Volition has been debated for thousands of years:  what is it, how is it possible for biophysical beings to behave in a voluntary manner, indeed, does volition exist?  Evolution of volition has rarely been part of the discussion.  In this paper, I argue that operant-conditioning studies provide evidence for evolved volition.  Three attributes are common to operant and voluntary behaviors.  One is that responses are goal-directed, purposeful, some say rational, or controlled by reinforcing consequences.  A second is that the responses vary – from random-like to repetitive – with predictability (or unpredictability) depending upon contexts and consequences.  A third attribute is that responses appear to be self-generated or, in operant terms, emitted.  These attributes are found in many species, simple to complex, but species also differ in details.  Taken together, the evidence supports an evolutionary basis of volition.