Be Your Best Friend If You'll Be Mine: Alliance Hypothesis For Human Friendship

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ScienceDaily (June 5, 2009) — University of Pennsylvania psychologists studying the cognitive mechanisms behind human friendship have determined that how you rank your best friends is closely related to how you think your friends rank you. The results are consistent with a new theory called the Alliance Hypothesis for Human Friendship, distinct from traditional explanations for human friendship that focused on wealth, popularity or similarity.

The study, performed by Penn cognitive psychologists Peter DeScioli and Robert Kurzban, has demonstrated that human friendship is caused, in part, by cognitive mechanisms aimed at creating a ready-made support group for potential conflicts. People call on friends for help in a variety of disputes, ranging from trivial arguments to violent fights. This study suggests that people have specialized decision processes that prioritize those individuals who tend to be most helpful in conflicts, those with fewer stronger commitments to others.
Researchers performed question-and-answer studies in which participants ranked their closest friends in a number of ways, including, for example, the benefits they receive from the friendship, the number of secrets shared and how long the friendship has been ongoing. Each time, whether participants were an online community, random passersby on a metropolitan street or undergraduate students in a laboratory, friendship rankings were most strongly correlated with individuals' own perceived rank among their partners' other friends.
"Historically, the main theory has been that humans build friendships in order to trade in goods and services," DeScioli, lead author, said. "The problem we focused on was that friendship involves more than exchange. People want friends who care about them and do not give just to get something back in return. We thought that theories about alliances might help explain why friends are primarily concerned with each others' needs rather than the benefits they can get in return for helping."
Traditional evolutionary approaches to explain human friendship apply the Theory of Reciprocal Altruism: Friends function as exchange partners; however, a wealth of empirical evidence from social psychology is inconsistent with the theory. For example, in prior studies it was shown that people do not keep regular tabs on the benefits given and received in close relationships. Also, people seem to help friends even when they are unlikely to be capable of repayment. For cognitive psychologists, it is unclear what humans and their complex brains are up to in creating these relationships.
The new Penn theory has origins in models of alliance building between nations, which prepare for conflict in advance but may not expect anything in return immediately.
"Friendships are about alliances," Kurzban, an associate professor, said. "We live in a world where conflict can arise and allies must be in position beforehand. This new hypothesis takes into account how we value those alliances. In a way, one of the main predictors of friendship is the value of the alliance. The value of an ally, or friend, drops with every additional alliance they must make, so the best alliance is one in which your ally ranks you above everyone else as well."
In short, the hypothesis is much more optimistic about the reasons for friendship than existing theories which point toward popularity, wealth and proximity as reasons for friendship.
"In this hypothesis," Kurzban said, "it's not what you can do for me, it's how much you like me. In this manner even the weakest nations, for example, or the least popular kid at the party with nary an alliance in the room is set up to be paired with someone looking for a friend."
More darkly, the new model also serves as an explanation for some petty human behaviors not explained by traditional friendship theories. For example, the Alliance Hypothesis explains why people are extremely concerned with comparisons to others in their social circle. It also explains how jealousies and aggression can erupt among groups of friends as alliances are shifted and maintained.
If the Alliance Hypothesis for Human Friendship is correct, then theories about alliances from game theory and international relations might help us better understand friendship. These theories suggest that people in conflict would benefit strategically from ranking their friends, hiding their friend-rankings and ranking friends according to their own position in partners' rankings. To employ these tactics in their friendships, people need to gather and store information about their friends' other friendships. That is, they have to readily understand the social world not only from their own perspective but also from the perspectives of their friends.
Although friendship is a core element of human social life, its evolved functions have been difficult to understand. Human friendship occurs among individuals who are neither relatives nor mates, so the function of this cooperative behavior is not as clear as when reproduction or genetic relatives are involved. Similar relationships have been observed in non-human species -- hyenas use partners to gain access to carcasses and male dolphins employ "wingmen" to attain females for mating — and considerable progress has been made in understanding these non-human relationships. But the functions of human friendship have been more elusive.
The study, appearing in the current issue of the online journal Public Library of Science One, was conducted by DeScioli and Kurzban of the Department of Psychology in the School of Arts and Sciences at Penn.
It was supported by a fellowship from the International Foundation for Research in Experimental Economics.
Adapted from materials provided by University of Pennsylvania, via EurekAlert!, a service of AAAS.

