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