THE HUMAN SPECIES 513 



surface are its chief manifestations. Skin color depends upon the number of pig- 

 ment cells present in the skin. Pigment cells are always present but may be so 

 few that the skin appears white, so numerous that the skin is brownish black, or 

 any shade between. Hair color results from varying amounts of two pigments, 

 one reddish and the other the same brown-black that appears in the skin. Eye 

 color is more complex but depends in part on the amount of brown-black pigment 

 present. In blue eyes this pigment is lacking. Head form furnishes several usable 

 traits, among them the height of the dome, the slant of the face, the breadth 

 across the cheek bones, the prominence of the brow ridges, and especially the 

 cephalic index, or ratio of breadth to length of the cranium. Heads are long when 

 the ratio is less than 0.75, medium when it is 0.75 to 0.80, and broad when it is 

 over 0.80. Actually the average for mankind is close to 0.79, and often only two 

 categories are distinguished — long when the ratio is less than this figure, and 

 broad or round when it is more. Many other traits are also taken into account, 

 among them the shape of the nose (Fig. 22.3), lips, eyelid folds (Fig. 31.4), and 

 external ear, the proportions of the jaws and palate, and the characteristics of 

 the teeth. Stature and body build must be used with caution because of their 

 responsiveness to differences in nutrition. 



Older and newer traits. With regard to any trait, we can often distinguish 

 between an older, more primitive condition and a newer, more advanced condi- 

 tion. We may designate these respectively as generalized and specialized. To cite 

 some examples, with the generalized condition in each case given first, we have 

 heavy vs. reduced brow ridges, large protruding vs. small straight face, receding 

 vs. prominent chin, broad and low-bridged vs. narrow and high-bridged nose, 

 normal vs. shovel-shaped incisor teeth, five-cusped vs. four-cusped molar teeth, 

 low-domed vs. high-domed skull, long and narrow vs. short and broad skull, 

 abundant vs. scanty hair, straight vs. wavy or curly or woolly or kinky hair, and 

 probably brown vs. either white or blackish skin. In each case the test is degree of 

 resemblance to the ancestral condition as found among fossil men or among the 

 higher living anthropoids. No subspecies or race of man has a monopoly on old 

 or new traits, though the Australoids have more of the former than any other 

 group. 



THE RACES OF MAN 



When one compares recent systems of race classification, his first 

 impression is that they differ greatly. Thus Hooton (1947) defines 20 

 "subraces" in 3 "primary races" and a category of "composites"; 

 Kroeber (1948) lists 14 races under 3 "primary stocks" and a group of 

 "doubtfuls"; Krogman (1948) divides man into 3 or possibly 4 "sub- 

 species" each with various races; Howells (1949) treats about 13 races and 

 many lesser groups and mixtures under 4 major divisions; Coon, Gam and 

 Birdsell (1950) recognize 30 human races as subdivisions of 6 "putative 

 stocks"; and Boyd (1950) is content with 6 races, 1 of which survives as 

 a mere remnant. 



Closer inspection of these classifications, however, shows that the 

 differences between them are more apparent than real and that the same 



