Extended Evolutionary Synthesis

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Massimo Pigliucci, a leading proponent of the extended evolutionary synthesis.

The extended evolutionary synthesis is an extension of the Modern Synthesis of evolution which revisits the relative importance of different factors at play in evolutionary theory, revisits several assumptions of the original synthesis, and augments the modern synthesis with additional causative factors in evolution.

The extended synthesis includes concepts and mechanisms such as multilevel selection theory, transgenerational epigenetic inheritance, niche construction and evolvability.

Early history

During the 1950s, biologist C. H. Waddington called for an extended synthesis based from his research on epigenetics and genetic assimilation. An extended synthesis was also proposed by Rupert Riedl, with the study of evolvability. In 1978, Michael J. D. White wrote about an extension of the modern synthesis based on new research from speciation.

In the 1980s, Stephen Jay Gould argued for an extended synthesis. This was based on his idea of punctuated equilibrium, the role of species selection shaping large scale evolutionary patterns and natural selection working on multiple levels extending from genes to species. Similar ideas were held by Niles Eldredge author of the book Unfinished Synthesis (1985).

Ethologist John Endler wrote a paper in 1988 discussing processes of evolution that he felt had been neglected. Others, such as researchers in the field of evolutionary developmental biology (evo-devo) called for an extended synthesis based on the opinion that the modern synthesis was mostly centered on genes and ignored the development of the organism, as well as morphological areas of biology.

Recent

The extended synthesis is still a work-in-progress, essentially having been launched in 2007 by a paper by Massimo Pigliucci in the journal Evolution, followed by a conference on the subject in 2008 at the Konrad Lorenz Institute for Evolution and Cognition Research. The participants of the conference published a book in 2010 titled Evolution: The Extended Synthesis, which has served as a launching point for work on the extended synthesis. Several of the topics included in the extended synthesis include:

• Showing the importance of the role of prior configurations, genomic structures, and other traits in the organism in generating evolutionary variations.
• Looking at how increasing dimensionality of fitness landscapes affects our view of speciation.
• Examining the role of multilevel selection in the major evolutionary transitions.
• Looking at new types of inheritance, including cultural and epigenetic inheritance.
• Examining the way that organismal development and developmental plasticity channels evolutionary pathways.
• Looking at how organisms modify the environments they belong to through niche construction.

Other processes such as evolvability, phenotypic plasticity, reticulate evolution and symbiogenesis are said by proponents to have been excluded or missed from the modern synthesis.

The goal of the extended synthesis is to take evolution beyond the gene-centered approach of population genetics to consider more organism- and ecology-centered approaches. Many of these causes are currently considered secondary in evolutionary causation, and proponents of the extended synthesis want them to be considered first-class evolutionary causes.

Biologist Eugene Koonin writing on the extended synthesis in 2009 wrote that "the new developments in evolutionary biology by no account should be viewed as refutation of Darwin. On the contrary, they are widening the trails that Darwin blazed 150 years ago and reveal the extraordinary fertility of his thinking."

Reception

Several biologists have contended that there is no need for an extended synthesis because the modern synthesis is able to fully account for the newer observations, while advocates for the extended synthesis think that the conceptions of evolution at the core of the modern synthesis are too narrow. Proponents of the extended synthesis think that even when the modern synthesis allows for the ideas in the extended synthesis, the modern synthesis, being used as a starting point, affects the way that biologists think about evolution. Proponents say that using terms and categories of the modern synthesis distort the picture of biology that modern experimentation has discovered. Therefore, they claim that the extended synthesis is necessary to help expand the conceptions and framework of how evolution is considered throughout the biological disciplines.

The ideas of the extended synthesis were positively reviewed by Anya Plutynski for the National Center for Science Education.

