Life Sum-Up

It seemed as if the world's geneticists were determined to demonstrate that their youthful science has grown as fast as Drosophila melanogaster, the precocious fruit fly that breeds a new generation every two weeks. There were 1,693 geneticists on hand at The Hague for the Eleventh International Congress of Genetics last week, along with 500 wives and 185 students. They took over 51 hotels, and there was even a babysitting service called "progeny park" to care for the 200 children. Doggedly they listened to 952 speeches, attended six plenary sessions and 25 symposiums, watched 13 films and 41 demonstrations. At the end, one weary visitor sprawled in an overstuffed chair in the lobby of the Kurhaus Hotel and held his hand over his head. "I'm fed up to here," he said, "and I'm sore in the buttocks too. It's just too much."

Significant Progress. Modern genetics is indeed too much for any one man; its rocketing growth has split it into countless specialties. At one extreme are the geneticists who deal with the chemistry of heredity and seldom see a whole living organism. Classical geneticists work in peculiar zoos, surrounded by cages of mice, jars of insects, cultures of yeasts or bacteria. Population geneticists study groups of wild creatures to see whether changes of environment affect hereditary traits. Practical geneticists use the latest tricks of science to breed new plant and animal strains. Geneticists who study humans are the most frustrated; they can seldom slice up their subjects or mate them experimentally.

Molecular genetics, fastest-growing branch of all, uses the newest techniques of biochemistry to explore the extraordinary molecular structures that exist in every living cell and control its growth and reproduction. Hopes are high that this science will soon come to a complete understanding of life's basic chemical processes. But for all the activity that was reported at the Hague congress, there has been no important breakthrough. Progress reports were filled with the promise of discoveries yet to come. A sampling:

> Dr. Ruth Sager of Columbia reported significant success in experiments with the long-known but little-understood genes that are not included in the chromosomes that carry most of the elements of a cell's heredity. When reproductive cells mate and divide, the nonchromosomal genes are portioned out by rules that seem to differ from the Mendelian laws governing the chromosome genes. Until now it has been assumed that the female descendants of a mating transmit all the nonchromosomal genes, but Dr. Sager thinks that male descendants occasionally transmit a few. Further experiments may link nonchromosomal genes with the inherited characteristics of many species.

> Dr. Wolfgang Beerman of West Germany's Max Planck Institute showed pictures of ropy, wormlike chromosomes with strange swellings, and reported on the delicate experiments with which he proved that the swellings are associated with active genes. Geneticists agree that active genes produce RNA (ribonucleic acid) and that RNA produces proteins. Dr. Beerman satisfied himself as to the meaning of the swellings he had photographed through his electron microscope, by finding RNA and protein where theory predicted they should be--right around the lumps on the chromosomes.

> Dr. William L. Russell of Oak Ridge had some unhappy news for the atom-age world. He presented impressive evidence that a dose of radiation stretched over a long period produces more mutation in mammals than the same dose concentrated in a short period. Since nearly all mutations are harmful to unborn generations, this finding makes even moderate amounts of long-lived radioactive fallout seem like a serious threat to man's future.

Band Wagon Effects. As he summed up the massive growth reported at the congress, Dr. Curt Stern of the University of California singled out molecular genetics as the most important new specialty in the science. "Life processes have been broken down to very simple basic reactions," said Dr. Stern. "Now we know what a gene is: namely, DNA (deoxyribonucleic acid), and we know what DNA is. The four substances that make it up are arranged in different combinations like a book written with just four letters."

The four-letter genetic code that carries the information that tells a fertilized cell to develop into a man or a pine tree is now the subject of avid research all over the world. In spite of optimistic announcements, the code has not yet been broken, and no great progress toward breaking it was reported at The Hague.

So intriguing is the research that Dr. Theodosius Dobzhansky of the Rockefeller institute was moved to warn that molecular genetics may be getting too popular. "It is both inevitable and good that the achievements of molecular genetics have gotten so much attention, but it is less good that a bandwagon effect has made some say that molecular work is all there is or should be to genetics."

Dr. Dobzhansky predicted that many new discoveries will soon be made about man's evolution. He does not accept the gloomy doctrine that the human species is headed for degradation because natural selection no longer operates in human society, or that human evolution stopped when civilization appeared. "Both are untrue," he said. "Natural selection is at work when a defective child dies or when a dwarfed man fails to find a mate. A high mortality rate is not necessary for natural selection to operate. The great danger to man is not the suppression of natural selection but what is called the population explosion. Man must regulate his behavior for the benefit of future generations. If he will not take measures to avoid the coming population crisis, he hardly needs to bother about genetics."

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