I'm convinced that blockchains will be the foundational substrate for artificial life - they're credibly neutral, censorship resistant, and globally distributed. 

Are there any alternative candidates?

I'm convinced that blockchains will be the foundational substrate for artificial life - they're credibly neutral, censorship resistant, and globally distributed. 

Are there any alternative candidates? 

https://en.wikipedia.org/wiki/Artificial_life

P2P networks (ie set of decentralized nodes) yes but unclear if a shared ledger/db (ie blockchain) is needed in all cases

Also, creating blockchains that are neutral and censorship resistant is hard, would ideally need to be a POW one (or variation of)