Crusio got in 1979 a master's degree and then in 1984 a PhD from the Radboud University Nijmegen. He performed research in behavior genetics, plant taxonomy, and vegetation science for his master's degree. His revision of the genus "Anubias" continues to generate interest. His work in plant taxonomy continued for several more years. He wrote about the genus "Samolus". In 1986 he described a new species of the Aroid genus "Lagenandra", "L.dewitii". Crusio studied the inheritance of the behavior of mice exploring a new environment for his PhD He also looked at the effects on this behavior of not being able to smell (anosmia). He used quantitative-genetic methods such as the diallel cross for this. Crusio worked as a postdoctoral researcher at the University of Heidelberg from 1984 to 1987. This was supported by a NATO Science Fellowship and an Alexander von Humboldt Research Fellowship. Crusio spent the year 1988 in Paris (France) supported by a fellowship from the Fyssen Foundation. He returned to Heidelberg as a senior research scientist. He was then recruited as "chargé de recherche" by the CNRS. He worked at first in an institute of the Paris Descartes University (Paris V). He was promoted to research director in 1994. In 1997 he moved to the CNRS campus in Orléans. Crusio became professor of psychiatry at the University of Massachusetts Medical School in Worcester, Massachusetts in 2000 and returned to the CNRS in 2005. He became a group leader in the "Centre de Neurosciences Intégratives et Cognitives" in Talence, a suburb of Bordeaux. He is currently adjunct director of the "Institut de Neurosciences Cognitives et Intégratives d'Aquitaine".