How Has the Human Population Grown Historically Early Hunter Gatherers Nomadic, With a Strong Sense of the Earth Practiced Intentional Birth Control Rise of Agriculture Necessary for Survival Animals became extinct via predation and altered habitat Humans began to cultivate own food

C. Agriculture Gives Rise to Cities Food Produced in Country, Consumed in City Food wastes are no longer returned to soil Soil becomes less productive Waste of Populations Concentrated in Cities Population Control in Medieval Societies Infanticide Plagues D. Industrialization View of Children During Early Phases of Industrial Growth Valued as cheap source of income and cheap labor Exponential growth of populations By 1900s, Birth Rate in Industrialized World Dropped Rise in standards of living Safe and inexpensive means of birth control introduced Increase in the cost of child rearing

MI L I O NS

Current World Population Population Clock Vital Events (per time unit) Global population was 6,379,870,732 On September 1, 2009 at 10:09 am The global population grows by: Nearly 2.3 persons per seconds Nearly 8,343 persons per hour Over 200,234 persons per day Over 73 million persons per year

How Much is a Billion? 1,000 seconds = 16.7 minutes 1 million-s = 16,677 min = 11.6 days 1 billion-s = 11,574 days = 31.7 years 1,000 pennies = ~ 88 ounces = 5.5 pounds 1 million pennies = 5,500 pounds (~1-Suburban) 1 billion pennies = 2,750 tons (~2 Space Shuttles)

Characteristics of a Population Size: # if individuals in a pop. at any given time -changes in response to changes in the env, competition and predation Density: # individuals/area Age Structure: # of males and females at each age, from birth to death.

Human Population Dynamics There are just three sources of change in population size — fertility mortality "natural decrease" refers to population decline resulting from more deaths than births migration Net migration is the number of immigrants minus emigrants

Rates of Global Pop. Change use: International Data Base http://www Rates of Global Pop. Change use: International Data Base http://www.census.gov/ipc/www/idbnew.html, then Online Demographic Aggregation CBR (crude birth rate) = # births / 1000 population 1990: 24 now: 20.6 CDR (crude death rate) = # deaths / 1000 population 1990: 9 now: 8.8 Annual Growth Rate (AGR%) = (b + i) – (d + e) 1990: 1.5% now: 1.19% growth rates have come down

Annual Growth Rate If you are only given the birth rate and the death rate, the formula is: AGR %= (birth rate-death rate) x 100 1000 people OR…AGR%= (birth rate-death rate) 10

Doubling Time Time it takes for a population to double itself, assuming that the current growth rate does not change. DT=70/AGR% You may be given the doubling time and asked to calculate the AGR% (EASY MATH!)

Overall, the world population is growing at a rate of about 1 Overall, the world population is growing at a rate of about 1.7 per cent; if this rate continues, the population will double in 42 years. Unabated, such a rate would lead to a point about 2000 years hence when the mass of humanity would weigh more, and be larger, than the Earth. But, the growth rate is decreasing

Maximum Population Growth W/o influence of biotic (living) and abiotic (non-living) …all populations will have a J curve (exponential) Environmental Resistance: Organisms cannot reproduce indefinitely because of these factors (shortage of water, light, space, nutrients) Carrying Capacity (K)=largest population that can be maintained for an indefinite period of time in a specific environment, assuming there are no changes.

Carrying Capacity, cont. Limit to # of organisms is caused by abiotic (light, temp, nutrients, weather, etc)… and biotic (food, prey, disease resistant, adaptable, etc) limiting factors. Population that is influenced by environmental resistance fluctuates and forms an S shape graph

Reproductive Strategies r- selected species: many small offspring little prenatal care adaptable to unstable climate high population growth rate Population size fluctuates wildly above and below carrying capacity (K) Low ability to compete small body size

Reproductive Strategies K-selected species: most live to reproductive age fewer, larger offspring low reproductive rate larger adults/body sizes lower population growth rate population size stable and close to carrying capacity (K) high ability to compete invest in parental care of young

Survivorship Type I: young don’t die easily; most death occurs at old age (K-strategists) Type II: RARE-death happens equally at all ages Type III: death common in early life and only the lucky survive (r-strategists) These are generalizations and few populations fit one curve exactly.

Density Effects on Population Some environmental events affect populations the same regardless of density=density independent (ex. Earthquakes, fires, bad weather) Some environmental events affect populations MORE if population is dense= density dependent (population control-ex. Competition for resources, predation, disease, etc)

Types of Fertility Rates that Affect Human Population Growth Total fertility rate (TFR) The average number of children born to a woman Average in developed countries = 1.5 Average in developing countries = 3.8 Worldwide 1990: 3.1 now: 2.76 Replacement fertility rate (RFR) The number of children a couple must have to replace themselves A RFR of 2.1 for developed countries with low infant and child mortality rates Africa RFR = 2.5

Factors that Affect Death Rates 1. Life Expectancy: avg. # of years to be lived by a person in the same country (good measure of quality of life) 2. infant mortality rate: IMR infant deaths per 1000 live births (infant < 1 yr) 1990: 62 now: 52.4 (normal in 1900: 200) ** # 1 cause of population increase is DEATH RATE, not increased births!

