Theodosius Dobzhansky, biologist, geneticist and philosopher of biology, was born in Nemyriv, Ukraine. He was one of the twentieth-century greatest scientists, engaged in the study of biological evolution. In his important work Genetics and the Origin of Species (1937), he made a synthesis between Mendel's genetics and Darwin's evolutionary theory. His philosophical thought conceived of human nature as subject to transformation and change, thus also fighting the racial prejudices of his time. Dobzhansky's philosophical reflections on evolution are affected by his religious beliefs, which, though with discretion, he never abandoned. His book The Biology of Ultimate Concern, published in 1967, a few years after his death, clearly witnesses this.