Per SE's own lore on the naming conventions page:
"Males do not take family names, as they are each considered the ‘origins’ of new families. In place of a family name, they are given a title that denotes their tribe, and their position within it. For a male Seeker of the Sun, there are only two positions available—breeding males (nunh – pronounced ‘noon’) and all others (tia – pronounced ‘tea-ah’). All males are born as tia. At any time in their lives, a tia can challenge the tribe nunh to battle. If the tia is victorious, he takes the nunh’s place as tribe breeding male (until he is challenged and defeated), and the nunh becomes a tia once again (if he survives the ordeal). This is done to ensure that the tribe’s offspring are of the finest stock. Depending on its size, a tribe may have multiple nunh (a ratio of one nunh per ten to fifty females is average).
There is only one other way a tia can become a nunh, and that is to leave his tribe, and start his own. This, of course, requires several females to accomplish, and most female Seekers of the Sun are rarely impressed by a male who cannot defeat a nunh.
Nunh status does not equate to leadership within a tribe, and in fact, very few nunh ever become leaders."
So the U and M tribes (that we see, there may be other U and M tribes out there) are supposed to be rare situations. That being said, the next seeker tribe we run into... my money is on the nuhn being leader again..... because SE.
Edit: bolded pertinent parts.
"Males do not take family names, as they are each considered the ‘origins’ of new families. In place of a family name, they are given a title that denotes their tribe, and their position within it. For a male Seeker of the Sun, there are only two positions available—breeding males (nunh – pronounced ‘noon’) and all others (tia – pronounced ‘tea-ah’). All males are born as tia. At any time in their lives, a tia can challenge the tribe nunh to battle. If the tia is victorious, he takes the nunh’s place as tribe breeding male (until he is challenged and defeated), and the nunh becomes a tia once again (if he survives the ordeal). This is done to ensure that the tribe’s offspring are of the finest stock. Depending on its size, a tribe may have multiple nunh (a ratio of one nunh per ten to fifty females is average).
There is only one other way a tia can become a nunh, and that is to leave his tribe, and start his own. This, of course, requires several females to accomplish, and most female Seekers of the Sun are rarely impressed by a male who cannot defeat a nunh.
Nunh status does not equate to leadership within a tribe, and in fact, very few nunh ever become leaders."
So the U and M tribes (that we see, there may be other U and M tribes out there) are supposed to be rare situations. That being said, the next seeker tribe we run into... my money is on the nuhn being leader again..... because SE.
Edit: bolded pertinent parts.
