Turnbull first became interested in African ethnology on a motorcycle trip in 1951 during which he viewed East Africa, the Congo, the Sudan, and Egypt. It was on this trip that he first visited the Pygmies. He then met the BaMbuti tribe, which he considered to have social institutions more humane and more sophisticated the ones that were practiced in western civilization. The people lived in peace not because they were ordered to by the laws, but because of their wish to be united and to be treated equally amongst themselves.
Later on in his life, in 1959, he met his partner Joseph Towles, with whom he exchanged marriage vows the following year. After his partner’s death, Turnbull donated all his research to the College of Charleston, and he insisted that this donation was to be named only after Towle’s name alone. He then died in Virginia in 1994 due to a complication of AIDS just like his partner.