Exploring Our World
The Nature of Mutations
Jerry Coyne defines mutations in his book: “Why Evolution is True” this way: “Where does this genetic variation come from (for evolution)? Mutations—accidental changes in the sequence of DNA that usually occur as errors when the molecule is copied during cell division.” p. 128
“Mutations are simply errors in DNA replication. Most of them are harmful or neutral, but a few can turn out to be useful. The useful ones are the raw material for evolution.” p.128
1. Mutations are very rare.
"The cell processes that copy genetic material and pass it from one generation to the next are usually accurate." Prentice Hall Biology -2006, Pg. 301
“In fact, the actual rate of mistakes is more like one in 10 billion.” (Miroslav Radman and Robert Wagner, The High Fidelity of DNA Duplication… Scientific America. Vol. 299, No 2, pg. 24
2. Most mutations are either harmful or neutral.
"Genetic mutations are spontaneous, chance changes, which are rarely beneficial, and more often have no effect, or a deleterious one." Luigi Cavalli-Sforza, head of the international Human Genome Diversity Project, (Genes, Peoples, and Languages, p. 176).
“To their surprise, the researchers found that 75.9% of synonymous mutations were significantly deleterious, while 1.3% were significantly beneficial.”
June 8, 2022
“By the same token, any random change in a gene's DNA is likely to result in a protein that does not function normally or may not function at all. Such mutations are likely to be harmful. Harmful mutations may cause genetic disorders or cancer. A genetic disorder is a disease caused by a mutation in one or a few genes.
March 4, 2022
3. Most mutations cause a net loss of genetic information.
“Most non-neutral mutations are deleterious. In general, the more base pairs that are affected by a mutation, the larger the effect of the mutation, and the larger the mutation's probability of being deleterious.”
http://www.nature.com/scitable/topicpage/genetic-mutation-1127
“DNA is a highly complex system of information. All known mutations result in a loss of information and complexity.”
4. Beneficial mutations are extremely rare.
"In some rare cases, a gene mutation may have positive effects. An organism may receive a mutation that makes it faster or stronger; such a mutation may help an organism - and its offspring - better survive in its environment.” “A very small percentage of all mutations actually have a positive effect.”
The US National Library of Medicine.
5. Some are caused by factors in the environment.
"Forms of radiation, such as X rays, cosmic rays, ultraviolet light, and nuclear radiation, are dangerous mutagens because the energy they contain can damage or break apart DNA." Prentice Hall Biology - 2006, Pg. 301
6. There are mechanisms in place that prevent change.
"Much like a book editor, enzymes proofread the DNA and replace incorrect nucleotides with correct nucleotides." Prentice Hall Biology - 2006, p. 301
"In spite of these mechanisms, however, changes in the DNA occasionally do occur." Prentice Hall Biology - 2006, p. 301
7. Harmful mutations can lead to the extinction of a species.
“If, on the other hand, a population’s mutation rate is too high, detrimental mutations may accumulate faster than natural selection can eliminate them. Eventually, the number of mutations can exceed the “error catastrophe threshold”, again leading to the extinction of a population. https://www.newscientist.com
“DNA is constantly subject to mutations, accidental changes in its code. Mutations can lead to missing or malformed proteins, and that can lead to disease or even extinction.” Genetics.thetech.org
Both theists and naturalists acknowledge that changes occur in the DNA of life forms; but does the extreme rarity of beneficial mutations make it the best source of beneficial change? I guess to coin a phrase: “Have scientists been putting most of their eggs in the wrong basket?” I know there are other sources to consider such as: inherited characteristics, BMP4 Protein, ALX1 Protein, gene flow, and genetic drift. However, wouldn’t those mostly be connected to selection? The changes have to occur first, before they can be passed on. Are mutations the best source of change? Many scientists do not believe so, for the above-mentioned reasons.
