connection between events, then facts are of no consequence. And for that 

 matter, the question itself has Uttle meaning. But if we assume that there are 

 relationships among events, and that we can unravel them, then we can begin 

 to use the facts to solve the great mystery^ — at least in part. 



Assuming thajt there is order in the universe, we attempt to interpret the 

 past by what we can see in the present. What is the connection between plants 

 and animals living today and those that lived last year, a hundred years ago, a 

 thousand years ago, or before people made records? From the bones in grave- 

 yards, from the shells in abandoned camp sites of primitive people, from the 

 carvings on ancient temples and paintings in ancient caves, from bones dug 

 out here and there the world over, we make up our answers. There must have 

 been elephants where Paris now stands. And there must have been horses and 

 camels in America long before there were any white men — or any Indians 

 either. The predecessors of those elephants and of those horses must have been 

 different. Were those different animals also the ancestors of the ones we see 

 today? And did water animals once dwell where now we see the Alps? 



Such guesses are logical. But are they plausible? To answer that we seek 

 other facts. How do mountains originate? How are layers of shale and lime- 

 stone actually formed? How are mountains worn away? What makes the 

 sea salt? How long does it take a river to remove a million tons of earth from 

 the middle of a continent? How fast does sediment build up the ocean bottom? 



The most important facts about the origin of life-forms have been dis- 

 covered since the beginning of the century, although there were good guesses 

 and preliminary scouting and experimenting before. Species do actually arise 

 from ancestors that were different. It is not necessary to "believe" that the an- 

 cestors of present-day life might have been different. It is almost impossible 

 to believe otherwise if one faces the facts — unless one dislikes the messenger's 

 voice. The facts of heredity, the facts of classification, the facts of develop- 

 ment, the facts dug out of the earth's crust and ocean-beds build up an 

 unassailable case for the descent of species from earlier forms, with modifica- 

 tion. Incidentally, these facts enable us to produce "artificial" species. 



We can do little more than speculate as to the origin of the first living 

 beings. But today speculating on such problems is considered futile unless it 

 suggests theories that we can test experimentally. We are far from making 

 life or from knowing how it came to be. We cannot even define life except as 

 a process, a changing — not as a thing. There is a vast difference between 

 "living matter" and chemical compounds as we know them in the laboratory. 

 Viruses, ferments, vague and almost formless bits suggesting minute bacteria, 

 seem in some ways to fall between the two. Life is certainly not something 

 by itself. It is a process of change inside organisms and also outside them, in 

 the surrounding world — which includes other organisms as well. It is a way 

 stuff behaves, under certain conditions, when it gets started. 



524 



