Gustaf de Vylder was born in 1827 in Sweden. Originally a surveyor, in 1844 he left this field to start a successful career as a xylographer and writer for several Swedish publishers. He also had a keen interest in natural history, especially entomology, and in 1871 he received a state grant to travel to southern Africa to pursue his studies and collect specimens. He spent two years in South Africa before he traveled to Namibia, establishing himself in Omaruru and collecting natural specimens and ethnographic objects.
Meeting Ondonga King Shikongo sha Kalulu in October 1873, de Vylder wrote in his diary that the ageing king "still looks good; in his young days he must surely have been quite a handsome man. He gave me young men as my companion and gave me the name of 'Okazepeendye' which means 'the scorpion-killer' because of the number of these insects that I have collected. The Damara call me 'Okazepombandye' or 'the jackal-killer' because of the number of these that I have killed." (De Vylder 1998:125) During his time with the Ondonga king and his sons, de Vylder purchased and bartered "ethnographic objects" from the royals. Several of these objects were identified as belonging to king Shikongo, princes Ikukutu and Kambonde.
In November 1874 in Omaruru, Gustaf de Vylder first met a Khoisan boy who would later be adopted by the Swede and given the name Joseph de Vylder.
"In the evening Mr Eriksson and I were sitting at his mother-in-law. He then showed me a Bushman boy who lay sleeping in a box. He had bought this child, who was almost dead from starvation, from a Baster; he had given a rifle for it. A Baster had killed the child's parents, and it had since then gone through many hands. Mr E had bought it only to save it from starvation. Mr Eriksson kindly gave this child to me and my wish to get a Bushman child was thereby granted. Mr E had given a rifle costing £5 for the cild. The child has been given the name Joseph, which suits him rather well as he, in the same manner as the patriarch, had been sold by his brothers. He is of the Onguaoa tribe" (from the published diary of de Vylder, entry 7 November 1874, Omaruru, 1998:218).
Joseph was born around 1868 and de Vylder brought him to Sweden in July 1875. While de Vylder's diary shows that the naturalist had real affection for his adopted son, he also exhibited Joseph as an anthropological specimen at a meeting held at the Swedish Anthropological Society on 16 October 1875 and again at the Royal Academy of Sciences on 20 October 1875 in front of an audience of "several hundred people" (Stockholms Dagblad 20 October 1875; see reports of de Vylder's lectures in the same newspaper on 9 September, 27 October, 4 November, 1875 and in the proceedings of the Anthropological Society, 16 October 1875). Joseph died of tuberculosis on 22 November 1880, in the care of foster parents in the south of Sweden, while de Vylder was on his second journey.
Returning to Sweden in 1875 de Vylder's substantial collections were purchased by Riksmuseet (the National Museum of Natural History). De Vylder returned to South Africa in 1879 and lived and worked there until 1887 when he went back to Sweden. He died in 1908.