Abstract Three databases (2961 georeferenced archeological sites, simulated climatic variables simulating a typical “warm” phase of the isotopic stage 3 (IOS3 project), and ethnographic of hunter–gatherers (HG)) were used to estimate the size, growth rate and kinetics of the metapopulation of HG during four periods of the Upper Paleolithic in Europe. The size of the metapopulation was obtained by multiplying a demographic density (per 100 km 2) by the size of the population territory of HG. Demographic density for each period was calculated by successively backprojecting a reference density obtained for the Late Glacial with inter-period growth rate of the archeological sites. From the Aurignacian to the Glacial Maximum, the metapopulation remained in a positive quasi-stationary state, with about 4400–5900 inhabitants (95% confidence interval (CI95%): 1700–37,700 inhabitants). During the Glacial Maximum, the metapopulation responded to the cold: (i) by moving the northern limits of its maximum expansion zone towards the low latitudes by 150–500 km from west to east, (ii) by concentrating in few refuge zones (mainly Périgord, Cantabria and the Ibérian coasts), (iii) by becoming perhaps distributed in smaller groups than during the pre and post Glacial Maximum. The metapopulation reached 28,800 inhabitants (CI95%: 11,300–72,600) during the mid-Late Glacial recolonisation.