1. Hunters and gatherers ( beg. Of man – 6000 BC) The world’s population was probably less than a few million GR % 2. Early, pre-industrial agriculture (6000 BC – 1500’s) Allowed a much greater density of people The first major increase in human population Pop = 500 mill.GR =.03% 3. Machine age (1600 – 1960) Industrial revolution led to rapid increase in human population Pop = 3 bill.GR =.1% 4. The Modern era (1960 – present) Rate of population has slowed in wealthy nations but continues to increase rapidly in poorer, less developed nations. Pop. = 7 bill.GR = 1.2%

What will determine the carrying capacity of the Earth?

 Population:  A group of individuals of the same species living in the same area of interbreeding and sharing genetic information.  Species:  All individuals that are capable of interbreeding.  Made up of populations  Population dynamics  The general study of population changes.

 Education  Higher standard of living In advanced, developed or 1 st world countries

 Technological and medical advances

 Wealthier nations  Low growth rate  Long life time  High population of elderly  Fewer children

 Poorer nations  High BR  High DR  Short lifetime  Children are important  Provide care for elderly parents  Help with income  It benefits the parents to have many children

 High birth rate and High death rate  Destabilizing

 Birth rate - # births/1000  Death rate - # deaths/1000  Growth rate – difference b/w BR and DR  Age Structure – proportion of population at each age  CAN HELP DETERMINE:  Current & future BR, DR & GR  Impacts environment  Implications for current & future social & economic conditions

 Pyramid  Column  Bulge  Inverted pyramid

 Population with many young  High BR & DR  Short lifetime  Developing countries

 BR & DR are low  High percent of pop. Is elderly  USA

 An event in the past caused an increase in the BR or DR for some age groups

 Increased elderly population  Lower DR  Long Lifetime  Ex. – Europe/Japan

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 Exponential growth and doubling time  The logistic growth curve  “S” shaped curve that is generated by the logistic growth equation.  A small population grows rapidly  But the growth rate slows down  The population eventually reaches a constant size.  Logistic carrying capacity  The population size at which births equal deaths and there is no net change in population

 Formula used for predicting the time when a current population will double in size

 Migration – immigration & emigration  Generally a small factor in the changes of pop. siz  Births – most significant  Total fertility rate = # of children a woman will bear during her lifetime.  Assumes that conditions of the past will be conditions of the future.

 Availability of birth control  Demand for children in the labor force  Base level of education of woman  Existence of public/private retirement systems  Populations religious beliefs, culture and traditions

 Lower Death Rates  People are living longer  Fewer infant deaths  Due to :  Improved standard of living  Cleaner water  Better sanitation  Dependable food supplies  Better health care

 Demographic transition:  Used to predict population trends based on BR and DR of a particular population  In the model- population growth can reach zero  High BR & DR or Low BR & DR  When a population moves from the first state to the second, it is called Demographic Transition.

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 Stage 1 - Pre-Industrial  Slow GR, High BR and High DR; due to harsh living conditions  Stage 2 – Transitional  High BR, DR has lowered due to better food, water, medicine, healthcare. This allows for rapid growth.  Stage 3 – Industrial  Growth fairly high, BR dropping to near DR. Many developing countries are in this state.  Stage 4 – Post-Industrial  GR approaches zero or below. (ex. Japan, Russia)

 r-adapted species  Rapid growth  Early maturity  Numerous offspring  Short life  No parental nuturing  Adapt to varyied environments  Pioneers (1 st )  Nich generalists  Prey  Low on food web

 K-adapted species  Slow growth  Late maturity  Few offspring  Long life  Parental nurturing  Adaptation to stable environment  Established conditions  Niche specialists  Predators  High on food web

Acute or epidemic disease  Appears rapidly in the population,  Affects a comparatively large percentage of it,  Declines then almost disappears, only to reappear later Chronic disease  Is always present in a population  Typically occurs in a relatively small but relatively constant presentation of the population  Examples include heart disease, cancer, and stroke

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 Maximum lifetime:  The genetically determined maximum possible age to which an individual of a species can live  Life expectancy:  The average number of years an individual can expect to live given the individual’s present age

1. Short-term factors Those that affect a population during the year in which they become limiting 2. Intermediate-term factors Those whose effects are apparent after one year but before ten years 3. Long-term factors Those whose effects are not apparent for ten years Some factors fit into more than one category

 Delay the age of first childbearing by women  Birth control  Biological and Social  Breast-feeding, which can delay resumption of ovulation  Abstinence  Induction of sterility with natural agents  Contraceptive devices  National Programs to Reduce Birth Rates  Formal family planning programs to  explain the problems arising from rapid population growth  Describe the benefits to individuals of reduced population growth.