350 BUREAU OF AMERICAN ETHNOLOGY [Bull. 181 



fibulae are thickened and porous. The long bones, which are light 



in weight, are bowed anteroposteriorly. 



Burial 76 {USNM S80888) .—Male, adult; an extended burial in 

 very poor condition. The skull, which shows slight lambdoid de- 

 formity is rather short, narrow, and high. Tooth wear is second 

 degree, with at least six of the teeth carious ; the maxillae are in too 

 poor condition to estimate the number of teeth lost during life. The 

 postcranial parts were discarded after examination in the laboratory. 



Burial 77 ( USNM 380889) .—Male ( ? ) , adult ; a semiflexed skeleton 

 in poor condition. The long narrow skull is too badly damaged for 

 measurement. The one tooth present is carious, and the fragment 

 of mandible gives evidence of the loss of a number of teeth during life. 

 The postcranial parts were discarded after examination in the 

 laboratory. 



Burial 78. — Only a few shell beads remained to represent this badly 

 disintegrated burial. The size of the pit suggested a flexed adult 

 skeleton. None of the bones could be preserved. 



COMPARISON OF THE TOLLIFERO AND CLARKSVILLE 



POPULATIONS 



The time interval that separates the ToUifero and Clarksville 

 populations suggests that physical differences will be found between 

 the two peoples, analogous to the cultural differences seen by the 

 archeologist. Such physical differences may be basically geno- 

 typic — due to genetic alterations brought about by natural selection, 

 genetic drift, admixture with neighboring groups, or population re- 

 placement; or they may be primarily nongenic — brought about by 

 external factors. The relatively short, time lapse separating the two 

 populations argues against major genetic drift unless migration can 

 be invoked. And, when one considers that the potential immigrants 

 are not likely to have been too different from the people they replaced, 

 this explanation is not too impressive. On the other hand, an external 

 agency of considerable importance, the introduction of agriculture, 

 can be demonstrated. In weighing the relative effect on pliysique of 

 possible genetic change against known environmental change, the in- 

 teraction of the two agents of change cannot be ignored. It is a matter, 

 then, not of excluding one or the other, but of deciding which played 

 the major role. 



Since it is easier to evaluate the possible physical changes produced 

 by laiown factors than those produced by unlmown, it is conven- 

 ient to start with the working hypothesis that, in this case, diet, 

 accompanying the introduction of agriculture, was the major 

 source of physical change. The changes in diet attributable to the 

 adoption of agriculture are not hard to estimate. For example, clear- 



