ADVANCE OF ANTHROPOLOGY. 481 



(e) After the neolithic ages, but still prehistoric, 

 come the metal ages, the copper age (" crowded 

 out almost everywhere in the Old World "), the 

 bronze age, and the iron age (the two last sometimes 

 coalescing). 



Even a moderate estimate would grant 10,000 

 years to the historical period in Egypt and Mesopo- 

 tamia, 20,000 to the metal ages, 70,000 to the neo- 

 lithic period, and behind that total of 100,000 years 

 (since the close of the last ice age) there stretches 

 the vista of the palaeolithic, and even then man had a 

 long history behind him. 



The interest of these figures is merely to sug- 

 gest that there was plenty of time for much evolution. 

 " Many things may happen in a long time," and the 

 acknowledged difficulty of interpreting human evo- 

 lution must not be exaggerated by forgetting that he 

 is not so young as he looks. 



Although the date of man's origin remains quite 

 uncertain, the work of the nineteenth century has 

 secured this result at least that man is of great an- 

 tiquity. It is a moderate estimate to suggest half 

 a million years. 



THE HUMAN SPECIES. 



The literature on the subject of the human 

 species is enormous, and when we seek for the result, 

 it seems preposterously small. Is there one species 

 of man or are there several ? It seems for the most 

 part a verbal discussion, depending on the definition 

 of the term species. 



The Linnaean conception of species, from which 

 Biology has not even yet quite freed itself, was that 



