What he described was a a brutal insurance against inbreeding...almost all tribal societies merely have the young women leave the village. It has been theorized by evolutionary biologists that the reason teenage girls are so at odds with their mothers is a remnant of one way to ensure out-migration of the women. Another point is this: when a young adult lives at home, it's usually the son and not the daughter.
Cabeza de Vaca is said to be the first European to mention the bison. He also mentions at one point of one group of Indians, "during the time I was among them I saw something very repulsive, namely, a man married to another. These are impotent and womanish beings who dress like and do the work of women." He would not be welcome in today's Democratic Party.
One of the four survivors was a Moroccan slave, Estevanico, whom he sometimes refers to as "the Negro." Not long ago I caught Henry Louis Gates talking about Estevanico's great explorations (greatly exaggering the number of miles he walked) but totally ignoring the others as if he either was alone or was the leader of the group.