Did the CAN bus standard evolve from something else?

[e100]

Whilst pondering the timing and cable length limitations associated with the in-frame ACK system I tried searching for the history of the CAN bus standard and the web just kind of says it was invented as a brand new thing in 1986.

Is that the whole story or did it evolve from something else, and was the use of an in-frame ACK system a completely novel idea at the time?