1. Human Population and Its Impact on the Environment

2. Population Characteristics 1.Size 2.Density 3.Distribution 4.Sex ratio 5.Age structure

3. World Population 1.Grew slowly until ~ 200 years ago 2.J-shaped curve for past 200 years 3.Shows uneven growth

4. Why is it growing so fast? 1. Humans expanded to almost ALL climate zones and habitats 2. Emergency of early and modern agriculture (grow more food & feed more people) 3. Death rate dropped b/c of improvements in:  Sanitation  Health care  Antibiotics  Vaccines

5. Past 100 years? Most of the increase in the world’s population over the last 100 years happened b/c of a sharp decline in death rate – NOT a sharp increase in the birth rate!

6. World Population Through Time 10,000 years ago – 5 million 1927 - 2 billion 1974 - 4 billion 1999 - 6 billion 2011 - 7 billion

7. Uneven Growth 1. 2010 – 1% of births came from more developed countries  0.17% growth rate / year 2. 2010 – 99% of growth came from middle to low income countries  1.4% growth rate / year  9x growth rate of more developed countries 3. By 2050 – 95% of new births will come from less developed countries

8. Most Populous Countries 2010 2050 China - 1.3 billion India - 1.7 billion India - 1.2 billion China - 1.4 billion U.S. - 310 million U.S. - 439 million Indonesia - 235 million Pakistan - 335 million Brazil - 193 million Indonesia - 309 million World Population By 2050: 7.8 to 10.8 billion people! Projections based on current average number of babies born.

9. Population Changes By-- 1. Crude birth rate = number of births / 1000 / year 2. Crude death rate = number of deaths / 1000 / year Human populations grow or decline through 3 factors:  Births (fertility)  Deaths (mortality)  Migration Population change = (Births + Immigration) – (Deaths + Emigration)

10. Earth’s Cultural Carrying Capacity Cultural carrying capacity= maximum number of people who could live in reasonable freedom and comfort indefinitely w/out decreasing the ability of the Earth to sustain future generations Earth cannot support 7+ billion people to the same standard of living as the majority of Americans.

11. Fertility Rate 1. Fertility rate: number of children born to a woman in her lifetime 2. Replacement level fertility rate: average number of children that couples in a population must have to replace themselves 3. Slightly higher than 2 kids / couple  ~2.1 in more developed countries  ~2.5 in less developed countries  * some children die before they reach reproductive age

12. Total Fertility Rate 1.Total fertility rate: average number of children born to a woman in a population during her reproductive years 2. Key role in determining a population’s size 3. TFR is lower in US than in India and Africa

13. US Population Growing Rapidly This represent only 150 years!

14. Leading causes of death in US in 2010 According to the CDC # 1 – Heart disease # 2 – Cancer # 3 – Chronic lower respiratory diseases # 4 – Stroke # 5 – Accidents # 6 – Alzheimer's disease

15. Factors that Affect Birth & Fertility Rates 1. Importance of children as part of the labor force 2. Cost of raising & educating children 3.Private or public pension system 4. Infant mortality rate 5. Urbanization 6. Educational and employment opportunities for women 7. Average age at marriage 8. Availability of legal abortions 9. Religious beliefs, traditions, and cultural norms

16. Factors that Affect Death Rate 1.Over past 100 years, world’s population grew because of a decrease in the death rate 2. Useful indicators of the overall health of country:  Life expectancy  Infant mortality rate 3. Between 1955 and 2010 global life expectancy increased from 48 years to 69 years  77 in more developed countries & 67 in less developed countries  expected to reach 83 years by 2050 in Japan & US  57 years or less in less developed countries & may even fall b/c of AIDS

17. Infant Mortality Rate 1.Number of infants out of every 1,000 that die before 1 st birthday 2. One of the best measures of society’s quality of life  country’s general level of nutrition & health care 3. High infant mortality rate indicates under-nutrition, malnutrition, & high incidence of infectious disease 4. High in US for 3 reasons:  Poor nutrition for poor expectant women  Drug addiction  High teenage birth rate Infant mortality rates (highest rates are the darkest colors)

18. US Age Structure Diagrams 2000202520502100

19. Age Structure Diagrams Rapid growth: wide base  Number of births will continue to rise even if women have 2 or fewer children Negative and zero growth: most population is seniors or older people  Population will decline  Not enough young people having babies to replace those who die  Can face labor shortages

20. Comparing 3 Countries 1.What percentage of the population of the Democratic Republic of Congo, the United States, and Germany are 0–4 years old? 2.Which of the three countries has the greatest proportion of people ages 65 and older?

21. Demographic Transition Industrialized and economically developed (less reliance on child labor) Education level increases, birth rate decrease Women work outside the home, birth rate decreases

22. Doubling Time The amount of time for a given population to double, based on the annual growth rate. Uses the rule of 70 Doubling time = 70 growth rate Example: a population that has a growth rate of 2% per year has a doubling time = __________. Afghanistan has a current growth rate of 4.8%. What is its doubling time? _______. 35 years 14.5 years The doubling time for Guadalajara, Mexico in 1993 was 34 years. Approximately, what was its growth rate? ____________ ~2% / year

23. Meta-populations 1.Metapopulation: a group of spatially distinct populations that are connected by occasional movements of individuals between them 2.It is a population of populations 3.Small populations are more likely to go extinct  Have less genetic variation in gene pool  More vulnerable than large populations to density independent limiting factors  Occasional immigrants from nearby populations add to size of the population and increase genetic variation Examples of organisms that live in metapopulations: reintroduced endangered species, butterfly species, and frog species

24. Survivorship Curves 1.Patterns of survival  Type I: K-selected Have high survival rate throughout most of their life; die as they reach old age EX: elephants, humans, whales  Type III: r-selected Low survivorship early in life; few individuals reach adulthood EX: salmon and mosquitoes  Type II: EX: Rodents, birds, and corals Relative constant decline in survivorship throughout life