Bibliometric comparison of Nobel Prize laureates in physiology or medicine and chemistry
The Nobel Prize is an annual award founded by the Swedish engineer, inventor, and entrepreneur Alfred Nobel (1833–1896) (Hansson et al. ). The Nobel Prize is awarded to those researchers whose work has been of the greatest benefit to humanity in the year in question. It is awarded in the fields of physics, chemistry, physiology or medicine, literature and peace efforts and is regarded as the highest scientific honor in the respective disciplines. There has also been an award in the field of economics since 1969, but this is not officially categorized as a Nobel Prize. Since the foundation was established in 1901, 609 Nobel Prizes have been awarded to 975 laureates, of which the Nobel Prize in physiology or medicine has been awarded to 225 persons to date. A Nobel Prize can be awarded to several researchers, each of whom is then considered a Nobel Prize laureate. As a rule, however, a Nobel Prize is not awarded to more than three researchers. The Nobel Prize in physiology or medicine has been awarded by the Nobel Assembly at Karolinska Institute since 1901 ( https://www.nobelprize.org/about/the-nobel-assembly-at-karolinska-institutet/ ; last accessed on 03/18/2024). In his will, Nobel had stipulated that the prizes should be awarded to the most worthy, regardless of their nationality, and he made no mention of gender. He decided to establish a foundation that would award annual prizes to researchers whose discoveries or inventions had contributed to the well-being of humanity in the previous year (Zárate et al. ). The gender gap in the number of Nobel Prize candidates and laureates in the fields of physiology or medicine is striking (Hansson and Fangerau ). The Nobel Prize Committee has been criticized for appearing to ignore the contributions of women in science (Mahmoudi et al. ; Silver et al. ; Valian ; Wade ). Many Nobel Prizes have direct or indirect pharmacological relevance (Table ). This background prompted us to perform a bibliometric analysis of the Nobel Prize laureates in physiology or medicine and chemistry (in this field only topics related to pharmacology) from 2006 to 2022. Most importantly, we wished to answer the question whether there is any bias against women in this group. We selected the last 15 years at the beginning of the research to capture contemporary research. In addition to that, the history of the Nobel Prize is also a history of changing processes in science and medicine (Hansson et al. ). Therefore, we wanted to analyze the current awarding practice. The 16th year was added because it was being awarded when we collected the data to remain as up-to-date as possible. The focus on recent Nobel Prizes also allows us to perform important comparisons with papers on gender aspects in science encompassing a similar historical period (Zehetbauer et al. ; Zöllner and Seifert ). Table provides an overview on the Nobel Prize laureates analyzed. The year of award, name, gender, year of birth, nationality of the laureate, research topic honored by the Nobel Prize, research institution, and country of the institution are provided, all publicly available ( https://www.nobelprize.org ). Every laureate is identified by a number used throughout this paper. We are not considering so much individual laureates in this paper but rather overarching patterns. Only in occasional cases, we mention a specific laureate to highlight a specific trait. For an in-depth analysis of individual Nobel Prize laureates, the reader is referred to the excellent work of Hansson et al. . The present paper is meant to provide a general bibliometric analysis of contemporary Nobel Prize laureates in the sense of a meta-analysis to identify overarching patterns and mechanisms underlying awarding of the Nobel Prize.   The list of Nobel Prize laureates was compiled via the Nobel Prize website ( https://www.nobelprize.org ). Nobel laureates ( n = 55) from the field of physiology or medicine and chemistry (in this field only topics related to pharmacology) were listed according to their age and gender, their nationalities, their publications, citations and research rankings, and subsequently their productivity peaks and their research locations. The inclusion criteria were all Nobel Prize laureates from the years 2006–2022 in the fields of physiology or medicine, supplemented by prize laureates in the field of chemistry who were honored for a research topic related to pharmacology. For each researcher, a bibliometric analysis was performed using the Clarivate database ( https://clarivate.com/products/scientific-and-academic-research/research-analytics-evaluation-and-management-solutions/ ; last accessed 06/08/2023). The Journal Impact Factor, which is calculated annually by Clarivate Analytics and published in the Journal Citations Reports, is widely used to compare journals. It is now frequently used to assess the quality of journals, although this use is controversial. For this work, publication numbers for each research year of each individual