I don't know, but I also don't think attempting to be all-embracing is necessarily a good idea.

If a community acts altruistically in the contexts that arise to be acted in, then new members of that community will tend to adopt altruistic values, and will in turn act altruistically in contexts that arise to be acted in. That's true regardless of what those contexts turn out to be.

They don't ever have to talk about altruism or look for ways to manifest altruism in contexts that don't seem to require it; indeed, doing so is one way that signaling ends up displacing doing.

Not that there's anything wrong with talking about one's values, any more than there's anything wrong with talking about one's tastes in food. But talking about food is a different kind of task than cooking or eating, and talking about altruism is different from behaving altruistically.

If a community gives up opportunities to behave altruistically in favor of talking, they communicate the value of talking rather than the value of altruism.

Incidentally, none of this is unique to altruism.