"Chameleon" (Herbie Hancock)

Until his Head Hunters album in 1973, Herbie Hancock mostly had been known for his bop and modal jazz work with his own bands and with Miles Davis.  He'd flirted with electronic instruments and funkier sounds on several experimental albums in the late 60s/early 70s.  But on Head Hunters, he went headlong into electric funk, inspired by the copious amounts of James Brown and Sly & The Family Stone that he was listening to in those days and transcendental meditation.  
Hancock recalls his decision to move toward funk in Chris Smith's 101 Albums That Changed Music (2009). "I was beginning to feel that we (the sextet) were playing this heavy kind of music, and I was tired of everything being heavy. I wanted to play something lighter."
As reedist Bennie Maupin recounts to author George Cole in The Last Miles (2007), the track "Chameleon" developed out of jam sessions that led up to the recording of the album:

"My participation was the little horn melody.  I had gone to a Wattstax concert…During the course of the afternoon, people would get up and dance. There was this dance that became popular called the "Funky Robot," and I was watching the kids doing it. I was studying the body movement and looking at the rhythm, and some patterns start coming into my head. So when we got back to the studio, somehow that stuff started coming out. We had the tape on and during a break.  We listened back, and it was pretty much by consensus that we should take a closer look at this one theme!” 

The name "Chameleon" ostensibly comes from the fact that the song, like a chameleon, changes in color and texture as it goes along, starting off as hard funk, transitioning into a hustling, bop-influenced jazz jam, and then transitioning back to the hard funk theme before fading out.
Probably the most famous part of the song is Hancock's keyboard bassline, played on an ARP synthesizer—the kind that Stevie Wonder was using on hits like "Superstition" about the same time.  But the equal contributions of drummer Harvey Mason, bassist Paul Jackson, and Maupin make the track the fluid, booty-shakin' jam that it is (which is why Hancock credited the song to the entire band).