THE ANNUAL INCREASE IN THE WORLD’S POPULATION HAS PEAKED AT ABOUT 88 MILLION IN LATE 1980S
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The word population comes from the Latin populus, meaning “the people.” It is used lớn refer to lớn a group of people living in a particular area, such as a city, country, continent, or the world. Few aspects of human societies are as fundamental as the size, composition, và rate of change of their populations. Such factors affect economic well-being, health, education, family structure, crime patterns, language, và culture—virtually every aspect of human society. The study of human populations is called demography.
Population Distribution
The world population is distributed unevenly around the globe. Sixty percent of the world’s people in 2013 lived in Asia. Africa had 15.5 percent of the total, followed by Europe with 10.4 percent. South America, Central America, và the Caribbean together had 8.6 percent. Five percent of the world’s people lived in North America. The final 0.5 percent lived in Oceania (including nước australia and New Zealand).
Another way lớn think about global population distribution is in terms of development regions. Countries are grouped into these broad regions based on their level of economic development. The more economically developed countries (or MEDCs) include the United States, Canada, Australia, New Zealand, Japan, và all of Europe. They are also called “more developed” or simply “developed” countries. The less economically developed countries (or LEDCs) include those of Africa, Asia (excluding Japan), Latin America & the Caribbean, and Oceania (excluding australia and New Zealand). They are also called “less developed” or simply “developing” countries. In 2013 some 83 percent of the world’s people lived in less developed countries. Two developing Asian countries, trung quốc and India, accounted for 37 percent of the total world population.
Encyclopædia Britannica, Inc.
Encyclopædia Britannica, Inc.
Population density is a measure of population in relation to lớn land area. It is expressed as the number of people per square mile or square kilometer. In 2012 the most densely populated continent by far was Asia, with an average of 343 people per square mile (132 per square kilometer). Next was Africa, with 92 people per square mile (35 per square kilometer). The most sparsely populated continent was Australia, with only 7 people per square mile (3 per square kilometer). Within continents, there are often significant differences in mật độ trùng lặp từ khóa from region lớn region & from country to lớn country. South Asia, for example, had an average density of 836 people per square mile (323 per square kilometer) in 2012, compared to lớn an average of 94 per square mile (37 per square kilometer) in Southwest Asia.
Components of Population Change
Populations change continually as a result of gains & losses. The most basic components of population change are births & deaths. By convention, the birth rate of a population is the annual number of births per 1,000 inhabitants; the death rate (or mortality rate) is the annual number of deaths per 1,000 inhabitants. The difference between these two rates is the rate of natural increase (or decrease, if deaths exceed births). The rate of natural increase is a net result of fertility trends, health conditions, & variations in the age composition of the population.
In most cases the populations of countries, regions, continents, & cities are affected not only by births và deaths but also by migration. The rate of natural increase combined with the effects of migration provides another measure, the rate of population growth. A high rate of natural increase can be offset by a large out-migration, and a low rate of natural increase can be countered by a large in-migration. Generally speaking, however, these migration effects on population growth rates are far smaller than the effects of changes in birth & death rates.
Population Composition
Demographers study many aspects of population in addition to kích thước and growth rate. They are also interested in the composition of the population in terms of such characteristics as age, sex, ethnic or racial category, and residential status (urban or rural).
Perhaps the most fundamental of these characteristics is the age distribution of a population. Age distributions differ among countries mainly because of differences in the levels and trends of fertility. A population with persistently high fertility, for instance, has a large proportion of children & a small proportion of aged people. A population in which fertility has been low for a long time has a smaller proportion of children and a larger proportion of aged people. Age distributions have also been affected by migrations, war losses, và differences in mortality, but these effects are generally less important than the influence of changes in fertility.
A second important characteristic of a population is the relative numbers of males & females who compose it. Generally, slightly more males are born than females (a typical ratio would be 105 or 106 males for every 100 females). On the other hand, it is quite common for males—for apparently biological reasons—to experience a higher death rate at virtually all ages after birth. Taken together, these general rules mean that during childhood males outnumber females of the same age, at some point in adulthood the numbers of males và females become equal, & at higher ages the number of females becomes disproportionately large. For example, among Europeans age 70 or older in 2010, the number of males for every 100 females was only about 61. Such discrepancies between the sexes within a population can affect marriage patterns & the birth rate.
The countries of the world vary greatly in their diversity of ethnicity or race. Such divisions in populations often are regarded as socially important, và statistics by race và ethnic group are therefore commonly available. The categories used for such groups differ from country to country, however. For this reason, international comparisons of ethnic và racial groups are imprecise, and this component of population structure is far less objective as a measure than are the categories of age & sex.