http://www. povertymap http://www.povertymap.net/pub/mipwa/sections/w-global/health-sanit/infant-mortality-2.htm

Migration Net migration is the number of immigrants minus emigrants

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

Population Pyramid with young cohorts

Population Pyramids High Growth: Afghanistan Population Pyramids on the Web High Growth: Afghanistan Moderate Growth: Mexico Zero Growth: U.S. Negative Growth: Austria or Italy

Demographic Transition Movement of a nation from high population growth to low population as it develops economically Transition as a result of four stages Stage 1—Birth and death rates are both high Stage 2—Death rates fall; birth rates remain high; growth rate rises Stage 3—Birth rates fall as standard of living rises; growth rate falls Stage 4—Growth rate continues to fall to zero or to a negative rate

The Demographic Transition                                                                                                                                                                 

Five Stages of the Demographic Transition Used to be 4, now 5 stages birth rates, death rates and growth rates systematically change through time as societies change: modernize, urbanize gain access to technology

Stage 1 high birth rates, high (at time erratic) death rates, low growth rates stage for much of human history, traditional societies practically no country today

Stage 2 high birth rates, declining death rates, rising growth rates improvements in sanitation (water) and medicine in Europe during Industrial Revolution in developing countries since the 50s/60s much of Africa today, some countries of Asia (Afghanistan, Nepal, etc.)

Stage 3 continued decline of death rates, declining birth rates, growth rates decline from high to lower levels change in behavior: adaptation to lower death rate, in particular infant mortality rate economic change: urbanization (incentive to have fewer children) Mexico today

Stage 4 & 5 Stage 4: low birth rates, low death rates, low growth rates United States today Stage 5: low birth rates, rising death rates, declining growth rates (if birth rates drop below death rates: negative growth rates) several countries of Europe today (Austria)

Demographic Trap Population Path of Most Less-Developed Countries (LDCs) “Trapped” in Stage 2 of Demographic Transition Before 1970, LDCs seemed poised to make transition thanks to economic growth Since 1970, economic growth has not kept pace with population High birth and low death rates result in explosive population growth Downward spiral in standard of living

Demographic Fatigue Condition characterized by a lack of financial resources and an inability to deal effectively with threats such as natural catastrophes and disease Possibility that countries suffering from demographic fatigues could slip back into Stage 1 of demographic transition

Age Structure & Population Projections Baby boomers - half of U.S. population; use most of goods and services; make political and economic decision baby-bust generation - born since 1965; may have to pay more income, health care and social security to support retired baby boomers; but face less job competition Better health --> later retirement of baby boomers --> keep high-salary jobs=less higher paying jobs for others

Tracking the baby-boom generation in the United States

Effects of Population Decline As percentages of 60+ aged people increases, population begins decline 60+population increase --> severe economic and social problems because 60+ consume more medical care Social Security costly public services Labor shortages require automation & immigration

Cutting Global Population Growth U. N.Conference on Population and Development, Cairo, 1994 8 goals to be met by 2015 (p. 276) are these goals wishful thinking? Replacement level fertility can be met in 15-30 years as shown by Japan, Thailand… Invest in family planning, reduce poverty, and elevate status of women

What Is Family Planning? Definition Measures enabling parents to control number of children (if they so desire) Goals of Family Planning Not to limit births For couples to have healthy children For couples to be able to care for their children For couples to have the number of children that they want

China’s Program Nation With Best Known Population Control Program Reasons Chinese Government Initiated Population Control Measures Freshwater and food at a premium for nation’s population Country experiencing population momentum Government Perks / Coercive Measures for Citizen Compliance Free education and health care Increased personal and family incomes Increased legal marrying age for women Contraceptives, abortions, and sterilizations free of charge Preferential housing and retirement income

Issues with Large World Population We may exceed the K for humans-poplulation and individual consumption determine the K for humans. World Hunger: highest TFR have the greatest hunger (usually) -800 million hungry, some starve to death (S. Asia and sub-Saharan Africa) -Enough food made for all, but unevenly distributed (some too poor to grow or buy) -Can control population growth & promote economic development in these countries

Issues with Large World Population Economic Effects: stable population promotes economic development -economy must grow at least as fast as the population for standard of living to improve Resource Consumption: country is overpopulated if level of demand on its resource base is damaging to the environment -People Overpopulation: environmental degradation because too many people, even though individual resource use is small

Issues with Large World Population -In developed countries, resource use/person is huge and deplete world’s resources with “consumptive” lifestyle (but we also use technology to find alternatives: ex. plastics for metal) Urbanization: people increasingly concentrated in cities (47%)=urbanization worldwide -developed country: not experiencing as much urban growth as developing (Bombay & Shanghai) -developing countries grew so fast that they formed shantytowns around the city with no sanitation or water.

-Many homeless in cities in developing countries (250,000 in Calcutta, India vs. 300,000-500,000 in ALL US cities) -Solution: Compact development (SMART growth)=compact, high density housing next to mass transit, jobs, shopping (ex. Portland, OR)

Solutions: Influencing Population Size Reduce the TFR (culture, religion, etc) Elevate the status of women (education, marriage age) Family Planning Governmental Policies (economic incentives or penalties)