Top 10 Interesting fact about Barbara McClintock

Top 10 Interesting fact about Barbara McClintock

Barbara McClintock was a pioneer of cytogenetics, the field of genetics studying the structure and function of cells. Her research focused on chromosomes and how they change during reproduction in maize. Her findings were very influential in the development of modern genetics.

Through her studies, she was became the first person to describe the cross-shaped interaction of homologous chromosomes during meiosis. This discovery provided insight into the process of genetic recombination and the transmission of genetic information from one generation to the next.

McClintock was born on June 16, 1902, in Hartford, Connecticut to homeopathic physician Thomas Henry McClintock and Sara Handy McClintock. She was the third of four children.

To learn more about Barbara McClintock, here are the top 10 interesting facts about her;

1. McClintock’s name was changed to reflect her personality

McClintock’s children, from left to right: Mignon, Malcolm Rider, Barbara and Marjorie – Wikipedia

McClintock was born Eleanor McClintock, which according to her parents was a “feminine” and “delicate” name that did not suite their solitary and independent child. Her parents changed her name to Barbara, which means “stranger” or “foreign”. The new name felt more masculine and more in tune with McClintock’s independent minded personality.

From a very young age, McClintock was described as a solitary and independent child. By McClintock’s own account. “My mother used to put a pillow on the floor and give me one toy and just leave me there. She said I didn’t cry, didn’t call for anything.”

Her parents nurtured her independent spirit by allowing her to pursue her interests and did not pressure her to perform in school or to conform socially.  

McClintock continue to reaffirm her solitary personality and independence of mind throughout her life, which she identified as her  “capacity to be alone”. As a young adult, she legally changed her name to Barbara.

2. McClintock almost missed out on going to college

McClintock family, from left to right Mignon, Tom, Barbara, Marjorie and Sara at the piano – Wikimedia Commons

McClintock graduated from Erasmus Hall High School in 1919 where she discovered her passion and love for science. To further her education, she wanted to enrol to Cornell University, a motion that her mother was against. This is because her mother feared that McClintock would become unmarriageable if she attended universality, a common attitude at the time.

Luckily, her father came to her rescue and she was able to join Cornell’s College of Agriculture in 1919. At Cornell, McClintock studied botany and graduated in 1923. Her interest in genetics began when she took her first course in that field in 1921 taught by C. B. Hutchison, a plant breeder and geneticist.

McClintock went on to pursue her postgraduate education still at Cornell, earning her MS and PhD in botany in 1925 and 1927, respectively.

Coming back to her mother, her fears were valid because McClintock never got married.

3. The telephone call that sealed her fate in genetics

McClintock’s interest in genetics began when she took her first course in that field in 1921 taught by C. B. Hutchison, a plant breeder and geneticist, while at Cornell. In an effort to exposure her more to the field of genetics, Hutchison invited McClintock to participate in the graduate genetics course at Cornell in 1922.

This invite may seem out of place, considering it was reported that women could not pursue a major in genetics at Cornell. However, recent research has shown that women were permitted to earn graduate degrees in Cornell’s Plant Breeding Department during the time that McClintock was a student at Cornell. This is well illustrate by the fact that both McClintock’s postgraduate majors were in botany.

McClintock pointed to Hutchison’s invitation as a catalyst for her interest in genetics: “Obviously, this telephone call cast the die for my future. I remained with genetics thereafter.”

4. Developed a way to visually see maize chromosomes

The relationship of Ac/Ds in the control of the elements and mosaic colour of maize – Wikipedia

McClintock’s cytogenetic research centred around finding a way to visualize and characterize maize chromosomes. She focused on observing cells from the microspore as opposed to the root tip. Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes.

In the 1930s, McClintock developed a new acetocarmine staining process that allowed her to visualize maize chromosomes and create the first genetic map for maize in 1931. Up until this point, geneticists had only hypothesized that genetic recombination could occur during cellular division, but it had not yet been visually demonstrated.

