Mary Putnam Jacobi was a physician and researcher in the United States whose work advanced the understanding of women’s health in the late nineteenth century. She held senior positions at institutions such as the New York Infirmary for Women and Children and the Woman’s Medical College of the New York Infirmary, both located in New York City, New York. At a time when women faced substantial barriers in both healthcare and academia, Jacobi conducted scientific research that challenged widely held misconceptions about women’s physiology, particularly regarding menstruation. By performing laboratory experiments and advocating for vivisection, which is the practice of performing operations on live animals for research purposes, Jacobi played a role in advancing medical techniques that influenced future research. Jacobi’s work not only contributed to a more scientific understanding of women’s biology but also led to greater inclusion of women in medical research and practice.

Joseph Grafton Gall researched and taught cell biology for over seventy years in the late twentieth and early twenty-first centuries in the United States. Much of his early work revolved around the structure and function of chromosomes, which are structures made of DNA and protein found in cells. As a professor at Yale University in New Haven, Connecticut, Gall and his graduate student Mary-Lou Pardue developed in situ hybridization, a technique that uses probes to identify the location of specific DNA sequences along a chromosome. With another graduate student, Elizabeth Blackburn, he also performed research on the structure of telomeres, which are the ends of chromosomes. Gall was an early advocate for women in STEM and trained many female scientists, many of whom became successful in their fields. Gall studied the structure and function of different forms of genetic information, namely DNA and RNA, helping to expand the understanding of how those molecules replicate within cells.

As a researcher in biochemistry, Frederick Sanger studied the structure of proteins, RNA, and DNA during the mid-twentieth century in Cambridge, England. He was the first person to determine the amino acid sequence of a protein, the hormone insulin, which regulates blood sugar levels. Later, he developed an efficient method for sequencing the nucleotide bases in DNA, an organism’s hereditary material. Named Sanger sequencing in his honor, the method was a staple of molecular biology techniques for over forty years. It formed the backbone of methods used for the Human Genome Project, the international effort to sequence the DNA in a human genome, and foreshadowed the development of more modern DNA sequencing techniques. Sanger is one of only a handful of individuals to receive two Nobel Prizes. Through his work elucidating the structure of biological molecules and devising methods to sequence them, Sanger fundamentally shaped the course of biology in the twentieth century.

Theodosius Dobzhansky studied genetics and evolutionary biology, primarily using fruit flies, in the Soviet Union and the United States during the twentieth century. Scholars credit his widely read 1937 book Genetics and the Origin of Species with providing one of the earliest and most impactful integrations of Charles Darwin’s theory of evolution by natural selection with Gregor Mendel’s theory of genetics and therefore contributing significantly to the Modern Synthesis. In his research, Dobzhansky studied wild populations of organisms such as fruit flies and found that populations of the same species can differ in the frequency of one or more genetic traits. Understanding the role of such genetic diversity in evolution became a central theme of his research. Later in his career, he wrote about the social implications of his research, including the relationship between biological and cultural notions of race. Through both his scientific papers and popular writings, Dobzhansky shaped the course of evolutionary biology in the twentieth century and influenced public discussions of race in the years following World War II.

Roberto Bachi researched statistics and demography at the Hebrew University of Jerusalem in Jerusalem, Israel, and was the director of Israel’s Central Bureau of Statistics from 1948 to 1971. The Central Bureau of Statistics was responsible for collecting, analyzing, and publishing demographic and economic data to inform government policy in the new state of Israel. In 1962, Prime Minister of Israel David Ben-Gurion established the first committee to address the Jewish birthrate, called the Committee for the Problems of Natality, and appointed Bachi to lead it. In that role, Bachi investigated population growth and demographic trends among Arab Palestinian citizens of Israel and among Jewish immigrant groups. His findings showed that while the overall Jewish birthrate was declining, Arab Palestinian fertility rates remained high, raising political concerns about maintaining a Jewish majority. Through his studies of the fertility of Jewish people in Israel and his comparative data on Jewish and Arab populations, Bachi helped to embed demographic concerns into Israeli national politics and Zionist policies.