disease may get worse under psychological stress, “says Prof. Soreq.

    “In the present study, we added obesity to the equation. We revealed that some anxiety-induced microRNA are not only capable of suppressing inflammation but can also potentiate metabolic syndrome-related processes. We also found that their expression level is different in diverse tissues and cells, depending on heredity and exposure to stressful situations,” explains Prof. Soreq.

    The family of microRNA genes is part of the human genome, which was considered until not too long ago as “junk-DNA.” However, microRNAs are now known to fulfill an important role in regulating the production process of proteins by other genes. These tiny RNA molecules, which are one percent of the average size of a protein-coding gene, act as suppressors of inflammation and are able to halt the production of proteins.

    The research paper, published in the journal Trends in Molecular Medicine, details the evidence linking microRNA pathways, which share regulatory networks in metabolic and anxiety-related conditions. In particular, microRNAs involved in these disorders include regulators of acetylcholine signaling in the nervous system and their accompanying molecular machinery.

    Metabolic disorders, such as abdominal obesity and diabetes, have become a global epidemic. In the USA, the prevalence of metabolic syndrome is as high as 35 percent. In other countries, such as Austria, Denmark and Ireland it affects 20-25 percent of the population.

    Anxiety disorders are harder to quantify than metabolic ones. They include obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD) and phobia. The full burden of the anxiety spectrum is difficult to assess, due to under-diagnosis and poorly defined pathophysiological processes.

    This newly revealed link offers novel opportunities for innovative diagnoses and treatment of both metabolic and anxiety-related phenomena.

    “The discovery has a diagnostic value and practical implications, because the activity of microRNAs can be manipulated by DNA-based drugs,” explains Prof. Soreq. “It also offers an opportunity to reclassify ‘healthy’ and ‘unhealthy’ anxiety and metabolic-prone states, and inform putative strategies to treat these disorders.”

     


  9. Gastrointestinal disorders involve both brain-to-gut and gut-to-brain pathways

    August 15, 2016 by Ashley

    From the Wiley media release:

    mind mazeNew research indicates that in patients with irritable bowel syndrome (IBS) or indigestion, there is a distinct brain-to-gut pathway, where psychological symptoms begin first, and separately a distinct gut-to-brain pathway, where gut symptoms start first.

    In the study, higher levels of anxiety and depression were significant predictors of developing IBS or indigestion within 1 year. People who did not have elevated levels of anxiety and depression at the start of the study but had documented IBS or indigestion reported significantly higher levels of anxiety and depression after 1 year.

    The researchers calculated that in one-third of individuals, a mood disorder precedes gastrointestinal disorder, but in two-thirds a gastrointestinal disorder precedes the mood disorder.

    “We believe these results are really a breakthrough in conceptualizing IBS. The data indicate some patients with IBS have a primary gut disease that may not only explain their gut symptoms but also their psychological distress,” said Prof. Nicholas Talley, senior author of the Alimentary Pharmacology & Therapeutics study. “There are now three studies we have done that have all shown this new gut to brain pathway. Targeting the gut is much easier than the brain, and in doing so we may be in reach of relieving not only gut pain but also anxiety and depression that arises from gut disease.”

     


  10. Altruism is favored by chance

    August 9, 2016 by Ashley

    From the University of Bath media release:

    sharing childrenWhy do we feel good about giving to charity when there is no direct benefit to ourselves, and feel bad about cheating the system? Mathematicians may have found an answer to the longstanding puzzle as to why we have evolved to cooperate.

    An international team of researchers, publishing in the Proceedings of the National Academy of Sciences, has found that altruism is favoured by random fluctuations in nature, offering an explanation to the mystery as to why this seemingly disadvantageous trait has evolved.

    The researchers, from the Universities of Bath, Manchester and Princeton (USA), developed a mathematical model to predict the path of evolution when altruistic “cooperators” live alongside “cheats” who use up resources but do not themselves contribute.

    Humans are not the only organisms to cooperate with one another. The scientists used the example of Brewer’s yeast, which can produce an enzyme called invertase that breaks down complex sugars in the environment, creating more food for all. However, those that make this enzyme use energy that could instead have been used for reproduction, meaning that a mutant “cheating” strain that waits for others to do the hard work would be able to breed faster as a result.

    Darwinian evolution suggests that their ability to breed faster will allow the cheats (and their cheating offspring) to proliferate and eventually take over the whole population. This problem is common to all altruistic populations, raising the difficult question of how cooperation evolved.

    Dr Tim Rogers, Royal Society University Research Fellow at the University of Bath, said: “Scientists have been puzzled by this for a long time. One dominant theory was that we act more favourably towards genetic relatives than strangers, summed up by J. S. Haldane’s famous claim that he would jump into a river to save two brothers or eight cousins.

    What we are lacking is an explanation of how these behaviours could have evolved in organisms as basic as yeast. Our research proposes a simple answer — it turns out that cooperation is favoured by chance.”

    The key insight is that the total size of population that can be supported depends on the proportion of cooperators: more cooperation means more food for all and a larger population. If, due to chance, there is a random increase in the number of cheats then there is not enough food to go around and total population size will decrease. Conversely, a random decrease in the number of cheats will allow the population to grow to a larger size, disproportionally benefitting the cooperators. In this way, the cooperators are favoured by chance, and are more likely to win in the long term.

    Dr George Constable, soon to join the University of Bath from Princeton, uses the analogy of flipping a coin, where heads wins £20 but tails loses £10:

    Although the odds winning or losing are the same, winning is more good than losing is bad. Random fluctuations in cheat numbers are exploited by the cooperators, who benefit more then they lose out.”