220 THE ABORIGINES OF POKTO RICO [eth. ann. 25 



can be detected at present on several islands, showing that the config- 

 unition of this region is changing. The evidences we have of man's 

 great antiquity on the North American continent are not decisive, but 

 conclusive studies are yet to be made also in the very localities on the 

 American continent, where man has probably lived the longest — the 

 tropical parts of South America. We can not satisfactorily estimate 

 how long the human race has been in the New World until careful 

 investigations have been made as to the age of his remains found in 

 the caves of Brazil, Venezuela, and the Antilles. Those who have 

 investigated the subject claim great age for the remains of man in 

 these regions. Climatic conditions, such as existed for instance in the 

 glacial period, may have rendered the greater part of North America 

 unfit for human occupation, but man may have lived in the West Indies 

 when the whole northern part of North America was uninhabited and 

 the Antilles were continuous land from north to south. 



