A population is defined as a group of organisms that breed with one another and live in the same space. We know that no population stays the same in size but it is important to study the trends in order to plan for the future. We know that a population has certain needs. It appears that the population density, the number of individuals in a given space, is more important for population survival than just the total number of individuals. The higher the population density, the more competition for resources comes into play.
It has been estimated that the world population is increasing by over 80 million each year and will continue to grow at this rate for the next 30 years. If this projection is correct, we will have a global population of 8.5 billion by the year 2030. What will happen to our environment and quality of life?
This is a good time to introduce the Human Population Growth chart. Have the student's brainstorm on reason why such a jump in human population is a relatively new phenomenon.
From: World Population: Toward the Next Century, Washington, DC: Population
Reference Bureau. Copyright 1994. Reprinted with permission.
The brainstorming can bring into play that in earlier times there were many more life hazards such as hunger, accidents and disease to contend with than we now experience. These hazards in earlier times plus a more migratory existence tended to lead to a shorter life.
The importance of agriculture, which began about 10,000 to 12,000 years ago, is also an important concept the student can discuss. Food became more plentiful and available, The nomadic type of life was given up for the farming of the land. Having a more stable food supply and a settled existence not only helped to lower the mortality rate but is believed to be one of the causes for an increased birth rate. Eventually the population increase caused a stain on the available resources and we were right back where we started with a scarcity of food.
The Industrial Revolution again caused a major life style change by using machine power instead of manpower. The introduction of modern farm machinery meant that fewer people were needed to produce food. People began to migrate to where the jobs were more plentiful. Large families were more an expense than help and slowly the birth rate began to decline. This population pattern is known as "demographic transition. This consists of three stages:
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a. Initial Period - High birth rate and high death rate.(Before Industrial Revolution)
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b. Second Stage - High birth rates and low death rates.(After Industrial Revolution)
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c. Third Stage - Low birth rate and low death rate.(Economic growth and education)
The industrialized countries that have gone through these stages of development are called developed countries.
Health research has played and continues to play a major role with population. Educating the population about the importance of cleanliness and sanitation helped increase longevity and decrease infant mortality by eliminating exposure to certain disease carrying organisms. Before the Industrial Revolution people were unaware of relationship between bacteria and disease. The invention of the microscope allowed the discovery of these tiny organisms, which eventually led to the discovery of antibiotics and vaccines.
The increase of population did not always increase at a steady rate. The plague, which eliminated about 1/3 of Europe's population, is the most noticeable event on the "World Population Growth Through History" chart. Exploitation of resources causing social and economic problems, hunger, migration and war are causes for variations in population growth. We say that the "threshold" is reached when these types of actions take place.
If you desire to have your students do a "hands-on" activity to become more familiar with the term "threshold," this might be the time to introduce the CEPUP MODULE "Determining Threshold Limits."
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NEEDS AND DEEDS
The unit now begins to discuss what the human population needs to survive and how some of our deeds will help or hinder survival. As we discuss the various needs and deeds, we must keep in mind that there are a variety ways to look at causes and solutions to environmental problems. Most of us have experienced situations where we wanted to do the "right thing" except it would not be to our advantage and so we rationalized why we did not do the "right thing." Environmental problems are faced with the same dilemmas and an open mind is necessary to properly evaluate each situation. .