| − | '''Chemical evolution''' describes a number of theories that assert that life originated through purely chemical transformations of nonliving matter.<ref>http://www.iscid.org/encyclopedia/Chemical_Evolution</ref> | + | '''Chemical evolution''' describes a number of theories that assert that [[Origin of life|life originated]] through purely chemical transformations of nonliving matter.<ref>http://www.iscid.org/encyclopedia/Chemical_Evolution</ref> |