John S. Steel practiced as a dentist in West Street, Durban, and was one of the town's prominent citizens for many years. He served on the town council in 1867, 1877-1880, 1882-1884, and 1886-1891. During these years he was active in several local societies devoted to the study of natural history.
Steel was present at the first general meeting of the Natural History Association of Natal, held on 3 February 1868, and at the society's "conversazione" on 13 March that year exhibited land and sea shells. In 1870 he was elected a member of its council, but the society ceased to function during the next year (though it continued to be listed in the Natal and Cape almanacs to 1874). During 1866-1868 he was joint vice-president of the Durban Horticultural Society and by 1871 was still a member of its committee. Around 1870-1871 he served also on the committee of the Natal Agricultural and Horticultural Society, which managed the Natal Botanic Garden in Durban. This society became the Durban Botanic Society in 1883. Steel served as a government representative on the committee of the latter for all or most of the years 1884 to 1904, and perhaps later. In May 1879 he attended the first annual meeting of the Natal Microscopical Society and the next year was elected its treasurer.
Steel collected natural history specimens from an early age and became the leading figure in the movement to establish a museum in Durban. In 1885 he acquired space for a possible museum in the new Town Hall and at a town council meeting in November that year proposed that a committee be appointed to report on the establishment of a museum. This committee, consisting of Steel as chairman assisted by councillors Robarts and Cunningham, recommended later that month that collections of natural history, geology and other specimens be housed in the room set aside for this purpose in the Town Hall, that a museum committee of twelve members be appointed, that the public be invited to donate specimens, and that the town council provide funds to equip the museum room. Steel's own collections found a home in what was named the Durban Public Museum (later the Durban Natural History Museum). As the moving spirit behind the museum movement he was elected president of the museum committee, a position he held until 1908, the year of his death, when he was succeeded by A.D. Millar*. He was also the museum's first honorary curator. After he resigned from this position at the beginning of 1895 the post was filled by John F. Quekett*.