The Expansion of Evolutionary Concepts 5 



hypothetical reasoning, the extrapolation of past evolutionary events 

 cannot be proven in the mathematical sense of x + x = 2x but can 

 be judged only in terms of statistical probability, that is, on the 

 probability that the data on the point in question support one 

 answer rather than another. 



The second simple fact concerning the difficulty of investigating 

 evolution is that it is difficult to investigate life. The units of living 

 matter are minute, yet each is composed of an unbelievably large 

 number of atoms and molecules arranged in a fantastically intricate, 

 yet orderly, architecture. Living matter is a curious type of self- 

 replicating machine that must keep running continuously; it can- 

 not stop and still be alive. So delicate is the balance between life 

 and death in this living machine that frequently probing experi- 

 ments destroy it, and the results are found to have dealt not with 

 life itself but with a bit of mutilated corpse. Consequently, not only 

 do we know relatively little about life, but much that we think we 

 know may prove to be erroneous. In the use of whole organisms for 

 experiment or observation, equal difficulties arise in manipulation 

 of the organism and in planning experiments so that of a surety all 

 unwanted variables are excluded. Investigators exhibit remarkable 

 ingenuity in surmounting these difficulties. 



In evolutionary studies to date, it seems that, when discovered, 

 the answer to one question leads directly to another question. In 

 effect, the more that is discovered about any given process of 

 evolution, the farther back one must go into the history of that 

 process to find its basic causes. It is becoming evident that all the 

 happenings from the beginning of the cosmos to the present time 

 are in reality changes in the organization of matter, changes peculiar 

 in this respect, that the effects of one process become the cause of 

 the next. For example, as investigators probe deeper into the mecha- 

 nisms and probable origin of life, they have become more and more 

 aware that life arose because of conditions and circumstances exist- 

 ing a long time ago in the pre-biological world of the earth. Cer- 

 tainly, primeval life could only contain the particular kinds of 

 elements which occurred on the earth at that time and could use 

 only the sources of energy then available. After life formed, it 

 could not evolve beyond the limits imposed by conditions on the 

 earth, and frequently the course of evolution was modified or 

 channelled by the dynamics of the earth. Concurrently, life itself 

 produced physical and chemical changes in the earth and its oceans 

 and atmosphere. Thus, to understand life more fully, we are con- 

 fronted with the necessity of knowing more about the earth itself, 