Basket Weaving May Have Taught Humans To Count

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ScienceDaily (June 3, 2009) — Did animals teach us one of the oldest forms of human technology? Did this technology contribute to our ability to count? These are just two of the themes due to be explored at a conference on basketry at the University of East Anglia.

The event, which takes place today and tomorrow (June 5-6), is part of Beyond the Basket, a major new research project led by the university exploring the development and use of basketry in human culture over 10,000 years.
Basketry has been practised for millennia and ranges from mats for sitting on, containers and traps for hunting, to fencing and barriers for animals or land, partitions and walls - all of which have been central to culture.
Beyond the Basket is a two-and-a-half year project funded by the Arts and Humanities Research Council as part of its Beyond Text programme. The research will explore the role of basketry in human culture and focus on various parts of the world, both in the past and present, from Europe to Amazonia, central Africa and Papua New Guinea.
The aim is to identify the mechanical traditions of making and the ways in which basketry is implicated in wider patterns of understanding, for example the order of society or the design of the universe. It will also show the impact of woven forms on other media, such as pottery, painting, and stone sculpture and architecture, and look at the future of basketry and the solutions it could offer to current issues, whether technical or social.
Project leader Sandy Heslop, of the School of World Art and Museology at UEA, said: “Basketry is a worldwide technology and is the interaction between human ingenuity and the environment. It tends to make use of, and therefore has to be adapted to, local conditions in terms of resources and environment.
“Without basketry there would be no civilisations. You can’t bring thousands of people together unless you can supply them, you can’t bring in supplies to feed populations without containers. In the early days of civilisations these containers were basketry.
“We may think of baskets as humble, but other people and cultures don’t. They have been used for storage, for important religious and ceremonial processes, even for bodies in the form of coffins.”
It is about 10,000 years ago that evidence for basketry starts to appear in North America, Asia, Europe and the Middle East. Today its uses and influences are still seen, from the bamboo scaffolding often used in Asia, to contemporary architecture, for example the ‘Boiler Suit’ - the name given to the ‘woven’ steel tiles encasing the boiler room at Guy’s Hospital in London.
Mr Heslop said: “Beyond its practical uses, basketry has arguably been even more influential on our lives, since it relies on the relationship of number, pattern and structure. It therefore provides a model for disciplines such as mathematics and engineering and for the organisation of social and political life.
“Given the range of uses of basketry the associations of the technology are very varied. Some are aggressive, others protective, some help create social hierarchies others are recreational.”
The conference, Beyond the Basket: Construction, Order and Understanding, will look at various themes including: design and production, environmental issues, commercial and historical perspectives, weaving in architecture, and the mathematics of basketry, as well as more anthropological and archaeological topics. Among the speakers will be experts from North and South America, as well as the UK.
Beyond the Basket will culminate in an exhibition and accompanying book in 2011. The exhibition will include ancient material recovered by excavation as well as more recent examples of basketry from around the world and will enable people to experience basketry directly.
For further information about Beyond the Basket and to view images visit http://projects.beyondtext.ac.uk/beyondthebasket
Adapted from materials provided by University of East Anglia, via AlphaGalileo.

High Population Density Triggers Cultural Explosions

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ScienceDaily (June 5, 2009) — Increasing population density, rather than boosts in human brain power, appears to have catalysed the emergence of modern human behaviour, according to a new study by UCL (University College London) scientists published in the journal Science.

