Femoral cortical thickness of North American Plains Indians • 109 



The Extended Coalescent settlement 

 pattern of small villages occupied for 

 only a short time may represent a re- 

 sponse to marginal economic condi- 

 tions, which in tum were the product 

 of a less favorable climate. . . . 

 Bryson has suggested (Baerreis and 

 Bryson, 1965) that the Neo-Boreal 

 conditions were modified somewhat 

 during the first half of the 18th cen- 

 tury. The larger and more permanent 

 Post-Contact Coalescent settlements 

 in South Dakota may represent a re- 

 sponse to this improvement in cli- 

 mate. (Lehmer 1971:128) 

 Late 1 7th and early 1 8th century popu- 

 lations in general were well off. As re- 

 flected by increased cortical thickness 

 and cortical area, the transition from 

 the Late Prehistoric to the Early Pro- 

 tohistoric was marked by a positive 

 change in nutritional status. A culmina- 

 tion of factors insured greater reserves 

 and diversity of resources that buffered 

 the villages against lean times. These 

 factors included agricultural inten- 

 sification to acquire surpluses for trade 

 and increased availability of meat ob- 

 tained through hunting and trade. 



Horses, first brought to the valley 

 from the southwest, circa 1739, were a 

 valued commodity in the middleman 

 trade, both as an object of trade and as 

 pack animals. Given the lag time be- 

 tween their introduction, initial use as 

 pack animals, and later use for riding, 

 the impact of the horse on the Ankara 

 economy would have been most signifi- 

 cant after 1750 (D.J. Blakeslee, pers. 

 comm.; Ewers 1955). Theoretically, 

 horses made it easier to locate and kill 

 wild game and to transport larger quan- 

 tities of meat to the village than possi- 

 ble during the prehistoric period when 

 dogs were used for this purpose (Holder 

 1970). The acquisition of the horse, 

 with a corollary increase in high- 

 quality protein in the diet, has been in- 

 terpreted as a primary reason why Post- 

 Contact Coalescent villagers show in- 

 creased femoral cortical thickness rela- 

 tive to their late prehistoric Extended 

 Coalescent antecedents (Cashion 1987; 

 Owsley 1985). Yet, as apparent in this 



more finely graded temporal analysis, 

 the Late Protohistoric period (1740- 

 1795) was not accompanied by dramat- 

 ic increases in femoral cortical thick- 

 ness. In fact, a subtle reverse occurs. 

 Medullary cavity diameters increased 

 markedly and mediolateral cortical 

 thicknesses began to drop. In contrast, 

 cortical areas did increase slightly be- 

 cause of the larger values for T. Al- 

 though this apparent inconsistency is 

 not easily interpreted, it is clear that the 

 major change (improvement) in Post- 

 Contact period nutritional status pre- 

 ceded the arrival of the horse. Any po- 

 tential nutritional benefits derived from 

 use of the horse were less significant. 

 Later effects of Euro-American con- 

 tact were negative and disruptive. Dis- 

 organized Coalescent villages suffered 

 higher levels of morbidity, population 

 losses from disease and warfare, and 

 sociocultural deterioration. "Between 

 1738 and 1845, there was considerable 

 instability of population marked by vil- 

 lage abandonment and relocation" 

 (Ramenofsky 1987:104). Catastrophic 

 population losses followed the intro- 

 duction and diffusion of acute infec- 

 tious diseases, including cholera, mea- 

 sles, smallpox and whooping cough 

 (Lehmer 1971; Ramenofsky 1987; 

 Trimble 1979,1985). Moreover, inter- 

 tribal conflict escalated as militant 

 nomadic groups moved into the middle 

 Missouri region after being pushed out 

 of the eastern woodlands. Arikara rela- 

 tions were poorest with the Dakota 

 Sioux, who arrived circa 1730-1740 

 (Owsley et al. 1977; Smith 1980). The 

 Sioux placed increasing pressure on the 

 Arikara as conflict over bottom lands, 

 which provided protection during the 

 harsh winters, and competition for 

 trade booty and the yield from the 

 Arikara gardens intensified. The period 

 of most intense warfare with the Sioux 

 dates to the historic period after 1790 

 (D.J. Blakeslee, pers. comm.). Tru- 

 teau's journal for his journey of 1794- 

 1796, for example, mentions an ex- 

 pected attack on an Arikara village by 

 500 Sioux warriors well armed with 

 guns(Truteau 1913-1914). 



The nutritional effects of these 

 changes are clearly registered in in- 

 creased medullary cavity diameters and 

 net reductions in femoral cortical bone 

 during the early Historic period. 

 Females seem to have been most af- 

 fected by the stresses of this turbulent 

 era. Although the direction and pattern 

 of change in bone mass are evident, es- 

 timated cortical areas were still higher 

 than during the Late Prehistoric period. 



In summary, cortical bone thickness 

 has proven to be a sensitive indicator of 

 changes in Arikara nutritional status 

 caused by environmental change. In 

 contrast, maximum long bone length 

 has not shown a significant response. 

 The difference between these variables 

 merits further consideration. More- 

 over, future research must examine 

 changes reported for the variable T. To- 

 tal subperiosteal diameters increased 

 through time, especially in males. Re- 

 cent research concerning the geometric 

 properties of lower limb bone di- 

 aphyses has shown the responsiveness 

 of cross-sectional shape to different 

 mechanical loadings associated with 

 behavior such as more frequent running 

 (Ruff 1987). Perhaps the increase in T 

 was a structural response to changes in 

 activity level. In the future, we plan to 

 consider possible variations in geo- 

 metric form by examining both the me- 

 diolateral and anteroposterior axes and 

 direct measurement of cross-sectional 

 area. 



Acknowledgments 



William Bass and Douglas Ubelaker 

 kindly granted permission to examine 

 these collections. Archeological recov- 

 ery was made possible by grants from 

 the National Science Foundation and 

 the National Geographic Society. Don- 

 ald Blakeslee and Daniel Rogers pro- 

 vided archeological and cthnohistorical 

 information. Steve Symes, Terry 

 Zobeck, and Maria Cashion were re- 

 sponsible for bone radiography and os- 

 teometry. Suggestions concerning ana- 

 lytical methodology were provided by 

 J. Dequeker. Dana Bovee helped pre- 



Zagreb Paleopathology Symp. 1988 



