PvM posted Entry 2945 on March 1, 2007 11:00 PM.
Trackback URL: http://www.pandasthumb.org/cgi-bin/mt/mt-tb.fcgi/2935
On Uncommon Descent Bill Dembski shows some confusion as to how to interpret the research by Oliver Rando and Kevin Verstrepen. While it may be that Dembski could not spare the time from his supposedly busy research (sic) schedule, a simple reading of the actual article would have resolved much of the confusion.
Remember to use the secret handshake whenever you need to get an ID paper past the Darwinian goalies: “Although these observations do not undermine Darwin’s theory, …”
ABSTRACT: According to classical evolutionary theory, phenotypic variation originates from random mutations that are independent of selective pressure. However, recent findings suggest that organisms have evolved mechanisms to influence the timing or genomic location of heritable variability. Hypervariable contingency loci and epigenetic switches increase the variability of specific phenotypes; error-prone DNA replicases produce bursts of variability in times of stress. Interestingly, these mechanisms seem to tune the variability of a given phenotype to match the variability of the acting selective pressure. Although these observations do not undermine Darwin’s theory, they suggest that selection and variability are less independent than once thought.
Rando OJ and Verstrepen KJ (2007) “Timescales of Genetic and Epigenetic Inheritance” (review) Cell, Vol 128, 655-668, 23.
The paper in question is actually quite interesting as it argues how some evidence suggests that some heritable phenotypes are “directed” environmentally.
The authors conclude that these examples suggest that contrary to the neo-Darwinian assumption, variation may not be totally random with respect to the environment and that this is actually not surprising from a Darwinian perspective.
At first sight, this close relation between variability and selective pressure contradicts today’s Neo-Darwinian view on evolution. This is only partially true, as the examples do not argue against the randomness of the majority of phenotypic variability. However, the facts lead us to believe that selective pressure and phenotypic variability are not completely independent. It is easy to imagine how organisms may have developed mechanisms to inluence their own phenotypic variability and escape the total randomness of ‘‘blind’’ mutations. Generating variability is a dangerous affair, with many changes leading to reduced, instead of improved, fitness. Hence, organisms that have developed methods to protect vital phenotypes for which abrupt changes in selection are unlikely while maximizing variability for phenotypes that have to respond to frequent variations in selective pressure may have had a selective advantage over individuals that did not have such systems. An analogous argument can be made for mechanisms that regulate the timing of variability.
In fact, these results show evidence of a concept I discussed before, namely evolvability. That there in fact exists a feedback loop from the environment to the source of variation should come as no surprise as selective pressures will select for sources of variability which have shown themselves to be more successful in the past. And while the past is no predictor for the future, such adaptations seem quite logic and quite compatible with the concept of variation and selection. In fact, these findings help us understand why evolution has been so ‘successful’ against ‘all odds’.
As the authors point out Darwin himself was quite aware of these possibilities:
It is interesting to note that in his book The Origin of Species Darwin wrote: ‘‘I have hitherto sometimes spoken as if the variations were due to chance. This, of course, is a wholly incorrect expression, but it serves to acknowledge plainly our ignorance of the cause of each particular variation. [The facts] lead to the conclusion that variability is generally related to the conditions of life to which each species has been exposed during several successive generations.’’ Hence, both Darwin and Lamarck, two of the founders of evolutionary theory, predicted that evolution itself may favor the development of self-guiding mechanisms, maximizing variability where and when it is most likely to yield positive changes while minimizing phenotypic variability when and where it is not needed. It is becoming increasingly difficult to argue that their general idea of nonrandom evolution was entirely wrong.
In other words, Darwin seems to have been a post-Darwinian, far ahead of his time :-)
So why this fascination of ID with the concept of epigenetic variability and ‘directed’ mutations? The answer is surprisingly simple: ID proponents believe that such concepts are anti-Darwinian and thus they form evidence in favor of Intelligent Design.
While most people would recognize that logical fallacies in this argument, this seems to be what drives many ID proponents.
Amongst the voices of ID, a few voices of reason speak out
Darwin never used the term random mutation. That was the product of the research by Morgan in the 1910’s and 1920’s which along with Mendelian genetics formed the basis of the modern synthesis in the late 1930’s, early 1940’s.
Darwin, I beliieve used the term spontaneous variations. So the papers by Schwartz, Woese, Margulis, etc. and that by Rando in this thread are in sync with what Darwin hypothesized as happening. The main difference is that Darwin nor anyone else witnessed anything but small changes happening through artificial selection so he proposed slow changes in nature just as Lyle proposed slow changes in geology.
At least, once again ID proponents have not only shown the scientific vacuity of Intelligent Design, but they also have shown how reading an abstract may not be sufficient.
At least I believe I have shown that most ID proponents, who object to the concept of ‘random mutations’, would make great Darwinists.
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