I don't remember the title or the author or even if it is something I read as a kid. The setup is Humanity lives in various space-based tribes spread across the solar system with various political 'issues'. At least some of these tribes use living space ships. Earth was abandoned millennia before due to ecological collapse and is believed to be a toxic wasteland. There are a number of references to a semi-mythical figure known as 'Gagarin the Joker' presumably referring to Yuri Gagarin. I think towards the end two of the protagonists land on Earth to find it has regenerated without mankind's presence.
I am fairly sure this is the answer:
The Helix and the Sword by John McLoughlin
I seem to remember a very cool biological computer called Pantalog 5 in the form of a big cat.
Hope that helps!