Early Life

Born as Eleanor McClintock on June 16, 1902, in Connecticut, Barbara's parents found her name too delicate for their spirited daughter, opting for the more robust name, Barbara. She began her education at the tender age of three, residing with her aunt and uncle in Brooklyn to ease her family's financial strain while her father built his medical career.

After graduating from high school in 1919, Barbara was eager to pursue higher education, but her mother was hesitant, fearing that advanced learning might hinder her marriage prospects. Thankfully, with her father's encouragement, Barbara enrolled in Cornell University’s College of Agriculture.

The Birth of a Geneticist

In the early 1920s, genetics was still a nascent field, with Gregor Mendel's principles only recently gaining traction. Most students at Cornell avoided genetics courses, but Barbara's fascination with the subject flourished in 1921.

"Some professional biologists were hesitant to embrace the groundbreaking ideas emerging in genetics. However, as the logical basis for genetic studies became clearer, this resistance diminished." — Barbara McClintock

Her professor, Dr. C.B. Hutchinson, recognized her potential and invited her to join a graduate course at Cornell in 1922.

"This phone call determined my future. From that point onward, genetics became my path." — Barbara McClintock

Alongside genetics, Barbara immersed herself in cytology, studying chromosome structures and their roles during cell division. By the time she received her B.Sc. in Botany in 1923, she was certain that her future lay in cytogenetics.

Despite the challenges women faced in pursuing majors in genetics at Cornell, Barbara went on to earn her Master's and Ph.D. in Botany in 1925 and 1927, respectively, establishing herself as a leader in maize genetics.

A Focus on Maize

Barbara's passion for genetics took a decisive turn after completing her Ph.D., as she aimed to map corn chromosomes similarly to T.H. Morgan's work with Drosophila. Each maize kernel represents an individual embryo, making maize an ideal subject for genetic analysis. While working as a Botany instructor at Cornell, she helped form a research group focusing on maize cytogenetics. Her 1929 paper in Genetics captured significant attention, introducing a novel method for visualizing maize chromosomes through carmine staining.

In 1930, she was the first to describe the cross-shaped interactions of homologous chromosomes during meiosis, proposing that this process involved the exchange of genetic material. The following year, Barbara and her colleague Harriet Creighton provided experimental evidence linking chromosomal crossover and genetic recombination.

Barbara's pioneering work earned her several postdoctoral fellowships from the National Research Council, allowing her to continue her research at Cornell, the University of Missouri, and Caltech. While at the University of Missouri, she learned to use X-rays as a mutagen from Lewis Stadler, which led her to hypothesize that chromosome tips are safeguarded by telomeres.

In 1933, she trained in Germany for six months under a Guggenheim Fellowship but returned to Cornell due to rising political tensions. Despite her accomplishments, securing a permanent position during the Great Depression proved difficult.

In 1936, Barbara accepted an assistant professorship at the University of Missouri, where she continued her research on chromosome stability and the effects of x-ray mutagenesis. However, she found teaching burdensome and felt sidelined in faculty discussions. In early 1941, she took a leave of absence to seek new opportunities, eventually accepting a visiting professorship at Columbia University. By December of that year, she became a full-time researcher at Cold Spring Harbor Laboratory, where she remained until her retirement in 1967.

Revolutionizing Genetics

At Cold Spring Harbor, Barbara's research led her to investigate the genetic basis of mosaic color patterns in maize. She discovered that certain kernel traits were unstable and could change across generations. Through meticulous studies, she established that some genes could "transpose" within chromosomes, turning physical traits on and off.

Between 1948 and 1950, Barbara hypothesized that these "controlling elements" could elucidate gene regulation in complex organisms. She presented her findings to her peers during a time when the DNA structure was still undiscovered. Her novel ideas faced skepticism, especially as they coincided with the revelations of DNA's structure by Watson, Crick, and Franklin.

After facing ostracism from mainstream science, Barbara ceased publishing her data in 1953, yet her research continued unabated.

"I was certain of my findings. Anyone confronted with the overwhelming evidence I had could only arrive at my conclusions." — Barbara McClintock

During the 1960s and 70s, as other scientists began to validate her work, Barbara finally received the accolades she deserved. It took three decades and significant advancements in technology before Dr. Nina Fedoroff could confirm the structures of transposons.

In 1983, Barbara McClintock was awarded the Nobel Prize in Physiology or Medicine for her discovery of genetic transposition, marking her as the only woman to win this honor unshared in that category.

Legacy and Inspiration

Barbara's dedication to science, passion for her work, and fierce independence contributed to her remarkable success. She remained single and, despite her shyness, enjoyed playing tennis and working with her corn. Her legacy as a trailblazer for women in science continues to inspire countless generations.

As I teach about transposons and epigenetics today, I am continually reminded of the profound impact of Barbara's work on our understanding of genomic instability and disease. Even with advanced genome sequencing technologies, the dynamic nature of genomes and the role of transposons in gene function remain areas ripe for exploration.

Timeline of Achievements

• 1902: Born as Eleanor McClintock, the third of four siblings.
• 1919: Graduated from Erasmus Hall High School, Brooklyn, NY.
• 1921-1922: Took genetics courses at Cornell University, shaping her career path.
• 1923: Earned B.Sc. from Cornell University.
• 1925: Obtained M.A. from Cornell University.
• 1927: Completed Ph.D. at Cornell University.
• 1927-1931: Served as an instructor in botany at Cornell University.
• 1931-1933: National Research Council Fellow.
• 1933-1934: Guggenheim Fellow.
• 1934-1936: Research Associate at Cornell University.
• 1936-1941: Assistant Professor at the University of Missouri.
• 1942-1967: Researcher at Cold Spring Harbor Laboratory.
• 1992: Passed away from natural causes.

Sources

About the Author:

Dr. Roopali Chaudhary, Content Editor for Women in Science at Sci-Illustrate Stories, holds an MSc in Genetics and a Ph.D. in Cellular & Molecular Biology. She is passionate about making science accessible through various outreach efforts.

About the Artist:

Miler Ximena López, a contributing artist at Sci-Illustrate Stories, finds great satisfaction in expressing ideas graphically, believing that art can foster positive connections and learning.

About this Series:

This series highlights the incredible contributions of women in science, celebrating their achievements through the collaboration of the Sci-Illustrate team, showcasing artwork and narratives that inspire future generations.