Thursday, November 27, 2008

Mais sobre sociedades de insectos - com aplicação nos mercados financeiros


As formigas e outros insectos "sociais" tornam-se melhores nas suas competências quando há trabalho de cooperação. o seu comportamento responde aos princípios de eficácia ergonómica representados pelos teoremas de Barlow-Proschan (complexo). Quando a competência individual é fraca, diz o primeiro teorema, a fiabilidade de um sistema de indivíduos que agem em conjunto é menor do que a soma das competências dos indivíduos que agem isoladamente; mas quando a competência individual é alta, acima de um certo nível, a fiabilidade do sistema baseado na cooperação é maior. De acordo com o segundo teorema, um sistema redundante, cujas partes podem ser intercambiadas várias vezes (como os membros da colónia), é mais fiável do que dois sistemas idênticos sem nenhum sistema de partes alternativas ou de back-up. O sistema de "fiabilidade" pode ser transposto para a crise financeira mundial...
A natureza é também especialista em simbioses. Quando dois tipos de organismos vivem numa simbiose estreita, como para as formigas cortadoras de folhas, com as suas culturas de fungos, há uma comunicação entre os dois. O fungus pode assinalar às formigas a sua preferência por certos substratos vegetais ou a necessidade de uma alteração de dieta para manter a diversidade nutricionak, ou mesmo a presença de um substrato prejudicial.



Friday, November 21, 2008

A inteligência dos insectos


Eis um artigo do New York Times sobre insectos, um livro por dois vencedores do Pulitzer. Os mecanismos da inteligência colectiva são cada vez mais estudados, e os cientistas sabem que existe uma consciência na natureza, e não apenas mecanismos repetitivos...

Ontem observei durante uma hora um formigueiro, de formigas grandes como há em ÁFrica, e vi-as retirar grãos de areia um por um das suas galerias. Noutro buraco estavam a acrescentar areia precisamente. Umas atiravam a areia para longe, quando a retiravam, mas outras não se davam ao trabalho e deixavam o seu grão mesmo à entrada. Precisamente o que veria  um gigante se olhasse para nós... Será que este também se interrogaria se existe ou não uma inteligência em nós, ou se estamos apenas a cumprir mecanismos?

"Hölldobler and Wilson’s central conceit is that a colony is a single animal raised to a higher level. Each insect is a cell, its castes are organs, its queens are its genitals, the wasps that stung me are an equivalent of an immune system. In the same way, the foragers are eyes and ears, and the colony’s rules of development determine its shape and size. The hive has no brain, but the iron laws of cooperation give the impression of planning. Teamwork pays; in a survey of one piece of Amazonian rain forest, social insects accounted for 80 percent of the total biomass, with ants alone weighing four times as much as all its mammals, birds, lizards, snakes and frogs put together. The world holds as much ant flesh as it does that of humans".

Friday, November 7, 2008

Não temos consciência de crenças religiosas...

The Evil Pleasure

Pascal Boyer in Nature on religion:

One important finding is that people are only aware of some of their religious beliefs.  ... For instance, experiments reveal that most people entertain highly anthropomorphic expectations about gods, whatever their explicit beliefs. ... Research has shown that unlike conscious beliefs, which differ widely from one tradition to another, tacit assumptions are extremely similar in different cultures and religions. ... Experiments suggest that people best remember stories that include a combination of counterintuitive physical feats ... and plausibly human psychological features.  ... Experiments show that it is much more natural to think "the gods know that I stole this money" than "the gods know that I had porridge for breakfast." ...

Humans are unique among animals in maintaining large, stable coalitions of unrelated individuals, strongly bonded by mutual trust.  Humans evolved the cognitive tools to ... gauge others' reliability. ... They can emit and detect costly, hard-to-fake signals of commitment. ... When people proclaim their adherence to a particular faith, they subscribe to claims for which there is no evidence, and that would be taken as obviously wrong or ridiculous in other religions groups.  This signals a willingness to embrace the group's particular norm for no other reason than that it is, precisely, the group's norm.



Thursday, November 6, 2008

Não há diferença entre o amor e o ódio?

Scientists prove it really is a thin line between love and hate

The same brain circuitry is involved in both extreme emotions – but hate retains a semblance of rationality

By Steve Connor, Science Editor
Wednesday, 29 October 2008

Michael Douglas and KathleenTurner played a couple with a stormy relationship in the 1989 film War Of The Roses

Michael Douglas and KathleenTurner played a couple with a stormy relationship in the 1989 film War Of The Roses

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Love and hate are intimately linked within the human brain, according to a study that has discovered the biological basis for the two most intense emotions.

Scientists studying the physical nature of hate have found that some of the nervous circuits in the brain responsible for it are the same as those that are used during the feeling of romantic love – although love and hate appear to be polar opposites.

A study using a brain scanner to investigate the neural circuits that become active when people look at a photograph of someone they say they hate has found that the "hate circuit" shares something in common with the love circuit.

The findings could explain why both hate and romantic love can result in similar acts of extreme behaviour – both heroic and evil – said Professor Semir Zeki of University College London, who led the study published in the on-line journal PloS ONE.

"Hate is often considered to be an evil passion that should, in a better world, be tamed, controlled and eradicated. Yet to the biologist, hate is a passion that is of equal interest to love," Professor Zeki said.

"Like love, it is often seemingly irrational and can lead individual to heroic and evil deeds. How can two opposite sentiments lead to the same behaviour?"

The study advertised for volunteers to take part in the study and 17 people were chosen who professed a deep hatred for one individual. Most chose an ex-lover or a competitor at work, although one woman expressed an intense hatred for a famous political figure.

Professor Zeki and John Romaya of the Wellcome Laboratory of Neurobiology analysed the activity of the neural circuits in the brain that lit up when the volunteers were viewing photos of the hated person.

They found that the hate circuit includes parts of the brain called the putamen and the insula, found in the sub-cortex of the organ. The putamen is already known to be involved in the perception of contempt and disgust and may also be part of the motor system involved in movement and action.

"Significantly, the putamen and the insula are also both activated by romantic love. This is not surprising. The putamen could also be involved in the preparation of aggressive acts in a romantic context, as in situations when a rival presents a danger," Professor Zeki said.

"Previous studies have suggested that the insula may be involved in responses to distressing stimuli, and the viewing of both a loved and a hated face may constitute such a distressing signal."

One major difference between love and hate appears to be in the fact that large parts of the cerebral cortex – associated with judgement and reasoning – become de-activated during love, whereas only a small area is deactivated in hate.

"This may seem surprising since hate can also be an all-consuming passion like love. But whereas in romantic love, the lover is often less critical and judgemental regarding the loved person, it is more likely that in the context of hate the hater may want to exercise judgement in calculating moves to harm, injure or otherwise exact revenge," Professor Zeki said.

"Interestingly, the activity of some of these structures in response to a hated face is proportional in strength to the declared intensity of hate, thus allowing the subjective state of hate to be objectively quantified. This finding may have implications in criminal cases."


Fonte: www.independent.co.uk/news/science