Are Humans Hardwired for Fairness?

Saw this article about why people turn down economically beneficial windfalls when they think they're being misteated. We talked about the irrationality of these decisions in upper-level economics classes a decade ago. Now those conversations are everywhere.

But this is interesting. From the article Are humans hardwired for fairness? in the journal Psychological Science. The Money Quote -

[T]he brain finds self-serving behavior emotionally unpleasant, but a different bundle of neurons also finds genuine fairness uplifting. What’s more, these emotional firings occur in brain structures that are fast and automatic, so it appears that the emotional brain is overruling the more deliberate, rational mind. Faced with a conflict, the brain’s default position is to demand a fair deal.

I wonder what that "fast and automatic" part of the brain is and why they contrast it with "deliberate and rational" parts of the brain. I've sent an inquiry to the authors of the article to find out and to fins out if deliberate (read slow) always goes hand-in-glove with rational. Are there any automatic but rational parts of the mind?

Nitpick: What does "[T]he brain finds self-serving behavior emotionally unpleasant" mean? Metaphor gazing is one thing, but does the brain itself conclude things? Do you find that phrasing, at the least, incomplete? How much of the brain has to be involved before you can say with authority, "the brain finds" something? Is there a difference between me finding something unpleasant, and my brain doing so? Is one the intermediate step to the other? And if so, which comes first?