Are humans evolving? Yes sexual selection genetic drift natural selection But humans vigorously oppose natural selection Civilization

Human populations Lec 15 2/23/01 Read: Chapter 8

Human populations Lec 15 2/23/01 World Population Clock

World Population: 6,212,638,147 at 10:15 am today at 10:15 am today each month 10,964,3104,583,4416,380,869 births deaths deaths natural increase natural increase each day 360, , , , , ,782 each hour 15,020 15,020 6,279 6,279 8,741 8,741 each minute

Regional population growth

5.1% of world’s population increasing 0.6% per year doubling time = 117 years doubling time = 117 years286,486,673

United States Population Picture l Baby boom period, following WWII peaked in 1957 altered age structure of population

Baby Boomers l BB encouraged growth of industries needed by young families. l Today these babies are having babies of their own. l People are now living longer.  By 2030, 20% of US pop will be >65

l US pop. Is still growing 1.1% per year. ä 0.6% natural increase ä 0.5% immigration ä Immigration projected to be 50% of U.S. population growth by 2050

Regional population growth 5.1% of world’s population increasing 0.6% per year doubling time = 117 years doubling time = 117 years286,486,673

Regional population growth 8.44% of world’s population increasing 1.8% per year doubling time = 38 years doubling time = 38 years

Regional population growth 12.9% of world’s population increasing 2.5% per year doubling time = 27 years 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 doubling time = 63 years

Regional population growth 12.3% of world’s population decreasing -0.1% per year

Fig. 7.1 Regional population growth 2.5% of world’s population Death rate has increased 30% since % of newborns have birth defects

Regional population growth 60.8% of world’s population increasing 1.5% per year doubling time = 46 years doubling time = 46 years

Natality in 1998

2.1 is replacement fertility

Longevity

Longevity 78

Longevity 76

72 for females 59 for men widest gap widest gapLongevity

69 Longevity

68 Longevity

65 Longevity

Longevity 49

Growth rate Population LDC = Less Developed Countries MDC = More Developed Countries

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

refugee children

DEMOGRAPHIC TRANSITION l Demographic Transition: Model of population growth based on historical, social, and economic development of Europe and N. America. ä High birth and death rates ä then ä Death rate falls, population grows ä then ä Industrialization - birth rate falls ä Death rates and birth rates equilibrate ä Stable population

Fig. 8.5

l Comfortable - This is a comfortable model, because it suggests that industrialization will naturally lead to stabilization of the population. l 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 Demographic Transition

Hunger, Food Production and Environmental Degradation l As human population grows so does demand for food. l Most people in developed countries purchase their own food. l Most people in less-developed countries must grow their own food. l Destruction of rainforest and natural areas

l 3 billion people live on less than $2 a day l Poverty breeds plagues war migration AND population increase