American Cyanamid biochemist Robert White-Stevens and former Cyanamid chemist Thomas Jukes were among the most aggressive critics, especially of Carson's analysis of DDT. According to White-Stevens, "If man were to follow the teachings of Miss Carson, we would return to the Dark Ages, and the insects and diseases and vermin would once again inherit the earth". Others attacked Carson's personal character and scientific credentials, her training being in marine biology rather than biochemistry. White-Stevens called her "a fanatic defender of the cult of the balance of nature", while former U.S. Secretary of Agriculture Ezra Taft Benson in a letter to former President Dwight D. Eisenhower reportedly said that because she was unmarried despite being physically attractive, she was "probably a Communist".