302 ESSENTIALS OF BIOLOGY 



IV. THE EVOLUTIONARY CAREER 



100. ON THE ORIGIN OF LIFE 



It was a consequence of the materialistic philosophy of the 

 last century that the " origin of life " was regarded as a problem 

 to be solved by science. It was generally held that when the 

 materials of the earth's crust had solidified and cooled so far as 

 to allow of the condensation of the water of the atmosphere 

 living things came into existence. It was thought that some of 

 the materials of the lithosphere, hydrosphere and atmosphere 

 became energized by solar radiation and then reacted with each 

 other so that very simple organisms came into existence. It is, 

 of course, certain that there was a phase of earth-history when 

 living, protoplasmic things could not exist. But there is no 

 plausible hypothesis as to the ways in which water, CO 2, inorganic 

 nitrogenous and other mineral substances reacted on each other, 

 and of themselves, so as to '' synthesize living matter " and the 

 arguments of Section I of this chapter will show how very unlikely, 

 or improbable, it was that such syntheses did actually occur. 

 At all events, no results of modern physiology have even tended 

 to throw light on the problem. 



And, of course, it may be the case that the problem is only 

 a pseudo-one and that it is just as foolish to inquire into the origin 

 of life as it would be to ask what w^as the origin of the universal 

 tendency to entropy-increase. We have no doubt that the 

 distinction, or degree of difference, between living and lifeless 

 things is a problem for physics. And we have no confidence that 

 the basal conceptions of physics have been established. That 

 being so, it is futile further to continue this discussion. From 

 the point of view of mathematical physics all that we can say 

 about the origin of a living organism is that it must have been 

 an ejiormously improbable occurrence. 



101. ON THE EARLIEST FORMS OF LIVING THINGS 



It is certain that conditions favourable for living things, as we 

 know them, were present on the earth at least 1,000 millions of 

 years ago. It is also certain that the oldest fossil remains are 

 found in rocks that are little over 500 millions of years in age. 

 Doubtless there w^ere living things on the earth throughout all 