High population density leads to greater exchange of ideas and skills and prevents the loss of new innovations. It is this skill maintenance, combined with a greater probability of useful innovations, that led to modern human behaviour appearing at different times in different parts of the world.
In the study, the UCL team found that complex skills learnt across generations can only be maintained when there is a critical level of interaction between people. Using computer simulations of social learning, they showed that high and low-skilled groups could coexist over long periods of time and that the degree of skill they maintained depended on local population density or the degree of migration between them. Using genetic estimates of population size in the past, the team went on to show that density was similar in sub-Saharan Africa, Europe and the Middle-East when modern behaviour first appeared in each of these regions. The paper also points to evidence that population density would have dropped for climatic reasons at the time when modern human behaviour temporarily disappeared in sub-Saharan Africa.
Adam Powell, AHRC Centre for the Evolution of Cultural Diversity, says: "Our paper proposes a new model for why modern human behaviour started at different times in different regions of the world, why it disappeared in some places before coming back, and why in all cases it occurred more than 100,000 years after modern humans first appeared.
"By modern human behaviour, we mean a radical jump in technological and cultural complexity, which makes our species unique. This includes symbolic behavior, such as abstract and realistic art, and body decoration using threaded shell beads, ochre or tattoo kits; musical instruments; bone, antler and ivory artefacts; stone blades; and more sophisticated hunting and trapping technology, like bows, boomerangs and nets.
Professor Stephen Shennan, UCL Institute of Archaeology, says: "Modern humans have been around for at least 160,000 to 200,000 years but there is no archaeological evidence of any technology beyond basic stone tools until around 90,000 years ago. In Europe and western Asia this advanced technology and behaviour explodes around 45,000 years ago when humans arrive there, but doesn't appear in eastern and southern Asia and Australia until much later, despite a human presence. In sub-Saharan Africa the situation is more complex. Many of the features of modern human behaviour – including the first abstract art – are found some 90,000 years ago but then seem to disappear around 65,000 years ago, before re-emerging some 40,000 years ago.
"Scientists have offered many suggestions as to why these cultural explosions occurred where and when they did, including new mutations leading to better brains, advances in language, and expansions into new environments that required new technologies to survive. The problem is that none of these explanations can fully account for the appearance of modern human behaviour at different times in different places, or its temporary disappearance in sub-Saharan Africa."
Dr Mark Thomas, UCL Genetics, Evolution and Environment, says: "When we think of how we came to be the sophisticated creatures we are, we often imagine some sudden critical change, a bit like when the black monolith appears in the film 2001: A Space Odyssey. In reality, there is no evidence of a big change in our biological makeup when we started behaving in an intelligent way. Our model can explain this even if our mental capacities are the same today as they were when we first originated as a species some 200,000 years ago.
"Ironically, our finding that successful innovation depends less on how smart you are than how connected you are seems as relevant today as it was 90,000 years ago."
Journal reference:
Adam Powell, Stephen Shennan, and Mark G. Thomas. Late Pleistocene Demography and the Appearance of Modern Human Behavior. Science, 2009; 324 (5932): 1298 DOI: 10.1126/science.1170165
Adapted from materials provided by University College London, via EurekAlert!, a service of AAAS.

Pedophiles Have Deficits In Brain Activation, Study Suggests

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http://www.sciencedaily.com/releases/2007/09/070920091209.htm

Science Daily — Pedophilia, the sexual attraction of adults to children, is a significant public health concern and it does not respond well to treatment. Additionally, the brain mechanisms underlying pedophilia are not well understood.
A new study being published in the September 15th issue of Biological Psychiatry is the first of its kind to use functional brain imaging to describe neural circuits contributing to pedophilia.
Using functional magnetic resonance imaging, or fMRI, Walter and colleagues report that pedophilic patients showed reduced activation of the hypothalamus, a brain region involved in regulating physiologic arousal and hormone release, as compared to healthy individuals when they were viewing sexually arousing pictures of adults.
Deficits of activation in the frontal cortex were associated with the extent of pedophilic behavior. In other words, when shown erotic pictures of adults, the brains of the pedophilic patients had reduced reactions in the pleasure center of the brain, indicating an altered sexual interest.
John H. Krystal, M.D., Editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System, comments that, "the ability to intervene rationally in this disorder is limited by shortcomings in our understanding of its neurobiology. The findings provide clues to the complexity of this disorder, [and] this deficit may predispose individuals who are vulnerable to pedophilia to seek other forms of stimulation." It is important to acknowledge and consider however, that it is currently unknown "whether this pattern of brain activation is a risk factor for the development of pedophilia or a consequence of their pedophilic sexual experiences," according to Dr. Krystal, and future research will be needed.
One of the study's authors, Georg Northoff, M.D., Ph.D., adds, "[These findings] may open the door for better understanding the neurobiology of this disorder which is of forensic, criminal and public concern. Our results may thus be seen as the first step towards establishing a neurobiology of pedophilia which ultimately may contribute to the development of new and effective means of therapies for this debilitating disorder."
The article is "Pedophilia Is Linked to Reduced Activation in Hypothalamus and Lateral Prefrontal Cortex During Visual Erotic Stimulation" by Martin Walter, Joachim Witzel, Christine Wiebking, Udo Gubka, Michael Rotte, Kolja Schiltz, Felix Bermpohl, Claus Tempelmann, Bernhard Bogerts, Hans Jochen Heinze, and Georg Northoff. Drs. Walter, Wiebking, Schiltz, Bogerts and Northoff are with the Department of Psychiatry, Otto-von-Guericke University of Magdeburg, Germany, while Drs. Rotte, Tempelmann, and Heinze are with the Department of Neurology. Drs. Witzel and Gubka are affiliated with the State Hospital for Forensic Psychiatry of Saxonia Anhaltina, Germany. Dr. Bermpohl is with the Department of Psychiatry and Psychotherapy at Charité Medical School, University Medicine Berlin, Germany. The article appears in Biological Psychiatry, Volume 62, Issue 6 (September 15, 2007), published by Elsevier.
Note: This story has been adapted from a news release issued by Elsevier.

