thomas hunt morgan and the columbia fly group in 1918 · mendelian genetics and ......

Thomas Hunt Morgan and the Columbia fly group in 1918

Unanswered Questions:What is the

physical nature of the

How are genes expressed? How do you

get from genetics to

development?

What does genetics tell us

about evolution?

A Qualified Victory“This now almost universal belief on the evolution (somehow) of species I think may be fairly attributed in large part to the ‘Origin.’” Charles Darwin to Joseph Hooker, 28 July 1868

“At the present day almost all naturalists admit evolution under some form.” Charles Darwin, Origin of Species(6th ed.; 1872), p. 201

“It seemed to us as if he somehow

couldn’t understand

natural selection. He had a mental block which was

so common in those days.”

Morgan’s Student, Herman J. Muller:

Population Genetics and Evolutionary Theory

J.B.S. Haldane (1892-1964)

Ronald Fisher (1890-1962)

Ronald FisherThe Genetical Theory of Natural

Selection (1930)

Mendelian Genetics and ...

Neo-Lamarckianism

MutationTheory

“The sole surviving

theory is that of Natural Selection”

“Quantitative work shows clearly that natural selection is a reality, and that, among other things, it selects Mendelian genes, which are known to be distributed at random through wild populations, and to follow the laws of chance in their distribution to offspring. In other words, they are an agency producing variation of the kind which Darwin postulated as the raw material upon which selection acts.”

JBS HaldaneCauses of Evolution (1932)

Theodosius Dobzhansky

(1900-75)

Standard map and inversions of chromosome 3 of D. pseudoobscura

The Evolutionary history and distribution of D. pseudoobscura

ksTheodosius Dobzhansky, Genetics and the Origin of Species (1937)

Ernst Mayr, Systematics and the Origin of Species (1942)

Julian Huxley, Evolution: The Modern Synthesis (1942)

George Gaylord Simpson, Tempo and Mode in Evolution (1944)

Bernhard Rensch, Neuere Probleme der Abstammungslehre: die transspezifische Evolution (1947)

David Lack, Darwin’s Finches (1947)

G. Ledyard Stebbins, Variation and Evolution in Plants (1950)

Ernst May in 1959:

“We are closer to

Darwin now and to

Darwin’s original

concepts than we have been

at any time during the

intervening period.”

Mayr Darwin

1790Immanuel Kant

“Absolutely no human reason … can hope to understand the production of even a blade of

grass by mere mechanical causes.”