Why everything you've been told about evolution is wrong.

Thảo luận trong 'Sách tiếng nước ngoài' bắt đầu bởi Despot, 6/10/13.

  1. Despot

    Despot Lớp 10

    Tất nhiên nói thế chỉ để tạo chú ý. Nhưng quả thật trong di truyền học và tiến hóa có nhiều bí ẩn hơn là những gì nằm trong bộ gen.

    Review by Peter Forbes , The Guardian (guardian.co.uk, Friday 19 August 2011)

    Time was when scientific revolutions – the discoveries of Newton, Faraday, Darwin, Einstein, Watson and Crick – reverberated around the globe. But although we are living through the greatest discoveries about the processes of life generally, and human beings in particular, the new findings hardly rate a blip on the collective consciousness. In March 2010 Oliver Burkeman wrote for this paper on the subject of epigenetics. The article was provocatively titled: "Why everything you've been told about evolution is wrong." It isn't, but I confidently predicted to anyone within earshot that this would finally set tongues wagging.

    I was wrong – there was not a flicker of public interest. Discoveries that Darwin would have swooned over apparently leave a modern audience cold. But this book, subtitled: "How modern biology is rewriting our understanding of genetics, disease and inheritance", is an attempt to put matters straight.

    Epigenetics is what happens when genes are actually in action: in the growth of the foetus, in responding to hormones and environmental stress, to learning, to maturation at puberty. In all of these processes genes are modified slightly and act differently from that point on. In short, epigenetics is where nature meets nurture. The grounds for excitement stem from the fact that this old and frequently sterile dichotomy is now being fleshed out with real knowledge of how genes are controlled and how they respond to life situations.

    When the human genome sequence was announced in 2001 the rhetoric was highly charged: this is a scroll; the book of life; a huge encyclopaedia; a sacred chain of code 3bn characters long. It is this that is misleading. The notion was that the genes were all and the cells that contained them were just off-the-peg bags. After all, in cloning, if you suck out the nucleus of a cell and replace it with the nucleus of a completely different kind of creature, it will grow into an adult dictated by the new, injected nuclear DNA. In 2010 the maverick biologist and entrepreneur Craig Venter announced that he had created life when he inserted an entirely synthesised DNA into a bacterial cell. But the fact is, he needed cells, and we still can't synthesis them. The cell tells the DNA what to do just as much as the DNA instructs the cell: you can't have one without the other.

    Genes don't just issue instructions: they respond to messages coming from other genes, from hormones and from nutritional cues and learning. Much epigenetics revolves around nutrition. If we drink a lot of alcohol an enzyme that metabolises it becomes more active – "upregulated" in the jargon. And similar mechanisms apply to much of our behaviour. The methods by which genes makes these responses often involve very small chemical modifications (usually the addition of a tiny methyl group to one base of DNA). It is almost certain that memory – a classic nurture problem: we learn something and it becomes biologically encoded – involves epigenetics. Once made, epigenetic changes can be very long lasting, which is how our long-term memory is possible.

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    Nguồn: TVE

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