Dorothy Crowfoot Hodgkin – a pioneer

The 1960s saw a major breakthrough for women in X-ray crystallography. Dorothy Crowfoot Hodgkin, an ex-student of Bernal, became the first and only British woman (so far) to win a Nobel Prize in science, obtaining the 1964 Nobel Prize in Chemistry for her work on solving the structures of “important biochemical substances”.

Hodgkin’s success in applying X-ray crystallography to the field of biology paved the way a range of life-changing medical treatments. Having developed techniques for solving the structures of complex biological molecules, her determination of the structure of penicillin in 1946 enabled researchers to optimise the manufacture of the first antibiotic treatment. In 1969, she solved the structure of insulin, helping to understand and treat diabetes, and in 1956, the structure of Vitamin B12, the most structurally complex of all vitamins.

However, despite her many achievements, sexist attitudes remained prevalent. The Daily Mail’s announcement of her award described her as an “Oxford housewife”, and crystallography continued to be underestimated as a technical discipline. Arguably driven by its reputation as ‘women’s work’, many chemists viewed it simply as a laboratory service. Jenny Glusker, Hodgkin’s post-doc during the 1950s, remembered being treated “just as technicians” by other scientists who “did not realise the amount of thought” required to do crystallography well.

Despite discrimination, Dorothy Crowfoot Hodgkin became one of history’s most important crystallographers. Her work was central to the transformation of X-ray crystallography into a tool that could create new treatments for disease and has undoubtedly saved many lives. She was also notable for nurturing female talent in her laboratory, and is an inspiring example of perseverance through disability — undeterred by the attacks of rheumatoid arthritis that affected her from her late twenties onwards. Hodgkin had an illustrious career spanning half a century and was known for her generous and hard-working nature.

Hodgkin’s success laid the foundation for further female X-ray crystallographers to find success on the international stage. Another notable Nobel Prize recipient is Israeli scientist Ada Yonath, who was awarded the Nobel Prize in Chemistry in 2009 for discoveries on the structure and function of ribosomes, the site of protein synthesis in cells. When she started the project in the late 1970s, the ribosome was thought impossible to crystallise and Yonath was “met with reactions of disbelief and even ridicule in the international scientific community”. However, she prevailed, and her achievements have been crucial in the development of antibiotics.

X-ray crystallography for all

The achievements of female crystallographers go beyond fame and prestige. Women have also been instrumental in the categorisation and dissemination of crystallographic knowledge through the creation of resources that are still used today.

Eleanor Dodson, who worked previously as Dorothy Hodgkin’s technician, has helped crystallographers worldwide access specialist software through the collaborative computing project CCP4, while the popular Crystal Structure Analysis: A Primer, co-authored byJenny Glusker, is now in its third edition (2010), having been first published in 1971.

Perhaps most significantly, the Cambridge Crystallographic Data Centre (CCDC) remains an internationally recognised source of structural data on small molecules. Founded in 1965 by Olga Kennard of the University of Cambridge, the CCDC is responsible for the maintenance of the Cambridge Structural Database (CSD), a crucial resource used today by scientists across the world.

A woman’s field?

Given its history and wide-ranging impact, the legacy of the Braggs in the field of X-ray crystallography is undeniable. However, it has also been argued that the prominence of women in crystallography may also be due to its ‘culture of collaboration’. Susan Lea, a professor of microbiology at Oxford, has noted that crystallography generally “involves six to eight disciplines”, with various specialists in constant discussion. Arguably, this ethos has naturally fostered a more inclusive atmosphere, with greater emphasis on an individual’s ability rather than gender.

You would be forgiven, after reading this article, for thinking that women have made up the bulk of X-ray crystallographers since the Braggs. However, the assertion that women are the majority in crystallography has always been false, fuelled by the achievements of a few prominent figures such as Lonsdale and Hodgkin.

In 1990, a study of the World Directory of Crystallographers found that the proportion of women was just 14% internationally; today, the International Union of Crystallography’s online list of eminent crystallographers is still more than 90% male. Moreover, while accurate current data is difficult to locate, International Union of Crystallography records show that women made up only 36% and 35% of all attendees at its 2014 and 2011 congresses. This is further evidence that, even in recent years, gender parity within the crystallographic community remains unaccomplished, reflecting similar struggles across the majority of other scientific disciplines.

X-ray diffraction pattern of crystallised protease enzyme. Jeff Dahl, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons.

In today’s world, as a result of greater access to education, women in science face fewer challenges. However, though increasing numbers of women are entering research careers in the life sciences, research suggests that they are still less likely than their male counterparts to make it to senior positions. Additionally, difficulties balancing a family and a career result in a drop-off at postdoc level onwards.These challenges are not consistent across the world: some regions (such as Central Asia and Latin America) are approaching gender parity in scientific research and development, but for many others (including Sub-Saharan Africa, South and West Asia, Europe and North America), female scientists make up less than a third of research personnel.

