Overlooked and Unknown: Women Who Contributed to DNA Discovery
Overlooked and Unknown: Women Who Contributed to DNA Discovery
Hey reader 👋🏼,
Did you know that nearly 26 million Americans have now taken a genetic test?
The combination of traditional genealogical methods and DNA analysis is referred to as genetic genealogy. One of the most important things to understand is increasing your knowledge of DNA research is a powerful tool that can potentially expand your knowledge of your family history and may aid in solving genealogical questions.
In November we announced, exclusively to the Without a Trace community, our comprehensive DNA Academy course by Trace.com. The first cohort has of learners has now leveled up their genetic genealogy skills and to say they loved it would an understatement!
In this comprehensive genetic genealogy course you will learn multiple techniques for demystifying and organizing your research, introducing you to essential tools and tried-and-true methods, while giving you the key skills and confidence to identify biological relations and leap over brick walls. Course seats are limited and are first come, first serve.
Now back to issue #63…
The scientific study of genetics began in 1854 with observations made by Gregor Johann Mendel. Of course, scientists expanded and deepened their investigations into the specifics of how inheritance and reproduction worked on a cellular level. As soon as they figured out the cellular functionality, they zoomed in further to understand how the science worked on a molecular level. Each step of the way, discovery after discovery was compiled and combined to arrive at important conclusions. Often, whoever published the conclusion first was who received the recognition for the discovery, but sometimes it was a matter of mere bias. This has left a big gap in the history regarding the individual scientists whose contributions made the conclusion possible. And unfortunately, that means that several women scientists were overlooked and forgotten. In the discovery of the structure of DNA, Rosalind Franklin’s work was a significant cornerstone to the conclusions made by James Watson and Francis Crick (the scientists who received credit and a Nobel prize for the discovery). But she wasn’t the only female scientist who contributed to our current understanding of DNA.
Overlooked and Unknown: Women Who Contributed to DNA Discovery
While we certainly cannot identify all of the women who contributed to the eventual discovery of DNA, how it functions, and how we can use it (nor all of the men who may have also gone unrecognized), here are some important scientists.
Nettie M. Stevens earned a doctorate from Bryn Mawr in 1903, and she stayed there as a researcher, post graduation. With a fellowship from the Carnegie Institution of Washington (D.C.) in 1904, she began a study with T.H. Morgan. The goal was to determine what caused the sex of an organism, in this case, aphids. The theory of the day was that some environmental cue or input would create the expression of male or female, and Morgan would research those possible external reasons while Stevens would perform a microscopic study of aphid egg and sperm cells to observe any differences between them.
Knowledge of chromosomes existed at this point, but not in detail. Stevens was able to see that there was a single difference in one chromosome, specifically with sperm. Some had a larger chromosome, while others had a smaller version of the same chromosome. These variants of the same chromosome would come to be known as X or Y. She expanded the study to other insects to confirm her findings while Morgan had no success, of course, trying to “make” male or female aphids “happen.”
Stevens’ work became overshadowed by Edmund Wilson, who seemed to arrive at the same conclusion at nearly the same time as she did, independently. Wilson enjoyed an established and well-respected reputation for his work, hence, why his article and research was preferred at the time. It should be noted, however, that Wilson cites Stevens’ work in his paper regarding the findings, acknowledging her discovery and agreeing with her.
Stevens published 40 papers between 1903 and 1912, when she unfortunately passed away. Beyond the discovery of the X and Y chromosomes, she was also the first to recognize that chromosomes in the body were paired structures.
In 1937, Florence Bell began her doctoral studies at the University of Leeds, joining a research project with supervisor William Astbury. She came recommended by Lawrence Bragg, who, with his father, William, developed the process of x-ray crystallography. Astbury had already been researching biological fibers like wool and whalebone. Bell took up the study of various other protein fibers from such sources as hair, jellyfish, and shark fins. In the course of her studies, she realized that DNA within cellular structures was also a fiber and could also be investigated using x-ray crystallography. The process of making x-ray crystallographic images was tedious, long, and dangerous with x-ray cathodes emitting radiation for long periods of time in the dark. But her work allowed her to understand that “the beginnings of life are closely associated with the interactions of proteins and nucleic acids,” as she wrote in her doctoral thesis in 1939.
Astbury and Bell published an image of DNA in 1938 that led them to describe the structure of DNA to be akin to a “pile of pennies.” Although this theory was later proved wrong, the work Bell performed was a necessary precursor to further DNA X-ray crystallography investigations.
Her contributions to Astbury’s research were significant, and he relied heavily on her expertise. When World War II began, Bell was called into service in 1941 to work on airborne radar systems for the war effort. Astbury sent a request to have her released from this service, but his request was denied. She never returned to his lab after marrying American serviceman, Captain James Sawyer. She relocated to the United States and worked as a research chemist in the petroleum industry before opting to leave her career to raise her children.
June Broomhead was another woman who took up the challenge of x-ray crystallography of biological structures. During and after her doctoral studies at Cambridge, Broomhead joined W.H. Taylor’s team of scientists at the Cavendish Laboratory. This team was working on X-ray crystallography identifications of molecular structures. The work required painstaking and repetitive mathematical calculations to arrive at a conclusion about complex 3-D structures—one structure could take months to solve. Broomhead was assigned to the structures of adenine and guanine, two of the four DNA nucleobases. She published her findings in 1948 and 1951. These published structures identified the location of hydrogen bonds and Broomhead’s theory of how they bonded within DNA with other nucleobases. Her conclusions gave James Watson a significant piece of the puzzle of how a helix could be formed with those hydrogen bonds and their placement within each nucleobase.
