Alfred Russel Wallace (1823-1913) was one of the most important and likeable British scientists of the 19th century. A field researcher of genius, he spent many years in Brazil and southeast Asia, identifying many new species and, independently of Darwin, before developing - in parallel to Darwin - the theory of evolution through natural selection. He effectively created the whole field of 'bio-geography', with the great split between Eurasian and Australasian flora and fauna, which runs through the Malay archipelago, now named the Wallace Line. His research on warning colouration and speciation continues to shape modern research.