The continued fight for gender equality in science

X-ray crystallography has shaped our understanding of the world around us by relating the properties of matter to their composition. Women’s discoveries in this field have driven some of humanity’s greatest scientific achievements and indisputably improved the quality of human life. The field was also highly unusual for its inclusion of women at a time where science was widely considered suitable only for men. Arguably, however, the inclusive influence of the Braggs was a localised anomaly: on a wider level, crystallography, as with the majority of other scientific disciplines, has always been male-dominated, and remains so today.

We must therefore continue to focus on equality and work to remove barriers to science education and careers, enabling women across the world to reach their full potential. Individual action like that shown by the Braggs helped influence the changing positions of women in the lab, but greater systemic change is needed if we are to achieve true gender equality in the sciences.

Part 1

On the surface, the history of X-ray crystallography appears to be dominated by female figures, but is this really the case?

Crystallography, the experimental science used to discern the internal structure of crystals, has existed for hundreds of years, enabling advancements in medicine, mineral, and material sciences. Unusually, following the invention of X-ray crystallography in 1912, the field became known for its association with female scientists. At a time where women were overlooked and discriminated against in science, as well as in society at large, many female crystallographers were able to find employment and rise to international prominence. Their legacy has stood the test of time: in 2004, the distinguished crystallographer Judith Howard went so far to say that crystallography is “an area of science in which women dominate”.

But just how accurate is this assertion? Was crystallography really a feminist utopia?

In this blog, we’ll be delving into the achievements of the inspiring women who shaped X-ray crystallography and examining how far the experiences of these trailblazers differed from other disciplines, both in the 20th century and today.

The origins of X-ray crystallography

While the term ‘crystallography’ was officially coined in 1723, X-ray crystallography, the discipline’s central experimental technique, was first developed in the early 20th century. In 1912, William H. Bragg, a British physics professor, and his son Lawrence were informed while on holiday that a significant scientific event had occurred. The German physicist Max von Laue had produced a regular pattern of spots on a film by shining X-rays through a crystal, marking the discovery of X-ray diffraction in crystals.

The theory that crystals contained some inherent internal regularity had existed for some time. However, Laue’s discovery was hugely significant, for two main reasons. Firstly, it confirmed Laue’s prediction that the supposed regular arrangement of atoms within a crystal were approximate to the intervals of a diffraction grating, providing the basis for accurate structural analysis of crystal structures. And secondly, in doing so, Laue had proved that X-rays could be described as waves, finally settling a debate that had been raging since their discovery in 1895.

The Braggs were instrumental in building upon Laue’s work. Crucially, since the pattern that Laue had observed was the result of X-rays being reflected by regular planes of atoms, Lawrence Bragg inferred that it was possible to use this approach to determine the precise arrangement of atoms within crystal structures. Lawrence’s interpretation eventually gave rise to the famous Bragg’s Law of X-ray diffraction, which is still used today. For their pioneering work, the Braggs jointly won the Nobel Prize in 1915.

The Bragg Legacy

In addition to these ground-breaking achievements, the Braggs were notable for their unusually progressive attitude towards female scientists, and actively encouraged women into the field of X-ray crystallography. In doing so, they enabled the careers of many women at a time when science was almost exclusively male-dominated. 11 out of 18 students in William Bragg’s research group were women.

Several of the Braggs’ students became prominent crystallographers in their own right. Kathleen Lonsdale was one of the first two women to be elected to the Royal Society (in 1945), and became the first female tenured professor at University College London.She also confirmed the structure of the benzene ring and used her status to campaign for women in science, drawing attention to the challenges of balancing family life and a career in research.

The Braggs also passed their values to their male students. Another prominent crystallographer and previous Bragg student, John Desmond Bernal, believed in equal opportunity for women and played a significant role in making crystallography one of the few physical sciences hiring significant numbers of women at that time.

The influence of the Braggs on the culture of crystallography is indisputable, with many of their tutees going on to start their own diverse and non-discriminatory lab cultures. A 1990 study argues that the Braggs started a ‘scientific genealogy’, directly extending to over 50 female crystallographers.

The ‘discovery’ of DNA

The rise of women in crystallography did not come without challenges. In 1962, James Watson and Francis Crick won the Nobel Prize in Chemistry for discovering the double helix structure of DNA. The discovery is often considered one of mankind’s greatest achievements, providing invaluable evidence of the relationship between molecular structure and function in living organisms.

However, it was later revealed that Watson and Crick had used female crystallographer Rosalind Franklin’s data (the infamous ‘Photo 51’) without her consent. Franklin did not share their Nobel Prize win, and had tragically died of ovarian cancer in 1958.

In his 1968 autobiographical account of the discovery, Watson criticised Franklin’s physical appearance, and referred to her patronisingly as “Rosy”, stating that she either “had to go or be put in her place”. Critically, however, Watson also revealed what seems to have been concealed from Franklin during her lifetime, despite her long friendship with Watson and Crick: that their ‘discovery’ would not have been possible without her work. Today, Franklin is often portrayed as a feminist icon and victim of societal prejudice against women in science. While more recent research paints a more nuanced picture (she reportedly did not consider herself to be a feminist “in any modern, meaningful sense”), her experience stands as testament to the sexist attitudes that permeated science at the time. It also shows that, despite increased opportunities for women in the field, crystallography was not immune to wider societal prejudices against women.