There is a well-known story about this discussed in Radiolab [2010] https://radiolab.org/podcast/91725-words/transcript
Here's ChatGPT summarizing one section:
> Younger signers had developed a richer vocabulary for mental states—concepts like believe, remember, forget, understand. They were much better than the original older signers at tasks requiring them to reason about what another person thinks or knows. Later, as the older signers picked up those mental-state terms from younger people, some of them improved on the same tests. Senghas describes it as language giving them new insight into other people’s thinking and motivations.
I see several likely stories:
* Much animal communication is practical, descriptive of the present (nothing abstract, or very few abstract concepts)
* If a species could expand its communication, it would give it more powerful tools and allow for more meaningful conversation with humans
* If such a thing is possible, it will be extremely disruptive to that species
I think if you could communicate about abstract ideas with your dog, you could exchange bedtime stories. However, I don't think such a thing is possible today, and it's not clear what species (if any, besides humans) will, in fact, be able to learn such things
I don't think it's particularly controversial to say "written language is a meaningful technology advancement for a civilization", though!
They're pretty damn interesting. Cats sometimes think hard about their responses. And they use metaphors. And express emotions.
There's always the suspicion this is a fake marketing exercise. But if it is, it's a very ornate and extended one.
I have no idea how we're supposed to communicate with aliens if we can't communicate with other mammals.
"They're really stupid and can't do calculus or invent FTL travel" isn't much of an excuse.