Earth does not need us, we need Earth for we have no other place in the universe to go. Earth will continue to live and thrive with or without us. Even if humanity were to destroy itself in a nuclear war, Earth will spring back to life within a matter of few thousand years. While modern science talks and works towards "controlling nature", the ancient vedic science talks about "milking the nature" without harming it in any way.
What is an Antigen? The human immune system will attack any foreign substance entering the body by generating antibodies which will attack and destroy them. Hence, these substances which trigger antib.