Only 6% of changes in DNA are due to natural selection per Motoo Kimura


Motoo Kimura, a Japanese neurophysiologist and geneticist, believed that only 6% of changes in DNA are due to natural selection, the process of evolution proposed by Charles Darwin. He argued that the other 94% of changes are due to random mutation and genetic drift.

Kimura's theory is known as the neutral theory of molecular evolution. It is based on the idea that most mutations have no effect on the fitness of an organism, and that they are therefore not subject to natural selection. Only mutations that have a positive effect on fitness are likely to be passed on to future generations.

The neutral theory of molecular evolution has been controversial, but it has gained increasing acceptance in recent years. It has helped to explain the high rate of genetic variation that is observed in natural populations.

Here are some of the evidences that support Kimura's theory:

  • The vast majority of mutations are silent, meaning that they do not change the amino acid sequence of the protein that they code for.

  • Many mutations have a negative effect on the fitness of an organism, but they are usually eliminated by natural selection.

  • The rate of molecular evolution is much higher than the rate of phenotypic evolution.

Kimura's theory has important implications for our understanding of evolution. It suggests that natural selection is not the only driving force of evolution, and that random mutation and genetic drift play a significant role. This has implications for our understanding of the evolution of complex traits, such as intelligence and disease resistance.


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