SIGNIFICANCE OF THE PILTDOWN DISCOVERY 2S5 



powerful wide ascending ramus are characteristic of all the 

 lower human jaws. And now we are faced with the curious 

 paradox that the Heidelberg mandible possesses a somewhat 

 shallower sigmoid notch and a much wider ascending ramus 

 than the Piltdown jaw. If, therefore, heidelbergensis be descended 

 from the Piltdown race, the ordinary course of evolution was 

 reversed, and the wide ascending ramus of heidelbergensis must 

 be regarded as a secondary acquirement. It would be rash to 

 say that this is an impossibility, but it is certainly a curious 

 conclusion. The family tree constituted on this hypothesis is 

 represented in fig. 3. H. heidelbergensis is here conceived to be 



Fig. 2. — Mandibular ramus from Piltdown superposed on that of Homo 

 heidelbergensis. Two- thirds of the natural size. 



(Reproduced by kind permission from the Quarterly Journal of the Geological Society.) 



a " degenerating " branch, given off from the main stem at a 

 point where the symphysis had become half-human. 



The only further comment that it is necessary to make on 

 this theory is that it is fatal to the conception that heidelbergensis 

 is directly ancestral to neandcrtalensis ; it would be too much to 

 believe that the immensely wide ascending ramus was acquired 

 and then lost again. 



If, however, we abandon the hypothesis that Eoanthropus 

 is directly ancestral to Homo, another explanation of the 

 characters becomes possible. Why, it may be asked, should 

 not heidelbergensis and Eoanthropus be descended from a not 

 distant ancestor which combined the primitive features of each, 



