Extended evolutionary synthesis

The extended evolutionary synthesis is a set of extensions of the earlier modern synthesis of evolutionary biology that took place between 1918 and 1942. The extended evolutionary synthesis was called for in the 1950s by C. H. Waddington, argued for on the basis of punctuated equilibrium by Stephen Jay Gould and Niles Eldredge in the 1980s, and relaunched in 2007 by Massimo Pigliucci.

The extended evolutionary synthesis revisits the relative importance of different factors at play, examining several assumptions of the earlier synthesis, and augmenting it with additional causative factors. It includes multilevel selection, transgenerational epigenetic inheritance, niche construction, and evolvability.

Not all biologists have agreed on the need for, or the scope of, an extended synthesis. Many have collaborated on a different synthesis in evolutionary developmental biology, which integrates embryology with molecular genetics and evolution to understand how natural selection operated on developmental processes and deep homologies between organisms at the level of highly conserved genes.

The modern synthesis was the widely accepted early 20th-century synthesis reconciling Charles Darwin's theory of evolution by natural selection and Gregor Mendel's theory of genetics in a joint mathematical framework. It established evolution as biology's central paradigm. The 19th century ideas of natural selection by Darwin and Mendelian genetics were united by Ronald Fisher, one of the three founders of population genetics, along with J. B. S. Haldane and Sewall Wright, between 1918 and 1932.Julian Huxley used the phrase "modern synthesis" in his admired 1942 book, Evolution: The Modern Synthesis.