The Major Transitions in Evolution

The Major Transitions in Evolution is a book written by John Maynard Smith and Eörs Szathmáry (Oxford University Press, 1995).^[1][2][3][4]

Maynard Smith and Szathmary authored a review article in Nature.^[5]

Transitions described in the book
Transition from:	Transition to:	Notes
Replicating molecules	"Populations" of molecules in compartments	Can't observe[clarification needed]
Independent replicators (probably RNA)	Chromosomes	RNA world hypothesis
RNA as both genes and enzymes	DNA as genes; proteins as enzymes
Prokaryotes	Eukaryotes	Can observe[clarification needed]
Asexual clones	Sexual populations	Evolution of sex
Protists	Multicellular organisms — animals, plants, fungi	Evolution of multicellularity
Solitary individuals	Colonies with non-reproductive castes	Evolution of eusociality
Primate societies	Human societies with language, enabling memes	Sociocultural evolution

Maynard Smith and Szathmáry identified several properties common to the transitions:

1. Smaller entities have often come about together to form larger entities, e.g. chromosomes, eukaryotes, sex multicellular colonies.
2. Smaller entities often become differentiated as part of a larger entity, e.g. DNA-protein, organelles, anisogamy, tissues, castes
3. The smaller entities are often unable to replicate in the absence of the larger entity, e.g. DNA, chromosomes, organelles, tissues, castes
4. The smaller entities can sometimes disrupt the development of the larger entity, e.g. meiotic drive (selfish non-Mendelian genes), parthenogenesis, cancers, coup d’états
5. New ways of transmitting information have arisen, e.g. DNA-protein, cell heredity, epigenesis, universal grammar.

As stated by the authors,^[6] this book was aimed at professional biologists and assumes considerable prior knowledge. They have also published a summary of their arguments in Nature^[7] as well as a presentation of their ideas for a general readership under the title The Origins of Life — From the Birth of Life to the Origins of Language.^[6] Two decades later, Eörs Szathmáry published an "update" of his thesis in the original book, and this update involved demoting sex from a major transition as well as promoting new transitions, such as the origins of plastids, to the list.^[8] The major transitions generally involve the formation of new levels of units of selection, consisting of ensembles of pre-existing entities. Therefore, the evolution of the major transitions can also be seen as the framework for studying the evolution of the levels of complexity in biology.^[9]

Their work has generated substantial interest and further research into major transitions,^[10] including a devoted issue of papers to the subject in 2016 in the journal Philosophical Transactions of the Royal Society B.^[11] Additional suggestions to the transitions concept include the inclusion of viruses as playing a role as major catalysts for evolutionary transitions in two ways. One, parasite-host arms race often leads to the formation of complex structures and levels of complexity to combat the threat of viruses. Two, gene transfer from viruses and virus-like elements may contribute important genes for the emergence of higher levels of organization.^[9] Others have noted that the concept of transitions in macroevolutionary history focuses on increases in the levels of complexity, whereas macroevolutionary events can also proceed through simplifications which undo these hierarchical increases in complexity (e.g. multicellular organisms losing adherence genes and so transitioning into unicellular organisms, or the animal and plant lineages with degenerated organelles such as mitosomes). Furthermore, simplifications can also enable other macroevolutionary complexifications (e.g. the bacterial endosymbiont that simplified into the integrated mitochondrial organelle). Thus, incorporating simplification dynamics will help further elucidate the emergence of life's lineages.^[12]

See also

• History of life
• Metasystem transition, a related notion developed by Valentin Turchin in 1977.
• Origin of life
• Great Filter

References

1. Maynard Smith, John; Szathmáry, Eörs (1995). The Major Transitions in Evolution. Oxford University Press. ISBN 978-0-19-850294-4. OCLC 939828932.
2. Sterelny, Kim (2007). Dawkins Vs Gould: Survival of the Fittest. Cambridge, U.K.: Icon Books. ISBN 978-1-84046-780-2. OCLC 76936307.
3. Benton, Michael (2009). "Paleontology and the History of Life". In Ruse, Michael; Travis, Joseph (eds.). Evolution: The First Four Billion Years. The Belknap Press of Harvard University Press. pp. 80–104. ISBN 978-0-674-03175-3. OCLC 1149059082.
4. Calcott, Brett; Sterelny, Kim, eds. (2011). The Major Transitions in Evolution Revisited. MIT Press. ISBN 978-0-262-29453-9. OCLC 727944851.
5. Szathmáry, Eörs; Smith, John Maynard (16 March 1995). "The major evolutionary transitions". Nature. 374 (6519): 227–232. Bibcode:1995Natur.374..227S. doi:10.1038/374227a0. PMID 7885442. S2CID 4315120.
6. Maynard Smith, John; Szathmáry, Eörs (2000). The origins of life : from the birth of life to the origin of language. Oxford University Press. ISBN 978-0-19-286209-9. OCLC 904281463.
7. Szathmáry, Eörs; Smith, John Maynard (16 March 1995). "The major evolutionary transitions". Nature. 374 (6519): 227–232. Bibcode:1995Natur.374..227S. doi:10.1038/374227a0. ISSN 0028-0836. PMID 7885442. S2CID 4315120.
8. Szathmáry, Eörs (18 August 2015). "Toward major evolutionary transitions theory 2.0". Proceedings of the National Academy of Sciences. 112 (33): 10104–11. doi:10.1073/pnas.1421398112. PMC 4547294. PMID 25838283.
9. Koonin, Eugene V. (19 August 2016). "Viruses and mobile elements as drivers of evolutionary transitions". Philosophical Transactions of the Royal Society B: Biological Sciences. 371 (1701): 20150442. doi:10.1098/rstb.2015.0442. PMC 4958936. PMID 27431520.
10. Calcott, Brett; Sterelny, Kim; Szathmáry, Eörs (2011). The major transitions in evolution revisited. MIT Press. ISBN 978-0-262-29570-3. OCLC 727944851.
11. Solé, Ricard (ed.). "Theme issue 'The major synthetic evolutionary transitions'". Philosophical Transactions of the Royal Society B: Biological Sciences. 371 (1701).
12. O’Malley, Maureen A.; Wideman, Jeremy G.; Ruiz-Trillo, Iñaki (1 August 2016). "Losing Complexity: The Role of Simplification in Macroevolution". Trends in Ecology & Evolution. 31 (8): 608–621. Bibcode:2016TEcoE..31..608O. doi:10.1016/j.tree.2016.04.004. ISSN 0169-5347. PMID 27212432.