Ongoing Natural Selection Against Damaging Genetic Mutations in Humans

The survival of the human species in the face of high rates of genetic mutations has remained an important problem in evolutionary biology. While mutations provide a source of novelty for the species, a large fraction of these genetic changes can also be damaging. A newborn human is estimated to have ~70 new mutations that the parents did not have. In a project conducted by Brigham and Women's Hospital research geneticist Shamil Sunyaev (photo), PhD, and University of Michigan professor Alexey Kondrashov, PhD, scientists studied natural selection in humans. Their findings were published in the May 5, 2017 issue of Science, where the scientists report that, as a species, humans are able to keep the accumulation of damaging mutations in check because each additional mutation that's added to a genome causes larger, and larger consequences, decreasing an individual's ability to pass on genetic material. The article is titled “Negative Selection in Humans and Fruit Flies Involves Synergistic Epistasis.” A damaging mutation is one that likely interferes with the biological function that a gene has for the organism. The researchers studied population samples from Europe, Asia, and Africa and found a significant depletion of individuals carrying a large number of highly damaging mutations overall. They inferred that if a new mutation occurs in a genome that already contains many damaging mutations, it has a stronger effect than if it occurred in a genome with just a few other damaging mutations.
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