Reynolds, an only child, was born Earl Frederick Schoene to William and Maude Schoene as the circus of which they were a part passed through Des Moines, Iowa. Earle's father and uncle Frederick performed as The Landry Brothers, trapeze artists and tightrope walkers for the John T. Wortham Shows (also known as John T. Wortham Carnival). Billboard noted, "The Landry Brothers work a neat and classy rope acrobatic turn for six minutes, in full stage, which brought the brawny lads one legit.". Before World War I made German names unpopular, according to Reynolds, the pair were billed as Schoene Brothers Aerial Artists. Depending on the season and the family's financial status, their circus acts alternated with vaudeville.
Earl took his stepfather's surname, added an "e" to his first name, earned the rank of Eagle Scout and graduated from Vicksburg High School in 1927. He went on to earn his BA and MA from the University of Chicago and his Ph.D. from the University of Wisconsin, all in Anthropology. He married Barbara Leonard in 1936 and they had three children: Tim (1936), Ted (1938), and Jessica (1944). From 1943 to 1951 Reynolds was Associate Professor of Anthropology at Antioch College and Chairman of the Physical Growth Department at the Fels Research Institute for the Study of Human Development, also at Antioch College.
In 1951 Earle joined the Atomic Bomb Casualty Commission (ABCC), established under the direction of the National Research Council's Division of Medical Sciences in March 1947. He was sent to Hiroshima to research the effects of radiation from the first atomic bomb on the growth of Japanese children. From 1951 until 1954 Earle completed the first of a series of longitudinal studies meant to be resumed after a one-year sabbatical. He wrote up his findings as "Report on a Three-Year Study, 1951-2-3, of the Growth and Development of Hiroshima Children Exposed to the Atomic Bomb, 1954." In summary he had found children exposed to radiation to be smaller than their counterparts with lowered resistance to disease and a greater susceptibility to cancer, especially leukemia. Because strontium-90 (produced by the atomic bomb) seeks the same areas of the bodies of growing children as calcium, such as the thyroid gland, children exposed to the bomb were also subject to thyroid cancer.
While in Japan, Reynolds designed and had built a yacht of 50 feet (15 m), the Phoenix of Hiroshima. From 1954-58 he, his wife Barbara, son Ted (16), daughter Jessica (10), and three young Japanese men from Hiroshima, Niichi ("Nick") Mikami, Motosada ("Moto") Fushima and Mitsugi ("Mickey") Suemitsu, sailed around the world.
The building of the boat took 18 months, one year longer than had been previously expected. The first leg of the voyage, from Japan to Hawaii, took 48 days.
In Honolulu for the second time, what had been a pleasure cruise took a serious turn. Across the dock from the Phoenix was a ketch of 30 feet (9 m), the Golden Rule. Its crew, four Quaker pacifists, Albert Bigelow, George Willoughby, Bill Huntington and Orion Sherwood were attempting to sail to the Marshall Islands to protest the United States' testing of 35 nuclear devices there. An injunction against American citizens entering the test zone was passed after the Golden Rule left port and it was brought back by the Coast Guard. Impressed by the reasoning and character of these men, Earle and Barbara joined the Society of Friends (Quakers) and considered taking over their protest in the Phoenix.
Reynolds was at that time one of the world's experts on the effects of radiation. In determining whether to deliberately enter the test zone, he considered a number of factors, such as the effects the radiation from the series of nuclear tests would have on the world environment, specifically increasing incidents of cancer, and the effects of this additional radiation on the Hiroshima and Nagasaki population, since both wind and ocean currents from the test site would carry radiation that direction. He considered unconstitutional the United States government's injunction declaring 390,000 square miles (1,000,000 km2) of ocean off-limits to American personnel during the series. Also, the forbidden zone blanketed any route by which the Reynolds family could conveniently sail back to Japan, as they had hoped to do as soon as possible to complete the circumnavigation. In addition, as the Marshall Islands were a Trust Territory of the U.S., Reynolds objected to the forced removal of Marshallese from their home islands for the purpose of detonating weapons which would almost certainly render their islands uninhabitable for years to come.
