Not only are we physically dependent, but spiritually dependent as well. Today there are close to 6 billion people on the planet. Like all populations, people are limited by the available resources and like all ecosystems where a population exists, the earth has limited resources. In the last two hundred years we have multiplied exponentially and our demand on the earth's resources has expanded beyond capacity. In many cases we have passed the point of no return and have lost thousands of plant and animal species to extinction.
Today there are thousands more tettering on the brink.
We will loose them too if we do pull back on our excessive lifestyles and face our past with honesty and begin to pay the piper. HERE if you want to understand a little about the ecological principles behind these effects. In general these activities cause the extinction of species and we are at the helm. The prime cause for excess in these destructive activities is the consumer orientated society of the developed world. If you took away the populations of Asia and Africa and even the Soviets we would be facing the same problems.