462 The American Naturalist. [June, 



Pouchet says : " Man is a creature of the writing-table and 

 could only have been invented in a country in which covering 

 of the feet is universal ; " he should have added the " eating- 

 table." From the average man our fashions and occupations 

 demand the play of the forearm and hand, the independent 

 and complex movements of the thumb and finger ; the out- 

 ward turning of the foot in walking. These are some of the 

 most conspicuous features of modern habit. 



The Skeletal Variations. 1 — In a most valuable essay by 

 Arthur Thomson upon " The Influence of Posture on the Form 

 of the Articular Surfaces of the Tibia and Astragalus in the 

 Different Races of Man and the Higher Apes," 2 we find clearly 

 brought out the distinction between congenital variations and 

 those which may be acquired by prolonged habits of life. It 

 is perfectly clear from this investigation that certain racial 

 characters, such as " platycnemism " or flattened tibia, which 

 have been considered of great importance in anthropology, 

 may prove to be merely individual modifications due to cer- 

 tain local and temporary customs. Thomson's conclusions are 

 that the tibia is the most variable in length and form of any 

 long bone in the body. Platycnemia is most frequent in tribes 

 living by hunting and climbing in hilly countries, and is asso- 

 ciated with the strong development of the tibialis posticus. 

 The great convexity of the external condyloid surface of the 

 tibia in savage races appears to be developed during life by 

 the frequent or habitual knee flexure in squatting ; it is less 

 developed where the tibia has a backward curve and is inde- 

 pendent of platycnemia, Another product of the squatting 

 habit is a facet formed upon the neck of the astragalus by the 

 tibia. This is very rare in Europeans; it is found in the gorilla 

 and orang, but rarely in the chimpanzee. We must therefore 

 be on our guard to distinguish between congenital or heredi- 

 tary skeletal characters which are fundamental and " acquired" 

 skeletal variations which may not be hereditary. The latter 



'For recent general articles see Blanchard, L'Atavisme cliez 1' Homme, Rev. de 

 Anthrop. 1885, p. 425 ; and Baker, The Ascent of Man, Proceedings of the Amer- 



2 Journal of Anatomy and Physiology, 1889, p. 617. 



