The universal ancestor
- 9 June 1998
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 95 (12), 6854-6859
- https://doi.org/10.1073/pnas.95.12.6854
Abstract
A genetic annealing model for the universal ancestor of all extant life is presented; the name of the model derives from its resemblance to physical annealing. The scenario pictured starts when "genetic temperatures" were very high, cellular entities (progenotes) were very simple, and information processing systems were inaccurate. Initially, both mutation rate and lateral gene transfer levels were elevated. The latter was pandemic and pervasive to the extent that it, not vertical inheritance, defined the evolutionary dynamic. As increasingly complex and precise biological structures and processes evolved, both the mutation rate and the scope and level of lateral gene transfer, i.e., evolutionary temperature, dropped, and the evolutionary dynamic gradually became that characteristic of modern cells. The various subsystems of the cell "crystallized," i.e., became refractory to lateral gene transfer, at different stages of "cooling," with the translation apparatus probably crystallizing first. Organismal lineages, and so organisms as we know them, did not exist at these early stages. The universal phylogenetic tree, therefore, is not an organismal tree at its base but gradually becomes one as its peripheral branchings emerge. The universal ancestor is not a discrete entity. It is, rather, a diverse community of cells that survives and evolves as a biological unit. This communal ancestor has a physical history but not a genealogical one. Over time, this ancestor refined into a smaller number of increasingly complex cell types with the ancestors of the three primary groupings of organisms arising as a result.Keywords
This publication has 32 references indexed in Scilit:
- A dissimilatory sirohaem-sulfite-reductase-type protein from the hyperthermophilic archaeon Pyrobaculum islandicumMicrobiology, 1998
- Maintaining genetic code through adaptations of tRNA synthetases to taxonomic domainsTrends in Biochemical Sciences, 1997
- Lessons from an Archaeal genome: what are we learning from Methanococcus jannaschii?Trends in Genetics, 1996
- Cell wall biochemistry in Archaea and its phylogenetic implicationsJournal of Biological Physics, 1995
- Cloning and nucleotide sequence of the gene for an archaebacterial protein synthesis elongation factor TuMolecular Genetics and Genomics, 1987
- Nucleoside modification in archaebacterial transfer RNASystematic and Applied Microbiology, 1986
- The evolution of the ribosomal ‘A’ protein (L12) in archaebacteriaSystematic and Applied Microbiology, 1986
- DNA‐Dependent RNA Polymerases of Thermoacidophilic ArchaebacteriaEuropean Journal of Biochemistry, 1982
- Origins of Prokaryotes, Eukaryotes, Mitochondria, and ChloroplastsScience, 1978
- The concept of cellular evolutionJournal of Molecular Evolution, 1977