Nobel Prize laureate were retrieved and listed in Clarivate with linear regression. Furthermore, with these data, we analyzed the publication peaks of the Nobel Prize laureates. In addition, the nationalities of the Nobel Prize laureates and their location of research were compiled and analyzed from University websites and the Nobel Prize website. In a further step, the subsequent statistical data analysis was initially carried out by using the Statistical Package for the Social Sciences software (SPSS® Version 25), ANOVA (variance analyses of women and men), and the excel program. We used GraphPad 8 to create the graphs with the statistical software R and the package ggplot2 for the relevant tests for frequency distribution, mean value determination, T -tests, p -tests, Pearson r , and the excel program to display the pie charts to illustrate the percentage differences between women and men. Whenever possible and meaningful, the results of women were compared with the results of men. We calculated cross-tabulations with the Cramer-V value and the significances for the number of Nobel Prize laureates, correlations to show the connections between the publications and citations, one-factorial ANOVA calculations and linear regressions to calculate the correlations when comparing female and male Nobel Prize laureates, and mean value determinations to show the comparison of the female and male results and the respective standard deviations. The results were presented and visualized in different graphics to show the respective totality, the female and the male characteristics.   We analyzed 41 Nobel Prize laureates (74.5%) from physiology or medicine, and 14 Nobel Prize laureates (25.5%) from chemistry (Fig. ). At 18.2%, the proportion of women receiving awards was significantly lower than compared to 81.8% of male award laureates (Fig. ). There is a clear difference between the genders in the subjects awarded the Nobel Prize: in physiology or medicine, only 14% of the prize laureates were women, while the proportion in chemistry of women was 36%. There was a significant difference between the genders ( p = 0.039) in relation to the average age of Nobel Prize laureates at the time of the Nobel Prize awarding. In average, the age of females was 60.1 years and of males 67.4 years (Fig. ). The oldest male and female Nobel Prize laureate had an age of 85 and 84 years, respectively. The youngest male and female Nobel Prize laureate had an age of 46 and 48 years, respectively. The standard deviation has a larger range for male Nobel Prize laureates than for female Nobel Prize laureates. Figure shows the nationalities of the Nobel Prize laureates. The USA dominated Nobel Prize awards, among both women (40%) and men (51%). However, notably, among women, three countries were represented that were not present among men. Specifically, female Nobel Prize laureates were recorded from Israel, Australia, and China. Conversely, the UK, Japan, Germany, Sweden, Denmark, Canada, India, Italy, Ireland, and Luxembourg were represented among men, but not women. Figure shows the relation between the number of publications and citations of all Nobel Prize laureates (panel A) and separately for women (panel B) and men (panel C). The point cloud of female Nobel Prize laureates is more scattered than that of male Nobel Prize laureates. Among the male laureates, two laureates stand out as having a significantly higher number of publications and citations than all other laureates. There are no such features among women. The Pearson correlation was calculated to show the correlation between citations and publications. It was r =0.763 for women and r =0.667 for men. The slope is almost identical for women and men, with a slightly flatter slope for women. Thus, there are no major differences between the genders. Figure shows the individual distribution of publication of Nobel Prize laureates (panel A). Both among men and women, there is a huge variation in the number of publications, ranging from more than 1.200 (Nobel Prize laureate No. 25) to 0 (Nobel Prize laureate No. 26). Overall, most publications of Nobel Prize laureates were published before the award (mean value for women was 273.9; and for men 284.5). After the award, the mean value of publications for women was 47.6, and for men 48.8. This reflects the fact that the award is usually given in late stages of the career (see Fig. ). However, it should also be noted that most of the researchers are still actively engaged in science after the Nobel Prize award. Figure shows the individual H-index (Hirsch-index) distribution among Nobel Prize laureates. Hirsch  defined the H-index as “an index to quantify an individual’s scientific research output. A scientist has index H if H of his or her papers have at least H citations each and the other papers have ≤ H citations each” (Hirsch ). The H-index is therefore intended to describe the reception of publications by individual academics in the scientific community. There is a huge variation in H-index of the Nobel Prize laureates, ranging from > 200 (Nobel