The division between rural and urban areas is another important characteristic of a population. For many decades there has been a nearly universal flow of populations from rural khổng lồ urban areas. In 2011 about 52 percent of the world’s people lived in urban areas, but there were significant differences from country lớn country based on the cấp độ of development. In the more developed regions, about 78 percent of the population was classified as urban, compared to lớn only 47 percent in less developed regions. However, urban populations are growing much faster in developing countries than they did in the past in developed countries—particularly in large cities. Of the 10 most populous urban agglomerations in 2011, 8 were in developing countries (Delhi, Mumbai, and Kolkata in India; Shanghai và Beijing in China; Mexico đô thị in Mexico; São Paulo in Brazil; and Dhaka in Bangladesh).
World Population Trends
Growth
Most of the growth in the world population has taken place in the modern era. The time required for the world population lớn reach its first billion stretched through all of human prehistory into the early 1800s. The second billion was added by 1930, & the 3-billion mark was reached by 1960. The fourth, fifth, & sixth billions were added by 1974, 1990, & 1999. The seven-billion population milestone was reached in 2011.
The primary cause of this tremendous spurt in population growth was the drop in death rates. During the 19th century death rates began to lớn fall in Europe, Canada, & the United States as industrialization triggered improvements in health và living conditions và as newly developed agricultural & transportation methods helped khổng lồ increase food supplies. Late in the 19th century birth rates also began lớn fall in these areas of the world, & population growth slowed. Meanwhile, death rates and birth rates remained high in Asia, Africa, & Latin America.
Medical and public-health technologies introduced after World War II reduced death rates in Asia and Latin America. Because these declines were not accompanied by declines in birth rates, these geographic areas experienced population growth that reached rates far higher than any previously experienced in Europe. The greatest population growth rates were reached in Latin America và in Asia during the mid- to late 1960s. In the 25 years between 1950 và 1975, the population of Mexico increased from 27,000,000 khổng lồ 60,000,000; Iran from 14,000,000 lớn 33,000,000; Brazil from 53,000,000 lớn 108,000,000; and china from 554,000,000 khổng lồ 933,000,000.
This “population explosion” in the developing world pushed the rate of world population growth lớn a peak of 2.07 percent annually between 1965 và 1970. The growth rate has been declining since then, mostly because of falling birth rates in developing countries—particularly in China. By 2005–10 the growth rate of the world population had dropped to lớn 1.20 percent annually. Because birth rates have declined at different rates in different regions, however, the rate of population growth also varies from place to place. The annual growth rate in more developed regions during 2005–10 was 0.42 percent; the rate in less developed countries was 1.37 percent, more than three times higher. The fastest-growing part of the world is Africa, which experienced an average growth rate of 2.55 percent between 1980 và 2013. The slowest-growing region is Europe, with an annual growth rate of only 0.2 percent over the same period.
Demographers project that almost all of the growth in the world population up to the over of the 21st century will take place in developing countries. In the period 2045–50, only 15 countries are projected to account for 75 percent of world population growth; all except one (the United States) are less developed countries of Africa và Asia. Even as population growth in Asia is projected to lớn fall in the second half of the 21st century, growth in Africa is expected lớn accelerate because of continued high birth rates. Overall, the proportion of the world population living in developing countries is projected to increase from 83 percent in 2013 to 88 percent in 2100. This trend will continue khổng lồ place tremendous pressures on developing countries, which have difficulty feeding, educating, & providing health care and jobs for the people they already have.
Aging
The general declines in birth & death rates have led khổng lồ the rapid aging of the world population as a whole. The percentage of the world population age 60 và older increased from 8 percent in 1950 lớn 12 percent in 2013. The aging of the population is particularly advanced in the more developed countries, where the number of people age 60 or older has already surpassed the number of children under age 15.
Less developed countries where birth rates remain high have much greater proportions of children than vì developed countries. In most African countries children under 15 ảo diệu more than 40 percent of the population, compared lớn 18 percent in the United Kingdom & just 14 percent in Italy—two European examples. Many of the resources of developing countries must be used to educate & care for dependent children, making less available for economic development that could provide jobs for them when they are older. In developed countries with aging populations—such as Italy, with 27 percent of its people age 60 và above—an increasing chia sẻ of resources goes to tư vấn the aged.
Infant Mortality
A good indicator of a country’s health status is its infant mortality rate—the number of deaths of children under age 1 per 1,000 live births in a year. The average rate in less developed regions in 2005–10 was 46—about 8 times the average of 6 in more developed regions. The rates are highest in Africa, led by Central Africa at 106. Nevertheless, developing countries have seen substantial declines in infant mortality as a result of improved sanitation and nutrition, increased access khổng lồ modern health care, and improved birth spacing through the use of contraception.
