It’s a matter of group size. If a group is too small, there are not enough hunters for their preferred method of running down game in relays. If the group is too large, they must range over too large an area to find game. But the prestige of a shaman is to some extent linked to the size of the group for which he or she is responsible.
This works fine as long as the shaman is more interested in the welfare of the group than in his or her own prestige. Now and then, however, a shaman inherits a group larger than that person is ready to handle and refuses to let relatives find mates in another group. None of the shamans I have known well have made that mistake. This year, however, we have two fighting over the eventual affiliation of two young people who want to stay together.
Jarn’s Journal is the journal of a fictional human-like alien stranded in Africa 125,000 years ago. He has become affiliated with a group of primitive humans, the People. The story is part of the back story of my science fiction.