Prize laureate No. 35) to 0 (Nobel Prize laureates No. 26). The mean value for women is 78.78, and 90.20 for men (panel B), with men having a much larger variation than women. The age-adjusted H-index was calculated by dividing the H-index by the age of the Nobel Prize laureates. The results show that women and men do not differ significantly in terms of their age-adjusted H-index (Fig. ). There was a large variation in this parameter, ranging from > 2.5 (Nobel Prize laureates No. 32 and 35) to 0 (Nobel Prize laureates No. 26). The mean value for women is 1.238, and of men 1.26 with a larger variance by men (0.36) than by women (0.250). Figure shows the average number of publications per year. The yellow line in panel A shows the year of the Nobel Prize awarding. The years to the left of 0 describe the time before the awarding (with a minus in front of the numbers), the numbers to the right describe the years after the awarding. The number of publications is highest on average at approximately 10 per year for around 20–24 years prior to receiving the Nobel Prize. However, the differences between the individual Nobel Prize laureates are very large. Women and men reach their productivity peak at about the same age. The 20 years immediately before the Nobel Prize awarding (especially the last two years) are more productive for Nobel Prize laureates than the time after the Nobel Prize (Fig. ). The average age of the year with the most publications to date is 53.44 years for female Nobel Prize laureates and 55.31 years for male Nobel Prize laureates. The standard deviation is significantly wider for male Nobel Prize laureates than for women (Fig. ). There was no significant difference between the groups. Figure shows the research locations at the time of the awarding. The addition of researchers from the University of Stanford, Scripps Institute, Rockefeller University, Harvard University, Yale University, and University of Berkeley (all USA) totals 36% (and therefore more than 1/3), but each individual university is not significantly overrepresented. Most of the other research locations are evenly distributed. Panel B shows the research locations of the female awardees. The 10 female awardees conducted research at 10 different universities, but 50% conducted research at a US university. Among the male awardees (panel C), there is also a fairly balanced distribution of research universities. In a direct comparison of countries, however, 58% of all award laureates conduct their research in the USA, 12% in Japan, 17% in the UK, and just 10% in four other countries.   A limitation of our work is the small database of female Nobel Prize laureates. In addition, we focused on quantifiable bibliometric parameters. Furthermore, there is a very large variation among the individual career paths and productivities of individual Nobel Prize laureates that is not appreciated by our analysis. Most strikingly, even without a single publication and, hence, a non-existant bibliometric track record, important scientific achievements can be made, e.g., 26. We had to limit our bibliometric analysis at a certain calendar date, but it cannot be excluded that in the future, recognition of female scientists having already been awarded the Nobel Prize changes. Even though the Nobel committees’ mandate is to honor scientific achievements for the benefit of humankind, their interpretation of this criterion was primarily based on their assessment of the groundbreaking nature of the science, while the applied or practical utility of this discovery or bibliometric values such as number of publications, citations, or H-index assessed in the current study are at best secondary factors when awarding the prize (Källstrand ). In fact, some Nobel Prize laureates (e.g., 17, 18, 23, 26, 40) have only few publications or no publications. Hansson et al.  state that it is difficult to measure this “greatest benefit to mankind” or brilliance in science in an objective way.   To the best of our knowledge, this is the first study that aims at providing a bibliometric comparison of female and male Nobel Prize laureates. Based on numerous studies pointing to a discrimination of women in science (Ceci and Williams ; Moss-Racusin et al. ; Ball ; Beaudry and Larivière ; Ceci and Williams ; Charyton et al. ; Harding ; Kulis and Sicotte ; Lubinski et al. ; Ma et al. ; Ross et al. ), it cannot be excluded that even among this group of absolute elite scientists, some sort of discrimination occurs. However, looking on numerous bibliometric parameters, we did not obtain evidence for a bias against women. Rather, for crucial parameters such as publications before the Nobel Prize, citations, age-adjusted H-index, productivity peak, and research location, we did not find evidence for systematic discrimination of female Nobel Prize laureates relative to male Nobel Prize laureates. Rather, women were awarded the Nobel Prize at a significantly younger age than men although both genders have a similar age with regard to the peak of research productivity. Thus, surprisingly, our study