- There are over 6 billion people on the planet.
- They are unevenly distributed
A Brief History of Human Population Growth
- Humans became successful at hunting about 100 000 years ago.
- At about 12 000 years ago humans populated all major landmasses except the Antarctica.
- The population at that time was probably 5 million.
- Being a hunter-gather made it difficult for the population to increase since they had a nomadic lifestyle.
Seeds and Breeds of Change
- Wheat and oats were first cultivated about 10 500 years ago.
- Rice became domesticated in China about 9 500 years ago.
- corn was cultivated in Mesoamerica (Central America)
- Domestication of sheep, goats and pigs occurred in 10 000 years ago, cattle 8 000 years ago, and horse 6 000 years ago.
- Adopting agriculture practices affected human population because it made them stationary.
- It was now possible to have large families, and individuals were able to become specialized in the workplace (artisans, scholars, and merchants).
- There is an uneven distribution of wild plants and animals and not all species can be domesticated.
- The distribution of these species determined which human populations had an opportunity to switch to agricultural practices and the advantages of that lifestyle
- Epidemic diseases spread rapidly through large populations and occur where population densities are high.
- Some diseases originated in domestic animals then evolved into those that could infect humans.
- Populations that were continuously exposed to diseases were able to develop some resistance to them.
- Even with all the deaths from diseases, the population reached 500 million in 1650.
The Impact of Science and Medicine
- Modern medicine developed in the 1600’s due to the cell and germ theories.
- The Industrial Revolution allowed for the mass production of industrial and consumer goods.
- The creation of fertilizers increased food production.
- The steam engine and combustion engine led us into the modern world.
- The population became more urbanized, and the death rates dropped with improved water quality, and the use of vaccines.
- This lead to the human population explosion, doubling every 50 years (see Table 5 on pg. 703)
- Demography is the study of human populations.
- Birth rates have remained stable to 25 births per 1000 individuals per year.
- Death rates have dropped to 13 deaths per 1000 individuals per year.
- This results in 1.6% average growth rate; 96 million people per year with a doubling time of 43 years.
- Differences in growth rate can be accounted for the age structures.
- United States exhibits zero population growth as individuals are evenly distributed throughout all ages, while Kenya is experiencing a growth momentum, where there are many young people.
The Demographic Transition Model
- When populations move from agricultural production to industrial the population size increases.
- A highly industrialized and economically secure country experiences a decrease in growth rate.
- Countries that are developing an industrial economy will experience a rapid population growth.
2. In the transitional stage there is a drop in death rates, but births remain high, so population size increases.
3. In the industrial stage populations stabilize as births decline.
4. In the postindustrial stage a zero population growth is experienced, where the birth and death rates are in balance.
- The gross national product is the total value of all goods and services produced by a country in a year.
- The more industrialized a country the higher is its GNP.
- Industrialized countries show an increase in average life expectancy due to the overall reduction of mortality among all ages.
- Even with the development of science and technology there are still 10 million children who die every year from preventable diseases and malnutrition.
- Countries that have the greatest life expectancy also have the lowest growth rate.; as we see in Canada.
- The average human life span has increased by 30 years in the past century alone.
- Currently 1 in 10 people are over 60, and this number will increase to 1 in 5 by the year 2050.
- This will have implications on pension and health care systems.
- The human population has increased from 70 million a year to 90 million per year.
- It is predicted that the world's population will peak at 9 billion by the year 2070 and will start to decline.
- Some believe that even if populations stabilize, individuals are still continuing to consume more than the Earth's carrying capacity
- Individuals in North America place a greater demand on Earth's resources than most other individuals on the planet.