Ecology is the fundamental backbone of environmental science and the natural component. Environmental science is the integration of ecology and human social sciences. Rachel Carson was an oceanographer. She noticed the woods were getting quieter and wrote Silent Spring, a book about the lost of birds due to the effects of DDT. The precautionary principle is the idea that new substances or nature modification techniques should be avoided if they are not understood or slightly worrisome. The idea is that unintended consequences are common and it is better to avoid them if at all possible.