History of Evolution Flashcards
what is essentialism? who thought it?
Aristotle
- the physics world and is life forms are fixed
- all members of a class share unchanging properties that define the class
- most controversial aspect of what Darwin proposed, was that species were NOT fixed in form
what is scala naturae?
the “great chain of being”
- life arranged hierarchically, culminating in divinity
god angels demons man higher animals lower animals vegetables minerals
who was Linnaeus?
father of modern taxonomy
- binomial nomenclature
- hierarchical taxonomy embodied scala naturae
who was Louis Leclerc?
- recognized that the differences between related species living in different parts of the world reflect the different environments they inhabit
- after migrating organisms have to somehow change to suit their new environment
- plants that live in desserts look like they should live in the desert and have characteristics that will allow them to live there
who was Lamarck? what was his theory?
transformism:
- lineages persist forever but change in form
- vague mechanism of “internal force”
- no extinction or branching of lineages
- first explicit scientific treatment of evolution
- he proposed a mechanism that is incorrect: some internal “force” causes parents to produce offspring slightly different from themselves which accumulates changes over time so species transform into another one
who was Cuvier? what was his theory?
who did he disagree with? why?
essentialism:
- disputed Lamarck’s claim that forms change gradually over time
- *correlation of parts: organisms are so integrated in form and function that any changes would lead to death
- first to establish extinction as fact
- attributed extinction to discrete catastrophic events
- reconstructed fossils
who was Hutton? what was his theory?
gradualism:
earth’s physical features gradually changed due to slow geological processes
who was Lyell? what was his theory?
uniformitarianism:
historical changes result from uniform geological process that STILL occur today (erosion, sedimentation, volcanism)
supplanted geological catastrophism
what is the difference between Hutton and Lyell?
Lyell: geological changes are occurring
Hutton: the geological processes are STILL going on so the impacts that people saw 100 years ago are still happening now
what are the implications of Hutton and Lyell’s theories?
- the earth is very old and is always slowly changing
- the past can inform the present and vice versa!
the complexity of the Earth’s history can be explained in terms of the processes that are observed today
what were the thoughts on evolution before darwin?
1) essentialism was dominant
- most people thought that species did not change
2) there was no satisfactory theory for biological diversity
- those who favored evolution like Lamarck has incorrect views of the process (transforms) and the mechanism
3) extinction and branching
- Cuvier demonstrated that extinction happened but even those who favored evolution didn’t think that species could split
4) uniformitariansim was promoted
- geologists like Hutton/Lyell argued that the Earth is old and constantly changing, not static like the essentialists thought
what was Darwin’s mechanism for evolution?
natural selection!!!!
descent with modification is the outcome of evolution
what is evolution?
descent with modification
what lead Darwin to his ideas about evolution?
- modern species resemble fossils
- modern domesticated animals can be made to vary through intentional selection (artificial selection)
- creatures in the archipelagos vary from island to island
- organisms may have very complex modifications that are necessary for their survival
what traits do domesticated varieties of species have?
- unlike wild species, most varieties are freely inter-fertile
- closely related varieties show more pronounced morphological differences that closely related wild species
what do people think is the cause of domesticated varieties?
each variety is descended from a unique ancestral species
domesticated varieties arose form wild ancestors that had the same or similar characteristics as the domesticated variety