Major Transitions In Evolution
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''The Major Transitions in Evolution'' is a book written by John Maynard Smith and
Eörs Szathmáry Eörs Szathmáry (born 1959) is a Hungarian theoretical evolutionary biologist at the now-defunct Collegium Budapest Institute for Advanced Study and at the Department of Plant Taxonomy and Ecology of Eötvös Loránd University, Budapest. He i ...
( Oxford University Press, 1995). Also Maynard Smith and Szathmary authored a review article in '' Nature''. Maynard Smith and Szathmáry identified several properties common to the transitions: # Smaller entities have often come about together to form larger entities. e.g. Chromosomes,
eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...
s, sex multicellular colonies. # Smaller entities often become differentiated as part of a larger entity. e.g. DNA & protein,
organelle In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the ...
s,
anisogamy Different forms of anisogamy: A) anisogamy of motile cells, B) egg_cell.html"_;"title="oogamy_(egg_cell">oogamy_(egg_cell_and_sperm_cell),_C)_anisogamy_of_non-motile_cells_(egg_cell_and_spermatia)..html" ;"title="egg_cell_and_sperm_cell.html" ;" ...
, tissues,
caste Caste is a form of social stratification characterised by endogamy, hereditary transmission of a style of life which often includes an occupation, ritual status in a hierarchy, and customary social interaction and exclusion based on cultura ...
s # The smaller entities are often unable to replicate in the absence of the larger entity. e.g. DNA, chromosomes, Organelles, tissues, castes # The smaller entities can sometimes disrupt the development of the larger entity, e.g. Meiotic drive (selfish non-Mendelian genes), parthenogenesis, cancers, coup d’état # New ways of transmitting information have arisen.e.g. DNA-protein, cell heredity, epigenesis, universal grammar. As stated by the authors, this book was aimed at professional biologists and assumes considerable prior knowledge. They have also published a summary of their arguments in ''Nature'' 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''. 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. 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. Their work has generated substantial interest and further research into major transitions, including a devoted issue of papers to the subject in 2016 in the journal ''
Philosophical Transactions of the Royal Society B ''Philosophical Transactions of the Royal Society B: Biological Sciences'' is a biweekly peer-reviewed scientific journal published by the Royal Society. The editor-in-chief is John Pickett (Cardiff University). Overview Each issue covers a spe ...
''. 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. 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 mitochondria and plastid organelles). 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.


See also

* Evolutionary history of life * Metasystem transition, a related notion developed by Valentin Turchin in 1977. * Origin of life


References

{{DEFAULTSORT:Major Transitions In Evolution, The Books about evolution 1995 non-fiction books Modern synthesis (20th century) Oxford University Press books Superorganisms