8 THE EVOLUTION OF MAN 



quil flowing, and occasionally catch and drown the unwary, 

 as they do to-day, to bury their remains under tons of sedi- 

 ments which are subsequently removed and their contents 

 exposed either by natural or by human agencies. The other 

 more fruitful source is the underground caverns of Europe- 

 abandoned subterranean river beds which are always to be 

 found in limestone countries and which, when opened to the 

 air through the eroding away of overlying materials by rain, 

 frost, and snow, formed an inviting retreat from inclement 

 weather and the assaults of savage beasts. These caverns thus 

 became the place of abode and often of sepulture of prehistoric 

 man, but were evidently not available for his tenancy until com- 

 paratively late in time (Mousterian, see table, page 4). 



Means of determining antiquity. The criteria for establish- 

 ing the antiquity of human remains are three. First, the 

 geological age of the strata wherein the remains lie; secondly, 

 the associated animals or artifacts or both; and third, actual 

 somatological distinctions from existing man. The first must 

 be most carefully weighed, and in general such is the very 

 natural scepticism even among scientists that it is well to have 

 corroborative evidence by unimpeachable witnesses both of the 

 discovery and the exhumation. It is further necessary very 

 carefully to distinguish between natural deposition of remains 

 and intrusive burial, such as is often practiced by mankind, 

 which places the subject among objects which may far ante- 

 date it in time. A scattered skeleton and one overlaid by abso- 

 lutely undisturbed deposits are both good criteria of contem- 

 poraneity, but chance often makes strange bedfellows. Thus 

 the finding by the writer of a glass bottle, bearing all the 

 marks of extremely recent manufacture, beneath the hip bone 

 of an extinct horse in an apparently undisturbed Pleistocene 

 deposit in Texas was a little disconcerting until the looseness 

 of the surrounding sand betrayed a filled-in animal burrow 

 into which the bottle had undoubtedly been thrust. The asso- 



