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segunda-feira, 22 de março de 2010

Teoria da Evolução está Errada ?

Porque tudo o que você aprendeu sobre a evolução está errado

E se a teoria de Darwin da selecção natural é imprecisa? E se a maneira como você vive agora afecta a expectativa de vida dos seus descendentes? O pensamento evolucionista está a passar por uma revolução...

"O que toda esta evidência mostra é que precisamos de uma compreensão muito mais subtil e matizada do darwinismo e da selecção natural", diz Shenk. "Acho que isso vai inevitavelmente acontecer entre os cientistas. A questão é quanta dessa nuance irá passar para a esfera pública... É realmente engraçado como é difícil ter esta conversa, mesmo com um monte de pessoas que compreendem a ciência. Estamos encalhados numa forma bastante limitada de ver tudo isso, e penso que parte disso vem dos termos"- tais como natureza e educar/criar -"que temos."

Este artigo no Guardian é bastante interessante. Fala sobre como afinal a visão de Lammarck, de que a experiência de vida dos seres vivos poderia passar biologicamente para os seus descendentes, pode não estar tão errada como ainda se pensa actualmente. Fala das histórinhas "just so" dos evolucionistas, que explicam tudo e não explicam nada. Sobre o raciocínio circular darwinista. Aborda a questão da transferência horizontal de genes através dos vírus e de como isso poderá revolucionar e complicar a visão darwinista da evolução e da selecção natural. Fala também do novo livro de Jerry Fodor "What Darwin Got Wrong" e de como há muitas questões que a visão darwinista tradicional não responde.

Destaco a seguir algumas porções do texto.

Epigenética e Lammarck:

As years of bestselling books by Dawkins, Daniel Dennett and others have seeped into the culture, we've come to understand that the awesome power of natural selection – frequently referred to as the best idea in the history of science – lies in the sheer elegance of the way such simple principles have generated the unbelievable complexities of life. From two elementary notions – random mutation, and the filtering power of the environment – have emerged, over millennia, such marvels as eyes, the wings of birds and the human brain.

Yet epigenetics suggests this isn't the whole story. If what happens to you during your lifetime – living in a stress-inducing henhouse, say, or overeating in northern Sweden – can affect how your genes express themselves in future generations, the absolutely simple version of natural selection begins to look questionable. Rather than genes simply "offering up" a random smorgasbord of traits in each new generation, which then either prove suited or unsuited to the environment, it seems that the environment plays a role in creating those traits in future generations, if only in a short-term and reversible way. You begin to feel slightly sorry for the much-mocked pre-Darwinian zoologist Jean-Baptiste Lamarck, whose own version of evolution held, most famously, that giraffes have long necks because their ancestors were "obliged to browse on the leaves of trees and to make constant efforts to reach them". As a matter of natural history, he probably wasn't right about how giraffes' necks came to be so long. But Lamarck was scorned for a much more general apparent mistake: the idea that lifestyle might be able to influence heredity. "Today," notes David Shenk, "any high school student knows that genes are passed on unchanged from parent to child, and to the next generation and the next. Lifestyle cannot alter heredity. Except now it turns out that it can . . ."

"If a geneticist had suggested as recently as the 1990s that a 12-year-old kid could improve the intellectual nimbleness of his or her future children by studying harder now," writes Shenk, "that scientist would have been laughed right out of the hall." Not so now."

Transferência horizontal de genes entre organismos através dos vírus:
Epigenetics is the most vivid reason why the popular understanding of evolution might need revising, but it's not the only one. We've learned that huge proportions of the human genome consist of viruses, or virus-like materials, raising the notion that they got there through infection – meaning that natural selection acts not just on random mutations, but on new stuff that's introduced from elsewhere. Relatedly, there is growing evidence, at the level of microbes, of genes being transferred not just vertically, from ancestors to parents to offspring, but also horizontally, between organisms. The researchers Carl Woese and Nigel Goldenfield conclude that, on average, a bacterium may have obtained 10% of its genes from other organisms in its environment.

To an outsider, this is mind-blowing: since most of the history of life on earth has been the history of micro-organisms, the evidence for horizontal transfer suggests that a mainly Darwinian account of evolution may be only the latest version, applicable to the most recent, much more complex forms of life. Perhaps, before that, most evolution was based on horizontal exchange. Which gives rise to a compelling philosophical puzzle: if a genome is what defines an organism, yet those organisms can swap genes freely, what does it even mean to draw a clear line between one organism and another? "It's natural to wonder," Goldenfield told New Scientist recently, "if the very concept of an organism in isolation is still valid at this level." In natural selection, we all know, the fittest win out over their rivals. But what if you can't establish clear boundaries between rivals in the first place?

