What is life? To prove that life exists, or did at one time, what signs should we be looking for?
Possible signs of life include a wide range of features on which we can focus. For example, cells walls or membranes made of simple carbohydrates encapsulate the most successful life-forms on our planet: bacteria. Fatty acids-chains of carbons, hydrogens and oxygens-are diagnostic of biosynthetic processes here on Earth. Certain proteins, such as DNA, can only arise from active biological processes. All of these processes and structures all have something in common, though: they use energy to renew themselves.
The authors of a paper released today in Astrobiology titled, “The Fuel Cell Model of Abiogenesis: A New Approach to Origin-of-Life Simulations,” suggest that rather than focusing exclusively on the structure of life, we should also be looking for the primary process of life: energy transport. To prove their point, the authors built miniature metabolic fuel cells out of elements that would have been available to life as it labored to evolve on Earth.