208 EVOLUTION AND GENETICS 



them and modern man is equivalent to that between Neohthic 

 cultures and modern civihzation with its highly developed arts and 

 complex industries. Cro-Magnon man had a brain apparently 

 adequate for the gradual development of such things, but the 

 difference is evident. Whether modern civilizations represent 

 merely a gradual accumulation of individual experiences and dis- 

 coveries, or in addition to this form of progress an actual increase 

 in mental power it is difficult to say, but it is highly prol^able that 

 the change in mental development which is so well demonstrated 

 by primitive species of man has continued ever since. Although 

 the ancient Greeks were intellectually our equals in so far as we can 

 judge, we must remember that they lived only two thousand years 

 ago, while primitive species of man occurred one hundred thousand 

 years ago according to geological estimates. The first seventy- 

 five thousand years of this period, leading up to the Cro-Magnon 

 race, show evidences of physical change in our ancestors, but only 

 those finishing touches incidental to the attainment of erect pos- 

 ture. In the last twenty-five thousand years there is no evidence 

 of significant physical evolution. Such changes as have come about 

 in man are associated with his intelligence; the development of 

 writing and other facilities for the exchange of ideas, perfection of 

 social organization, the control of food supply and other phases of 

 enviromnent have all contributed to the attainment of our modern 

 state, and none has required any different physical equipment from 

 that of the earliest members of our species. 



In this record, fragmentary though it be, is the story of Homo 

 sapiens. One hundred thousand years ago he did not exist. The 

 mute remains of that period show us that other species did occur, 

 half ape and half man, and that they were succeeded by still others 

 which we can definitely call human, although much more primitive 

 than any known race. By comparing the anatomical structures 

 disclosed by these remains with existing arboreal primates — the 

 great apes, — and man we find reason to believe that all came from 

 a single source, a great arboreal primate in many ways hke the 

 apes of the present. This ancestral species probably existed in 

 Asia, but change of climate and consequent change of flora resulted 

 in his becoming in part terrestrial, and with his adaptation to 

 terrestrial life he developed migratory powers which account for 

 the appearance of fossil remains in Europe, and the later occur- 

 rence of man in all the world. 



