How did digits evolve? While it is clear that they derive from genetic programs already present in fish, their precise origin remains a matter of debate. An international team led by the University of Geneva (UNIGE) with EPFL, the Collège de France, and the universities of Harvard and Chicago has come up with an unexpected answer: Digits may have evolved from the reuse of an ancient region of the genome, initially active in the formation of the fish cloaca rather than their fins.