Page six 



EVOLUTION 



February, 1931 



Man's Day Begins 



By SIR JAMES HOPWOOD JEANS 



A NTHROPOLOGISTS and geologists tell us that man 



/\ 



has existed on earth for something like 300,000 years: 



we must go this far back to meet our ape-like ancestry. Be- 

 tween them and us some 10,000 generations of men have 

 walked the earth, most of whom have probably given some 

 thought, in varying degree, to 

 the significance of their exis- 

 tence and the plan of the uni- 

 verse. 



Of these 10,000 generations 

 of men, the first 9,990 unhesi- 

 tatingly regarded the earth as 

 the center, and terrestrial life as 

 the central fact, of the universe. 

 As was suited to its majesty 

 and dignity as the abode of 

 man, the earth stood still while 

 the celestial sphere spun around 

 it, covering in the earth much 

 as a telescope dome covers in 

 the telescope; and this dome 

 was spangled with stars, which had been thoughtfully added so 

 as not to leave the central earth unilluminated at night. Ten 

 generations at most have been able to view the problem of their 

 existence in anything like its proper astronomical perspective. 



The total age of the earth far exceeds the 300,000 years or 

 so of man's existence. The evidence of geology, and of radio- 

 activity in rocks in particular, shows that it must be some- 

 thing like 2,000,000,000 years, which is several thousand times 

 the age of the human race. Old Mother Earth must regard 

 man as a very recent apparition indeed; he has just appeared 

 to burrow into her, burn her forests, put her waterfalls into 

 pipes, and generally mar the beauty of her features. If Tie has 

 done so much in the first few moments of his existence, she 

 may well wonder what is in store for her in the long future 

 ages in which he is destined to labor on her surface. 



For in all probability the life in front of the human race 

 must enormously exceed the short life behind it. A million. 



Sir James Jeans 



humanity is at the very beginning of its existence — a new born 

 babe, with all the unexplored potentialities of babyhood; and 

 until the last few moments its interest has been centered, abso- 

 lutely and exclusively, on its cradle and feeding bottle. It 

 lias just become conscious of the vast world existing outside 

 itself and its cradle; it is learning to focus its eyes on distant 

 objects, and its awakening brain is beginning to wonder, in 

 a vague, dreamy way, what they are and what purpose they 

 serve. Its interest in this external world is not much developed 

 yet, so that the main part of its faculties is still engrossed with 

 the cradle and feeding bottle, but a little corner of its brain 

 li beginning to wonder. 



Taking a very gloomy view of the future of the human 

 race, let us suppose that it can only expect to survive for 2,000,- ' 

 000,000 years longer, a period about equal to the past age of 

 the earth. Then, regarded as a being destined to live for three- 

 score years and ten, humanity, although it has been born 

 in a house 70 years old, is itself only 3 days old. But only in 

 the last few minutes has it become conscious that the whole 

 world does not center round its cradle and its trappings, and 

 only in the last few ticks of the clock has any adequate concep- 

 tion of the size of the external world dawned upon it. 



For our clock does not tick seconds, but years; its minutes 

 are the lives of men. A minute and a half ago the distance of 

 a star was first measured and provided a measuring rod for the 

 universe. A quarter of a minute ago, Hertzsprung and Shap- 

 ley showed how the peculiar stars known as Cepheid variables 

 provide a longer measuring rod, and taught us to think in dis- 

 tances so great that light takes hundreds of thousands of 

 years to traverse them. With the last tick of the clock, 

 Hubble, using the same measuring rod, has found that the 

 most remote objects visible in the biggest telescope on earth 

 are so distant that light, traveling 186,000 miles a second, 

 takes about 140 million years to come from them to us. * * * 



Our * * * infant, mankind, has made the great discovery of 

 the existence of the outer world, has formed some concep- 

 tion of his size, and adjusted his ideas, not by a process of slow 

 revelation, but by a brain flash of the last few seconds. In his 



million years hence, so far as we can foresee, the sun will prob- mature years and his staid old age he is no doubt destined to 

 ably still be much as now, and the earth will be revolving round make many sensational discoveries, but he can never again 



it much as now. The year will be a little 

 longer, and the climate quite a lot colder, while 

 the rich accumulated stores of coal, oil, and 

 forest will have long been burned up; but there 

 is no reason why our descendents should not 

 still people the earth. Perhaps it may be un- 

 able to support so large a population as now, 

 and perhaps fewer will desire to live on it. On 

 the other hand, mankind, being three million 

 times as old as now, may — if the conjecture 

 does not distress our pessimists too much — be 

 three million times as wise. 



Looked at on the astronomical time scale, 



A high promise for fu- 

 ture human achievement 

 is here suggested by an 



From Annual Report of Smithsonian Institution, 

 1929, pp. 165-8. 



live through the immortal moments at which 

 he first grasped the immensity of the outer 

 world. We only live through a few ticks of 

 his clock. * * * The wonderful thing is that 

 fate has selected for us what is, perhaps, in 



eminent physicist. In the some ways the most sensational moment of all 



next issue, in an article on the life of our race. 



"WHAT IS MAN BE- 



COMING?", Ales Hrd- 



licka will discuss Man's 



probable physical future 



front the viewpoint of an 



anth ropologist. 



.SCIENCE LEAGUE OF AMERICA 



Champions Freedom of Science Teach- 

 ing. Every evolutionist invited to join. 

 Particulars from Maynard Shipley, Pres. 

 830 Market Street, San Francisco. 



