"The lymmes of generacion were shewed manyfestly." [Caxton, "The subtyl historyes and fables of Esope, Auyan, Alfonce, and Poge," 1484]Hence, limb-lifter "fornicator" (1570s). To go out on a limb in figurative sense is from 1897. Life and limb in ref. to the body inclusively is from c.1200.
"Midway Signs Limey Prof to Dope Yank Talk" ["Chicago Tribune" headline, Oct. 18, 1924]