2 74 THE ORIGIN AND EVOLUTION OF LIFE 



Undoubtedly the most promising field for future palaeon- 

 tological research and discovery is in Asia. The links in the 

 series of mammals — especially in the line known as the Pri- 

 mates leading into the ancestors of man, namely, the Lemurs, 

 Monkeys, and Apes — are probably destined to be found in 

 this still very imperfectly explored continent, for it is indicated 

 by much evidence that the still unexplored region of northern 

 Asia was a great centre of animal population and of adaptive 

 radiation into Europe on the west and into North America 

 on the northeast. Ancient vertebrate fossils from this vast 

 region are as yet absolutely unknown, but will doubtless be 

 discovered, and it is here that the Eocene, and perhaps the 

 Oligocene ancestors of man are likely to be unearthed, that 

 is, in deposits of the first half of the Tertiary Period. Fos- 

 sil records of the descent of man during the second half of 

 the Tertiary also, namely, from the Oligocene Epoch to the 

 close of the Pliocene time, we believe may be discovered in 

 Asia, most probably in the region lying south of the Hima- 

 layas. 



This subject of prehuman ancestry and evolution is re- 

 served for the concluding series of Hale Lectures, but in our 

 search for suggestions as to the causes of evolution, especially 

 along the lines of internal physicochemical factors and the 

 doctrine of energy, man himself is proving to be one of the 

 most helpful of all mammals because chemically, physically, 

 and experimentally man is the best known of all organisms at 

 the present time. 