In 2005–10 Iceland’s infant mortality rate was the lowest in the world at 2.0 deaths per 1,000 births, followed by Singapore’s at 2.2. Surprisingly, the infant mortality rate of 6.9 in the United States, one of the world’s wealthiest countries, was higher than that of 39 other countries; this was largely because of high rates in poverty-stricken areas in the U.S.
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Life Expectancy
The infant mortality rate has a strong bearing on life expectancy at birth, or the average number of years a newborn baby can be expected khổng lồ live if conditions remain as they are. In the Middle Ages, when infant mortality rates were probably well above 200 per 1,000 births, life expectancy was 30 years or less. By 2005–10 life expectancy had reached 69 years for the world as a whole, up from 47 percent in 1950–55. The average life expectancy in more developed regions stood at 77, compared to 67 in the developing world. Japan had the world’s highest life expectancy at 83 years, followed by Switzerland, Australia, and Italy at 82 years. The average was about 78 years in the United States.
The countries with the lowest life expectancies are concentrated in Africa, where the regional average age in 2005–10 was just 56 years. Beginning in the late 1980s, the life expectancies of some African countries began to lớn fall because of the aids epidemic. In Southern Africa, where the disease hit hardest, life expectancy fell from 62 years in 1990–95 to 52 years in 2005–10 before beginning khổng lồ stabilize.
For reasons that are not well understood, life expectancy in almost all countries is higher for women than it is for men. Life expectancy for a girl born in France between 2005 và 2010 was about 84 years, seven years more than the 77 years for baby boys. The gap is narrower in many developing countries of Africa và Asia. In Kenya, for example, life expectancy in 2005–10 was about 58 for women và 56 for men.
Trends in the United States
In 1790, when the first census was taken, the population of the United States was 3.9 million. Before the American Civil War (1861–65), the U.S. Population increased by about one-third every 10 years. Between 1860 và 1940 the trend was toward a gradual slowing of growth, caused by a decrease in the birth rate và by restricted immigration after 1921. During the Great Depression of the 1930s, the population growth rate fell lớn a low of 7.3 percent. A postwar baby boom, which peaked in 1957, helped boost growth khổng lồ 14.5 percent between 1940 và 1950 & to 18.5 percent between 1950 and 1960. The increase then dropped khổng lồ 13.4 percent in the 1960s, 11.4 percent in the 1970s, & 9.8 percent in the 1980s. The growth rate surged khổng lồ 13.1 percent in the 1990s, which was a period of broad economic prosperity. Between 2000 and 2010 the growth rate fell lớn 9.7 percent. Demographers project that the U.S. Population growth rate will continue to fall steadily throughout the 21st century.
As in other countries, population in the United States is influenced by birth rates, death rates, and migration. The birth rate has fluctuated over the decades, with the changes often corresponding to lớn the health of the national economy. The birth rate stood at 30.1 per 1,000 people in 1910, fell to below 19 in the Great Depression years of the 1930s, rose khổng lồ 25 in the 1950s during the baby boom, and fell again to a then-record low birth rate of below 15 in the mid-1970s. Despite further fluctuations since then, including an unexpected rise in the early 1990s, demographers expect the rate to fall from the 2005–10 level of 14 percent. In contrast, the death rate is projected lớn rise in the mid-21st century as baby boomers reach advanced ages. In the same period, natural increase (birth rate minus death rate) is expected khổng lồ be surpassed by international migration as the leading source of population growth in the United States. The United States is the world’s top destination for immigrants.
The United States is part of the world trend of aging populations, with an increasing proportion of its people in the middle- and upper-age brackets. At the beginning of the 20th century, 34 percent of the population was under age 15. By 2010 less than 20 percent of the U.S. Population were children under 15. The median age—the age at which half of the population is younger và half is older—rose from 30 in 1950 khổng lồ 37 in 2010. The number of retired people has increased at a faster rate than the number of so-called productive workers (aged 18 to 64) và will increase still faster as more members of the baby-boom generation—people born between 1946 and 1964—reach retirement age. This means that workers will have to be increasingly productive to lớn supply goods and services to lớn the aged. At the same time they may have to lớn pay relatively more in taxes lớn provide pensions for retirees & medical care for the aged who are ill.
