1 History of Evolutionary Thought

2 Early Ideas On Earth’s Organisms Aristotle believed species were fixed creations arranged by their complexity Aristotle believed species were fixed creations arranged by their complexity Idea lasted 2000 years Idea lasted 2000 years

3 Early Ideas On Earth’s Organisms Linnaeus – 1 st to group similar organisms and assign them Latin names Linnaeus – 1 st to group similar organisms and assign them Latin names Two word name (Genus species) Two word name (Genus species) Known as Binomial nomenclature Known as Binomial nomenclature

4 : Contributor’s to Darwin’s thinking included:  Georges Cuvier – Catastrophism: fossils showed that natural disasters caused species extinction  James Hutton – Gradualism: changes on Earth occurred by small steps over long periods of time

 Charles Lyell – Uniformitarianism: geologic processes that shape Earth are uniform through time  Changes that shaped Earth in the past are still happening today 5 Contributor’s to Darwin’s thinking included:

6 Charles Lyell Proposed theory of Uniformitarianism Proposed theory of Uniformitarianism Geological processes occur at uniform rates by building & wearing down Earth’s crust Geological processes occur at uniform rates by building & wearing down Earth’s crust Proposed that the Earth was millions of years old instead of a few thousand years old Proposed that the Earth was millions of years old instead of a few thousand years old

7 : Contributor’s to Darwin’s thinking included:  John Baptiste Lamarck – Inheritance of Acquired Characteristics and Law of Use and Disuse  Thomas Malthus – struggle for existence (due to limited resources)  Alfred Russel Wallace – organisms evolved from common ancestors

8 Jean–Baptiste Lamarck’s Theory of Evolution One of the first scientists to understand that change occurs over time. One of the first scientists to understand that change occurs over time – proposed that all organisms evolve toward perfection and complexity 1809 – proposed that all organisms evolve toward perfection and complexity

Stated that changes in an environment caused an organism’s behavior to change Stated that changes in an environment caused an organism’s behavior to change This change led to greater use or disuse of a structure or organ, and the structure would become larger or smaller as a result This change led to greater use or disuse of a structure or organ, and the structure would become larger or smaller as a result Said acquired changes were passed on to offspring Said acquired changes were passed on to offspring 9 Jean–Baptiste Lamarck’s Theory of Evolution

10 Lamarck’s Theory of Use and Disuse If a body part were used, it got bigger and stronger If a body part were used, it got bigger and stronger –Lamarck thought that the long necks of giraffes evolved as generations of giraffes reached for higher leaves in the trees If body part NOT used, it deteriorated If body part NOT used, it deteriorated

11 Lamarck’s Theory of Inheritance of Acquired Characteristics/Traits Proposed that by selective use and disuse of organs, organisms acquired or lost certain traits during their lifetime Proposed that by selective use and disuse of organs, organisms acquired or lost certain traits during their lifetime These traits were then passed on to their offspring These traits were then passed on to their offspring Over time this led to new species! Over time this led to new species!

12

13 Lamarck’s Mistakes Lamarck did NOT know how traits were inherited Lamarck did NOT know how traits were inherited –We now know traits are passed through genes Genes are NOT changed by activities in life Genes are NOT changed by activities in life Change through gene mutation occurs before an organism is born Change through gene mutation occurs before an organism is born

14 Evolutionary Timeline