Reality → Life → Evolution → Mutations
Spontaneous point mutations in the DNA of germline cells are the primary driving force of evolution. Point mutations are rare: only 1 in every 1010 base pairs incurs an error during replication, most commonly in the form of substitution of a nucleotide, a spontaneously occurring rare event that can be explained by quantum effects [1] . Other types of DNA changes include insertions, deletions and frameshifts. In addition, chromosomal aberrations do occur [2] . External factors can also cause mutations [3] . Most mutations are either neutral or have negative effects, only few are beneficial [4] .
In his 1944 book What is Life?, Schrödinger explains how heritable mutations are related to 'quantum jumps' (see also Genetics, Note 1 ).
Unequal crossing over is one of the rare chromosomal changes with potentially detrimental effects that can happen during meiosis.
Non-spontaneous, externally caused DNA changes can be caused by ionizing radiation and certain chemicals (mutagens).
The high incidence of internally and externally caused DNA changes would normally upset a species' genome in a short time, were it not for the cell's capability to repair DNA. The delineation of how some of these repairs work was awarded with the 2015 Nobel Prize in Chemistry.