Complex systems and Mars missions help understand how ...( Understanding how life started remai...)

Understanding how life started remains a major challenge for science. At a European Science Foundation (ESF) and COST 'Frontiers of Science' conference in Sicily in October, scientists discussed two new approaches to the problem. The first applies complex systems theory to the chemistry that preceded early life. The second involves studying Mars, which may yield ample evidence about what Earth was like when life evolved.

Gnter Von Kiedrowski, of Ruhr Universitt Bochum in Germany, described the new and emerging science of complex systems chemistry. The field takes the opposite approach from that of the genomics pioneer Craig Venter, who wants to build a minimal living cell. "Venter wants to see what is left if you knock out everything but what is needed to survive," says Von Kiedrowski. "We want to look at how you get to that from the bottom up. Darwin's tree of life must have roots, and it is our mission to find them."

Complex systems chemistry uses computer models to simulate combinations of reactions, involving membrane forming reactions, self-replicating nucleic acids and metabolic energy-producing reactions. Then it examines how these systems develop in time and space. Breaking the symmetry

One promising area is the discovery of reaction systems that lead to the spontaneues generation of chiral asymmetry. It is a universal property of life that compounds such as amino acids and sugars exist exclusively in a one-handed form although both forms are equally likely from an energetic point of view. It is quite difficult to achieve this asymmetry in non-living chemical reactions. Chemistry tends to create equal proportions of the different forms, which behave like objects and their mirror images. "The recipe for asymmetry is the co-occurence of positive and negative feedback loops within such systems," says Von Kiedrowski.

Complex systems chemistry cannot tell the story of life entirely. "We are in the same position as the ph
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