The Oxford English Dictionary defines “freak of nature,” as meaning an “abnormally developed individual of any species”. According to the OED, 1847 is the year that "freak of nature" enters common parlance.  That very same year, the periodical Punch identified a growing popular demand for living curiosities. Under the heading “The Deformito-Mania,” Punch bemoaned the public’s “prevailing taste for deformity, which seems to grow by what it feeds upon” (90).

Sources: 

http://www.branchcollective.org/?page_id=68

Durbach, Nadja. “On the Emergence of the Freak Show in Britain.” BRANCH: Britain, Representation and Nineteenth-Century History. Ed. Dino Franco Felluga. Extension of Romanticism and Victorianism on the Net. http://www.branchcollective.org/?ps_articles=art_emergence_of_the_freak

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