Mutations driving evolution are informed by the genome, not random, study suggests

(Phys.org) A study published in the Proceedings of the National Academy of Sciences by scientists from Israel and Ghana shows that an evolutionarily significant mutation in the human APOL1 gene arises not randomly but more frequently where it is needed to prevent disease, fundamentally challenging the notion that evolution is driven by random mutations and tying the results to a new theory that, for the first time, offers a new concept for how mutations arise.

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Implications for biology, medicine, computer science, and perhaps even our understanding of the origin of life itself, are potentially far reaching.

A random mutation is a genetic change whose chance of arising is unrelated to its usefulness. Only once these supposed accidents arise does natural selection vet them, sorting the beneficial from the harmful. For over a century, scientists have believed that a series of such accidents has built up over time, one by one, to create the diversity and splendor of life around us.

However, it has never been possible to examine directly whether mutations in the DNA originate at random or not. Mutations are rare events relative to the genome’s size, and technical limitations have prevented scientists from seeing the genome in enough detail to track individual mutations as they arise naturally.

To overcome this, Prof. Adi Livnat of the University of Haifa, Director of the Sagol Lab for Evolution Research, lead author Dr. Daniel Melamed and the team developed a new ultra-accurate detection method and recently applied it to the famous HbS mutation, which protects from malaria but causes sickle-cell anemia in homozygotes.

Results showed that the HbS mutation did not arise at random, but emerged more frequently exactly in the gene and population where it was needed. Now, they report the same nonrandom pattern in a second mutation of evolutionary significance.

The new study examines the de novo origination of a mutation in the human APOL1 gene that protects against a form of trypanosomiasis, a disease that devastated central Africa in historical times and until recently has caused tens of thousands of deaths there per year, while increasing the risk of chronic kidney disease in people with two copies.