EvolutionEvolution:Change through space and timeBiological Evolution:Genetically based change in a line of descent over time (descent with modification)Individuals of populations show different forms of their traitsThe frequencies of different forms relative to one another can change over successive generationsCommon public perception of evolution is orthogenesis (straight line) - IncorrectBranching - CorrectDevelopment of Evolutionary ThoughtThe earliest roots of modern evolutionary theory begins with origin myths & superstition to explain the natural worldRoots of western philosophy:Stoic Philosophers (1st century AD):- followers of Zeno (humans free from passion)- recognized fossils as evidence of past life that had been destroyed by catastrophesAristotle (350 BC):Created the “Scala naturae”, a hierarchy of lifeRise of Rome and Christianity: - A chain of being from lowest to highest forms (each being was a separate link in the chain)- all links were designed & forged at the same time at center of creation and were immutableDevelopment of Evolutionary ThoughtSir Thomas Aquinas (1300 AD): humans are divineHomunculus theory (soul transferred at fertilization)Albertus Magnus (1300 AD):- removed humans from scale of natureTheory of creationism:- god created the earth and all life on it- life was immutable and did not change- the earth is young (6000 - 10,000 yrs) Development of Evolutionary ThoughtBasic questions about life:Development of Evolutionary Thought1. Biogeography: (examination of global distribution of animals)OstrichAfricaRheaSouth AmericaEmuAustraliaObservations: - many plants and animals are unique to isolated places- certain species separated by great distances resemble one anotherBasic questions about life:Development of Evolutionary ThoughtQuestions: - How did so many species get from one point of creation to isolated places on earth?- What did the similarities and differences among them mean? 1. Biogeography: examination of the global distribution ofanimalsObservations: - many plants and animals are unique to isolated places- certain species separated by great distances resemble one anotherQuestions about life:Development of Evolutionary Thought2. Comparative Morphology: (the study of similarities and differences in body plans between major groups1111112222223333334444555Observations: - human arms, whale flippers, bat wings differ in size, shape and function- yet have similar locations in the bodyQuestions about life:Development of Evolutionary Thought2. Comparative Morphology: the study of similarities and differences in body plans between major groupsQuestions: - Why are some animals that are so different in some features so much alike in others? Observations: - human arms, whale flippers, bat wings differ in size, shape & function, yet have similar locations in the bodybackbonepelvic girdle coccyx (bonessmall boneattached topelvic girdlethighboneattached topelvic girdle- Why were there parts with no functions?Questions about life:Development of Evolutionary Thought3. Geology: Fossil remains of plants and animals Questions: - What did this increasing complexity represent?- Were these these fossils layers separated in time?- Could these organisms be related? Observations: - distinct layers of rock contained distinct fossils- deep layers contained simple fossils and shallow layers contained similar but more complex fossilsQuestions about life:Development of Evolutionary ThoughtFindings from Biogeography, Comparative Morphologyand Geology did not fit well with beliefs of creationismNovel Hypotheses: 1. If dispersal of all species from a center of creation was not possiblebecause of barriers 2. If organisms were not created in perfect states- then species may have originated in more than one place- then species may have been modified over timeDevelopment of Evolutionary ThoughtErasmus Darwin (late 1700’s) - competition play role in species formation (not creation)- animals change in response to changes in the environment- offspring inherit these changes (life on earth could have descended from a common ancestor)Georges Louis Leclerc de Buffon (early 1700’s)- life was not immutable but changed by degeneration- environment influences modifications - earth was old - 70,000 years (Hid his views in a 44-volume naturalhistory book series)James Hutton & Charles Lyell - Geologists (mid 1800’s) -Theory of Uniformitarianism (Uniformity)(changes in the earth occurred slowly, gradually and at uniform rates) - age of earth determined by sedimentation rates - earth was old (1-2 million years)Development of Evolutionary ThoughtWilliam Smith (Paleontologist) (mid 1800’s) - layer of fossils in the Cliffs of Dover, Great Britain - linked age of rocks to age of fossilsGeorges Cuvier (anatomist/biologist) (mid 1800’s)-Species go extinct due to catastrophes-Theory of Catastrophism(survivors not new species, fossils represent species that were destroyed)Development of Evolutionary ThoughtJean Baptiste de Lamarck (mid 1800’s) - Inheritance of Acquired Characteristics (traits) (environmental pressures and internal needs bringabout permanent changes in body form and function) - Behavioral changes modified traitsEx: Giraffe (process of orthogenesis)A B C DCharles Darwin (biologist) (mid 1800’s)- 1825 attended University of Edinburgh (medicine) , transferred to Cambridge (clergy) and graduated in 1831- At 22 years old took a job as ships naturalist- 5 years voyage 1831-1836 (H.M.S Beagle) - Survey of geography, oceanography, geology & biologyDevelopment of Evolutionary ThoughtCharles Darwin - biologist (mid 1800’s)3 Major Findings:1. As environment changes so does species composition2. Fossils are related to organisms today but are also structurally different3. Galapagos islands: island animals were related to mainland species but locally different in form and function Ex: FinchesDevelopment of Evolutionary ThoughtCharles Darwin - biologist (mid 1800’s)Questions: 1. If the earth was very old then wasn’t that enough time for species to evolve in diverse ways? 2. If so, how did they evolve? (1856 began writing)Development of Evolutionary ThoughtThomas Malthus (1798)- “Essay on the Principle of Population”(geometric growth of populations)- All populations have the capacity to produce more more individuals than the environment can supportAlfred Russel Wallace