The Scientist Who Knew Every Kernel by Name

In 1944, geneticist Barbara McClintock stood in her Cold Spring Harbor cornfield and did something her colleagues found baffling. She could identify individual maize plants the way a mother recognizes her children in a crowd. While other scientists studied corn in bulk, McClintock examined each kernel under her microscope with such patience that she noticed what no one else could see — genes that moved, rearranging themselves within the chromosomes like words shifting in a living sentence.…