284 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1953 



of the Equator, and most of them are within 10°. In all of them there 

 is little seasonal change. Aside from these uniformities, they repre- 

 sent a variety of environments, including shady forests, grasslands, 

 deserts, and coast lines. Since we have a good idea what black skin is 

 good for, we can discover no particular reason for it in the forests. 

 Bright equatorial sun is, however, a problem in grasslands, deserts, 

 and on the water. 



Returning to the rest of the animal kingdom, we find that grass- 

 land and desert mammals are generally light or tawny colored (Bux- 

 ton, 1923) . This is true of animals whose skins are protected by hair. 

 A few animals, however, are naked like man, and these are black or 

 dark gray. They include the elephant, rhinoceros, hippopotamus, 

 buffalo, and certain types of pig. These animals reach their peak 

 of numbers and development in the grasslands or desert fringe; ex- 

 cept for the rhino they enter the forest, where they are fewer and less 

 favored. Their color, carried in from the sunlight, is neither an 

 advantage nor a disadvantage in the shade. 



In Africa the blackest Negroes live in the grasslands. In the for- 

 est we find two kinds of people: Pygmies, who are not completely 

 black, and Negroes. The Pygmies hunt, the Negroes farm. The 

 two exchange products. Since the Negroes make the arrowheads 

 and nets with which the Pygmies hunt, the latter would have a hard 

 time living without either these implements or the plantains which 

 the Negroes give them for food. Furthermore, the food plants which 

 the Negroes cultivate are of southeast Asiatic origin, and they could 

 hardly have been introduced later than the first millennium B. C. 

 Since southern India got iron during this same millennium, and the 

 motive which brought people across the Indian Ocean to Africa was 

 a search for iron, it is unlikely that the Negroes entered the forest 

 to live much before the time of Christ. If we look at Melanesia we 

 see again that the forest is poor in game, the principal animal being 

 the pig, escaped from domestication. The pig came in with agri- 

 culture, and neither can have been introduced much before the first 

 millennium B. C. Therefore, the j)resent black-skinned populations 

 of these two tropical forest areas must be historically recent; black 

 skins go with grasslands or deserts and have entered forests in num- 

 bers only with agriculture. In the Belgian Congo the forest Negroes 

 are decreasing in numbers while the Pygmy population remains con- 

 stant. If we look back to the Pleistocene, we see that the glacial ad- 

 vances and retreats in the north were accompanied by a succession 

 of pluvial and interpluvial periods in the Tropics. At least once the 

 Sahara was blooming with grass and flowers, and at other times the 

 forest was reduced to a fraction of its present area. 



Wliy, one may ask, did not black skins develop in the Americas, 

 where land within 10° of the Equator runs along a course of 4,000 



