Human population

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Human population

  1. 1. HUMAN POPULATION 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 1
  2. 2. • 3.1.-Population Dynamics • 3.1.1-Describe the nature and explain the implications of exponential growth in human populations. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 2
  3. 3. What is the carrying capacity of Earth for humans? This question is difficult to answer. • Estimates are usually based on food, but human agriculture limits assumptions on available amounts. • Human population growth rate has been growing more than exponentially. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 3
  4. 4. HUMAN POPULATION GROWTH 1999 1975 domestication of plants, animals 9000 B.C. (about 11,000 years ago) 8/22/2013 Guru agriculturally based urban societies ESS-TOPIC HUMAN POPULATION beginning of industrial, scientific revolutions 4
  5. 5. What is HUMAN POPULATION? • The total number of persons inhabiting a co untry, city, or any district or area. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 5
  6. 6. What is Exponential growth? • Exponential population growth is when the birth rate is constant over a period of time and isn't limited by food or disease 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 6
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  8. 8. Measures of population changes are 1. Crude Birth Rate 2. Crude Death Rate 3. Rate of Natural Increase 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 8
  9. 9. What is CRUDE BIRTH RATE? • Crude birth rate is the childbirths per 1,000 people per year. This is a common measure of fertility for a given population. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 9
  10. 10. • Therefore, the formula for crude birth rate is The crude birth rate = number of births per year Total population x 1000 Example. In 2007, there were 3,250 births in a city with population of 223,000. Therefore: CBR = 3,250 x1000 223,000 CBR =14.57 So, there were 14.57 births for every 1,000 people in the city. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 10
  11. 11. • The crude birth rate could be of concern for particular countries who may be experiencing population decline, or for national governments who are worried about population growth rates that are higher than their country can sustain 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 11
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  16. 16. • The birth rate is usually the dominant factor in determining the rate of population growth. It depends on both the level of fertility and the age structure of the population. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 16
  17. 17. CRUDE DEATH RATE • The death rate, while only a rough indicator of the mortality situation in a country, accurately indicates the current mortality impact on population growth. • This indicator is significantly affected by age distribution, and most countries will eventually show a rise in the overall death rate, in spite of continued decline in mortality at all ages, as declining fertility results in an aging population. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 17
  18. 18. How to calculate Crude Death Rate? The crude death rate = number of death per year Total population x 1000 Example. In 2007, there were 4,000 death in a city with population of 2,000,000. Therefore: CBR = 4,000 x1000 2,000,000 CDR =2 So, there were 2 death for every 1,000 people in the city. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 18
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  23. 23. Rates of Global Pop. Change • CBR (crude birth rate) = number of births per 1000 population – 1990: 24 Today: 21.3 • CDR (crude death rate) = number of deaths per 1000 population – 1990: 9 Today: 8.93 • Growth rate = birth rate - death rate (often in %) – 1990: 1.5% Today: 1.3% – growth rates have come down 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 23
  24. 24. Special Kinds of Fertility and Mortality Rates • TFR (total fertility rate) = – number of children born to a woman during her reproductive years (or life time) – 1990: 3.1 2000: 2.8 • IMR (infant mortality rate) = – infant deaths per 1000 live births (infant < 1 yr) – 1990: 62 2000: 56 (1900: 200) 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 24
  25. 25. RECAP What is Human population? What is Crude Birth Rate? Formula What is Crude Death Rate? Formula What is Exponential growth? 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 25
  26. 26. Population, population change, growth rates • Population: number of persons • Population change: increase in the number of persons (per year) • Growth rates: rate of change (per year) 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 26
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  30. 30. Doubling Time Doubling time = the number of years it would take a population to double its size at its current growth rate. Doubling time (T) = 70 . annual percentage rate Doubling time (T) = 70 . = 50 years 1.4 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 30