5. McClintock discovered Chromosome Cross-Interactions

Barbara McClintock holding Lasker Award and an ear of corn – Wikimedia Commons

Between 1948 and 1950 McClintock challenged the existing concept of the genome as a static set of instructions passed between generations by introducing the concept of transposons, also called jumping genes. Simple put, McClintock had observed that some genes could be mobile, which was in contrast to the already existing theory that genes were stable entities arranged in an orderly linear pattern on chromosomes.

McClintock stabled upon this discovery when she was studying chromosome breakage in maize. During this study, she observed a chromosome-breaking locus that could change its position within a chromosome. She theorized that these mobile elements regulated the genes by inhibiting or modulating their action.

She also hypothesized that gene regulation could explain how complex multicellular organisms made of cells with identical genomes have cells of different function.

This discovery was critical in providing answers into the process of genetic recombination and the transmission of genetic information from one generation to the next.

6. McClintock research was beyond her time

Barbara McClintock with one of her results – Wikipedia

In 1950, she documented and reported her discovery to demonstrate that genes are responsible for turning physical characteristics on and off in a paper entitled “The origin and behavior of mutable loci in maize” published in the journal Proceedings of the National Academy of Sciences. However, her work was not immediately understood and accepted by her contemporaries.

In an effort to help her priors understand her findings, she presented all her statistical data, and undertook lecture tours to universities throughout the 1950s to speak about her work. She also published a paper in Genetics in 1953. Unfortunately, despite all her efforts, McClintock described the reception of her research as “puzzlement, even hostility”.

Not wanting to face alienation from the scientific mainstream, McClintock stopped publishing accounts of her research on controlling elements in 1953, but continued with her research.

7. McClintock’s disappointment with the scientific community

Variegated maize ears – Wikipedia

Mimicking George Bernard Shaw: “Progress is impossible without change, and those who cannot change their minds cannot change anything.”

McClintock was on the verge of facing alienation from the scientific community because her research contradicted an existing theory. This is very ironical because scientist have always been regarded as open-minded people who challenge already existing theories, formulate new theories and prove these theories,

Expressing her disappointment, McClintock wrote in 1973, “Over the years I have found that it is difficult if not impossible to bring to consciousness of another person the nature of his tacit assumptions when, by some special experiences, I have been made aware of them. This became painfully evident to me in my attempts during the 1950s to convince geneticists that the action of genes had to be and was controlled.”

She continues, “It is now equally painful to recognize the fixity of assumptions that many persons hold on the nature of controlling elements in maize and the manners of their operation. One must await the right time for conceptual change”

8. She conducted research into the mutating properties of X-rays

During the summers of 1931 and 1932, McClintock worked with geneticist Lewis Stadler at the University of Missouri and introduced her to the use of X-rays as a mutagen.

This proved to be very useful to McClintock because exposure to X-rays can increase the rate of mutation above the natural background level, making it a powerful research tool for genetics.

Through her work with X-ray-mutagenized maize, she was able to create the first ever genetic map of corn’s makeup.

9. Nobel Prize winner

McClintock giving her Nobel Lecture – Wikipedia

The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. It one of the highest achievements an intellectual can attain.

McClintock received the Nobel Prize for Physiology or Medicine in 1983 for her discovery of  “mobile genetic elements”. This was more than 30 years after she initially described the phenomenon of controlling elements.

By winning this award, she became the first woman to win that prize unshared and the first American woman to win any unshared Nobel Prize.

10. The first woman to be awarded the National Medal of Science

A portrait of US president Richard Nixon Photo sourced from Wikimedia

The National Medal of Science is an honour bestowed by the President of the United States to individuals in science and engineering who have made important contributions to the advancement of knowledge in the fields of behavioural and social sciences, biology, chemistry, engineering, mathematics and physics.

In 1970, McClintock was awarded the National Medal of Science by then-President Richard Nixon in recognition of her groundbreaking work in the field of genetics. This was a great honour for her as this award is the highest honour bestowed by the United States government upon scientists, engineers, and inventors.

During the ceremony, Nixon said: “I have read [explanations of your scientific work] and I want you to know that I do not understand them. But I want you to know, too, that because I do not understand them, I realize how enormously important their contributions are to this nation. That, to me, is the nature of science.”