Ewan St. John Smith studied pharmacology at the University of Bath before conducting his PhD in the laboratory of Peter McNaughton FMedSci at the University of Cambridge. During this time he became interested in how sensory neurones are activated by acid, which lead to him conducting a postdoc in the laboratory of Gary Lewin in Berlin at the Max-Delbrück Centre for Molecular Medicine to examine the acid insensitivity of naked mole-rats, research that was funded by a research fellowship from the Alexander von Humboldt Foundation. Pursuing interests in the evolution of chemosensing he then spent a year in the laboratory of Niels Ringstad at NYU School of Medicine, with a Max Kade Foundation fellowship, investigating how carbon dioxide activates sensory neurones in the nematode worm Caenorhabditis elegans.