Rev. David Duckworth Fraser was educated at the Free Church Training College and Andersonian University in Glasgow, Scotland, during the mid-1850s. After some time as commercial master at the high school in Inverness he taught mathematics at the Academy at Rothesay, Scotland. He came to the Cape Colony in June 1873 to become headmaster of the first-class undenominational public school in Bedford, Eastern Cape. From 1876 to 1880 he was captain of the Bedford volunteers, and for some time served on the committee of the local library. From the beginning of 1891 he was appointed deputy inspector of schools in the Department of Education of the Cape Colony, stationed in Port Elizabeth. He remained in this post to 1902, the year before his death.
Following a proposal by Dr John Shaw* in January 1888, the South African Geological Association was formed in Grahamstown in June that year. The founding meeting took place just after the annual Teachers' Conference had ended in Grahamstown, to enable more persons to attend. Reverend Fraser, who had just been elected president of the South African Teachers' Association for 1888/9, was in the chair and was elected as a member of the new association's committee. One of his sons, David Duckworth Fraser junior*, was also a foundation member. At the inaugural meeting Reverend Fraser delivered the first paper, "Sketch of the geology of the Division of Bedford", in which he described his observations of the volcanic intrusions (and the heavy metals contained in them) and the sedimentary rocks of the upper Karoo beds, with particular reference to the shell and plant fossils he had found. Many of his observations were said to have been checked by his son. The plant fossils were donated to the Albany Museum, for such a donation was briefly mentioned by the museum's Director, S. Schonland* in 1893. The Frasers had also collected rock specimens, which they donated to the museum in 1887. Reverend Fraser remained an active member of the association throughout its short life, attending the annual meetings in 1889 and 1890. At the latter he was elected its president.
The annual meetings of the South African Geological Association were held immediately after the annual Teachers' Conference. Following his year as president of the South African Teachers' Association Reverend Fraser served as vice-president for 1889/90. At the Teachers' Association's meeting in Port Elizabeth in 1890, following the sudden death of president-elect Dr John Shaw, he was elected president for 1890/1. His contributions to teaching included the publication Test exercises in the colonial weights and measures. A handbook to the arithmetic of the fourth standard (Cape Town, 1890).
In February 1891 Reverend Fraser and his son both became members of the Eastern Province Naturalists' Society (Port Elizabeth, 1884-1923). Two years later, in February 1892, the father chaired one of its meetings. In 1893 one or both of them donated Glossoptera and other fossil plants from the lower Beaufort beds at Bedford to the British Museum (Natural History).
Fraser was married to Margaret, born Taylor, with whom he had two sons and two daughters.