Why are heritable mutations important for evolution?

Answer 1

Genetic mutation is one of the mechanisms that provides the reproductive variation that drives evolution. It deactivates alleles, and introduces new alleles into the genome though insertion into, deletion from, duplication of, point mutation of and frameshifts of existing sequences.

Answer: Heritable mutations were postulated as a possible source of genetic variation to ennable natural selection to have material to work changes in organisms. This mechanism of variation was seen as vital to evolution from the time that the implications of genetics as discovered by Mendel was realised.

Unfortunately for evolution, there has never been discovered a single example of a mutation adding new genetic information (although occasionally mutations are beneficial, which is not always the same thing). Richard Dawkins was asked about this very issue in an interview and could not provide one single example of an information-adding mutation. This is no small problem for their is a staggering amount of new information necessary to be written into the DNA to change a microbe into a microbiologist (for example).

Actually mutations are universally shown to be causing genetic degradation in all multicellular life, In humans this is believed conservatively to amount to 100 new mutations per person per generation. Mostly these mutations are small such that natural selection does not 'see' them to eliminate them and so they accumulate in the genome of mankind like rust on a car. The rate of mutation which we observe today would lead to the extinction of the entire human race in a much shorter period of time than is commonly realised. This knowledge led one evolutionary geneticist to ask 'why are we not all dead already?' It is precisely because these deleterious mutations are inherited and retained in the genome and not selected against that the problem arises.

According to geneticist Dr John Sandford, from Cornell University, there is close to unanimous agreement among geneticists regarding human genetic degradation, even though most continue to believe in evolution. Sandford cites recent papers by geneticists such as Muller, Noal, Kondrashov, Nachmann/Crowell, Walker/Keightley, Crow, Lynch et al, Howell, Loewe and Sandford himself (in print). Sandford highlights Loewe's contention in a paper published in 2010 (in The Proceedings of the National Academy of Science) that there is a fitness decline of between 3-5% per generation. Sandford himself from his modeling believes it is not as dire. Another geneticist, Robert Carter, points out that the key issue is not that there are no beneficial mutations but that the deleterious ones are so subtle that they are not selected against, and so the net effect is downhill.