Scientists Recreate Evolution Of Complexity Using ‘Molecular Time Travel’
…just a few small, high-probability mutations increased the complexity of a molecular machine more than 800 million years ago…the researchers showed that a new component was incorporated into the machine due to selective losses of function rather than the sudden appearance of new capabilities.
The group found that the third component of the ring in Fungi originated when a gene coding for one of the subunits of the older two-protein ring was duplicated, and the daughter genes then diverged on their own evolutionary paths.
“It’s counterintuitive but simple: complexity increased because protein functions were lost, not gained. Just as in society, complexity increases when individuals and institutions forget how to be generalists and come to depend on specialists with increasingly narrow capacities.”
“The mechanisms for this increase in complexity are incredibly simple, common occurrences. It’s not as if evolution needed to happen upon some special combination of 100 mutations that created some complicated new function.”
Thornton proposes that the accumulation of simple, degenerative changes over long periods of times could have created many of the complex molecular machines present in organisms today. Such a mechanism argues against the intelligent design concept of “irreducible complexity,” the claim that molecular machines are too complicated to have formed stepwise through evolution.
“I expect that when more studies like this are done, a similar dynamic will be observed for the evolution of many molecular complexes,” Thornton said.
“These really aren’t like precision-engineered machines at all. They’re groups of molecules that happen to stick to each other, cobbled together during evolution by tinkering, degradation, and good luck, and preserved because they helped our ancestors to survive.”