  31. 31. Doubling Time • Number of years in which a population reaches twice its size • Doubling time can be approximated using growth rates • doubling time = 70 : growth rate – – – – 8/22/2013 rate: 1.4 doubling time: 49 rate: 2.0 doubling time: 34.5 rate: 0.5 doubling time: 138 rate: -0.5 doubling time: ???? Guru ESS-TOPIC HUMAN POPULATION 31
  32. 32. How to calculate Rate of Natural Increase? • The rate of natural increase shows the rate at which people are added to a given population by births and deaths (ignoring migration). It is usually represented as follows: • Rate of Natural Increase Crude Birth Rate - Crude Death Rate 10 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 32
  33. 33. For example, Madagascar's crude birth rate 37.89 The crude death rate 7.97 37.89 -7.97 10 29.92 =2.992% 10 divide that by 10 and the result is 2.992%, Madagascar's rate of natural increase 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 33
  34. 34. Why has the world’s population grown at such different rates throughout history? • Births • Deaths • Migration Natural increase = births – deaths Net migration = immigrants – emigrants 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 34
  35. 35. What is mortality? • Mortality rate is a measure of the number of deaths (in general, or due to a specific cause) in a population, scaled to the size of that population, per unit of time 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 35
  36. 36. What is fertility rate ? • The total fertility rate (TFR), sometimes also called the fertility rate, period total fertility rate (PTFR) or total period fertility rate (TPFR) of a population is the average number of children that would be born to a woman over her lifetime • The number, which ranges from more than 7 children per woman in developing countries in Africa to around 1 child per woman in Eastern European and highly-developed Asian countries. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 36
  37. 37. Fertility Rates Births per woman <2 4-4.9 2-2.9 5+ 3-3.9 No Data 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 37
  38. 38. What affects fertility rates? • • • • • • • • • Importance of children to labor force Urbanization Cost of raising and educating children Education and employment options for women Average age of marriage Availability of pension plans Availability of legal abortions Availability of birth control Religious beliefs, traditions and culture 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 38
  39. 39. What affects death rates? • • • • • Higher food supplies Better nutrition Improved medical and health technology Improved sanitation Safer water supplies 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 39
  40. 40. Indicators of overall health • Life expectancy • Infant mortality Growth = natural increase – net migration 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 40
  41. 41. Infant deaths per 1,000 live births <10 <10-35 <36-70 <71-100 <100+ Data not available 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 41
  42. 42. Population (2002) 288 million 174 million 130 million United States (highly developed) Brazil (moderately developed) Nigeria (less developed) Population projected (2025) Infant mortality rate 346 million 219 million 205 million 6.8 33 75 Life expectancy 77 years 69 years 52 years Fertility rate (TFR) 2.1 2.2 5.8 %Population under age 15 % Population over age 65 Per capita GNI PPP (2000) 8/22/2013 21% 33% 44% 13% 5% 3% $34,100 $7,300 $800 © 2004 Brooks/Cole – Thomson Learning Guru ESS-TOPIC HUMAN POPULATION 42
  43. 43. © 2004 Brooks/Cole – Thomson Learning Developed Countries Rate per 1,000 people 50 40 Rate of natural increase 30 Crude birth rate 20 Crude death rate 10 Rate of natural increase = crude birth rate – crude death rate 0 1775 1800 8/22/2013 1850 Guru 1900 1950 ESS-TOPIC HUMAN POPULATION Year 2000 2050 43
  44. 44. © 2004 Brooks/Cole – Thomson Learning Developing Countries 50 Rate per 1,000 people Crude birth rate 40 Rate of natural increase 30 Crude death rate 20 10 0 1775 1800 8/22/2013 1850 Guru 1900 1950 ESS-TOPIC HUMAN POPULATION Year 2000 2050 44
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  46. 46. Age Structure • Age structure—the proportion of the population in each age class. • Age structure influences whether a population will increase or decrease in size. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 46
  47. 47. Age Structure • Countries that have high rates of growth usually have more young people than older people. • In contrast, countries that have slow growth or no growth usually have an even distribution of ages in the population. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 47
  48. 48. Age Structure • Age structure can be graphed in a population pyramid, a type of double sided bar graph. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 48
  49. 49. Age-Structure Diagrams 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 49
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  51. 51. Population Pyramids • Graphic device: bar graph • Shows the age and gender composition of a region • Horizontal axis: gender – male: left-hand female: right-hand – absolute number of people or % • Vertical axis: age – 5-year or 10-year age groups 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 51
