Signaling Humanity on The Road

It could be that I'm you're run-of-the-mill, desensitized American male, but I didn't get what the big deal was about cannibalism in Cormac McCarthy's "The Road" when I read it a couple years ago. Watching the movie, though, I had William Flesch's "Comeuppance" in mind, and I saw that there was a struggle, often between father and son but sometimes within each of them, to maintain their humanity in the face of such devastation. I suppose I understood this while first reading the book, but the struggle to remain "strong reciprocators" seemed somewhat beside the point, what with all the grieving and starvation and all. But Papa's and the boy's "carrying the fire" is important precisely because of these difficulties.

One criticism of Flesch's theory keeps rearing its head in my mind (a head rearing in my mind?): costly signaling, like that of the man and his son as they survive while also continuing to be strong reciprocators, is an explanation for many non-adaptive behaviors. But as I look around at the world and see more and more examples of costly signaling I have to wonder, what isn't costly signaling? Is the idea testable? Does incorporating it into the paradigm of natural selection render that theory untestable? The problem here is that costly signaling is too broad of a concept, one whose precise mechanics I've yet to see spelled out.