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I still don't understand you, echo. The Tasmanian devil example is completely irrelevant when discussing whether DNA mutates at random or not.You still seem to want evolution and mutation to mean the same thing. They don't, and no one here is saying they do.Again, random mutation is one of the sources of variety in DNA that non-random natural selection can act upon.
many of the genetic changes leading to human-specific characters may be the result of the fixation of harmful mutations.
The researchers identified fast evolving human genes by comparing our genome with those of other primates. However, surprisingly, the patterns of molecular evolution in many of the genes they found did not contain signals of natural selection. Instead, their evidence suggests that a separate process known as BGC (biased gene conversion) has speeded up the rate of evolution in certain genes. This process increases the rate at which certain mutations spread through a population, regardless of whether they are beneficial or harmful.........This contrasts the traditional Darwinistic view that they are the result of natural selection in favour of adaptive mutations.
This process increases the rate at which certain mutations spread through a population, regardless of whether they are beneficial or harmful.........This contrasts the traditional Darwinistic view that they are the result of natural selection in favour of adaptive mutations.
As Darwin knew nothing about genetic mutation, describing this as "non-Darwanistic" strikes me as a heaviy biased editorial slant. All this appears to say is that mutations might occur more rapidly than previously though.
Random mutation is disease such as cancer.
Echo - we're not saying that evolution is random, but that mutation, one of the sources for variation that evolution can act upon, is.
As far as I can tell, your problem is with step one, but this is astonishingly well demonstrated in humans, bacteria, mice, you name it... and yes, those "copying errors" are both permanent and random. To suggest they could be anything else is frankly ludicrous (or requires the intervention of some form of intelligent, intervening deity... of course the thing about intelligent deities is we can't disprove them, only point out that there's an entirely satisfactory and more parsimonious solution which does not require one).
Possibly what you need to do is go away and read up on transcription. In which case you could start with wikipedia:http://en.wikipedia.org/wiki/Transcription_(genetics)Once you understand why random mutations are not, or should not be, a conceptual problem, maybe you could come back and discuss this further.
In a Feb. 17, 2008 symposium at the American Association for the Advancement of Science (AAAS) annual meeting in Boston,* Miller will argue that science itself, including evolutionary biology, is predicated on the idea of "design" -- the correlation of structure with function that lies at the heart of the molecular nature of life.Miller is a cell biologist and the Royce Family Professor for Teaching Excellence at Brown.Miller will argue that the scientific community must address the attractiveness of the "design" concept and make the case that science itself is based on the idea of design -- or the regularity of organization, function, and natural law that gives rise to the world in which we live.He points out that structural and molecular biologists routinely speak of the design of proteins, signaling pathways, and cellular structures. He also notes that the human body bears the hallmarks of design, from the ball sockets that allows hips and shoulders to rotate to the "s" curve of the spine that allows for upright walking."There is, indeed, a design to life -- an evolutionary design," Miller said. "The structures in our bodies have changed over time, as have its functions. Scientists should embrace this concept of 'design,' and in so doing, claim for science the sense of orderly rationality in nature to which the anti-evolution movement has long appealed."
I agree that some copying errors are probably completely random...
There’s no way for the RNA polymerase to ensure that the correct letter is always incorporated at the right spot. “Statistically, we would expect to see a hundred-fold more errors than we actually do, so we know that some error correction must be happening. Otherwise, many more proteins in our bodies would malfunction,” says Dr Cohen.Biological experiments have shown that the RNA polymerase slides both forwards and backwards along the RNA sequence it has created. What’s more, it has miniature scissors that can then cut out the last few letters of RNA.So how are errors corrected? Intelligent typesetters would remove the last few letters when they spot an error. The new model suggests how the backward sliding stalls when passing an error, so wrong letters can be snipped off and copying can resume.
Again, random mutation is one of the sources of variety in DNA that non-random natural selection can act upon.
It's the entire basis of genetic clocks.