Minimal Life: Drawing the line
On the afternoon of the second day of NSF’s Minimal Life workshop, Eric Smith of the Santa Fe Institute in New Mexico provided a much-needed synthesis.
He examined the trade-offs of having a super-pared-down genome and the need to leech off of the environment — parasites, for example, can only survive with bare-bones genomes because they farm out most of their metabolic needs to their hosts. He presented his not surprising, but necessary, quantitative data showing that the more dependent an organism is on its environment, the less metabolically complete its own genome is.
Smith discussed the metabolic and biosynthetic pathways that seem to be universally needed for life, which all involve the same five precursors (the famous CHNOPS from high school chemistry), the same cofactors, and produce pretty much the same amino acid nucleotides. But while it’s hard to find the complete networks for all these necessary bits and pieces at the level of an individual species, they are indeed wrapped into a nice little package at the level of the ecosystem. The boundary between organism and ecosystem, then, is more fluid and less important than most people assume.