Earle, Barbara, Ted (20), Jessica (14) and Mikami cleared "for the high seas" on June 11, 1958. The family had not decided whether or not to enter the forbidden zone but Mikami, whose mother and brother had been in the bombing, never wrestled with the question. For days after the nuclear weapon was dropped, his mother had crawled through the radioactive rubble, searching for her brother-in-law. She never found his body.
By July 1, at the edge of the invisible perimeter of the zone, everyone came to a consensus. Earle announced by radiotelephone, on the international frequency for ships at sea, "The United States yacht Phoenix is sailing today into the nuclear test zone as a protest against nuclear testing..."
The next morning, 65 nautical miles (120 km) inside the forbidden zone, the Phoenix was intercepted and stopped by the American Coast Guard cutter Planetree. Two armed Coast Guard officers jumped aboard and put Reynolds under arrest. He was flown back to Honolulu for trial. A jury convicted him of entering a forbidden area. The sentence was overturned on appeal.
Within 19 months Earle and his family were involved in another protest voyage. With the Pacific Ocean again open to American citizens, they sailed without incident back to Hiroshima.
In October, 1961, the USSR resumed its own nuclear testing. The Reynolds family plus Tom Yoneda sailed to Nakhodka in protest (The nearest military port, Vladivostok, was inaccessible in winter).
In 1962, Reynolds was invited to captain the Everyman III, on which members of A Quaker Action Group (AQAG) sailed from London to Leningrad via Belgium, the Netherlands, Germany, Denmark, and Sweden. This boat of 48 feet (15 m), too, was stopped at sea by armed soldiers. This time the crew were tied up with ropes. That same year, Reynolds and Professor Tatsuo Morito of the University of Hiroshima co-founded the Hiroshima Institute of Peace Science (HIPS). Reynolds became a spokesman for the Japanese peace movement and attempted to work with its Gensuikyo branch until he found it too political for his taste, reporting to the press, "Peace cannot be achieved in an atmosphere of hatred."
Earle and Barbara divorced in 1964 and Earle married Akie Nagami, a citizen of Hiroshima and a graduate of Hiroshima Women's College where Earle was guest Professor of Anthropology. Together Earle and Akie continued his voyages in the Phoenix. In 1967 a multi-national crew delivered nearly a ton of medical aid to the Red Cross Society of North Vietnam for civilian victims of the Vietnam War. They spent eight days visiting hospitals in Hanoi and Hai Phong and observing the effects of American bombing on outlying villages. Two other voyages to Vietnam followed.
Earle and Akie made two attempts to sail the Phoenix to Shanghai as a gesture of "friendship and reconciliation" from an American and a Japanese citizen to the people of China, although the Japanese government refused to grant Akie a passport on the grounds China and Japan had no diplomatic relations. In 1968 the Phoenix was stopped on the high seas by a Japanese ship. Two years of litigation followed in Japanese courts. In 1969, with a crew of six Americans, the Phoenix was stopped 20 nautical miles (37 km) offshore by Chinese authorities and their entry was prohibited.
After these attempts to sail to China, the Japanese government passed a new immigration law cracking down on "undesirable aliens" (1970) and Reynolds was expelled from his adopted country of 13 years. He and his wife sailed to San Francisco and settled in Ben Lomond, California. He taught Peace Studies at the University of California at Santa Cruz and at Cabrillo College while Akie earned an MA in Peace Studies from Antioch College and worked as a career counselor at UCSC, specializing in peace-making careers and in placing students in overseas jobs. His seminar class founded the Peace Resource Center at Merrill College on the UCSC campus in 1975 but it became a casualty of financial cutbacks in the 1980s. Over a two-week period in 1981, 1900 activists were arrested at Diablo Canyon Power Plant. It was the largest arrest in the history of the U.S. anti-nuclear movement and against nuclear weapons research. Reynolds was one of those arrested.
In a 1986 interview, Earle commented on his life work: "I've been a kind of a renegade scientist. As soon as I stepped over the boundaries, as soon as my findings became politically sensitive, I lost my credibility as a scientist. Now a scientist will stand on a podium and say what I was saying 30 years ago. I'm like a voice in the wilderness that finally begins to hear answering voices."