Historian Douglas Brinkley, author of "Silent Spring Revolution," discusses American biologist Rachel Carson's work on environmental pollution and the impact her 1962 book "Silent Spring" had on the conservationist movement in the United States during the following decade. He also talks about the leadership of Presidents Kennedy, Johnson, and Nixon on environmental issues and the landmark legislation dealing with conservation that was passed during the 1960s and early 1970s.     Learn more about your ad choices. Visit megaphone.fm/adchoices