642 



ORGANIC EVOLUTION 



Fiq 25-17 By studying freezing-point depressions (indicated here by ihe numbers) of modern seas and '^e blood of 

 'modern anLals and compa 'ng these with indirect evidence for similar data on anc.en. seas and pr.m.t.ve an- 

 mals, it has been possible to trace animals from the sea onto land. For an explanation see text. 



water to land as determined by other 

 studies. All physiological and biochemical 

 data that have been carefully examined 

 supplement those gathered from other dis- 

 ciplines supporting the theory of evolu- 

 tion. Many other substances present in the 

 bodies of higher animals can be traced to 

 their origins in lower forms, which certainly 

 lends support to the thesis that they have 

 a common origin. It would be difficult to 

 explain them any other way. 



From animal distribution 



There are many places on the earth's 

 surface that are idyllic spots for a large 

 variety of animals, yet none occupies these 

 regions. If animals were created simul- 

 taneously, why are not all of the favorable 



places in the world occupied by those that 

 are fitted for such environments? Only in 

 the light of evolution, both physical and 

 organic, can a satisfactory answer be found 

 for this situation. 



Interplay of two evolutions, one of the 

 earth itself, the other of the animals and 

 plants upon it, has taken place. The young 

 earth changed violently at first, gradually 

 quieting down as it grew older and finally 

 becoming inhabited with living things. 

 Once life originated and new species began 

 to appear, any subsequent alterations of 

 the earth's surface or climate drastically 

 affected the life then existing. Such changes 

 as the rise and fall of large areas of the 

 earth's surface and sharp climatic shifts 

 were most important in deteraiining not 



