It was! The whole book plays a lot with various types of consciousness. Although that was a bit of a spoiler, so out of respect I'll give a somewhat obfuscated link and just say if you're reading something by Alastair Reynolds right now you should consider that before following the link:
(Reynolds' got enough books in his bibliography I don't feel like I'm spoiling anything by mentioning his name - I suspect I could come up with any random plot point and he's probably written it in somewhere)
Ah, I thought this was going to be Karl Schrœder's Permanence, in which (unless I'm confusing it with a different book) a background point is that consciousness is only really useful in some niches, and most spacefaring species eventually lose it.
John Varley had a short story with that idea, too. A spacefaring race that is only conscious when needed. Good sarcastic lecture about how consciousness is overrated by those who have it.
https://openlibrary.org/books/OL26809698M
(Reynolds' got enough books in his bibliography I don't feel like I'm spoiling anything by mentioning his name - I suspect I could come up with any random plot point and he's probably written it in somewhere)