This strikes me as the old nature vs. nurture debate - trying to determine which human behaviors are hard wired and which are learned. Like most complex questions I don't think there is a single right answer, but my current theory is that humans have more hard wired behavior than most people like to admit. It is precisely because of our language skills that we can rationalize behavior that has it's root cause in the more animal regions of the brain.

To put it another way - most people think they are rational. Most people act irrationally. To me it is animal instinct that is cause of greed, war, social hierarchy, etc. and it is so ingrained in society that we don't question it's root cause which most likely boils down to atavistic tendencies.

To me this fall in the reptilian reflexes box. Accelerating signal related to increasing proximity => act.