Publication: Darwin's The Origin of Species (1859)
Challenged Traditional Views:
The earth is young
The earth's surface is unchanging
Species are unchanging
Humans are not influenced by natural laws
Carolus Linnaeus (1707-1778)
Founder of taxonomy; classified organisms by physical characteristics.
Believed species were fixed and unchanged over time.
Georges Cuvier (1769-1832)
Developed paleontology; recognized extinction through fossil studies.
Proposed catastrophism to explain extinctions: local catastrophic events led to species replacement.
Geologists James Hutton and Charles Lyell
Advocated for uniformitarianism: changes in Earth's surface occur gradually; processes still operational today.
Implication: Earth must be older than 4000 years.
Thomas Malthus (1766-1834)
Wrote An Essay on the Principle of Population; examined the relationship between food production and population growth.
Jean-Baptiste Lamarck (1744-1829)
Proposed that species evolve through use and disuse of traits and inheritance of acquired characteristics.
Suggested evolution driven by an innate drive towards complexity.
Darwin's Education: Studied theology at Cambridge University.
HMS Beagle Voyage (1831-1836):
Collected specimens; observed geological uplift and unique species in the Galápagos Islands.
Hypothesis: Species from South America colonized the islands and adapted over time.
Noticed variation among species such as tortoises and finches on different islands.
All Galápagos finches likely evolved from a common ancestor in South America.
In June 1858, received a manuscript from Alfred Russel Wallace, who proposed a similar idea of natural selection.
Prompted Darwin to publish The Origin of Species in 1859.
Descent with Modifications: Evolution explained through heritable variations within species.
Natural Selection: Individuals with advantageous traits survive and reproduce better than others, leading to adaptation.
Lamarck:
Inheritance of acquired characteristics.
Darwin:
Natural selection as the primary mechanism for evolution and adaptation.
Major Components:
Variation within populations.
Heritability of traits.
Differential reproductive success.
Individuals vary in traits.
Traits under genetic control can be inherited.
More offspring are produced than can survive; thus, some fail to reproduce.
Inferences from Natural Selection:
Higher fitness translates to more offspring.
Accumulation of favorable traits leads to population change over time.
Natural selection acts on individuals, but populations evolve over generations.
Evolution lacks a predetermined goal; adaptations depend on environmental context.