shows that the research accomplishments of female Nobel Prize laureates are actually recognized earlier than those of men. This strongly argues against the Nobel Prize committee being discriminatory against women although the current Nobel assembly is male-dominated. There are six Nobel Committee members for physiology or medicine, five male members and just one female member ( https://www.nobelprize.org/about/the-nobel-committee-for-physiology-or-medicine/ ; last accessed 03/29/2024). In case of systematic discrimination of females, we would have expected that female Nobel Prize laureates are much older than their male counterparts and need to have many more publications and citations and a higher H-index. This was, however, not the case. We also did not notice overrepresentation of a specific country or research institution among female Nobel Prize laureates. Thus, it appears that the current Nobel Committee tries to look for the best candidates for the Nobel Prize independently of gender. This is supported by the fact that concerning contemporary Nobel Prize laureates in the topics discussed here (Table ), there has never been such an egregious case of omitting females as the non-consideration of Rosalind Franklin who made seminal contributions to the identification of the DNA structure (Conti ). The most controversial case of non-consideration for the Nobel Prize in recent times in the fields considered here probably concerns a male (Salvador Moncada for the nitric oxide/cGMP pathway), where bias against him coming from a developing country was speculated to have played a role (Lancaster ). In the present study, representation of citizens from developing countries is poor as well (Table ). Scientists coming from developed countries dominate the field regarding Nobel Prize awards. The number of female Nobel Prize laureates with a relation to pharmacology is much smaller than the number of male Nobel Prize laureates. A gender gap is not only observed for the Nobel Prize but also for other scientific awards (Hansson ). Hence, our present study complements the current knowledge on gender imbalance concerning scientific awards. The study of Zehetbauer et al.  showed that the number of female first authors in pharmacology-related papers, mostly reflecting PhD students and postdocs, is much higher than the number of female senior authors, the latter reflecting group leaders conducting independent research. This study suggests that the major drop of female researchers occurs between the PhD student and postdoc stage versus group leader stage. This career stage often collides with family planning. Thus, a major factor accounting for the small number of female Nobel Prize laureates is the smaller number of female researchers who enter an intellectually independent research career: an unwritten prerequisite for getting eligible for the Nobel Prize. All of the Nobel Prize laureates in Table fulfill the criterion of long-term research as intellectually independent investigator. But it must also be taken into consideration that both female and male scientists are not just passive objects in a career system but that they also make active decisions about what they do and what they do not do in their scientific careers (Zöllner and Seifert ). The latter study epitomized that female German pharmacologists invest much less in social capital (scientific visibility in the German science community via the journal “Biospektrum”) than their male counterparts although they are very much encouraged to do so by the Executive Board of the German Pharmacological Society and although the time effort needed to become visible is low. Visibilty is important for being recognized a potential award candidate. The study also noted substantial gender differences between various scientific fields regarding investment in visibility. The aspect of voluntary conscious decisions of individuals is, unfortunately, substantially underrated in the current gender discussion in science.   The group of Nobel Prize laureates is a very small group of elite researchers, and only the minority of all important research accomplishments is awarded the Nobel Prize (Pohar and Hansson ). Thus, it will be very important to expand this type of bibliometric research to a larger population of scientists, independently of an award. One approach could be to analyze, the group of the leading 10.000 or 100.000 scientists globally and relying on an integrative approach including number of publications, citations, and H-index. The advantage of analyzing many scientists is that it is much easier to analyze cultural differences among different countries. It will also be worthwhile, in 10 years from now, to repeat the current study and compare how Nobel Prize laureates from 2006 to 2022 compare with Nobel Prize laureates from 2023 to 2032. Interviews should be conducted with scientists regarding their professional choices. Lastly, it will be important to analyze the contributions of scientists from developing countries, both male and female, who may not have received the Nobel Prize.   