Bacterial survival in antibiotics has been taken as proof of evolution in action. But in-depth studies of the specific mechanisms for antibiotic resistance in bacteria show that no evolutionary processes are involved. One recent study even mentioned the possibility that bacteria are able to fine-tune the shapes of their own biochemicals in order to circumvent the harmful effects of antibiotics.

Antibiotics are tiny chemicals that can kill bacteria, and their use can wipe out almost all the individuals of a bacterial population. But a few bacteria sometimes survive and grow in the presence of the antibiotic, although at a slower pace.

How do bacteria acquire antibiotic resistance? Often, a small number were already resistant before the antibiotic was applied. There is no innovation in such cases, but merely a shift in which strain of bacteria dominates the habitat. That’s not evolution.

Sometimes the DNA of bacteria changes, and this can alter their protein shapes. Though these subtle alterations almost always decrease the protein’s job efficiency, they can ward off antibiotics that would ordinarily disrupt certain proteins….

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