RELATIVE GROWTH AND GENETICS 



233 



tions of the limbs, e.g. in human pygmies, may probably be 

 accounted for, wholly or in large part, along these lines. 



Similarly, the general sexual differences in limb-proportions 

 in man, women usually having relatively short arms, and 

 relatively shorter legs, with in either case the distal portion 

 of the limb short relatively to the proximal portion (see e.g. 

 Hooton, 1931, p. 255) may also be due to altered time-relations 

 of relative growth. The curves given by Davenport (1926) 



Fig. 10 1. — Body-build in Human Beings. View of a solid model, illuminated 

 from the top of the page, showing distribution of relative chest-girth in 



man from birth to 20 years. 



Ordinates, relative chest-girth (chest girth as a percentage of stature). Abscissae, age in years. 

 The mean relative chest-girth diminishes to about 15 years, then rises again. There are several 

 well-marked modes for relative chest-girth which persist throughout, indicating the presence of 

 distinct genetic types. 



give strong confirmation to this view. See also Wallis (1932) 

 who finds, as is to be expected on the basis of the ideas set 

 forth in this volume, that relative limb-size in boys and girls 

 is more strongly correlated with absolute height than with age. 

 If the main principles involved would appear to be compara- 

 tively simple, the detailed complexity which may occur in 

 certain cases can be realized by reference to the problem of 

 the size of the eye and its two lobes in various members of 



