Ella Deloria. Also known as Anpetu Sa Win (Beautiful Day Woman). This was probably taken around 1915 when she was studying in New York City at Columbia Teacher's College and working with Franz Boas, the "father of American anthropology".
Here is one of my favorite quotes from her book Speaking of Indians:
Kinship was the all-important matter. Its demands and dictates for all phases of social life were relentless and exact; but, on the other hand, its privileges and honorings and rewarding prestige were not only tolerable but downright pleasant and desirable for all who conformed. By kinship all Dakota people were held together in a great relationship that was theoretically all-inclusive and co-extensive with the Dakota domain. Everyone who was born a Dakota belonged in it; nobody need be left outside.
This meant that the Dakota camp-circles were no haphazard assemblages of heterogeneous individuals. Ideally, nobody living there would be unattached. The most solitary member was sure to have at least one blood relatives, no matter how distant, through whose marriage connections he was automatically the relative of a host of people. For, in Dakota society, everyone shared affinal relatives, that is, relatives-through marriage, with his own relatives-through blood.
Before going further, I can safely say that the ultimate aim of Dakota life, stripped of accessories, was quite simple. One must obey kinship rules; one must be a good relative. No Dakota who has participated in that life will dispute that. In the last analysis every other consideration was secondary-- property, personal ambition, glory, good times, life itself. Without that aim and the constant struggle to attaint it, the people would no longer be Dakotas in truth. They would no longer even be human. To be a good Dakota, then, was to be humanized, civilized. And to be civilized was to keep the rules imposed by kinship for achieving civility, good manners, and a sense of responsibility toward every individual dealt with. Thus only was it possible to live communally with success; that is to say, with a minimum of friction and a maximum of good will.
Great-great aunt, Ella Deloria, Speaking of Indians, p 24-25.