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 Darwinismaround 1900, a period Julian Huxley would later referto as the “eclipse of Darwinism”.

The Eclipse of Darwinism around 1900

Samuel Butler, victorian novelist (1835-1902)

Edward Drinker Cope, American Paleontologist (1840-1897)

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 1864-1870?

The American school of Neo-Lamarckian Paleontology

August Weismann (1834-1814)

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

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)

Herbert Spencer, “The inadequacy of natural selection”, 1893Weismann, “The Allmacht (all-sufficiency) of natural selection”, 1893

Feud between Herbert Spencer and Weismann

“Unpermissibly weak!”

“As if that were certain!”

Paul Kammerer (1820-1926)

The Inheritance of Acquired Characteristics, 1924 (English Translation)

Neo-Lamarckism continues deep into 20th Century

Conrad Hal Waddington (1905–1975)

Epigenetic Landscape

Branching Track Model of Development

Organisers and Genes, 1940

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

"A New Factor in Evolution” (1896) by American psychologist James Mark Baldwin

American Naturalist 30: 441-451,536-553.(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: 110-117

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: 495-502.