EditorialSheep herding breeds appear to have a high number of genetic variants associated with a neurodevelopmental process known as axon guidance, which ensures that neurons are wired together correctly. (Brittainy Newman/The New York Times)
EditorialA pharmacist fills a syringe with a dose of the Pfizer coronavirus vaccine at a clinic in Nashville, Tenn. on May 13, 2021. (Brett Carlsen/The New York Times)