Latham was more interested, however, in ethnology and philology. In 1849 he abandoned medicine and resigned his appointments. In 1852 he was given the direction of the ethnological department of
The Crystal Palace, as it moved to
Sydenham. Latham was a follower of
James Cowles Prichard, and like Prichard took ethnology to be, in the main, the part of
historical philology that traced the origin of
races through the genealogical relationships of languages. He frequently lectured in this area. As a baseline he used the three-race theory of
Georges Cuvier. Along with Prichard, however, Latham criticised Cuvier's use of the "
Caucasian race" concept; and he preferred to avoid the term "race", referring instead to "
varieties of man", as a reaction to the rise of
polygenist theory around 1850. However, he followed in 1854 by writing
The Native Races of the Russian Empire. Latham moved on, though, from Prichard's assumption (now sometimes called "languages and nations"), that the historical relationships of languages matched perfectly the relationships of the groups speaking them. In 1862 he made a prominent protest against the central Asian theory of the origin of the
Aryan race. He supported views which were later advocated by
Theodor Benfey, Parker,
Isaac Taylor, and others. The controversy over Latham's views on Indo-European languages following his
Comparative Philology (1862) did permanent damage to his scholarly reputation. ==Later life==