Barbara McClintock: The Secret of Maize

Quiet brilliance. Like Gregor Mendel before her, Barbara McClintock quietly dedicated most of her scientific life to the study of one plant, and her discoveries revealed important genetic secrets. Also like Mendel, she worked alone, led a spartan lifestyle, and was not recognized by her contemporaries for her most groundbreaking discovery.

Focused. McClintock was born on June 16, 1902, in Hartford, Connecticut, to a physician father and piano-teacher mother. She was a bright, solitary, and thoughtful child who was unusually self-sufficient. Despite her mother's concerns that she would become "unmarriageable," McClintock attended Cornell University's College of Agriculture where tuition was free. She coupled heavy class-loads with a busy social calendar, but as she pursued her advanced degrees, she began to focus solely on her work. She would completely immerse herself in research for the rest of her life.

From student to instructor. After earning her Ph.D., she became an instructor at Cornell and worked on the first of her major contributions to genetics by studying the chromosomes of maize, also known as Indian corn. She and graduate student Harriet Creighton described the process of crossing over, when chromosomes exchange material during cell division. This work brought her onto the world stage and she became a respected scientist in her field.

An instructor no more. Despite her recognition, becoming a professor at Cornell was not an option because these positions were not offered to women. Instead, she supported herself with a grant from the National Research Council, conducting research wherever she could borrow lab and field space. During this period she described, for the first time, chromosome anomalies such as ring chromosomes, deletions, inversions, and translocations.

Cold Spring Harbor. In 1942, McClintock finally found a research home at Cold Spring Harbor Laboratories (CSHL) on Long Island. She was at her best when she could completely lose herself in her work, and CSHL offered both freedom and isolation. For the next 50 years, she lived a simple lifestyle with few possessions, tending her maize, observing kernel color, and looking at cells through the microscope.

Transposition. Through careful observation, McClintock discovered something remarkable: certain sections of maize chromosomes detached and moved to other chromosomes as part of a regulation mechanism. Nothing like this had ever been seen before and she amassed years of data to explain and defend her observation. However, when she presented her work, very few of her contemporaries understood or believed it. Many years passed before similar mechanisms were found in other organisms and her research was validated.

Finally, recognition. While waiting for the world to catch up with her, McClintock continued her research. In the 1980s, the importance of her work was finally recognized, and the awards followed, including an unshared Nobel Prize in medicine or physiology in 1983 (the first for a woman). McClintock was accepting of the attention surrounding her awards, but she wanted most to return to her maize. She continued her teaching and research at CSHL until her death at age 90 on September 2, 1992.

This page appears in the eBook Essentials of Genetics, Unit 2.4