Prevalence of People (1969)

PREVALENCE OF PEOPLE* ROY O. GREEP\ It is a principle ofnature that no species can multiply indefinitely without hindrance, and Homo sapiens is on a collision course with disaster. That man is becoming more numerous is common knowledge. Population pressure is feltinmany aspects ofour daily lives. We feel it in morning traffic, in housing, in pollution ofour air and water, in the destruction of natural beauty, and in the gradual erosion ofindividual freedom and loss ofprivacy. From the air, likewise, one sees the ugly, cancerous growth of urban sprawl with metastases extending into fresh cuts of the bulldozer. Our large metropolitan areas are overcrowded and rotting at the core with festering slums and ghettos. Yet, population growth is one of the most ignored ofthe major problems facing the peoples ofthe world, including the United States, today. We may occasionally glance at an article in the Sunday paper about the population explosion and what the future has in store. The figures are astronomical, impersonal, and not readily translated into reality. Never before in all the vast range ofman's history have excessive numbers been a serious threat to his species. In earlier days when the famous Four Horsemen of the Apocalypse—war, pestilence, famine, and death—strode the land, man was not troubled by an undue increase innumbers. Unhappily, theprospects, even for our time, are beyond thepowers ofthe imagination to conceive. Man is a creature of nature, and nature has her own harsh system of keeping the population ofanimal species in check. Most wild species are held in check by food supply, disease, and prédation, and also, as recently discovered, by loss offertility when overcrowding occurs. Some species, such as the jackrabbit, muskrat, deer, and lemming, go through cyclic changes in population density. They die offin great numbers at regular * This is a modified version ofa paper which appeared in the HarvardAlumni Bulklin. Publication costs were kindly contributed to Perspectives by E. R Squibb & Sons. t Department of Anatomy, Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115. 332 Roy O. Greep · Prevalence ofPeople Perspectives in Biology and Medicine · Spring i960 intervals and then proceed to replenish their stock. Lemmings relieve their population pressure every four years, and, contrary to popular belief, they do not migrate to the sea but simply move into an unfavorable climate and die. These population crashes are now known to be due to the psychophysiological trauma ofovercrowding—sometimes referred to as "pathological togetherness." Not only is the present pace of human population growth unprecedented , but, more alarmingly, it is accelerating. In order to get a better appreciation ofwhat is afoot, it will be helpful to glance quickly at how the human species has faired in absolute numbers over the long reaches of history. At the beginning of the Christian era, or some 10,000 years from the dawn ofhuman civilization, man had reached a total population of250,000,000; 1,500 years later he had only reached the half-billion mark. But from there on he has been doing better. He made it to I billion in 1840, 2 billion in 1930, and 3 billion in 1961. We are now working on the fourth billion at the rate of70,000,000 per year, or a city of 190,000 persons every day, seven days aweek. The earlyfigures are informed estimates and may be offby a considerable margin, but that makes little difference. The important point is that for the modern era—or from about 1800, when census taking became a common practice—the figures involve very little, ifany, guesswork as to what has been happening. There are two favorite means of measuring the rate of population growth and ofdetermining trends: one is by the annualpercentage increase, and the other is by the number of years required for a doubling of the population. They are, ofcourse, related. The annual percentage increase expresses the difference between the number ofbirths and the number of deaths. For example, ifthe birth rate were thirty-five per thousand and the death rate twenty-five, then the difference is ten per thousand or, as generally expressed, 1 per centannual increase. Atayearly growthrate of1 per cent it will take not 100 years to double...