HUMAN POPULATION CRISIS
If you were to take a standard sheet of writing paper .1mm thick and cut it into two sheets, placing one atop the other, it would then be .2mm thick. Cutting the stack of two and making a stack of 4 sheets, it would then be .4mm thick. Believe it or not, if you continued to do this just one hundred times, doubling the size of the stack each time, the thickness of the stack would be 1.334 x 1012 light-years. This is an example of exponential or geometric growth, where the rate of growth is always proportional to it's present size.
Exponential growth has also applied to the the human population. The population began growing very slowly, but over generations our growth rate has increased more and more rapidly, similar to a snowball affect. It took the human population thousands of years to reach 1 billion in 1804. However, it took only 123 years for us to double to 2 billion by 1927. The population hit 4 billion in 1974 (only 47 years), and if we continue at our current rate, the human population will reach 8 billion around the year 2028. Doubling from our present count of 7 billion to 14 billion will have a much greater impact than our last couple doublings combined.
Overpopulation isn't just population density (amount of people per landmass). Overpopulation applies much more so to the number of people in an area exceeding the resources and the carrying capacity of the environment necessary to sustain human activities. So much focus is placed on the rapid population growth in third world countries. However, when we compare lifestyles of the rich countries vs. the poor countries, the rich countries are a much greater problem. For example, Americans constitute less than five percent of the world's total population, but consume 26% of the world's energy. Just as much as the population size, we need to consider the resources consumed by each person, and the damage done by technologies used to supply them. Overpopulation is when the number of people can not be permanently maintained without depleting resources and without degrading the environment and the people's standard of living. Because we are rapidly using up resources around the world, virtually all nations are overpopulated. This applies even more so to the rich nations. As we use up the resources, the earth's carrying capacity continues to decrease.
Just like with people, an overpopulation of animals is not defined by the number of animals that could hypothetically fit within a specific area, but rather when the number of animals that occupy their habitat are not capable of behaving as they naturally would. Unfortunately, the animals' behavior is often altered not so much by their number, but by humans encroaching upon their habitat and then claiming the animal to be a nuisance to man. We should practice the saying "live and let live", but we do not have the resources to do this while our number continues to increase.
Lifespan/Quantity vs. Quality
Nature is a balance of existence. In order to coincide with nature, we must balance the number of lives which we produce with the saving and extending of lives. We mustn't use resources any faster than they can be reproduced. We need to respect ourselves by learning to respect the environment which we rely upon for our own existence. If not, we will cease to exist.