252 LIFE: ITS NATURE AND ORIGIN 



structural and physiological changes that underlie the happenings 

 at macro-levels. How complex these happenings may be, can be 

 seen, for example, from the papers of Professor Sewall Wright, 11 

 from T. Dobzhansky's book "Genetics and the Origin of Species" 

 (1941) and from G. G. Simpson's book "Tempo and* Mode in 

 Evolution" (1944). 



We have no space here to enter these interesting fields of 

 ecology and paleontology which deal with a very real phenomenon 

 — natural selection. But as Sir Wm. Bateson remarked, its func- 

 tion is to select, preserving beneficial and destroying harmful 

 changes, and remaining indifferent to neutral ones. Bateson also 

 stated: 12 We cannot see how the differentiation into species came 

 about. Variation of many kinds, often considerable, we daily 

 witness, but no origin of species. But that particular and essential 

 bit of the theory which is concerned with the origin and nature of 

 species remains utterly mysterious. The claims of natural selec- 

 tion as the chief factor in the determination of species have con- 

 sequently been discredited. Our doubts are not as to the reality 

 or truth of evolution, but as to the origin of species, a technical, 

 almost domestic problem." 13 Bateson became a geneticist "in the 

 conviction that there at least must evolutionary wisdom be found." 

 Actually, the basic problem may be put thus: By what material 

 mechanism are heritable changes in bionts produced and trans- 

 mitted?" 



Our answer to this question is simply expressed: The primal 

 cause of evolution is a heritable change in existing and potential* 

 biocatalysts, leading to heritable changes in form, function and 

 behavior, and therefore to heritable changes in reaction to and 

 interaction with the surrounding conditions of life. Some of these 

 conditions affect the living unit as an individual, for example, 

 ability to secure and survive on existing food, and to accomplish 

 successful mating. Other conditions affect principally groups or 

 populations, e.g., the existence of adequate food and group com- 

 petition for it, geographical factors involving isolation, and 

 ecological factors involving attrition between groups (red squirrels 

 vs. grey squirrels, carnivores vs. herbivores). Another set of condi- 

 tions upon which living things depend involves the presence in air, 

 water or soil of many essential substances and the absence of 



* This refers to the transmission of new, or increased amounts of, specific mole- 

 cules which may in later development modify existing catalysts or help form new 

 catalysts. 



