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.

Months of upheaval at the Centers for Disease Control and Prevention have undercut the agency’s work, employees said, and put the future of vaccines into doubt.