Evolution

Evolution the underlying theme woven throughout the text, refers to the processes that have transformed life on earth from its earliest forms to the enormous diversity that characterizes it today

24 November 1859 On Origin of the Species by Means of Natural Selection by Charles Darwin

Origin of the Species Made 2 major points: –Species evolved from ancestral species and were not created –Natural Selection is the mechanism that could result in this evolutionary change

Origin of the Species Challenged Western culture Darwin’s viewpoint contrasted sharply with the currently accepted concepts: –the earth’s age –the 1 week creation

Origin of the Species Many Greek philosophers believed in the gradual evolution of life However: –Western Culture was influenced by Plato and Aristotle

Platonic Philosophy Idealism – essentialism 2 coexisting worlds  an ideal eternal “real” world  an illusionary imperfect world “ours”

Platonic Philosophy Variations in plant and animal populations were imperfect forms of the ideal forms Evolution would be counterproductive in a world where ideal forms were already perfect

Aristotle Philosophy Organisms range from simple to complex. Occupied levels of an ascending ladder. (scala naturae) Species are fixed and do not evolve Lasted for 2000 years

Creationist - Essentialist Species were individually created and fixed became embedded I western thought as the Old Testament account of creation from the Judeo-Christian culture fortified prejudice against evolution

Creationist - Essentialist Natural Theology: a philosophy that a creator’s plan could be revealed by studying nature Adaptations of organisms were evidence that a creator had a purpose for each

Creationist - Essentialist Natural Theology’s major objective was to classify each species of God’s created steps of the Aristotle ladder

Carolus Linnaeus

Carolus Linnaeus A Swedish physician and botanist, sought order in the diversity of life ad majorem Dei gloriam –For the greater glory of God

Carolus Linnaeus Known as the father of taxonomy binomial nomenclature – binomial nomenclature Developed a classification scheme which included a ranking hierarchy

Carolus Linnaeus The clustering of species in taxonomic groups did not imply evolutionary trends Purpose was to reveal God’s plan Deus creavit, Linnaeus disposuit (God creates, Linnaeus arranges)

Georges Cuvier

Georges Cuvier Realized that life’s history was recorded in fossil-containing strata and documented the succession of fossil species in the Paris Basin

Georges Cuvier Noted that each strata was characterized by unique set of fossil species and that the older the statrum, the more dissimular the flora and fauna from modern life forms

Georges Cuvier Understood that extinction had been a common occurance in the history of life since, new species appeared and others disappeared

Georges Cuvier He was still an opponent to evolution: –Differences in species due to catastrophic events (droughts, fires floods)

Georges Cuvier New species result of: –Localized catastrophe resulted in mass extensions –Repopulation of out side species

Theories of Ecological Gradualism Gained popularity that would influence Darwin’s concept

Theories of Ecological Gradualism Principle that profound change is the cumulative product of slow, continuous process

Theories of Ecological Gradualism Proposed by James Hutton –1875 Scottish Geologist

Theories of Ecological Gradualism He proposed that we look it was possible to explain the various land forms by looking at mechanisms currently operating in the world example: canyons formed by erosion exposing fossils

Charles Lyell Expanded Huton’s concept into the theory called uniformitarianism

Charles Lyell Uniformitarianism: –in this theory, geological processes are uniform and have operated from the origin of the Earth to the present.

Charles Lyell Idea that the geological processes are so uniform that their rates and effects must balance out through time Example: process of mountain building is followed by erosion

Darwin Rejected uniformitarianism but was intrigued by the conclusions of Hutton and Lyell –1. Earth must be ancient (>6000 yr) –2. substantial change could occur over time

Jean Baptiste Lamarck First published a document trying to explain the model of evolution in 1809

Jean Baptiste Lamarck Believed that evolution was driven by innate tendency toward increasing complexity – As organisms attain perfection they become better and better adapted to their environment

Jean Baptiste Lamarck Proposed 2 mechanisms 1. Use and Disuse use it or loose it 2. Inheritance of acquired characteristics by genetics

Althought his theory was in error, Lamarck deserves credit for proposing: –1. Evolution is the best explanation for fossil record and extant diversity of life –2. The Earth is Ancient –3. Adaptation to the environment is primarily product of evolution