Fausto Intilla
www.oloscience.com

Adult Brain Can Change, Study Confirms

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http://www.sciencedaily.com/releases/2007/09/070905155440.htm

Science Daily — It is well established that a child's brain has a remarkable capacity for change, but controversy continues about the extent to which such plasticity exists in the adult human primary sensory cortex.

Now, neuroscientists from MIT and Johns Hopkins University have used converging evidence from brain imaging and behavioral studies to show that the adult visual cortex does indeed reorganize--and that the change affects visual perception.
The authors believe that as scientists find ways to use this adaptive ability, the work could have relevance to topics ranging from learning to designing interventions for improving recovery following stroke, brain injury, or visual disorders.
Animal studies conducted two decades ago and using single cell recording of neurons found that the adult animal brain can change, but shed little information about the adult human brain. In 2005, a functional magnetic resonance imaging (fMRI) study led by Professor Nancy Kanwisher at the McGovern Institute for Brain Research at MIT found evidence of plasticity in the visual cortex of adults with macular degeneration, an eye disease that deprives regions of the cortex of visual information.
But another fMRI study of macular degeneration found no such evidence, and an animal study using both single cell recordings and fMRI also questioned the 20-year-old animal work.
Lead author Daniel Dilks, a postdoctoral associate in Kanwisher's lab who conducted the current work while a graduate student at Johns Hopkins in senior author Michael McCloskey's lab, jumped into the fray when he found BL, a stroke patient.
BL's stroke damaged the optic radiation fibers, which transmit information from the eye to the primary visual cortex, but the cortex itself remained intact. The damage eliminated input from the upper left visual field to the corresponding region of the primary visual cortex, thereby depriving a region of cortex and creating a blind area in the upper left visual field.
The researchers wanted to find out what happened to that deprived piece of cortex. "We discovered that it took on new functional properties, and BL sees differently as a consequence of that cortical reorganization," explains Dilks.
BL had reported that things "looked distorted" in the lower left visual field (below his blind area). The researchers hypothesized that the distortions resulted from cortical reorganization in the deprived cortex. To isolate that distortion, they had BL fixate on a center dot while objects, such as squares, appeared in various parts of the visual field. As expected, BL saw nothing when a square appeared in his blind area.
But when the square appeared just below the blind area, he perceived the square as a rectangle extending upwards into the blind area. Likewise, he saw triangles as "pencil-like", and circles as "cigar-like".
Subsequent fMRI studies confirmed that the visually deprived cortex (representing the upper left visual field) was responding to information coming from the lower left visual field. The deprived cortex assumed new properties, a hallmark of plasticity, and that explained the visual distortions.
Dilks is continuing this work in postdoctoral studies in Kanwisher's lab. In addition to Michael McCloskey, John Serences of University of California Irvine, and Benjamin Rosenau and Steven Yantis, both of Johns Hopkins, coauthored the Journal of Neuroscience paper. An Integrative Graduate Education and Research Traineeship and a Graduate Research Fellowship, both from the National Science Foundation, and the NIH funded the Johns Hopkins work.
The study appears online Sept. 5 in an advance publication of the Journal of Neuroscience.
Note: This story has been adapted from a news release issued by Massachusetts Institute of Technology.

Fausto Intilla

www.oloscience.com