76 LABORATORY MANUAL OF ANTHROPOMETRY 



would seem to have some value, which future work may prove. Its 

 angles at n and I subtend the basion-bregma height; the angles at 6 

 and ba subtend the nasion-inion (Bi-B^). It is presented here merely 

 as a suggestion. 



II. THE VERTEBRAL COLUMN, WITH THE 

 RIBS AND STERNUM 



The Vertebral Column, with the Ribs and Sternum. One of the most 

 frequently emphasized differences between man and the apes is that of 

 the degree of forward curvature of the vertebral column in the lumbar 

 region (lordosis) . This curve which, in its extreme form, is characteristic 

 of the human back, is displayed to a much lesser degree in the Simiidae, 

 and in the gibbons (Hylobates), the lowest of the family, is but slightly 

 indicated. 



It is thus generally considered, and with much probability, that this 

 lumbar curve has been gradual attainment in the evolution of man, and 

 that, in all probability, the curve would be found to be less in the lower 

 races, and thus serve as a racial criterion. 



The ideal and only complete method of studying this and the other 

 curves of the vertebral column is by means of accurately made sagittal 

 sections taken through frozen bodies, but owing to the obvious difficulties, 

 this had been done in only a few cases, and includes only representatives 

 of races of higher culture. Much can be done, however, by the study 

 of the separate vertebrae, since the character of the curve is conditioned 

 largely by the proportions of the bodies of the vertebrae involved. By 

 measuring the antero-posterior thickness, of the lumbar centra in the 

 median line, both dorsally and ventrally, and then comparing the two, 

 it is found that these parts are wedge-shaped, the most anterior one 

 slightly, increasing gradually to the fifth, in which this character is the 

 most pronounced. It is to this that the lumbar curve is largely due, and 

 thus the degree of curvature may be ascertained by obtaining the above 

 measurements of the vertebral centra. 



As a sufficiently exact measurement is difficult or impossible, and as 

 the differences between the dorsal and ventral measures of single vertebrae 

 are but slight, Turner, who first proposed this method, obtained more 

 accurate figures by adding together the measurements obtained from 

 twelve individual spinal columns, and comparin r the sums.* Thus, the 

 ventral measure of the 12 fourth lumbar vertebrae was 336 mm. while 

 the dorsal measures of the same parts was only 313. In the 12 fifth lumbar 

 vertebrae the corresponding numbers were 337 and 281, a more pro- 

 nounced difference, since the ventral measures were practically identical, 



* TURNER, SIR WILLIAM: Report on the Human Crania and Other Bones of the 

 Skeletons Collected During the Voyage of H. M. S. Challenger in the years 1873-76. 

 Part li. The bones of the Skeleton, publ. in 1886 in the Reports of the Challenger 

 Expedition, Zoology, Vol. XVI, pp. 1-136. 



