Dogon people
His early books on the subject of extraterrestrial life and interstellar travel – "Worlds Beyond" (1975), "Messages from the Stars" (1978) and "Life off Earth" (1983) – led him to investigate UFOs. But he became a sceptic, a position reinforced by his findings about the Rendlesham case. He was one of the first to offer an explanation for the so-called Sirius Mystery involving the supposedly advanced astronomical knowledge of the Dogon people of Mali, west Africa.