Mesobiotic Emergence: molecular and Ensemble Complexity in Early Evolution

In addition to the visible complexity expressed in the morphogenesis of multicellular organisms, two levels of microscopic complexity may be discerned within every living cell. The first level is related to covalently bonded structures, namely molecules. The second level has to do with the generation of non-covalent molecular assemblies. Origin of life research has largely focused on the first complexity level, i.e. the appearance of covalent biopolymers. We present a life emergence scenario based mainly on the second complexity level. We argue that homeostatic molecular ensembles, for which we have coined the term “mesobiotic,” have assumed a half-way position between prebiotic organic synthesis and full-fledged cellular (biotic) life.