Philip Giltner Miles was born on 10 August 1922 in Olean, New York. After attending the Lawrenceville School, Miles served in the Army Air Corp for three years during World War II. In 1948, he earned his Bachelor of Science degree at Yale University, where he played basketball and tennis. Miles completed his Ph.D. in Botany in 1953 at Indiana University.

The University of Chicago employed Miles as a research associate from 1953-1954, when he left to accept a research fellowship at Harvard University. While at Harvard, Miles met John "Red" Raper, a longtime friend and collaborator, who was a strong influence on Miles' decision to research in the field of experimental mycology.

In 1956, Miles left Harvard and joined the faculty of the Biology Department as an assistant professor. From 1968-1969, Miles was co-chair of the department and became full chair in 1972. In 1974, the Biology Department was split into two divisions: the Biology Division and Division of Cell and Molecular Biology. Miles served a director of the Biology Division from 1974-1976. As a leader in the department/division, Miles helped to develop the curriculum still used.

Miles was a part of the University as both a private and public institution. Throughout his tenure he was involved in numerous University and Faculty of Natural Sciences and Mathematics committees. He was active in the faculty senate and was an advisor to the student senate. Miles was passionate about his obligation to teach students, even when it restricted his research. He was much loved by students and continued teaching classes after his official retirement in 2002.

Outside of the University, Miles frequently traveled to Asia to pursue his research. In 1963, Miles traveled to Okayama Japan as a Fulbright Research Scholar and obtained similar grants-in-aid for other trips. Miles' has taught and conducted research at Okayama University (Okayama, Japan), National Taiwan University (Taipei, Taiwan), Academia Sinica (Taipei, Taiwan), Tottori Mycological Institute (Tottori, Japan), Chinese University of Hong Kong, and other academic and research institutions. On these trips Miles' lectured and gave workshops on mushroom cultivation and basic mycology.

In other professional activities, Miles was as committed to his field. He served as editor for the Mushroom Journal of the Tropics, Micologia Neotropical Applicada, and Micologia Applicada Internatal. Miles also served as President of the World Society of Mushroom Biology and Mushroom Production. In 1998, he won the State University of New York Chancellors Award for Excellence in Teaching, in addition to other teaching awards.

Miles died on 13 July 2007 at the age of 84. He was survived by his wife, Eleanor (Allen); two sons, Philip G. Jr. and Allen R.; and a daughter, F. Curtis.