Evolution
description
Transcript of Evolution
EvolutionEvolution
EvolutionEvolution• 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 185924 November 1859
On Origin of the Species by Means of Natural
Selection
by Charles Darwin
Origin of the SpeciesOrigin 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 SpeciesOrigin 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 SpeciesOrigin of the SpeciesMany Greek philosophers believed
in the gradual evolution of life
However:–Western Culture was
influenced by Plato and Aristotle
Platonic PhilosophyPlatonic Philosophy
Idealism – essentialism
2 coexisting worlds an ideal eternal “real” world an illusionary imperfect world
“ours”
Platonic PhilosophyPlatonic 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 PhilosophyAristotle 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 - EssentialistCreationist - 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 - EssentialistCreationist - 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 - EssentialistCreationist - Essentialist
• Natural Theology’s major objective was to classify each species of God’s created steps of the Aristotle ladder
Carolus Carolus LinnaeusLinnaeus
1707-1778
Carolus LinnaeusCarolus Linnaeus
• A Swedish physician and botanist, sought order in the diversity of life
• ad majorem Dei gloriam–For the greater glory of God
Carolus LinnaeusCarolus Linnaeus
• Known as the father of taxonomy– binomial nomenclaturebinomial nomenclature
• Developed a classification scheme which included a ranking hierarchy
Carolus LinnaeusCarolus 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 CuvierGeorges Cuvier1769-18321769-1832
Georges CuvierGeorges Cuvier• Realized that life’s history was recorded in
fossil-containing strata and documented the succession of fossil species in the Paris Basin
Georges CuvierGeorges 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 CuvierGeorges Cuvier• Understood that extinction had
been a common occurance in the history of life since, new species appeared and others disappeared
Georges CuvierGeorges Cuvier• He was still an opponent to
evolution:–Differences in species due to
catastrophic events (droughts, fires floods)
Georges CuvierGeorges Cuvier• New species result of:
–Localized catastrophe resulted in mass extensions
–Repopulation of out side species
Theories of Ecological Theories of Ecological GradualismGradualism
• Gained popularity that would influence Darwin’s concept
Theories of Ecological Theories of Ecological GradualismGradualism
• Principle that profound change is the cumulative product of slow, continuous process
Theories of Ecological Theories of Ecological GradualismGradualism
• Proposed by James Hutton–1875 Scottish Geologist
Theories of Ecological Theories of Ecological GradualismGradualism
• 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 LyellCharles Lyell
• Expanded Huton’s concept into the theory called uniformitarianism
Charles LyellCharles Lyell
• Uniformitarianism:–in this theory, geological processes
are uniform and have operated from the origin of the Earth to the present.
Charles LyellCharles 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
DarwinDarwin
• 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 LamarckJean Baptiste Lamarck
• First published a document trying to explain the model of evolution in 1809
Jean Baptiste LamarckJean 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 LamarckJean 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