Question

Humans developed antibiotics to fight bacterial infections. However, some antibiotics are no longer effective in killing the bacteria they once killed. How does the theory of evolution explain this?

Answer 1

After being exposed to the antibiotic, individual bacteria acquired the ability to resist the antibiotic.

Answer 2

Genetic variation in bacterial made it possible for some individuals to have resistance to the antibiotic, survive, and reproduce is a statement that explains the theory of evolution very well. Some of the bacteria that became resistant to the antibiotics, passes this down the genes for drug resistance. I hope the answer helps you.