Stephen Vickers Boyden was a human ecologist, immunologist and author who was born on 8 February 1925 in Croydon, United Kingdom and died on 26 December 2025 in Canberra, Australia, aged 100.[1][2] In 1947, he graduated in veterinary medicine at the Royal Veterinary College in London, worked at the University of Cambridge and the Rockefeller Institute in New York.[1][2] In 1951, he received his PhD in immunology from the University of Cambridge under Ian Beveridge and introduced the "tanned red cell" method for antibody titration, which is the most sensitive and widely used.[1][2] He worked for a year at the Pasteur Institute in Paris and then for eight years in Copenhagen as head of the WHO Center for Research on Immunization against Tuberculosis.[1][2] From 1960 he worked at the John Curtin School of Medical Research at the Australian National University in Canberra, where he invented the Boyden chamber to study chemotaxis.[1][2] In the 1970s, he directed the Hong Kong Human Ecology Program, the first comprehensive ecological study of the metropolis.[1][2] He developed the concept of biohistory, which examines the interplay of biological and cultural processes in human history, estimating that the ecological impact of humans has increased ten-thousand-fold since the beginning of history, mostly in the last century.[1] He was Professor Emeritus of the ANU, Fellow of the Australian Academy of Science (FAA), Royal Society of Arts (FRSA), awarded Membership of the Order of Australia (AM) in 1998 and the Centenary Medal in 2001.[1][2]