MAN AND THE BIOLOGICAL WORLD 589 



tested by reference to relevant data. The biologist cannot pretend to 

 more than a layman's knowledge of the social sciences or humanities. 

 They are concerned with inquiries into special and uniquely human 

 phases of man's behavior that lie mostly outside of his competence or 

 concern. He does, however, retain the right to scrutinize the biological 

 assumptions and implications that are inherent in these other points of 

 view in the light of his own body of established fact and principle. Thus 

 he can find no more than unsupported wishful thinking, or at most an 

 appeal to now discredited biological hypotheses, to support belief in any 

 form of biological inheritance of acquired characters. This statement 

 holds not merely for morphological features but also for habits, emotions, 

 attitudes, or any other qualities supposed to be impressed upon the germ 

 plasm by experience or training. 



Here, it seems to us, is the crux of the problem. We owe all of civiliza- 

 tion to the invention and evolution of culture, and nearly all of the 

 humanities, sciences, and arts to cultural inheritance. But it was a product 

 of organic evolution that became capable of inventing and developing 

 culture, and it is an organic germ plasm that must continue a stock 

 capable of utilizing and maintaining it. 



Our ecological ties with the organic world are also often forgotten or 

 ignored. Civilization has given man increasing control over his environ- 

 ment and an ever-expanding power to exploit it, without supplying 

 correspondingly evident indications of the consequences involved. Much 

 that man does he does blindly. He has not freed himself from the "web 

 of life," however much he may have lengthened some of the strands. A 

 great deal of his apparent freedom comes from the social and economic 

 division of labor that tends to conceal the interwoven strands; the city 

 dweller is less conscious of ecological ties than is the farmer. 



We depend upon agriculture to produce the many plants and animals 

 required by man for food and clothing and for much of his shelter and 

 industrial needs. 1 Nearly all of agriculture is applied biology and much 

 of it applied ecology, and however much it may be controlled or modified 

 by social or economic forces, it is still dependent upon the basic relation- 

 ships of organic food chains. The farmer is faced with the problem of soil 

 fertility and finds that this involves the activities of many soil organisms 

 as well as those of his crops. He must also deal with weeds, with insect 

 pests, and with diseases caused by viruses, bacteria, fungi, and animal 

 parasites which are transmitted or harbored by still other animals and 

 plants. Soils and crops, pests and competitors are all affected by the 

 physical environment and its fluctuations, and so perpetuate another 



1 The increasing use of synthetic fibers, plastics, and the like is in large part simply 

 an extension of the role of agriculture, since most of these products use plant tissues 

 as raw materials. 



