Will the 2012 Mac Pro boot from Snow Leopard?

I'm contemplating upgrading my 2008, 8 core intel mac and getting a refurbished 2012 12 core 2.4 ghz mac pro. My plan, regardless of what future mac I purchased, was to keep my old maching ONLY becuase there are times I need to access my old Retrospect backups. Retrospect only works in OS 10.6.8, that is, the version of Retrospect that allows me to access my crusty old backups ;-). These backups are old client projects and can generate me $ from time to time. Anyway, I was toying with the idea of getting a newer mac, and, in the event it would actually boot from this old hard drive with 10.6.7, I would then sell the old mac. Does anyone have the answer to this?