Thomas Henry Huxley PC FRS FLS (4 May 1825 – 29 June 1895) was an English biologist (comparative anatomist), known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution.Huxley's famous debate in 1860 with Samuel Wilberforce was a key moment in the wider acceptance of evolution, and in his own career. Huxley had been planning to leave Oxford on the previous day, but, after an encounter with Robert Chambers, the author of Vestiges, he changed his mind and decided to join the debate. Wilberforce was coached by Richard Owen, against whom Huxley also debated about whether humans were closely related to apes.Huxley was slow to accept some of Darwin's ideas, such as gradualism, and was undecided about natural selection, but despite this he was wholehearted in his public support of Darwin. Instrumental in developing scientific education in Britain, he fought against the more extreme versions of religious tradition.In 1869 Huxley coined the term 'agnostic' describing his own views on theology, a term whose use has continued to the present day (see Thomas Henry Huxley and agnosticism).Huxley had little formal schooling and was virtually self-taught. He became perhaps the finest comparative anatomist of the latter 19th century. He worked on invertebrates, clarifying relationships between groups previously little understood. Later, he worked on vertebrates, especially on the relationship between apes and humans. After comparing Archaeopteryx with Compsognathus, he concluded that birds evolved from small carnivorous dinosaurs, a theory widely accepted today.The tendency has been for this fine anatomical work to be overshadowed by his energetic and controversial activity in favour of evolution, and by his extensive public work on scientific education, both of which had significant effects on society in Britain and elsewhere.