Transposon mutagenesis was first studied by Barbara McClintock in the mid-20th century during her Nobel Prize-winning work with corn. McClintock received her BSc in 1923 from Cornell’s College of Agriculture. By 1927 she had her PhD in botany, and she immediately began working on the topic of maize chromosomes. In the early 1940s, McClintock was studying the progeny of self-pollinated maize plants which resulted from crosses having a broken chromosome 9. These plants were missing their telomeres. This research prompted the first discovery of a transposable element, and from there transposon mutagenesis has been exploited as a biological tool.