Ralph D. Hermansen had a 40-year career in materials science and engineering. He has worked on many diverse engineering projects, including an atom smasher, classified weapons programs, design of the Boeing 737 and 747 airplanes, military aircraft and their electronic platforms, space satellites, missiles, automotive electronics, and telephony and other commercial applications. He planted his roots with Hughes Aircraft Corporation in his later career and eventually retired from there as a Senior Scientist. Career-wise, he has contributed numerous technical articles to journals and magazines, has 21 patents, and has several published books related to his career field. One of his most recent is Polymeric Thermosetting Compounds, available from Apple Academic Press. Ralph adopted a second career path after retiring in 1998, that of multidisciplinary science writer. His primary focus has been evolutionary science, which is incredibly diverse. Ralph's goal in writing Down from the Trees was to help curious readers learn the facts in plain language without battling the jargon and see that our prehistoric past is fascinating and filled with unsolved puzzles.