  52. 52. What is Population Pyramid? • A population pyramid, also called an age structure diagram, is a graphical illustration that shows the distribution of various age groups in a population which forms the shape of a pyramid when the population is growing. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 52
  53. 53. • It show how many individuals are alive in different age groups in a country for a given year. • They also show how many are male and female. • Population numbers are always on the x-axis and age groups on the y-axis. • The overall stage can depict the stage of development of the country at a particular time. • LEDC’s tend to have expanding populations so they are wide at the bottom, whereas MEDC’s tend to have stationary or contracting pyramids as birth rates fall and individuals live longer. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 53
  54. 54. Stage 1: High birth rate; rapid fall in each upward age group due high death rates; short life expectancy. Stage 2: High birth rate; fall in death rate as more living to middle age; slightly longer life expectancy. Stage 3: Declining birth rate; low death rate; more people living to old age. Stage 4: Low birth rate; low death rate; higher dependency ratio; longer life expectancy. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 54
  55. 55. • It typically consists of two back-to-back bar graphs, with the population plotted on the Xaxis and age on the Y-axis, one showing the number of males and one showing females in a particular population in five-year age groups • Males are conventionally shown on the left and females on the right, and they may be measured by raw number or as a percentage of the total population. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 55
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  57. 57. Describe and explain the main features of the population pyramid below This population pyramid has a very wide base showing that there are a lot of babies born every year. This shows that there is a good medical service within the country. The different sectors from 5 - 9 up to 25 - 29 decreases very quickly and decreases even more quickly on the male side. This is good for the country, as there are fewer people to feed and educate. As the ages increase up through the pyramid, it gets narrower and narrower. This might be because as people get older they leave the country in search of a job or a better 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 57 standard of living
  58. 58. 3.1.3• Analyse age/sex pyramids and diagrams showing demographic transition model 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 58
  59. 59. How can economic development help reduce birth rates? • Demographers have developed a hypothesis known as the DEMOGRAPHIC TRANSITION. • It states that as countries become industrialized, first death rates go down and then their birth rates decline. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 59
  60. 60. AUGUST SUMMATIVE • • • • • Date :3.09.2013 Total Marks :45(IB Format) Time : 1 hour Syllabus :Human Population Unit :3.1.1, 3.1.2, 3.1.3 & 3.1.4 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 60
  61. 61. AUGUST FORMATIVE • • • • Human Population Worksheet Total Marks :40 Will be given today Due date : 29:08:2013 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 61
  62. 62. Demographic Transition 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 62
  63. 63. What is Demographic Transition? • The "Demographic Transition" is a model that describes population change over time. • The demographic transition model (DTM) is the transition from high birth and death rates to low birth and death rates as a country develops from a pre-industrial to an industrialized economic system. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 63
  64. 64. FIVE STAGES IN DTM Stage 1 - High Fluctuating Stage 2 - Early Expanding Stage 3 - Late Expanding Stage 4 - Low Fluctuating Stage 5- Only Possible in some countries 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 64
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  66. 66. Stage One-DTM Both high birth rates and death rates fluctuate in the first stage of the population model giving a small population growth. There are many reasons for this: Birth Rate is high as a result of: 1. Lack of family planning 2. Need for workers in agriculture 3. Religious beliefs Death Rate is high because of: 1. High levels of disease 2. Famine 3. Lack of health care 4. War 5. Lack of education Typical of Britain in the 18th century and the Least Economically DevelopedESS-TOPIC HUMAN POPULATION Countries 8/22/2013 Guru 66
  67. 67. STAGE TWO-DTM • Birth Rate remains high. Death Rate is falling. Population begins to rise steadily. • Reasons Death Rate is falling as a result of: 1. 2. 3. 4. Improved health care (e.g. Smallpox Vaccine) Improved Hygiene (Water for drinking boiled) Improved sanitation Improved food production and storage • Typical of Britain in 19th century; Bangladesh; Nigeria 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 67
