"Jocko Homo" is the B-side to Devo's first single, "Mongoloid", released in 1977 on Devo's own label, Booji Boy Records and later released in the UK on Stiff Records. The song was re-recorded as the feature song for Devo's first album, Q: Are We Not Men? A: We Are Devo! on Warner Bros. Records in 1978. The original version peaked at #62 on the UK Singles Chart. It is based on a chant from the 1932 movie Island of Lost Souls. "Jocko Homo" introduced the call-and-response "Are we not men?" / "We are Devo", and is generally considered to be Devo's anthem. The title is taken from a 1924 anti-evolution tract called Jocko-Homo Heavenbound by B. H. Shadduck, where it is explained as meaning "ape-man". The song revolves around an idiosyncratic descending guitar riff and absurdist lyrics.

The song's verses primarily concern themselves with the satirical view of devolution, noting foibles in human society. Most versions include a bridge that begins with "God made man, but he used the monkey to do it..." This is a response and reference to the Uncle Dave Macon song "The Bible's True" (1926), an anti-evolution song. The song also contains several call and response choruses, including the repeated chant "Are we not Men? / We are Devo!" "Jocko Homo", in its variations, has also contained other chants between the main verses and the closing chant. These include "We Accept You / We Reject You / One of us! One of us!" (a reference to Tod Browning's Freaks) and "I've got a rhyme that comes in a riddle / O-Hi-O! / What's round on the ends and high in the middle? / O-Hi-O!", which references Devo's home state of Ohio.

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