As a boy, influenced by his father's porcelain manufacturing plant at Mogi das Cruzes, he wished to follow a career in engineering, but changed radically when he had the opportunity in high school to attend a lecture by noted French physician and professor André Dreyfus and a screening of the film "The Story of Louis Pasteur", starring Oscar-winning actor Paul Muni in the title role.
Following Dreyfus' advice, in 1938 he enrolled in a course of natural history at the University of São Paulo, continuing to work in biological research under his mentor.
In 1942, Pavan became involved in a pioneering research project on the genetics, taxonomy and ecology of Drosophila fruit flies, financed by the Rockefeller Foundation under the direction of the noted Russian-American biologist Theodosius Dobzhansky.
In particular, Dr. Pavan introduced into biology the cytogenetical study of Rhynchosciara angelae, a fly which is noted for its giant chromosomes, thus facilitating the determination of the loci of genes.
He returned to Brazil in 1975, and, after officially retiring from his post at the University of São Paulo, he accepted the position of full professor at the recently founded State University of Campinas, working as departmental chairman and dean of the Instituto de Biologia da Universidade Estadual de Campinas (Institute of Biology) until a second retirement.