Born in Dublin on 19 January 1845, he was second son of Henry Yeo of Tansey, Ceanchor Road, Howth, J.P., clerk of the rules, court of exchequer, by his wife Jane, daughter of Captain Ferns.
Yeo was educated at the Royal School Dungannon, and at Trinity College Dublin, where he graduated moderator in natural science in 1866, proceeding M.B.
In 1868 he gained the gold medal of the Dublin Pathological Society for an essay on renal disease.
[1] Yeo worked with David Ferrier, a fellow professor of neuro-pathology at King's College, on cerebral localisation in monkeys.
Yeo was known from 1875 as the first secretary of The Physiological Society, originally a dining club, but with a purpose of thwarting antivivisection campaigners; he resigned in 1889.
[5] Ferrier was taken to court under the Act in 1881, but was acquitted, having testified that he only witnessed procedures carried out by Yeo.