The migration patterns of the first modern humans show that people moved beyond their familiar hunting grounds at a rate of about miles per generation.

According to the early human migration patterns they moved for about two to three miles per generation.

Explanation:

First of all, we need to contextualize here to understand why humans only moved as far as three miles per generation. Now, to start I would like to point out something. Early human groups weren't a settled group of civilizations, they were nomads and collectors, in the best cases they started to develop crop farming methods but that was really unlikely. So they depended almost solely on gathering and hunting. Thus, they weren't really able to get enough resources to perform long trips. They followed animal groups to hunt them down and that was also a reason to only move in small distances. Because in that time animals had plenty of places to move in the same areas. Also because if they had enough resources in a single place there was no real reason to leave. But that changed when settlements and civilizations developed. Rivalry for resources was a major migration factor.

corrupt also means cruel