Tendência para violar segundo a visão darwinista e as histórias "just so":
It is a decade since the biologist Randy Thornhill and the anthropologist Craig Palmer published The Natural History of Rape. In the book, they made an argument that – however obnoxious at first glance – seemed, to many, to follow straightforwardly from the logic of natural selection. Evolution tells us that the traits that flourish down the generations are the ones that help organisms reproduce. Evolutionary psychology argues that there's no reason to exclude psychological traits. And since rape is indeed a trait that occurs all too frequently in human society, it follows that a desire to commit rape must be adaptive. There must be a genetic basis for it – a "rape gene", in the words of some media stories following the book's publication – because, in prehistoric times, those men who possessed the tendency would reproduce more successfully than those who didn't. Therefore, the authors concluded, rape was – to use a loaded term that has been getting Darwinians in trouble since Darwin – "natural".

Far more than biologists, evolutionary psychologists bought in to the ultra-simple version of natural selection, and so they stand to lose far more from advances in our understanding of what's really been going on. They were always prone to telling "just-so stories" – spinning plausible tales about why some trait might be adaptive, instead of demonstrating that it was – and numerous recent studies have begun to chip away at what evidence there was. (That waist-to-hip ratio finding, for example, doesn't seem to hold up in the face of international and historical research.) And now, if epigenetics and other developments are coming to suggest that environment can alter heredity, the very terms of the debate – of nature versus nurture – suddenly become shaky. It's not even a matter of settling on a compromise, a "mixture" of nature and nurture. Rather, the concepts of "nature" and "nurture" seem to be growing meaningless. What does "nature" even mean if you can nurture the nature of your descendants?

Jerry Fodor e o seu livro "What Darwin Got Wrong" e o raciocínio circular do darwinismo:
I called Fodor and asked him to explain his point in language an infant school pupil could understand. "Can't be done," he shot back. "These issues really are complicated. If we're right that Darwin and Darwinists have missed the point we've been making for 150 years, that's not because it's a simple point and Darwin was stupid. It's a really complicated issue."

Fodor's objection is a distant cousin of one that rears its head every few years: doesn't "survival of the fittest" just mean "survival of those that survive", since the only criterion of fitness is that a creature does, indeed, survive and reproduce? The American rightwing noisemaker Ann Coulter makes the point in her 2006 pro-creationist tirade Godless: The Church of American Liberalism. "Through the process of natural selection, the 'fittest' survive, [but] who are the 'fittest'? The ones who survive!" she sneers. "Why, look – it happens every time! The 'survival of the fittest' would be a joke if it weren't part of the belief system of a fanatical cult infesting the Scientific Community."

This argument, perhaps uniquely among all arguments ever made by Coulter, feels persuasive, not least because it is a reasonable criticism of some pop-Darwinism. In fact, though, it's entirely possible for scientists to measure fitness using criteria other than survival, and thus to avoid circular logic. For example, you might hypothesise that speed is a helpful thing to have if you're an antelope, then hypothesise the kind of leg structure you'd want to have, as an antelope, in order to run fast; then you'd examine antelopes to see if they do indeed have something approximating this kind of leg structure, and you'd examine the fossil record, to see if other kinds of leg died out.

Perto ou longe de compreender as origens e o desenvolvimento da vida?:
The irony in all this is that Darwin himself never claimed that it was. He went to his deathbed protesting that he'd been misinterpreted: there was no reason, he said, to assume that natural selection was the only imaginable mechanism of evolution. Darwin, writing before the discovery of DNA, knew very well that his work heralded the beginning of a journey to understand the origins and development of life. All we may be discovering now is that we remain closer to the beginning of that journey than we've come to think.

Fonte: The Guardian, 19 de Março de 2010

0 comentário:

A origem da vida não é consensual. A evolução dos seres vivos não é consensual. A teoria de Lamarck, a teoria de Darwin, e outras, propuseram a transformação dos seres vivos ao longo do tempo.

Mas o evolucionismo e o darwinismo não explicam de forma satisfatória a complexidade dos seres vivos. A biologia molecular e a biologia celular revelam mecanismos cuja origem os darwinistas nem se atrevem a tentar explicar.

Este blog trata da Teoria do Design Inteligente, Darwinismo e Teoria da Evolução