June married nuclear physicist George Lindsey and relocated with him to Ottawa, Canada. She worked at the National Research Council for a few years, but ultimately opted to focus on raising her children. Even though her findings were an important factor in understanding DNA’s double helix bonds, she was not cited in their landmark article published in 1953. She was cited in a follow-up article published in 1954. It wasn’t until 1974 that her contribution was even understood, when historian Robert Olby recounted the process by which the double helix of DNA was discovered. Even then, June Broomhead and Florence Bell (both noted in the book), were footnotes to the final outcome. In an interview in 2019, Lindsey did not seem to be bothered much by the oversight. She just recently passed away on 4 November 2021 at the age of 99.
Rosalind Franklin is probably the best known “unrecognized” woman to contribute to the discovery of the structure of DNA. She graduated in 1945 from Cambridge and joined John Randall’s research laboratory at King’s College, working there on her own projects. She was known for her ability to capture exceptional X-ray crystallography images by controlling the moisture content of her samples to get the best image possible. Her technique allowed her (with assistant Raymond Gosling, whom she acknowledged) to produce “Photo 51.” This image was THE image that allowed Watson and Crick to understand the structure of DNA. Franklin was working on different aspects of the DNA structure, looking at phosphorus and sodium bonds, publishing “Molecular configuration in sodium thymonucleate,” in Nature in April 1953.
The story behind the “unrecognized” part of Franklin’s contribution to DNA’s double helix structure is that a colleague who worked with Franklin, Maurice Wilkins, took the image to Watson and Crick without Franklin’s knowledge or permission. Wilkins worked in the same lab as Franklin and wrote his own paper in the April 1953 issue of Nature, also describing aspects of DNA chemical structures. It should be noted that Watson and Crick conducted no research of their own, instead working on a more theoretical level using models to understand structures based on the findings produced by other scientists. All of the input from X-ray crystallographers’ calculations and analyses were amalgamated by Watson and Crick into the double helix structure that they presented in their own paper in, you guessed it, that same April 1953 issue of Nature. Their paper received more attention in the general public possibly because it was simplified in its language and omitted the “challenging for a lay-person” scientific findings that Franklin’s and Wilkins’ papers had included.
Watson, Crick, and Wilkins were awarded the Nobel Prize in 1962. In 1999, Watson admitted that seeing Franklin’s photo was “the key event” that allowed them to understand the structure. In looking back at the Nobel award, Franklin would not have been eligible to receive it because she died in 1958, and the award is never awarded posthumously. But it’s also noted that she was never nominated, either, during her lifetime.
It is surely no mystery to genealogists that one of the side effects of history passing is the loss of the details. We take history classes, but it’s all just a high-level summary with splashes of highlights until you really dig in. Unfortunately, that means significant details can become left behind, and what we “know” is simply inaccurate. One thing that digging into history gives us is not only the real story of how we got here, but also who got us here. In this case, history can teach us that women were significantly involved each step of the way toward the discovery of DNA’s structure—a discovery that ultimately allows us all to realize our own personal histories more readily and reliably. We acknowledge them and their hard work, and we thank them for it.
Just Like Parties, the More the Merrier: The Importance of Multiple Family Members Taking Autosomal DNA Tests
A common misconception regarding DNA testing is the belief that one person in a family is sufficient and that there would be no need for other family members to test. In reality, descendants of each generation do not inherit the same DNA from their ancestors. In fact, other than identical twins, not even siblings receive the exact same segments of DNA; therefore, multiple test takers within a family can broaden the number of DNA matches and, in turn, increase the amount of data which can be utilized to address your genealogical questions.
With regard to DNA, inheritance refers to the process by which genetic material is passed from a parent to their offspring. The manner and quantity of genetic information passed differs by DNA type and can include genetic traits, as well as mutations. The inheritance process can result in members of the same family having similar characteristics, such as hair color or type, height, facial features or other physical traits, as well as passing down certain diseases, such as hemophilia and cystic fibrosis, among others.
A child will inherit only 50% of the total DNA of each parent, and the average halves for each subsequent generation. For example, a person will receive approximately 25% of their DNA from each of their grandparents and approximately 12.5% from each of their great-grandparents. However, for each generation beyond their parents the approximate amount of shared DNA can result in a considerably large range of actual DNA shared, with the average always equal to the estimated amount. At approximately 5-7 generations, a person no longer receives DNA from every ancestor in a given generation.
Why is that? The answer is recombination. At its simplest, recombination can be thought of as the shuffling of DNA that occurs prior to conception at the time of the creation of the egg and sperm in preparation for the next generation of offspring. It is the process by which the DNA is exchanged between the two copies of a chromosome (paternal pair and maternal pair). Crossover points are cut at the same location of each chromosome, and the DNA segments are swapped, forming a new chromosome. Instead of receiving identically intact copies, you get combinations of DNA segments from your antecedents.
What does all of this actually mean? It boils down to this — due to the recombination process, you have received different DNA from your parents than any of your siblings who are not your identical twin, as well as different DNA from your grandparents than your first cousins have. This results in a possibility that you could have DNA matches that your family members do not have and these matches may lead to discoveries that would not have otherwise been possible.
Good luck on your journey of genealogical discovery utilizing DNA!
DNA is not a stand-alone answer to answering genealogical questions. Traditional document-based research is an integral part of genetic genealogy. Learn more about the analysis of records in our archived blog post, The Human Element or enroll in our DNA Academy: Genetic Genealogy course to learn skills necessary to utilize your DNA test results to explore your family history.
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