ORGANIC EVOLUTION 367 



use and indicating the existence of man of less developed 

 skill. These latter implements carry the traces of a tool- 

 making creature back into the Tertiary period. 



Besides the stone implements there are many sketches of 

 extinct animals by prehistoric artists, scratched on bone, 

 ivory, slate, and on the walls of caves. The inference to be 

 drawn from these sketches is that man was alive in central 

 and southwestern Europe when the hairy mammoth and 

 the reindeer occupied the same territory. The crude sketches 

 of palaeolithic man, just referred to, merge by gradations 

 into the more carefully drawn, and sometimes colored 

 sketches, of neolithic man. Those of the Cave of Altamira, 

 in Spain, are very notable products of neolithic artists. They 

 have been described and many of them reproduced in colored 

 illustrations in Cartailhac and Breuil's La Caverne d'Altamira, 

 (1906). They represent the golden period of prehistoric art. 



The range of discovery of fossil human relics gives evidence 

 of a wide geographical distribution of primitive races during 

 the palaeolithic time. Variations in the degree of skill in 

 the manufacture of stone implements, as well as in other 

 particulars, have brought to archaeologists the recognition of 

 different culture periods, which are well exhibited in different 

 parts of France and Central Europe. Not less than six cul- 

 ture periods of palaeolithic man are recognized, indicating 

 that the prehistoric period of human development was far 

 longer than the entire historic period. 



It is, however, to fossil remains of primitive man that we 

 must look for evidences of structural changes that have 

 taken place in the human frame. 



Of all the bony parts the skull is the most interesting for 

 comparison, since its size and configuration indicate in a 

 general way the degree of development of the brain, and, as 

 a consequence, the relative grade of intelligence. 



One of the most famous documents of ancestral history is 



