SCI 1101 CH8 Outline
SCI 1101 CH8 Outline SCI 1101
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Date Created: 09/04/16
Lecture Outlines Chapter 8 Human Population Withgott/Laposata Fifth Edition © 2014 Pearson Education, Inc. This lecture will help you understand: § Human population growth § Different viewpoints on this growth § Population, affluence, and technology’s effects § Demography § Factors affecting population growth § Population and sustainable development © 2014 Pearson Education, Inc. Central Case Study: China’s One-Child Policy § In 1970, China’s 790 million people were exhausting their resources and faced starvation if growth continued § The government instituted a one-child policy § The growth rate plummeted § The policy is now less strict § The successful program has had unintended consequences § Killing of female infants and an imbalance in male to female ratios § Increasing number of elderly and fewer young people in the workforce © 2014 Pearson Education, Inc. Our World at Seven Billion § Populations continue to rise in most countries, particularly in poverty-stricken developing nations. § Growth in poorer nations leads to stresses on society, the environment, and people’s well-being § China’s stringent policies have greatly slowed growth there, but other countries may wish to slow their growth without the measures used by China § India’s growth continues and if not changed will surpass China’s population It would take 30 years, counting once each second, to count to a billion! It would take 210 years to count to 7 billion! © 2014 Pearson Education, Inc. The human population is growing rapidly § Our population grows by over 70 million each year § It took until 1800 to reach 1 billion § In 1930 (130 years later) we reached 2 billion § We added the most recent billion in 12 years § Growth rates vary from country to country § Some countries are over 3%, while other country’s populations are shrinking § The current world growth rate is 1.2% § At this rate, the human population of the planet would double in 58.3 years © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Is population growth a problem? § Better tech, sanitation, medication, and increased food supply have increased growth § Death rates drop, but not birth rates § Infant mortality rate = the death rate in children;; has dropped dramatically § Population growth was seen as good § Support for elderly, a larger labor pool § Thomas Malthus’s An Essay on the Principles of Population (1798) § Humans will outstrip food supplies § War, disease, starvation reduce populations © 2014 Pearson Education, Inc. Is population growth a problem? § Neo-Malthusians: population growth will increase faster than food production;; cause famine and conflict § Paul Ehrlich’s Population Bomb (1968) predicted that civilization would end by the end of the 20th century § Intensified food production fed more ppl § Cornucopians argue that we will continue to find new resources and tech to support pp § Environmental scientists argue that there are finite resources § Land is limited, extinct species are gone forever § Quality of life will suffer with unchecked growth § Less space, food, wealth per person © 2014 Pearson Education, Inc. Some national governments now fear falling populations § Policymakers believe population growth increases economic, political, and military strength § But growth is correlated with poverty, not wealth § Strong, rich nations have low growth rates § Weak, poor nations have high growth rates § Some nations offer incentives for more children § Elderly need social services § 66% of European governments think their birth rate is too low § 49% of non-European nations feel their birth rates are too high Population is one of several factors that affect the environment § The IPAT model: I = P × A × T × S § Total impact (I) on the environment results from: § Population (P) = individuals need space and resources § Affluence (A) = greater per capita resource use § Technology (T) = increased exploitation of resources, but also pollution controls and renewable energy § Sensitivity (S) = how sensitive an area is to human pressure (ex. arid land vs rainforest) § Further model refinements include the effects of education, laws, and ethics on the formula Population is one of several factors that affect the environment § Impact equates to pollution or resource consumption § Humans use 25% of Earth’s net primary production § Technology has increased efficiency and reduced our strain on resources, resulting in further pop growth § For example, increased agricultural production § Modern China’s increasing affluence is causing: § increased resource consumption § farmland erosion, depleted aquifers, urban pollution Demography § Demography = the application of population ecology to the study of change in human pop. § All population principles apply to humans § Environmental factors limit population growth § There is a carrying capacity for all species, including humans § Humans raise the environment’s carrying capacity through tech. § How many humans can the world sustain? § 1 billion to 33 billion: prosperity to abject poverty § Population growth can’t continue forever Demography is the study of human population § Demographers study: § Population size § Density and distribution § Age structure § Sex ratio § Birth, death, immigration, and emigration rates § Population size § Current world population is just over 7 billion © 2014 Pearson Education, Inc. Population density and distribution § Population size alone does not tell whole story § People are not distributed equally over the planet (clumped distribution) § Highest density: temperate, subtropical, tropical biomes and close to water § Cities are local high-density areas § Lowest density: away from water, extreme environments § Increased density impacts the environment © 2014 Pearson Education, Inc. Age structure § Age structure describes the relative numbers in each age class within a population § Age structure diagrams (population pyramids) show age structure § Wide base denotes many young § High reproduction, rapid population growth § Even age distribution: remains stable as births keep pace with deaths § Narrow base denotes fewer young than old § Population will likely decline over time © 2014 Pearson Education, Inc. Age structure § Many populations are getting older § Median global age today is 28, but it will be 38 by 2050 § The elderly will need care and financial assistance § Taxes will increase for Social Security and Medicare § But fewer dependent children may mean lower crime rates, and the elderly can remain productive Age structure § China’s age structure is changing § In 1970, the median age was 20;; by 2050 it will be 45 § By 2050, over 300 million will be over 65 § Fewer people will be working to support social programs to assist the elderly © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Sex ratios § Unequal sex ratios can impact population growth § Human sex ratios at birth slightly favor males § For every 100 females born, 106 males are born § In China, 120 boys were reported for 100 girls § Culture values males over females § The government’s one-child policy § Females have been selectively aborted § The undesirable social consequences? § Many single Chinese men § Increased risk of HIV § Teenage girls are kidnapped and sold as brides © 2014 Pearson Education, Inc. Population change results