Something is considered “Living” when they exhibit two main biological functions Two Main Functions of Life metabolism: “do chemistry to change internal consistence” replication: “copying cell information” theories of origin of life Manfred Eigen ("RNA-World" theory): genes form, constructing enzymes, forming cells Alexander Oparin: cells form, creating enzymes as needed, forming the genes to encode them Freeman Dyson: Dyson’s Model of Life—basically the Oparin model, but with more specifics about how genes evolve