GENETICS IN THE SERVICE OF MAN — GLASS 301 



Here again the geneticist may interpose a prediction. The simul- 

 taneous coincidence of two mutations, say to penicillin resistance and 

 to streptomycin resistance, is of an order of probability so low (about 

 10-^*') as to be truly negligible. Start out with two antibiotics to 

 which the infectious agents have never been exposed, and use them 

 together; and use a high enough initial dose to leave no survivors — 

 except, of course, your patient. In this way the antibiotics may con- 

 tinue to serve mankind in the future. But meanwhile, penicillin and 

 streptomycin must be given a rest. 



In recent decades the shade of Malthus has once again risen to 

 trouble us. Clearly, if the general life expectancy doubles, then even 

 without any increase in births at all there are twice as many mouths 

 to feed at any one time as there were before. But there are also more 

 than twice as many adults with unmodified (or but slightly mod- 

 erated) yearning to have children and rear families. The world 

 population has soared, in spite of wars and famines, from one and a 

 half billions of people, a century ago, to two and a half billions today. 

 Fertile land is almost fully occupied. How can we feed another billion 

 people, whom we may expect inevitably to arrive before the slowly 

 dropping birth rate overtakes the still declining death rate? The 

 immediate answer, if there be one, lies in the almost unheralded 

 achievements of geneticists in increasing the food supply. 



On September 28, 1954, there died in Princeton, N. J., a geneticist 

 who never received a Nobel prize or made a fortune. To most Ameri- 

 cans George H. ShuU remains completely unknown. Yet this man, 

 together with a few others who made his theoretical achievement a 

 practical possibility, has brought about a two-thirds increase in the 

 United States yielcl-per-acre of the corn crop with no further require- 

 ment for labor, and has added literally billions of dollars to the income 

 of our nation. 



In fact, a true agricultural revolution, though scarcely recognized, 

 has resulted from the discovery of hybrid corn. During the war years 

 1942-44, in the face of acute shortages of labor and of bad weather, 

 and at a time when the corn acreage of the United States was still only 

 about one-half planted with hybrid corn, the increased yield amounted 

 to approximately 50 percent— a total of 1,800,000,000 bushels worth 

 two billion dollars. Hybrid corn thus in a sense paid for the entire de- 

 velopment of the atomic bomb. Even more important, it was a large 

 factor in preventing this time the aftermath of hunger that followed 

 the end of the first World War ; for the amount of food we were able 

 to ship to the desolated countries of Europe in 1946-47 was more than 

 equaled by the increase in the corn crop attributable to the planting of 

 hybrid corn. The hunger and chaos of eastern Europe in 1918 and 1919 

 furnished communism with the seedbed in which it first rose to politi- 



