I think as soon as we are able to simulate climate variability, thereby resettlement to other continents, connected by an ice cap, will be more plausible in the framework of present reality, and we, moreover, will less need a faster migration rate. Speaking of polar caps, if I am not mistaken, the suitability of a group in a cell is simulated, but a possible reserve of migration potential is not considered, which would accelerate the movement of individuals across the continent, since groups would more efficiently populate spaces without stopping, for example, in the desert, but moving on.