喜欢这个,哈哈,it's a mess.
"Darwinists are a little bit like the pre-Darwinists before them, who would have marveled at the perfection of God's creation," he told BBC News.
"We tend to marvel at the Darwinian perfection of organisms now, saying 'this must have been highly selected for, it's a tuned and sophisticated machine'.
"In fact, it's a mess - there's so much unnecessary complexity."http://www.bbc.co.uk/news/science-environment-13445951
Protein flaws responsible for complex life, study says
By Jason Palmer
Science and technology reporter
BBC News
Tiny structural errors in proteins may have been responsible for changes that sparked complex life, researchers say.
A comparison of proteins across 36 modern species suggests that protein flaws called "dehydrons" may have made proteins less stable in water.
This would have made them more adhesive and more likely to end up working together, building up complex function.
The Nature study adds weight to the idea that natural selection is not the only means by which complexity rises.
Natural selection is a theory with no equal in terms of its power to explain how organisms and populations survive through the ages; random mutations that are helpful to an organism are maintained while harmful ones are bred out.
But the study provides evidence that the "adaptive" nature of the changes it wreaks may not be the only way that complexity grew.
Single-celled life gave rise to more complex organisms, and with them came ever-more complicated networks of gene and protein interactions.
Michael Lynch, an evolutionary theorist at Indiana University, teamed up with Ariel Fernandez of the University of Chicago, both in the US, to look specifically at protein structure.
They considered 106 proteins shared among 36 modern-day organisms of widely varying complexity, from single-celled protozoa up to humans.
The pair were studying "dehydrons" - regions of proteins that make them more unstable in watery environments.
These dehydrons - first discovered by Dr Fernandez - make the proteins more sticky in water, thereby raising the probability that they will adhere to other such proteins.
The analysis showed that organisms with smaller populations - such as humans - had accumulated more of these defects than simpler organisms with vastly higher population numbers.
The suggestion is that it is the acquisition of these defects, with sticky proteins more likely to work together in ever-more complex protein-protein interactions, that nudged cellular complexity upward.
"We've tried to bridge the gap between protein structure and evolution and believe we've uncovered evidence that proteins develop mild defects in organisms with smaller population sizes, over the great divide from bacteria to unicellular eukaryotes to invertebrates up to us vertebrates," said Professor Lynch.
These slight defects may decrease protein function even as they increase protein cooperation.
The authors suggest then that other adaptations occur that "undo" the deleterious effects of the sticky proteins.
For example, the protein haemoglobin that carries oxygen in our blood, is made of four identical subunits, each with a range of dehydron flaws; simpler organisms have globin molecules that accomplish the same job with just one subunit.
But the overlap of the four subunits actually masks the flaws in each one.
The authors stress that they are not arguing against natural selection as a process; they say rather that it can be aided by "non-adaptive" mechanisms.
"There's been this general feeling that complexity is a good thing and evolves for complexity's sake - that it's adaptive," Professor Lynch told BBC News.
"We've opened up the idea that the roots of complexity don't have to reside in purely adaptational arguments.
"It's opening up a new evolutionary pathway that didn't exist before."
'A mess'
Ford Doolittle of Dalhousie University agrees that this mechanism, separate from Darwin's vision of natural selection, is an important consideration.
The haemoglobin protein in our blood contains four identical subunits co-operating "Darwinists are a little bit like the pre-Darwinists before them, who would have marveled at the perfection of God's creation," he told BBC News.
"We tend to marvel at the Darwinian perfection of organisms now, saying 'this must have been highly selected for, it's a tuned and sophisticated machine'.
"In fact, it's a mess - there's so much unnecessary complexity."
While he called the Nature study "important and interesting", he disagrees with the mechanism that allows organisms to recover from the protein flaws.
He has long argued for a "presuppression" mechanism, in which some organisms may have a way to overcome the limited functionality of the slightly damaged proteins, and those that do survive best.
"He's putting the cart before the horse," Professor Doolittle said of Professor Lynch's idea that subsequent mutations solve the problems raised by the protein changes.
"But we both agree that much of complexity does not have an adaptive explanation."
- Re: BBC: Protein Flaws Responsible for Complex Lifeposted on 05/23/2011
这些个BBC,最近好象BBC的科技新闻多这样,好会作秀。
怕是跟现代行为艺术家学的,如果都这样,以后中国一定世界第一,创造新闻就
是了。这点,中国人一学就会。达尔文不解孟德尔,虽隐隐有感觉到了,这是真
的,也是老得不得了的事。达尔文扎实作自己的事。这篇文章的帽子当不属于达
尔文本身,达尔文的狗?达尔文主义者,达尔文迷。
解了道平面几何题就嘲笑起了达尔文,嗯,达尔文真是块好耙子!
- Re: BBC: Protein Flaws Responsible for Complex Lifeposted on 05/23/2011
没觉得这和进化论有什么不同之处。不都是现变异后选择吗?基因变异不是指有预谋
有计划的选择啊?
关于complexity 咖啡有过很好玩的讨论。
http://www.mayacafe.com/forum/mcpost.php?t=1186451987
http://www.mayacafe.com/forum/mcpost.php?t=1202695654
- posted on 05/23/2011
回复 #2 Susan> 没觉得这和进化论有什么不同之处。不都是现变异后选择吗?
同感。看了标题就有这个疑问,看了全文还是一样。基因变异是基因水平,protein flaws 是分子水平,但总体而言,都是无方向无目的的随机变异受到进化过程的规范化和选择。
> "In fact, it's a mess - there's so much unnecessary complexity."
这句话很好地验证了上述观点。不利生存的变异被淘汰了,但剩下的未必都有利生存。
这也是对智能设计的很好的驳斥。他们的设计者为什么要无端搞出来些不必要的复杂性呢?
谢小麦,咖啡读书会会长。 :-)
- posted on 05/24/2011
谢谢苏三的链接。我稍后来看。
你们说的是:变异--> 选择 --> 进化,就是这段解释。
"Natural selection is a theory with no equal in terms of its power to explain how organisms and populations survive through the ages; random mutations that are helpful to an organism are maintained while harmful ones are bred out. "
这篇研究说的是:small "population size" --> more (mild) gene defects (midly deleterious mutation)--> selection (for protein cooperation at the expense of protein function) --> evolution (towards complexity).
强调的是population size (non-adaptive mechanism),虽然natural selection is still an important part of the story (but it's not the whole picture).
看了一下这个人,原来population size就是他的specialty. 他的维基条目。
http://en.wikipedia.org/wiki/Michael_Lynch_(geneticist)
另外关中,你如果非要封我什么“会长”,麻烦你先把收入的十分之一交给我。入教好歹交个什一税。
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