In addition khổng lồ the aging of the U.S. Population, great shifts have occurred in internal migration và settlement. For decades the American people have been moving away from the Northeast và Midwest và to the South và West. Between 2000 and 2010 the South & West grew at rates of 14.3 percent và 13.8 percent, respectively, compared lớn population growth rates of 3.9 percent for the Midwest and 3.2 percent for the South. The fastest-growing U.S. States during that decade were Nevada, Arizona, Utah, Idaho, & Texas. The U.S. Population also continues lớn shift from the country to the city. Just 5 percent of the population lived in urban areas in 1790; the figure grew to lớn 64 percent by 1950 and to 82 percent by 2010. Since 1920, in most larger American cities, the rate of population growth has been much greater in surrounding suburban communities than within cities themselves.
Additional Reading
Aaseng, Nathan. Overpopulation: Crisis or Challenge? (Watts, 1991).Alonso, William, ed. Population in an Interacting World (Harvard Univ. Press, 1987).Fagan, B.M. People of the Earth, 6th ed. (Scott, Foresman, 1989).Heer, D.M., và Grigsby, J.S. Society & Population, 3rd ed. (Prentice, 1992).Nam, C.B., and Philliber, S.G. Population: A Basic Orientation (Prentice, 1984).Newman, J.L., & Matzke, G.E. Population: Patterns, Dynamics, and Prospects (Prentice, 1984).
Căn cứ vào trạng từ thời hạn “in the late 19805" phải động từ trong câu này buộc phải chia sinh sống thì thừa khứ đơn.
=> Đáp án là C (has peaked
Tạm dịch: Sự ngày càng tăng hàng năm của dân 56 trái đất đã đạt đỉnh vào lúc 88 triệu vào cuối trong thời điểm 1980.
Mark the letter A, B, C, or D lớn indicate the correct answer khổng lồ each of the following questions.
The whole matter is farther complicated by the fact that Amanda & Jo refuse lớn speak to lớn each other.
Mark the letter A, B, C, or D lớn indicate the word(s) OPPOSITE in meaning lớn the underlined word(s) in each of the following questions.
She was like a cát on hot bricks before her driving t est.
Mark the letter A, B, C, or D lớn indicate the correct answer khổng lồ each of the following questions.
At the ______ level, you can join three-year or four-year colleges.
Mark the letter A, B, C, or D khổng lồ indicate the correct answer khổng lồ each of the following questions.
They ______ sacrifices so that their only child could have a good education.
Read the following passage và mark the letter A, B, C, or D lớn indicate the correct answer lớn each of the question.
There are three basic types of classroom learning styles: visual, auditory, & kinesthetic. These learning styles describe the most common ways that people learn. Individuals tend to lớn instinctively prefer one style over the others; thus each person has a learning style that is dominant even though he or she may also rely somewhat on the other approaches at different times & in different circumstances.
Visual learners prefer khổng lồ sit somewhere in the classroom where no obstructions hinder their view of the lesson. They rely on the teacher"s facial expressions and toàn thân language to aid their learning. They learn best from a blend of visual displays và presentations such as colorful videos, diagrams, và flip-charts. Often, these learners think in pictures and may even close their eyes to visualize or remember something. When they are bored, they look around for something to watch. Many visual learners lack confidence in their auditory memory skills and so may take detailed notes during classroom discussions & lectures. Auditory learners sit where they can hear well. They enjoy listening và talking, so discussions và verbal lectures stimulate them. Listening lớn what others have khổng lồ say & then talking the subject through helps them process new information. These learners may be heard reading lớn themselves out loud because they can absorb written information better in this way. Sounding out spelling words, reciting mathematical theories, or talking their way across a map are examples of the types of activities that improve their understanding.
Kinesthetic learners may find it difficult to sit still in a conventional classroom. They need lớn be physically active and take frequent breaks. When they are bored, they fidget in their seats. They prefer lớn sit someplace where there is room to lớn move about. They benefit from manipulating materials and learn best when classroom subjects such as math, science, & reading are processed through hands-on experiences. Incorporating arts-and-crafts activities, building projects, và sports into lessons helps kinesthetic learners process new information. Physical expressions of encouragement, such as a pat on the back, are often appreciated.
In addition to these traditional ways of describing learning styles, educators have identified other ways some students prefer lớn learn. Verbal learners, for example, enjoy using words, both written and spoken. Logical learners are strong in the areas of súc tích and reasoning, Social learners vị best when working in groups, whereas solitary learners prefer lớn work alone. Research shows that each of these learning styles, as well as the visual, auditory, & kinesthetic styles, uses different parts of the brain. Students may prefer to lớn focus on just one style, but practicing other styles involves more of the brain"s potential and therefore helps students remember more of what they learn.
