The history of evolutionary thought Flashcards
Describe the earliest forms of evolutionary thoughts
Platonic forms- each living thing = representation of ideal form which was perfect and unchanging- so any variation within species = imperfections
Great chain of being- organisms do not change their position:
- most advanced = humans
- most primitive = rocks
Describe Linnaeus’ role in the history of evolutionary thought and how is different to today?
Binomial system = 2 part system- species + genus
involved devising names for organisms based on how they were grouped e.g. species, family, class etc
Similar system used today, but Linnaeus grouped according to similarities- but today evolutionary relationships are concerned
Describe Lamarks role in the history of evolutionary thought
was he right / wrong and why ?
Suggested organisms change to suit their environment- the more a characteristic is used, the bigger + stronger it becomes e.g. giraffes neck would stretch
- incorrect- somatic cells changing during an organisms lifetime will have no effect on off-spring only the reproductive cells
Describe Cuvier’s role in the history of evolutionary thought
Founded science of comparative anatomy- applied to fossils + living organisms:
Catastrophism- strong evidence provided from fossil record that suggests no connection between one time period and another
= one group of organisms become extinct then another comes along- no belief of evolution
Describe the role of Charles Lyell in the history of evolutionary thought
Wrote principles of geology- more concerned with rocks
- suggested principle of uniformitarianism = present is key to past + earth has changed in a uniform way
- didn’t believe in evolution but convinced by Darwin
Describe how Darwin’s ideas of evolution were initially developed
Darwin’s Finches- Galapagos islands:
- Finches beak sizes varied depending on the island they inhabited as they were specialised to exploit different ecological niches
-Darwin’s geology = found on extant sloth that was clearly related to extinct giant sloth species- doesn’t fit with Cuvier’s catastrophism
Who was Darwin influenced by and what were they interested in ?
Lyell + Malthus:
- interested in consequences of expanding human populations- wrote an essay = principle of population
Describe the role of Wallace in the theory of evolutionary thought
= collector of different species for museums
Wallace line- runs through Indonesia with different faunas on either side:
- Asian fauna = rhinos, tigers
- Australian fauna = kangaroos, koalas
He wrote on “tendency of varieties to depart indefinitely from original type”- contained his theory of natural selection which was sent to Darwin
What was the name of Darwin’s book and when was it published ? + why?
Origin of species by natural selection- 1859:
Still contained flaws but publication was forced as others (Wallace) were theorising the same thing- not much was known about inheritance
Describe the 3 ideas that evolution by natural selection is based on
- Variation- organisms differ in important + selectable ways
- Competition between organisms in a population so not all will survive- variations influence survival chances
- Inheritance- successful individuals pass on favourable characteristics to their offspring
Describe the major flaws in Darwin’s theory
Understanding of inheritance:
- Considered to be blending inheritance = characteristic of each parent mixed e.g. large + small = medium
- doesn’t account for variation
How was Darwin’s major flaw resolved?
Mendel’s Pea Plants:
Observed that some characteristics were lost through generations but reappeared in later generations
- Suggested inheritance determined by simple factors = GENES
Where is there conflict in Mendel and Darwin’s and how is this resolved?
Darwin’s theory suggest gradual changes
whereas
Mendel’s suggest major changes
- Resolved by combining both ideas = Neo-Darwinism
