POPULATION GROWTH OVERPOPULATION UNDERPOPULATION TERMS Demographic equation Population momentum J-shaped curve S-shaped curve Homeostatic plateau Carrying capacity Malthusian and neo-Malthusian Population policies: Eugenic, pro-natalist, expansive What causes growth? Growth is due not only to natural population increase, but to immigration and emigration, and changes in life expectancy. For example, in the United States the NIR is .6%, with a doubling time of 117. But when immigration is added, the overall growth rate is 1.2% with a doubling time of only 58 years. The demographic equation This is a formula for determining the overall growth rate of a REGION: It takes into account the natural change (difference between births and deaths) and the net migration amounts (difference between in- migration and out-migration). Demographic Equations Growth Rate (%) = Birth Rate – Death Rate +/– Migration ON A GLOBAL SCALE, ALL POPULATION CHANGE IS DUE TO NATURAL CHANGE! Population momentum Even if fertility rates decline, the numbers of births can continue to grow. If the cohorts at the bottom of the population pyramid are large, those young people will eventually enter their reproductive years, and will in turn have children. Population Momentum What is doubling time? The amount of time it takes for a population to double. This will of course vary as the TFR varies: an increase in the TFR causes the doubling time to drop dramatically. Examples Limits on population growth According to Malthus, population would increase geometrically while food production could only increase arithmetically. Thus war, famine and disease act as checks on population growth. However………… People are continually replaced. For everyone who dies, many more are born: There were about 70 million deaths in all of humankind's wars over the past 300 , years, which still is less than a 1-year replacement period at present NIR. Exponential growth (J-shaped curve)-- Assumes no limitations on resources. . S-shaped curve The top of the S-curve represents a population size which is supportable by the resource base. When population is equivalent to the carrying capacity of a certain area, it is said to have reached a homeostatic plateau. Homeostatic populations Population Growth Exponential vs. Logistical Growth What is overpopulation? A value judgment which reflects a conviction that an environment or territory is not able to adequately support its present population. *It is not only due to numbers but also to carrying capacity: maximum number of individuals an area can support on a sustained basis given the prevailing technology. Carrying capacity is related to the level of economic development: how the population is able to make use of the land. MDC’s, with better resource usage and access to imported food, do not have the same experience with population density as LDC’s. Neo-Malthusians Policy makers began to realize they needed to not only lower death rates, but also foster a decrease in birth rates: this came to be known as Neo-Malthusianism. Programs are aimed to limit population through birth control and family planning. Types of government policies Expansive population policies: Communist countries such as Russia and China, as well as the Nazis, encouraged large families in the past. Now some European countries are doing so again, with tax incentives and other measures, to counter their aging populations. Pro- natalist policies Policies which are intended to encourage the population to increase the birth rate; I.e. increase the population. These types of policies would be implemented in Stage 4 countries where the birth rate has been declining. E.g.: Russian Day of Conception •An opposite approach is a eugenic population policy, such as the way the Nazis treated „mental defectives‟, the Jews and others. Some have accused Japan of this type of policy due its discrimination against non-Japanese, with tax incentives and the allocation of its resources. Lastly, there are restrictive policies, such as are now pursued in India and China, and which range from the tolerance of birth control on the low end of restriction to the prohibition of large families or the one-child policy of China. The “Oops” Factor Sometimes population practices have unforeseen consequences. Sweden promoted increasing the CBR, only to have to deal with an increase of children in one small cohort, and then the subsequent decrease as their economy faltered. Now they are talking about having sexy TV programs on at night to…………. Some contradictions in population policies: Or—what about the friction of distance? Is it always relevant? Despite the Roman Catholic Church’s opposition to birth control, the countries nearest the Vatican have the lowest CBR. Meanwhile—the Philippines, very far from Rome, are experiencing growth of 2.2%. Church and state have fought over the issue, and the church appears to be winning. An example in Islam: The opposite effect In Saudi Arabia where Mecca is located, there is 3% growth rate, one of the world’s fastest rates. Yet in Indonesia, the growth rate is only 1.6%: Muslim leaders objected to birth control, but the government was able to negate their influence and institute a family planning program. Was Malthus right? Some feel that the Earth’s capacity is far greater than we think. Others argue that it is like a spaceship with finite capacities, citing problems like air pollution, malnutrition, starvation, deforestation, etc. Either the increase in the global population proves the failure of natural controls to limit births or to increase deaths, or……… Or are we smarter than he thought? People have been able to circumvent those natural controls: Slowing population growth Control global population numbers.
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