Lecture January 3: Short History of Evolutionary Thought

A good overview can be found on http://www.umcp.berkeley.edu/history/evotheory.html

Early ideas expanded on Aristoteles

The great Chain of Beings. Linear order of species (from simple to complex). Influental to this day when people think of "higher" and "lower" species. Static system and laid down at creation.

Carl Linnaeus (mid-1700)

Hierarchical classification (also type specimen system, binomial nomenclature) was presented as disclosing the true (static) order of nature as laid down at creation. Read more at http://www.linnean.org/html/history/index.htm.

Jean Baptiste Pierre Antoine de Monet (Chevalier de Lamarck)

Lamarck worked mostly on invertebrates. He developed a dynamic system, in which organism evolve from simple to complex through a mechanism of use and disuse. Organisms pass on aquired traits to their offspring. The latter believe was a common thought at that time. Lamarck's Ideas conflicted with the views of established scientists, e.g. Georges Cuvier, who founded vertebrate paleontology as a scientific discipline and created the comparative method of organismal biology, did not believe in organismic evolution.

Charles Darwin

Published the Origin of Species 1859, emphasising selection as the agent of evolutionary change. Some of Darwin's books can be read onthe web at http://www.literature.org/authors/darwin-charles/. The idea of Natural Selection was although developed by Alfred Russel Wallace(1858), and (less known) by Patrick Matthew(1831). Variability - Individuals in a population or species are not identical. Limited resources - the envirnoment of a species set limitations, ther is not enough food or nesting space etc. Competition and overpopulation - a successful species will increase in numbers and will be come competetive about resources. Survival of different types - Different types respond differently to environmental pressures, some types can handle some stresss better than others (e.g. don't die) and will have more offspring on the long run.

Gregor Mendel

Did large scale experiments on plant hybrids and came up with a new interpretation of the mode of inheritence that was different from "Blending". His results publsihed in 1866 were not used for some 30 years. His papers/work were rediscovered in 1900 independently by Karl Correns, Hugo de Vries and Erich von Tschermak. More information on the web : http://hermes.astro.washington.edu/mirrors/MendelWeb/homepage.html

Modes of Inheritence

Mendelians vs Biometricians

1880 Auguste Weismann postulates that germ line cells create sex cells and somatic cells, and that during the life time of an indiviudal the soma cannot affect its sex cells. In 1900 Hugo De Vries, Carl Correns, and Erich Tschermak described and/or rediscovered Mendel's papers. Scientists adopting the Mendelian Inheritance mechanism (Mendelians) put forward mutations (discovered by De Vries) against Natural Selection [and its implied gradual change]. They were opposing Biometricians (Francis Galton and Karl Pearson); adopting Natural Selection), who developed many regression and correlation methods.

R. A. Fisher, Sewall Wright, and J. B. S. Haldane

Ronald A. Fisher John B. S. Haldane Sewall Wright Fisher, Haldane, and Wright reconciled natural selection with Mendelian genetics in the period 1918-1930.