Theodosius Dobzhansky died in Davis (California). He was a biologist, geneticist, and philosopher of biology and was among the major 20th century scientists who studied evolutionary biology. He authored the important work Genetics and the Origin of Species (1937), in which he synthesized Mendel’s genetics with Darwin’s evolutionary theory. His philosophical thought tended toward the idea of human nature as subject to transformations and mutations, which he used to challenge the racial outlooks of his time (it should be noted that the term “nature,” as used here, does not primarily refer to the metaphysical nucleus that individuates the human being as person). Dobzhansky’s philosophical reflections on evolution are developed from the point of view of a believer, a point of view to which he remained, albeit discreetly, faithful. His work, The Biology of Ultimate Concern, published in 1967 a few years before his death, testifies to this.