Left, Geneticist Theodosius Dobzhansky adjusts a fly maze in 1965. Dobzhansky, through his work with fruit flies, helped reconcile Charles Darwin’s theory of evolution and Gregor Mendel’s principles of heredity and was instrumental in advancing the idea that natural selection occurs through gene mutation. Right, Biochemist and geneticist Craig Venter photographed in 1998. Using a technique known as shotgun sequencing, Venter’s private venture nearly beat out a government-funded international collaboration to sequence the first human genome.

American Philosophical Society/Science Source; Zuma Press/Alamy Stock Photo