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  72. 72. STAGE THREE-DTM Birth Rate starts to fall. Death Rate continues to fall slowly. Population rising. Reasons: 1. Family planning available 2. Lower Infant Mortality Rate 3. Increased standard of living 4. Changing status of women • Typical of Britain in late 19th and early 20th century; China; Brazil 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 72
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  76. 76. STAGE FOUR-DTM • Both birth rates and death rates remain low, fluctuating with 'baby booms' and epidemics of illnesses and disease. This results in a steady population. Typical of USA; Sweden; Japan; Britain 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 76
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  79. 79. STAGE FIVE-DTM • A stage 5 was not originally thought of as part of the DTM, but some northern countries are now reaching the stage where total population is declining where birth rates have dropped below death rates. • One such country is Germany, which has taken in foreign workers to fill jobs. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 79
  80. 80. Area Birth Rate Reason No contraception Death Rate Couples have many babies to compensate for the high death rate caused by poor health care LEDCs High Large families need to work on the land to contribute to family income Reason Poor medical facilities Disease High Poor nutrition High Infant mortality Children look after old Religious reasons NICs People are used to having many children. Takes time for culture to change Decreasing High/ Decreasing As an economy develops money becomes available for better health care Housing improves Changing status of women Better childcare Children are expensive MEDCs People know their children are going to survive so they can keep their families small Low Better health care Low Widely available contraceptives 8/22/2013 Guru Changing status of women ESS-TOPIC HUMAN POPULATION Better standard of living 80
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  82. 82. What are the main factors that affect the growth of a population?  The main factors that make populations grow are births and immigration.(The action of coming to live permanently)  The main factors that make populations decrease are deaths and emigration.(moving from one place) 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 82
  83. 83. • Two types of population curve • S Population Curve • J Population Curve 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 83
  84. 84. TYPES OF POPULATION CURVE • Two modes of population growth. • J-Shape curve is also known as- Exponential curve occurs when there is no limit to population size. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 84
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  86. 86. • S-Shape curve is also known as - Logistic curve shows the effect of a limiting factor • S-Sigmoid 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 86
  87. 87. What is S-Shaped Curve? • In S - shaped or sigmoid growth the population show an initial gradual increase in population size in an ecosystem, followed by an exponential increase and then a gradual decline to near constant level. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 87
  88. 88. • In population of an ecosystem which factors determining the S shape curve? 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 88
  89. 89. The curve obtained by plotting growth and time is called a growth curve. It is a typical sigmoid or S- shaped curve. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 89
  90. 90. What is J shaped? • A curve on a graph that records the situation in which, in a new environment, the population density of an organism increases rapidly but then stops abruptly as environmental resistance • It may be summarized mathematically as: I. dN/dt = rN (with a definite limit on N) II. where N is the number of individuals in the population, t is time, and III. r is a constant representing the rate of increase for the organism concerned. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 90
  91. 91. • The growth of population is measured as increase in its size over a period of time and populations show characteristic patterns of growth with time. • These patterns are known as population growth forms. 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 91
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  93. 93. What is Carrying Capacity ? • Carrying Capacity is the maximum number of a species or load that can be sustainably supported by a given environment i.e without destroying the stock • Population remain stable when the death rate and the birth rate are equal and so there is no net gain or reduction in population size 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 93
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  95. 95. Semester Syllabus • • • • • Systems & Models The Ecosystem Conservation & Biodiversity Global Warming Human Population 8/22/2013 Guru ESS-TOPIC HUMAN POPULATION 95

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