Somatic Evolution By Epigenetics
The state of a cell may be changed epigenetically, in addition to genetic alterations. The best-understood epigenetic alterations in tumors are the silencing or expression of genes by changes in the methylation of CG pairs of nucleotides in the promoter regions of the genes. These methylation patterns are copied to the new chromosomes when cells replicate their genomes and so methylation alterations are heritable and subject to natural selection. Methylation changes are thought to occur more frequently than mutations in the DNA, and so may account for many of the changes during neoplastic progression (the process by which normal tissue becomes cancerous), in particular in the early stages. Epigenetic changes in progression interact with genetic changes. For example, epigenetic silencing of genes responsible for the repair of mutations in the DNA (e.g. MLH1 and MSH2) results in an increase of genetic mutations.
Famous quotes containing the words somatic and/or evolution:
“Parents must not only have certain ways of guiding by prohibition and permission; they must also be able to represent to the child a deep, an almost somatic conviction that there is a meaning to what they are doing. Ultimately, children become neurotic not from frustrations, but from the lack or loss of societal meaning in these frustrations.”
—Erik H. Erikson (20th century)
“Historians will have to face the fact that natural selection determined the evolution of cultures in the same manner as it did that of species.”
—Konrad Lorenz (19031989)