UNIVERSALITY IS DIGITAL. “All known life achieves universality (at least in a limited sense) by using the digital sequence structure of informational polymers. Such universality would be exceedingly difficult to engineer in an analogue-only system given the challenges associated with building reaction networks where each (programmed) reaction is chemically orthogonal to all other reactions.”
http://rsif.royalsocietypublishing.org/content/10/79/20120869.short