from birth, death, immigration, and emigration § Whether a population grows, shrinks, or remains stable depends on rates of birth, death, and migration § birth and immigration add individuals § death and emigration remove individuals § Technological advances § The increased gap between birth and death rates resulted in population expansion Population change results from birth, death, immigration, and emigration § Immigration/emigration have become more important § War, civil strife, and environmental degradation cause people to flee their homes § Each year, 25 million refugees escape poor environmental conditions § This movement causes environmental problems § No incentives to conserve resources § Overall global growth rate has declined in recent years § But world population continues to grow © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. Many nations are experiencing the demographic transition § In countries with good sanitation, health care, and food, people live longer § Life expectancy = avg. # of years that an individual is likely to continue to live § Has increased with reduced rates of infant mortality § Demographic transition = a model of economic and cultural change § Explains the declining death and birth rates in industrializing nations § Populations undergo four stages Many nations are experiencing the demographic transition § Pre-industrial stage = both birth and death rates are high § High birth rate to compensate for high infant mortality § Population growth is slow § Transitional stag= e declining death rates due to increased food production and medical care § Birth rates remain high since people are not used to the low infant mortality rates § Population grows quickly Many nations are experiencing the demographic transition § Industrial stage = birth rates fall as jobs provide opportunities for women outside the home and children are not needed in the workforce § Difference between birth and death rates shrinks § Population growth slows § Post-industrial stage = birth and death rates are low and stable § Population stabilizes or even shrinks © 2014 Pearson Education, Inc. Is the demographic transition a universal process? § It has occurred in Europe, the U.S., Canada, Japan, and other nations over the past 200–300 years § But it may or may not apply to developing nations § The transition could fail in cultures that: § Place greater value on childbirth § Grant women fewer freedoms For people to attain the material standard of living of North Americans, we would need the natural resources of four and a half more Earths Population and Society § Many factors affect fertility in a given society: § Access to family planning § Rates of infant mortality § Levels of women’s rights § Level of affluence § Importance of child labor § Government support for retirees Family planning is a key approach for controlling growth § Family planning = efforts to control the number and spacing of children;; the greatest single factor slowing population growth § Clinics offer advice, information, and contraceptives § Birth control = effort to control the number of children born by reducing the frequency of pregnancy § Contraception = deliberate prevention of pregnancy through a variety of methods § Rates range from less than 10% (14 countries in Africa) to 84% (China) Family planning is a key approach for controlling growth § Low use of family planning may have different causes § Rural areas may have limited availability § Religious doctrines or cultural influences may reject family planning § Family planning gives women control over their reproductive window = time frame where a woman can become pregnant § Potential to produce 25 children during the window § Family planning may delay first reproduction, space births, or “close” the window when desired family size is achieved © 2014 Pearson Education, Inc. Increasing affluence lowers fertility § Poorer societies have higher population growth rates § Consistent with the demographic transition theory § High fertility to ensure some children would survive and be able to contribute to farm labor § More affluent societies can provide: § Better medical care, reducing infant mortality § Education for children (removing them from the workforce and making them an economic liability) § Social security for the elderly § Educational opportunities for women © 2014 Pearson Education, Inc. Expanding wealth can increase the environmental impact per person § Affluent societies have enormous resource consumption and waste production § People use resources from other areas, as well as from their own § Ecological footprints are huge § People in affluent societies have larger ecological footprints § One American has as much environmental impact as 3.8 Chinese or 8 Indians or 14 Afghans § Not only is the world population increasing, but the consumption per person is also rising Expanding wealth can increase the environmental impact per person § Biocapacity = the amount of biologically productive land and sea available to us § Ecological deficit = ecological footprint > biocapacity § Ecological reserve = ecological footprint < biocapacity § We are running a global ecological deficit § Humanity’s global ecological footprint exceeds biocapacity by 50% § The richest 20% of the world’s population uses 86% of the world’s resources § Anthropocene (relating to or denoting the current geological age, viewed as the period during which human activity has been been the dominant influence on © 2014 Pearson Education, Inc. HIV/AIDS is exerting major impacts on African populations § The AIDS epidemic is having the greatest impact since the Black Death in the 14th century § Of 34 million infected, two-thirds live in sub-Saharan Africa;; 3800 die/day § Low rates of contraceptive use spread the disease § Infant mortality is 14 times that of the developed world § Life expectancy has dropped from 60 years in the 1990s to 40–50 years today § HIV is also well established in the Caribbean and in Southeast Asia, and it is spreading in eastern Europe and central Asia © 2014 Pearson Education, Inc. Demographic change has social and economic repercussions § Demographic fatigue = occurs when governments face overwhelming challenges related to population growth § With the added stress of HIV/AIDS, governments are stretched beyond their capabilities § Problems grow worse and citizens lose faith § Good news: HIV transmission has slowed recently Population goals support sustainable development § 1994 UN conference on population and development § Rejected top-down, command-and-control approaches that pushed contraceptives and preset targets § Urged education and health care § Urged addressing social needs (like poverty, sexism) from the bottom up § To generate a high quality of life for all people, developing nations must slow population growth § Developed nations must reduce resource consumption Conclusion § The human population is larger than at any other time § Rates are decreasing but populations are still rising § Most developed nations have passed through the demographic transition § Expanding women’s rights slows population growth § How will the population stop rising? § The demographic transition, governmental intervention, or disease and social conflict? § Sustainability requires a stabilized population to avoid destroying natural systems and leave a quality world
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