Further reading

Defend the extended synthesis

• Arnold, Anthony J; Fristrup, Kurt. (1982). The Theory of Evolution by Natural Selection: A Hierarchical Expansion. Paleobiology. Vol. 8, No. 2. pp. 113–129.
• Boto, Luis. (2010). "Horizontal Gene Transfer in Evolution: Facts and Challenges". Proc Biol Sci 277: 819-827.
• Carroll, Sean B. (2008). Evo-Devo and an Expanding Evolutionary Synthesis: A Genetic Theory of Morphological Evolution. Cell 134: 25-36.
• Endler, John. (1986). The Newer Synthesis? Some Conceptual Problems in Evolutionary Biology. Oxford Surveys in Evolutionary Biology 3: 224-243.
• Gilbert, Scott F. (2000). "A New Evolutionary Synthesis". In Developmental Biology, 6th edition. Sinauer. ISBN 0-87893-243-7
• Jablonka, Eva; Lamb, Marion J. (2008). Soft Inheritance: Challenging the Modern Synthesis. Genetics and Molecular Biology 31: 389-395.
• Koonin, Eugene. (2009). "Towards a postmodern synthesis of evolutionary biology". Cell Cycle 8: 799-800.
• Koonin, Eugene. (2009). "The Origin at 150: is a new evolutionary synthesis in sight?" Trends Genet 25: 473-475.
• Müller, Gerd B. (2014). EvoDevo Shapes the Extended Synthesis. Biol Theory 9: 119-121.
• Pennisi, Elizabeth. (2008). Modernizing the Modern Synthesis. Science 321: 196-197.
• Postdarwinism: "The New Synthesis". A review of Ecological Developmental Biology: Integrating Epigenetics, Medicine, and Evolution, by Scott F. Gilbert and David Epel (Sinauer, 2009).
• "Post-modern synthesis?" A review of Developmental Plasticity and Evolution by Mary Jane West-Eberhard (Oxford University Press, 2003).
• Schrey et al. (2012). "The Role of Epigenetics in Evolution: The Extended Synthesis". Genetics Research International, vol. 2012, Article ID 286164, 3 pages.
• Weber, Bruce H. (2011). Extending and Expanding the Darwinian Synthesis: The Role of Complex Systems Dynamics. Studies in History and Philosophy of Biological and Biomedical Science 42: 75-81.
• Whitfield, John. (2008). "Biology theory: Postmodern evolution?" Nature 455: 281–284.

Criticism of the extended synthesis

• Craig, Lindsay. (2010). The So-Called Extended Synthesis and Population Genetics. Biological Theory 5: 117-123.
• Dickens, Thomas; Rahman, Qazi. (2012). "The extended evolutionary synthesis and the role of soft inheritance in evolution". Proceedings of the Royal Society: B biological sciences, 279 (1740). pp. 2913–2921.
• Felsenstein, Joseph. (1986). Waiting for Post-Neo-Darwin. Evolution. Vol. 40, No. 4. pp. 883–889.
• Haig, David. (2007). Weismann rules! OK? Epigenetics and the Lamarckian Temptation. Biology and Philosophy 22: 415-428.
• Kurland CG, Canback B, Berg OG. (2003). "Horizontal Gene Transfer: A Critical View". Proc Natl Acad Sci U S A 100: 9658-9662.
• Lynch, Michael. (2007). The frailty of adaptive hypotheses for the origins of organismal complexity. Proceedings of the National Academy of Sciences 104: 8597-8604.
• Mayr, Ernst. (2004). 80 years of watching the evolutionary scenery. Science 305: 46-47.
• Merlin, Francesca. (2010). "Evolutionary Chance Mutation: A Defense of the Modern Synthesis’ Consensus View". Philosophy & Theory in Biology 2: 22.
• Stebbins, Ledyard G; Ayala, Francisco J. (1981). Is a New Evolutionary Synthesis Necessary? Science. New Series, Vol. 213, No. 4511. pp. 967–971.

External links

• Should Evolutionary Theory Evolve? The Scientist.