System for the simulation of the evolution of a region of the scalp of a subject over time, comprising a means of observation of the said hair region able to output digital observation data, a first digital data processing means capable of classifying elementary parts of the said region on the basis of the observation data, a second digital data processing means capable of simulating the evolution of the said hair region as a function of the data emanating from the first digital data processing means, and a means of displaying the data emanating from the second digital data processing means.