2 8o SCIENCE PROGRESS 



talers are not certainly known to extend back farther than the 

 Acheulean Age, but behind them we are acquainted with the 

 existence of three still more ancient species. Unfortunately 

 each of these is only known from a single discovery, as follows : 

 the Ape-man of Java, Pithecanthropus eredus (Dubois); the 

 Heidelberg man, Homo heidelbergensis (Schcetensack) ; and the 

 Piltdown Race, Eoanthropus dawsoni. 



The Javan specimen is very distinct from Eoanthropus, from 

 the Neandertalers, and still more, of course, from man — so 

 distinct indeed that the creature may even be nearer to the 

 Simiidce than to the Hominidce. As for H. heidelbergensis, only 

 one lower jaw of the species has been discovered, so that 

 it is impossible to speak with any confidence! of the characters 

 of this type. The jaw has indeed been variously described 

 as akin to Pithecanthropus (by Duckworth), and as the first and 

 most primitive of the Neandertalers (by Keith). Only a small 

 fragment 1 of the Javan animal's jaw was found, but so far as 

 it is possible to judge it seems probable that heidelbergensis 

 claimed closer affinity with the Neandertalers than with Pithecan- 

 thropus. The Heidelberg mandible is not very unlike the various 

 jaws of neandertalensis that have been unearthed, but it would, 

 of course, be unsafe to assume from this that the complete 

 skeletons of the two types were also similar, and it is not 

 even possible to be absolutely certain that this most ancient 

 mandible was associated with the very receding forehead which 

 is so characteristic alike of the Neandertalers and of Pithecan- 

 thropus. 



It is, however, when we compare the well-preserved Heidel- 

 berg jaw with the right half of a mandible that was found with 

 the skull at Piltdown that we find ourselves face to face with 

 certain most remarkable facts. These two jaws are utterly 

 unlike one another. And in various respects each diverges 

 more from the other than either differs from a human jaw. 

 At first sight this is perhaps not very surprising, since it might 

 have been foreseen that in the last stages of the upward evolution 

 of the Primates towards humanity, as in the earlier stages, 

 side branches would have been thrown off. When, however, 

 the differences between the extinct species are examined in 

 close detail, the problem becomes puzzling in the extreme. 

 The inter-relationships of the several kinds in the family tree 

 1 The fragment has not yet been described. 



