bystander
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加入时间: 2004/02/14
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作者：bystander 在 罕见奇谈 发贴, 来自 http://www.hjclub.org
Here are some excerpts from my paper on the ideas of Margulis and Kauffman:
“…life forms did make an eventual leap up the ladder of evolution over eons of time from prokaryotes to eukaryotes (unicellular organisms with nuclei) and then from unicellular organisms to multicellular creatures of increasing complexity. Was such “progress” the result of sheer chance? Or was it the inevitable outcome of some natural law? Are there any other mechanisms at work apart from random variation and natural selection?
“The community of biologists seems divided when confronted with such questions. Lynn Margulis, Professor of Botany at the University of Massachusetts, contends that the Darwinist camp focus too narrowly on competition alone. Of at least equal importance, she argues, is her own idea of “symbiosis” which offers an explanation for the evolution of prokaryotes into eukaryotes and the formation of more complex life forms.”
“Mragulis argues that eukaryotes might have emerged when one prokaryote absorbed another, smaller one, which became the nucleus; and multicellular organisms might likewise have been formed through the symbiosis of eukaryotes. According to Margulis, symbiosis is one of the crucial mechanisms of evolution as it provides us the clue to understanding the emergence of new forms of life – organisms form symbiotic alliances through genetic absorption and infiltration which improves their chances of survival.”
“When this theory was first proposed in the 60s, it was ignored, dismissed or ridiculed by the mainstream biologists. But Margulis’ views soon gained wider acceptance because they were backed up by solid evidence from her own research work on the evolution of microbes. It has now been established, for example, that gene transfer is a very common phenomenon in the world of microorganisms.”
[snip]
“Among the many scientists who contemplate the origin of life, Stuart Kauffman of the Santa Fe Institute is perhaps the most interesting and controversial figure. Regarded by many as the guru of the new science of “complexity”, “emergent order” or “self-organization”, Kauffman favors a holistic, non-reductionistic approach in his inquiry of complex systems and phenomena.”
“Life forms, according to this approach, emerges as complex wholes which cannot be explicated through an analysis of their components such as genes and molecules. To account for life’s origin, Kauffman proposes that when the molecular diversity of a prebiotic chemical system increases beyond a threshold of complexity, “life” emerges as a collective property of that system as a whole.”
“To put it another way, when the chemical reactions among the molecules are complex enough to sustain autocatalytic metabolisms, the entire system undergoes a dramatic transition which resembles the “phase change” that happens when liquid water freezes. Life then arises spontaneously and inevitably as the emergent property of this self-sustaining network of autocatalytic molecules.”
“Having stated how dynamic order can be generated spontaneously within a complex system, Kauffman goes on to challenge the central tenet of evolutionary biology, i.e. natural selection. The Darwinians conceive of nature as the blind tinker working on random mutations of genes and organisms, but Kauffman argues that natural selection as such could hardly have been the source of order of the biological world.”
“For Kauffman, one of the aims of the new science of complexity is to find laws that explain how order of the biosphere emerges spontaneously through “self-organization”, the order-generating force that works within all complex systems from single cells to economies. Whether there really are such laws of complexity, however, still remains a matter of hot dispute.”
作者：bystander 在 罕见奇谈 发贴, 来自 http://www.hjclub.org |
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笑看老马的“科学观”
