Weed to Wonder: How Humans Changed Corn and Corn Changed Human Society

Barbara McClintock's World

Discovering Jumping Genes

For the first half of the 20th century, genes were seen as objects with fixed positions on the chromosomes. However, in the 1950s, Barbara McClintock showed that certain DNA fragments, termed transposons, can be activated to "jump" from one position on a chromosome to another. She hypothesized that transposition provides a means to rapidly organize genes in response to environmental stress.