Evolution Notes:
History of Evolution Thought: Scientists who helped
Darwin’s idea
1785: Hutton: proposes Earth is shaped by geological
forces; Earth is millions of years old Geologic Time
Scale
1798: Malthus: Human population will grow faster than
the space and food provided
1809: Lamarck: Inheritance of acquired traits (use/disuse
hypothesis); 1st to suggest mechanism in changing
organisms
1831: Darwin: Traveled to the Galapagos Islands,
observed differences in tortoises and finches that led to his
theory of evolution
1833: Lyell: explained processes that have shaped the
Earth
1858: Wallace: writes to Darwin regarding natural
selection based on his studies of plant and animal
distribution
1859: On the Origin of Species (The Origin of Species:
By Means of Natural Selection or The Preservation of
Favored Races in the Struggle for Life) is published
Evidence for Evolution:
Fossil Record: Examining various fossils from different
time eras
Geographic Distribution of Species: Examining similar
but unrelated species on different continents suggesting
common ancestor but descent with modification
Homologous Structures: Structures from the same
embryonic tissue but having various forms in the mature
organism (human arm, bird wing, fish flipper)
Comparative Embryology: Examining embryos for
homologous structures
The Fossil Record and the Geologic Time Scale:
 Fossils can be entire organisms or part of organisms
 Fossils can be preserved in ice, amber, sedimentary rock
 Sometimes fossils are casts or outlines of the organisms
preserved but the organism is gone
 Fossil Dating:
o Relative dating: comparing with other fossils,
youngest fossil on top/oldest on bottom
o Radioactive dating: using the half-life of a
radioactive element in a rock layer
Geologic Time Scale: Major Events:
 65 million years ago: Extinction of the dinosaurs
 2 million years ago: Humans (as we know them) came
into existence