Genetic Death

If atom bombs do not do the job first, the human race may destroy itself just as effectively in a slower, subtler way. Last week, in the Bulletin of the Atomic Scientists, Nobel-Biologist Hermann J. Muller of Indiana University warned that even the peaceful use of atomic energy may kill off the human species by loading its germ plasm with too many "mutated" genes.

Biological Time Bombs. Each reproductive cell (of plants, animals or men) contains submicroscopic particles (genes) which pass hereditary characteristics from one generation to another. When a gene is altered or damaged, a "mutation" or sudden change results. If the mutation is "dominant," it affects the next generation.

Usually it is "recessive." The altered recessive gene lurks in the germ plasm for generations, like an infinitesimal time bomb, waiting to combine with a similar gene in a cell of the opposite sex. Then, reinforced, it makes its influence felt. Theoretically, a mutation may be beneficial, but most of them are not. Some mutations kill the developing embryo. Some deform or otherwise handicap the young organism.

There are already many mutations stored away in the human species. They were caused by natural agents, such as cosmic rays striking through the sex organs. But man-made agents can cause mutations faster. Last year, Professor Muller won a Nobel prize for proving that X rays beamed through fruit flies can breed a crop of monstrosities (TIME, Nov.11).

Fruit-fly generations are short: even recessive mutations show up fairly quickly. Human mutations may not do their work for thousands of years. But, says Dr. Muller, "finally they must cause the dying out of one of the descendent individuals that carries the harmful mutation, either through his direct death ... or through his failing to reproduce--in either case his 'genetic death.' "

Delayed Peril. Dr. Muller has often said that physicians should go easy with X rays, to avoid "genetic deaths." Far more dangerous, obviously, is the use of atomic energy, which gives off floods of X rays (gamma rays). "When an atomic bomb . . . kills 100,000 people directly," Dr. Muller says, "enough mutations may have been implanted in the survivors . . . to cause at least as many genetic deaths . . . dispersed throughout the population over . . . thousands of years."

Not only bombs are genetically perilous. "Undoubtedly," says Dr. Muller, "the peacetime uses of atomic energy are coming, if civilization survives at all. But . . . due precautions must be taken against possible mutational effects. . . . With [greater] use of atomic power . . . the problem of disposing of the radioactive byproducts . . . becomes more and more general. . . . The simple lead screens which suffice to protect people's reproductive organs from X rays are quite inadequate. . . . The immediate effects of small exposures may be quite invisible, and the mutational effects are so remote that there will be a strong temptation ... to disregard them. Yet these tiny effects, as regards mutation, are cumulative over an indefinite period. . . . Exposure to the radiation . . . repeated generation after generation . . . could in time succeed in destroying the human gene system beyond recovery."

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