'Mutations that would be harmful in a single pair of genes can be tolerated if those genes have first been duplicated. Gene duplication in a diploid organism provides a second pair of genes so that one pair can be safely mutated and tested in various combinations while the essential functions of the parent pair are kept intact. Possible benefits: * Over time, one of the duplicates can acquire a new function. This can provide the basis for adaptive evolution. * But even while two paralogous genes are still similar in sequence and function, their existence provides redundancy ("belt and suspenders"). This may be a major reason why knocking out genes in yeast, "knockout mice", etc. so often has such a mild effect on the phenotype. The function of the knocked out gene can be taken over by a paralog. * After gene duplication, random loss of these genes at a later time in one group of descendants different from the loss in another group could provide a barrier (a "post-zygotic isolating mechanism") to their interbreeding. Such a barrier could cause speciation: the evolution of two different species from a single ancestral species. ' Source: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mutation_and_Evolution.html

It does not support evolution. That is now becoming quite clear. “As the number of unexplained, irreducibly complex biological systems increases, our confidence that Darwin’s criterion of failure has been met skyrockets toward the maximum that science allows.” (Darwin’s Black Box—The Biochemical Challenge to Evolution, Michael J. Behe, pages 39-40) In other words, recent findings in the field of molecular biology raise serious doubts about Darwin’s theory. “The result of [the] cumulative efforts to investigate the cell—to investigate life at the molecular level—is a loud, clear, piercing cry of ‘design!’ The result is so unambiguous and so significant that it must be ranked as one of the greatest achievements in the history of science. The discovery rivals those of Newton and Einstein, Lavoisier and Schrödinger, Pasteur, and Darwin. The observation of the intelligent design of life is as momentous as the observation that the earth goes around the sun.”—Darwin’s Black Box, pages 232-3.

On a molecular level, organisms are remarkably similar to one another. The substances found in a bacterial cell are almost exactly like the substances in your cells, and the work in very much the same ways. An organism like a chimpanzee is even more similar to us on a cellular level (DNA, proteins, signalling mechanisms, etc). And in the same way that your closest relations are the most similar to you genetically, we consider organisms that are more genetically similar to us to be our relations on an evolutionary scale. If an organism is ever found that is remarkably different than the rest of us, like an organism that doesn't use DNA or RNA to pass down its traits, it would suggest that evolution as we know it is erroneous. As is, though, we see exactly what we would expect if all organisms descended from a common ancestor.