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Explore the complex factors influencing human population growth, including natural selection, genetic drift, and demographic transitions. Discover how regions like the United States experience unique population trends, from baby booms to increasing longevity. Consider the challenges of balancing growth rates, resources, and environmental impact as the world population continues to rise. Delve into the implications of these trends on social, economic, and environmental systems. This informative read sheds light on the ever-evolving nature of human populations.
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Are humans evolving? Yes sexual selection genetic drift natural selection But humans vigorously oppose natural selection Civilization
Read: Human populations Lec 15 2/23/01 Chapter 8
Human populations Lec 15 2/23/01 World Population Clock
World Population: 6,212,638,147 at 10:15 am today births deaths natural increase each month 10,964,310 4,583,441 6,380,869 each day 360,470 150,688 209,782 each hour 15,020 6,279 8,741 each minute 250 105 146
286,486,673 Regional population growth 5.1% of world’s population increasing 0.6% per year doubling time = 117 years
United States Population Picture peaked in 1957 • Baby boom period, following WWII altered age structure of population
Baby Boomers • BB encouraged growth of industries needed by young families. • Today these babies are having babies of their own. • People are now living longer. • By 2030, 20% of US pop will be >65
US pop. Is still growing 1.1% per year. • 0.6% natural increase • 0.5% immigration • Immigration projected to be 50% of U.S. population growth by 2050
286,486,673 Regional population growth 5.1% of world’s population increasing 0.6% per year doubling time = 117 years
Regional population growth 8.44% of world’s population increasing 1.8% per year doubling time = 38 years
Regional population growth 12.9% of world’s population increasing 2.5% per year doubling time = 27 years
Population Age Structure Diagrams rapid growth slow growth decline
Regional population growth 0.5% of world’s population increasing 1.1% per year doubling time = 63 years
Regional population growth 12.3% of world’s population decreasing -0.1% per year
Fig. 7.1 Regional population growth Death rate has increased 30% since 1992 2.5% of world’s population 10% of newborns have birth defects
Regional population growth 60.8% of world’s population increasing 1.5% per year doubling time = 46 years
Natality in 1998 2.1 is replacement fertility
Longevity 78
Longevity 76
72 for females Longevity 59 for men widest gap
Longevity 69
Longevity 68
Longevity 65
Longevity 49
MDC = More Developed Countries LDC = Less Developed Countries • Population • Growth rate
96% of world population growth now occurs in developing regions of Africa, Asia, & Latin America 90% of world’s births and 77% of the world’s deaths now occur in the Less Developed Countries
DEMOGRAPHIC TRANSITION • Demographic Transition: Model of population growth based on historical, social, and economic development of Europe and N. America. • High birth and death rates • then • Death rate falls, population grows • then • Industrialization - birth rate falls • Death rates and birth rates equilibrate • Stable population
Demographic Transition • Comfortable - This is a comfortable model, because it suggests that industrialization will naturally lead to stabilization of the population. • Problem - Can a model developed in Europe and NA be applied to less-developed countries ? Population growth rate is much faster Resources are no longer abundant
Hunger, Food Production and Environmental Degradation • As human population grows so does demand for food. • Most people in developed countries purchase their own food. • Most people in less-developed countries must grow their own food. • Destruction of rainforest and natural areas
3 billion people live on less than $2 a day • Poverty breeds plagues war migration AND population increase