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POPULATION TRENDS of
Earth's population, or the number of people living on the plan-et, constantly increases. In fact, in the time it takes you to read this sentence at least two more people will be born. Population figures are always approximations. No one can know exactly how many people there are in the world because of the birth and death records are not always well kept, especially in developing countries. In general it is considered that the total population of the world is exceeding 6 billion people. Stages of population growth. The population growth rate has not always been as high as it is today. Scientists who study popu-lation trends, have found that population growth rates differ in different parts of the world and vary with the levels of a country's economic development. As a nation develops, it moves through the four stages of population growth. In the first stage of population growth, the number of people increases slowly. The birth rate, or the number of children born per 1.000 people is high. But the death rate, the number of people who die per 1.000 people, also is high. Few children live to be adults. Sickness, malnutrition, and starva-tion kill large numbers of people every year. Life expectancy is the average number of years a person is expected to live-is only about 30. This means that the rate of natural increase, or the difference between the birth rate and the death rate remains low. In the second stage of population growth, technological advance-es in farming, nutrition, medicine, and sanitation, result in increased supplies and the date/time in health care. So people live longer and many more children than before live to become adults. The death rate drops rapidly and the population begins to grow rapidly. In the third stage most children live to be adults. In order to raise their standard of living many adults begin limiting the size of their families, thus lowering the birth rate. The population still grows, but at a lower rate than before. Finally, in the fourth stage both the birth rate and the death rate are very low. At this stage, the population growth rate slowed dra-matically and may even approach zero population growth, or a point at which the birth rate and the death rate are about equal. In stage four, the rate of natural increase is almost as slow as it was in stage one. The four stages of population growth may not always apply to every country of the world but the understanding of the demographic tendencies bassist helps put the world's population growth into perspective. Uneven distribution of population. People make their homes in every geographic region except Antarctica but the world's pop-ulation is not evenly distributed over the earth. In some places hundreds of thousands does of people live within the limits of a single city. In other places only a few people live scattered over miles and miles of farmland or wilderness. More people live in areas with fertile soil and a mild climate, for example, than in areas with rug-ged terrain and a harsh climate. The number of people per sq. km of land is given a so-called population density. Nearly 90 percent of the world's land area remains empty or are sparsely populated with. The remaining 10 percent is densely populated with. For example, Asia has 55 percent of the world's people and 13 percent of its land. Hence the population density here is very high. Population movements. Over a period of time population pat-terns were influenced by two population movements. One is mi-gration, the movement of people from place to place. The other i5 urbanization, the movement of people from rural areas to urbasi areas within nations. The many migrations that have taken place throughout his-tory have helped to give many a mixture of populations, ethnic groups, race5 languages and religions. Migration does not add to world population. But it does change the population of specif-ic areas. Migration from one country to another can be classified as emigration or immigration. Emigration is the movement of people out of a country. Immigration is the movement of people into a country. People migrate for many reasons. Oppression, war, natural catastrophes, or force some people from their homes. Other people move to an area because they are attracted by better conditions or new opportunities — political or religious freedom, better jobs, a more favorable climate, and so on. In the early 19th century, for example, more than 50 million people left their homelands in Eu-rope to seek better opportunities in North and South America. The movement of people from rural to urban areas has been taking place for thousands does of years. In recent years, however, the ur-banization has taken place at a faster rate than ever before. Ur-banization has increased dramatically over the last 200 years. To-day 70 percent or more of the people in industrialized nations live in urban areas. In developing countries, the urban population is generally about 30 percent. However, urbanization in many de-veloping countries is increasing rapidly. One of the most striking features of contemporary urban growth is the increase of large cit-ies with a million or more people. Most of these million cities are in the economically developing world and they have a tendency to grow rapidly. (See text Baghdad; text Mexico City; Unit 18 text Lagos, Nigeria; etc.)
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