Isn't this backwards a bit or did I get it wrong - not sure if I am phrasing this right. But to simplify from a laymen's perspective a reading of The Selfish Gene - all creatures will work to continue their genetic line unless misdirected as you describe. So if in some way continuing their genetic offspring is something that activates their opioid receptor, that's what we'll do, creating and raising offspring or as grandparents/cousins/aunts/uncles, helping raise relatives. This can be applied generally to all life on earth.
Successful propagation strategies propagate, and therefore become prevalent. Life has no goal; it doesn’t try to propagate. It’s just the result of an evolved process that happens to correlate strongly with propagation. Most processes in organisms have an arbitrary first order objective like getting those happy chemicals. The fact that these first order objectives have a second order effect of survival and reproduction is a wholly unsurprising coincidence.
