Biological Metaphors of the Individual - The same common name can designate different scientific objects, whose trajectories in history we can trace. Individual is an interesting case study, and a typical example of a constitutive metaphor in science. The old meaning, moving from philosophy to science, has changed along two centuries. The new meaning in population genetics is based on the difference among individuals. Thus, individual as a constitutive metaphor becomes the real epistemological engine of modern evolutionary theories. Keywords: Biological metaphors, Evolution, Population Genetics, Individual, Metaphor, Semantic change.