I like the story, but (spoilers):
Surely the central premise is not true in our world? Many animals are kind to non-kin, and this seems to continue alongside increased animal intelligence. I don’t see why the default path to higher intelligence would not look like homo sapiens, where the initial ancestors capable of forming a society are “stupid” and don’t optimize completely for genetic fitness, allowing pro-social patterns to take hold.
Spoiler block was not supposed to be empty, sorry. It’s fixed now. I was using the Markdown spoiler formatting and there was some kind of bug with it I think, I reported it to the LW admins last night. (also fwiw I took the opportunity now to expand on my original spoilered comment more)