Science: Man's Hope

"How large," asks Dr. Harrison Brown, "can the human population become? To what extent, if any, does man still possess the power to determine his destiny?"

Many books by neo-Malthusian prophets of doom have attempted to answer these questions. Most of them have been superficial, emphasizing minor and easily corrected threats to man's food supply, such as erosion of farmlands. Others have ignored the enormous possibilities of man's scientific techniques. Brown's The Challenge of Man's Future (Viking Press; $3-75) is in a different class. Geochemist Brown of CalTech is thoroughly at home in the tangle of sciences that bear on man's future on earth. He is also at home in history and sociology, and unlike most scientists, he is a good writer. The result is a readable and frightening book.

In 1798, the gloomy Rev. Thomas Robert Malthus made his famed pronouncement that human populations, unless checked by enemies or disasters, tend to increase until finally checked by hunger. Malthus foresaw only catastrophe ahead. In fact he predicted that within 50 years Britain would be in disaster because of overpopulation. Malthus was wrong in his prediction. Around him in England, as he was writing, his countrymen were developing the machine culture that permitted a new cycle of human expansion. But many scientists are convinced that in his broader sense Malthus may still be proved right. Today's neo-Malthusians maintain that catastrophe has only been postponed, that overpopulation, starvation and misery will yet catch up with industrial man.

Ancient Pattern. Can man, who dominates other life, do nothing to keep his species in equilibrium with the earth? With great clarity, Dr. Brown describes the interrelated factors that have affected populations in the past. It is not a happy picture. Except for brief "Golden Age" respites, man has suffered biologically, like any other animal. His women have borne so many children that not all could be fed. They have died in infancy, or lived brief, sickly, hungry lives. Each period of abundance has brought a jump in population, followed by famine and pestilence.

This is still the pattern, says Brown, for that part of the human race which is still in the agricultural stage. Only the industrial one-third of the world's population escapes the Malthusian trap. Dr. Brown is not sure that it will escape for long.

He does not believe, however, that the final reckoning will come because of material factors. He concedes that there is some limit, far in the future, to the number of humans that the earth can support, but many bugbears dear to the neo-Mathusians he dismisses as of little moment. Industrial man will need, and can get, ever-increasing supplies of energy. Coal and oil may burn out in a relatively short time, but sunlight and atomic energy can take their place. He points out that one ton of ordinary granite, from which the continents are largely made, contains as much energy in the form of uranium and thorium as 50 tons of coal. He thinks this energy can be drawn on when needed.