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Much of the debate that followed publication of the Origin focused on the question of evolution itself, rather than on Darwin’s proposed mechanism. After.

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Presentation on theme: "Much of the debate that followed publication of the Origin focused on the question of evolution itself, rather than on Darwin’s proposed mechanism. After."— Presentation transcript:

1 Much of the debate that followed publication of the Origin focused on the question of evolution itself, rather than on Darwin’s proposed mechanism. After the fact of evolution had become established, however, Darwin’s proposed mechanism came under close scrutiny. Beginning about 1880, many scientists—including some of Darwin’s most ardent defenders—expressed discomfort with the element of randomness in the theory of natural selection, suspecting that random variation, even if selected, could not alone produce the seemingly endless examples of living biological adaption. This situation led to the advocacy of various strands of anti- Darwinism, ultimately culminating in a crisis for Darwinism around 1900, a period Julian Huxley would later refer to as the “eclipse of Darwinism”. The Eclipse of Darwinism around 1900

2 Samuel Butler, victorian novelist ( )

3 Edward Drinker Cope, American Paleontologist ( ) Bitter feud with O. C. Marsh over both his Neo-Lamarkianism and dinosaur fossils Religious motivation in his denial of Darwinism at Haverford College from ? The American school of Neo-Lamarckian Paleontology

4 August Weismann ( ) Darwinism purged of its “Lamarckian” elements! (but in fact unleashed a backlash of anti-Darwinian sentiment) In 1889 cut the tails off of 1,500 rats over 20 generations

5 From Simpson, GG, Life: An introduction to Biology, 1957 (modified from Wilson, EB, The Cell in Development and Evolution, 1896) Das Keim Plasma: a theory of heredity (1892)

6 Herbert Spencer, “The inadequacy of natural selection”, 1893 Weismann, “The Allmacht (all-sufficiency) of natural selection”, 1893 Feud between Herbert Spencer and Weismann “Unpermissibly weak!” “As if that were certain!”

7 Paul Kammerer ( ) The Inheritance of Acquired Characteristics, 1924 (English Translation) Neo-Lamarckism continues deep into 20th Century

8 Conrad Hal Waddington (1905–1975) Epigenetic Landscape Branching Track Model of Development Organisers and Genes, 1940

9 Genetic Assimilation (Waddington, 1953) (idea also developed by I. I. Schmalhausen, referred to as “stabilizing selection”)

10 "A New Factor in Evolution” (1896) by American psychologist James Mark Baldwin American Naturalist 30: , (also Lloyd Morgan and Henry Fairfield Osborn at about same time) “Organic” Evolution The learned (voluntary or conscious?) behavior of a species or group can shape the evolution of that species or group. Learned Behavior Genetically Encoded Instinct Coined the “Baldwin Effect” by G. G. Simpson in an article whose purpose was to challenge importance of the idea “The Baldwin Effect” (1953) Evolution 7:

11 Hinton and Nowlan’s Simulation of the Baldwin Effect [Put Figure on here] Hinton and Nowlan (1987) How learning can guide evolution Complex Systems 1:


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