Animals losing migratory routes? Devasting consequences of scarcity of ‘knowledgeable elders’

Small changes in a population may lead to dramatic consequences, like the disappearance of the migratory route of a species. A study carried out in collaboration with the SISSA has created a model of the behaviour of a group of individuals on the move (like a school of fish, a herd of sheep or a flock of birds, etc.) which, by changing a few simple parameters, reproduces the collective behaviour patterns observed in the wild. The model shows that small quantitative changes in the number of knowledgeable individuals and availability of food can lead to radical qualitative changes in the group’s behaviour.Until the ’50s, bluefin tuna fishing was a thriving industry in Norway, second only to sardine fishing. Every year, bluefin tuna used to migrate from the eastern Mediterranean up to the Norwegian coasts. Suddenly, however, over no more than 4-5 years, the tuna never went back to Norway. In an attempt to solve this problem, Giancarlo De Luca from SISSA (the International School for Advanced Studies of Trieste) together with an international team of researchers (from the Centre for Theoretical Physics — ICTP — of Trieste and the Technical University of Denmark) started to devise a model based on an “adaptive stochastic network.” The physicists wanted to simulate, simplifying it, the collective behaviour of animal groups. Their findings, published in the journal Interface, show that the number of “informed individuals” in a group, sociality and the strength of the decision of the informed individuals are “critical” variables, such that even minimal fluctuations in these variables can result in catastrophic changes to the system.”We started out by taking inspiration from the phenomenon that affected the bluefin tuna, but in actual fact we then developed a general model that can be applied to many situations of groups “on the move,” explains De Luca.The collective behaviour of a group can be treated as an “emerging property,” that is, the result of the self-organization of each individual’s behaviour. “The majority of individuals in a group may not possess adequate knowledge, for example, about where to find rich feeding grounds” explains De Luca. “However, for the group to function, it is enough that only a minority of individuals possess that information. The others, the ones who don’t, will obey simple social rules, for example by following their neighbours.”The tendency to comply with the norm, the number of knowledgeable individuals and the determination with which they follow their preferred route (which the researchers interpreted as being directly related to the appeal, or abundance, of the resource) are critical variables. …

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Stress undermines empathic abilities in men but increases them in women

Stressed males tend to become more self-centered and less able to distinguish their own emotions and intentions from those of other people. For women the exact opposite is true. Stress, this problem that haunts us every day, could be undermining not only our health but also our relationships with other people, especially for men. Stressed women, however, become more “prosocial,” according to new research.These are the main findings of a study carried out with the collaboration of Giorgia Silani, from the International School for Advanced Studies (SISSA) of Trieste. The study was coordinated by the Social Cognitive Neuroscience Unit of the University of Vienna and saw the participation of the University of Freiburg. This is the main finding of a study just published in Psychoneuroendocrinology, carried out with the collaboration of SISSA in Trieste.”There’s a subtle boundary between the ability to identify with others and take on their perspective — and therefore be empathic — and the inability to distinguish between self and other, thus acting egocentrically” explains Silani. “To be truly empathic and behave prosocially it’s important to maintain the ability to distinguish between self and other, and stress appears to play an important role in this.”Stress is a psycho-biological mechanism that may have a positive function: it enables the individual to recruit additional resources when faced with a particularly demanding situation. The individual can cope with stress in one of two ways: by trying to reduce the internal load of “extra” resources being used, or, more simply, by seeking external support. “Our starting hypothesis was that stressed individuals tend to become more egocentric. Taking a self-centred perspective in fact reduces the emotional/cognitive load. …

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