you question is strange in its phrasing, what do you mean?

Being human is not voluntary for anybody, we cannot volunteer our own birth(s) whether we want to be (to exist). Only our parents or scientists can decide or volunteer that on our behalf; for us to exist (to be allowed/permitted to come into existence.

Is being human propulsive? what do you mean? you might possibility say that the urge to reproduce is compulsive and this in itself has a degree of propulsive-ness attached to it, to our behaviour, but we did not volunteer for this condition we possess, that was given to us by, God, Allah, Evolution, Richard Dawkins, Visiting Aliens or the Fairies , it all depends upon your believes. 

We cannot volunteer our own birth(s)<- you may say or write this in either the singular or plural.