AS THE BIOLOGIST SEES IT 



If this is to be our starting point we ask 

 the paleontologist if he has found a more 

 or less continuous series of human fossils 

 running forward from Pithecanthropus, 

 both as to time and evolutionary develop- 

 ment, up to now. His answer inclines 

 to be, Yes. But, in truth, he has found 

 comparatively few actual fossils or relics 

 of human bodies and very considerable 

 gaps exist in the series both as to 

 gradations in structure and time periods 

 represented. In fact, only one of his 

 undoubted human relics goes back in 

 geologic time to a period approaching 

 that represented by Pithecanthropus. 



This oldest one is known as the " Heidel- 

 berg jaw " because it was found in the 

 Elsenz Valley not far from Heidelberg 

 and is a lower jaw bone with almost all 

 of the teeth in place. Comparing it with 

 the present human jaw it is notable for its 

 unusual size, lack of protruding chin, and 

 great strength and thickness combined 

 with unusual width of the region for the 

 attachment of the muscles used in masti- 

 29 



