The Ethnological Society of London (ESL) was a learned society founded in 1843 as an offshoot of the Aborigines' Protection Society (APS). The meaning of ethnology as a discipline was not then fixed: approaches and attitudes to it changed over its lifetime, with the rise of a more scientific approach to human diversity. Over three decades the ESL had a chequered existence, with periods of low activity and a major schism contributing to a patchy continuity of its meetings and publications. It provided a forum for discussion of what would now be classed as pioneering scientific anthropology from the changing perspectives of the period, though also with wider geographical, archaeological and linguistic interests.
In 1871 the ESL became part of what now is the Royal Anthropological Institute of Great Britain and Ireland, merging back with the breakaway rival group the Anthropological Society of London.
At the time of the Society's foundation, "ethnology" was a neologism. The Société Ethnologique de Paris was founded in 1839, and the Ethnological Society of New York was founded in 1842. An earlier Anthropological Society of London existed from 1837 to 1842; Luke Burke who was a member published an Ethnological Journal in 1848.
The Paris society was set up by William Frederic Edwards, with a definite research programme in mind. Edwards had been lecturing for a decade on the deficiency of considering the races as purely linguistic groups. The Oxford English Dictionary records the term "ethnology" used in English by James Cowles Prichard in 1842, in his Natural History of Man, for the "history of nations". The approach to ethnology current at the time of the Society's founding relied on climate and social factors to explain human diversity; the debate was still framed by Noah's Flood, and the corresponding monogenism of human origins. Prichard was a major figure in looking at human variability from a diachronic angle, and argued for ethnology as such a study, aimed at resolving the question of human origins.