immortal Posted November 7, 2010 Share Posted November 7, 2010 (edited) Experiments in molecular biology indicate that the stepwise model of evolution accumulating favorable modifications is not happening. Trillions of trillions of organisms have been exposed to selection pressure and thus far there have been no examples of multistep pathways greater than three steps observed. Even the couple of three step examples included steps that were not favorable. One can point to several single and two step mutations that provide some adaptation advantage but do not progress any further. The illustration is interesting but it does not describe what is actually going on. It seems that even the slight small mutations can induce big changes over an entire population. This link shows how microevolution is coupled to macroevolution. It does'nt always have to be a series of small favorable mutations that accumulates over time to produce complex structures.My linkhttp://biology.ucsd.edu/news/article_020602.html This statement mischaracterizes the issue. Molecular studies seem to demonstrate that functional pathways don't exist at all, rather all stepwise routes involve unfavorable mutations that render natural selection incapable of preserving the unfavorable modifications that are later needed to generate new functional molecular components and cellular function controls.. Not necessarily. My previous link falsifies your statement and also there can be mutations that have a neutral effect on the organism. Here is a report on one such study of the salmonella bacterium whereby the researchers employed a technique to generate mutations anywhere and in the genome. They found that regardless of the mutation each and every mutation had the same small negative impact on fitness of 0.5%. With no selection advantage the model you described becomes impotent because if one wants to posit that the accumulation of many mutations can bring about new function, then one has to maintain that the accumulation of negative impacts eventually makes positive and this is counter to your model. I think you have come to your own conclusion by highlighting those points which suits your argument and completely ignoring other valid points. From your link it was stated that "doctoral candidate Peter Lind showed that most mutations reduced the rate of growth of bacteria by only 0.500 percent. No mutations completely disabled the function of the proteins, and very few had no impact at all." You have completely missed this point. Yes there may be some negative effects from the mRNA but it is left to natural selection to decide whether to keep it or eliminate it. Evolution works by cumulative selection i.e accumulation of good designs. If there are negative effects from a mutation then Natural selection will effectively filter it out unless those mutations are not dominant and does not affect the phenotype of the individual. No mutations are positive or negative and bad or good by themselves it depends on the environment that they are interacting with. What is negative in one environment can be completely turn out to be positive in the other. So yes accumulation of negative impacts may be positive in some other environment which may even go on to fix this variation through out the population. So its definitely not counter to my model. Correct. However while we continue to look for natural processes that are more capable than the ones identified and observed today, Genetic Engineers are racing ahead with teleological process that do explain observed diversity. I find it interesting that many people prefer to be blind of that reality.. I don't know about others but I am not blind to that and I also don't know what is the problem with other mainstream biologists but my problem is that I am a student of engineering who loves biology too much and hence most of the times I have to think about things which are not deeply related to this topic and in the process I forget what I know or what I read previously about this field. After doing some recall. Yes today the geneticists never look the genome of any population as before they say that the DNA in the genome are not as static as we assumed previously they are more dynamic with genes jumping around here and there and there by providing variations to populations in different ways apart from the single point mutations that we usually see normally. Some of the terms and concepts they usually use are Molecular drive ,Transposition, Molecular coevolution and structured responses from genome to changes in the environment. So the genome is more dynamic than we previously thought so don't be surprised to see how the organisms survive this variations in the entire genome when even small single mutation can cause havoc in the system. It seems that these genome variations are fixed when these genomes interact with the environment differently. Its like the environment is providing a solution to a genomic problem. Even though all these mechanisms are different from natural selection they influence the genome independently only upto a certain threshold point above which natural selection comes into the picture and introduces some constraints. So you can not completely eliminate evolution by natural selection from the picture. It seems that you are also not agreeing on the concept of common descent through modification. I earlier read from a creationist website how he was trying to falsify this concept by starting to compare individual genes which provide specific functions to an organism through out the animal kingdom and made statements like this gene is 45% similar between a horse and a cow and said that this gene was most similar between humans and chickens. So he asked how we can accept common descent. Definitely this is a serious error we don't try to establish descent with modification using single genes or gene families. A single gene may be in normalizing selection in one population and may be continuosly co-evolving in some other species. A gene may be more similar between humans and chickens compared with the same gene between humans and chimps because the gene in humans and chickens may be in a normalizing selection and has not evovled until it branched off at some point in history and whereas the gene in the chimp may be co-evolving with some other competing population of a difeerent species. I think it is fair as long as you try to find loopholes that are their in the theory but its not fair to induce faith in something by completely ignoring a well established truth. We don't need scientific reasoning to have faith in something. Let's not bring faith to the level of science and by the way those teleological models of yours will definitely be very much different from the scientific models so if you want to accept a teleological model you don't have to attack a model which is based on science. Edited November 7, 2010 by immortal Link to comment Share on other sites More sharing options...
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