'.'J IND1 INS 01 l HI. PLAINS. 



were created by one tribe and then passed OD to other-. 

 •This is an important point because among anthropolo- 

 gists there are two extreme theories to account for 

 similarities in culture, one that all like cultural traits 

 wherever found had a common origin, the other that 

 all were invented or derived independently by the 

 tribes practising them. The former is often spoken 

 of as the diffusion of cultural traits, the latter as inde- 

 pendent development. It is generally agreed, how- 

 ever, that most cultures contain traits acquired by 

 diffusion (or borrowing) as well as some entirely original 

 to themselves, the whole forming a complex very 

 difficult to analyze. Returning to these Plains Indian 

 societies we find among several tribes (Blackfoot, 

 Gros Ventre, Arapaho, Mandan, and Hidatsa) an 

 additional feature in that the societies enumerated in 

 our table are arranged in series so that ordinarily a man 

 passes from one to the other in order like school children 

 in their grades, thus automatically grouping the mem- 

 bers according to age. For this variety, the term age- 

 society has been used by Dr. Kroeber. Thus, it 

 appears that while in certain general features, the 

 soldier band system of police is found among all tribes 

 in the area, there are many other interesting differences 

 distributed to varying extents. For example, the age 

 grouping is common to but five tribes while among the 

 Arapaho it takes a special form, the age grouping being 

 combined with appropriate ceremonial, or dancing 

 functions, including practically all the adult males in 

 the tribe. An unusually complete Bet of the regalia 



