It's a type of natural selection called "group selection", and it's taboo, because it's very tempting to invoke it to explain away all sort of apparent paradoxes - but it requires very tricky circumstances to work at all, if it even can, and it's rare for the explain-away-ers to bother to show why it works in their particular instance.
You're confident, but evolutionary biologists largely don't agree with you. I strongly recommend you glance over some of the reasons why at the Wikipedia article: https://en.wikipedia.org/wiki/Group_selection
In a nutshell - "The problem with group selection is that for a whole group to get a single trait, it must spread through the whole group first by regular evolution... a group where altruism was universal would indeed outcompete a group where every creature acted in its own interest, so group selection might seem feasible; but a mixed group of altruists and non-altruists would be vulnerable to cheating by non-altruists within the group, so group selection would collapse."
