Broken proof reader causes cancer, as reported in ScienceNOW, 14 Feb 2004. When DNA is being copied a protein named DNA polymerase proofreads the new DNA to make sure it has been copied correctly. Any mismatches can then be repaired straight away by other proteins. A team of scientists at the University of Washington, Seattle, USA led by pathologist Bradley Preston, studied mice with defective proofreading proteins and found they developed skin and gastro-intestinal cancers. They then crossed proofreading defective mice with others that had defects in the mismatch repair proteins and produced offspring with the highest mutation rate they had ever seen. These mice all died of cancer by 3 months of age.
Editorial Comment: Mutations are supposed to be the source of new and better evolved organisms. However, none of the high mutation mice showed any sign of evolving into better mice. In fact, cancer is the best example of how mutations destroy living things, and do not build new living things. DNA proofreading and repair are essential for living things to stay alive and well, but these processes ensure that DNA information does not change, i.e. does not evolve. (Ref. cancer, mutations, DNA)