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Section 8.1
SBI 3U1
pp. 326 - 331
Scientific
Contribution to a
Theory of Evolution
and… Darwin’s voyages
and….developing
Theory of Natural
Selection
Where did we come from?
• Old Ideas - influenced by religion &
philosophy-stated that all life forms
on Earth have existed, unchanged,
since Creation.
• ~1600’s-European scholars used
“empirical studies” to explain the
natural world-uses Observation &
Experiment to form ideas &
hypotheses about nature.
George-Louis Leclerc, Comte de
Buffon (1707-1788)-French naturalist
• Noted similarities
between humans and
apes, speculated that
they may have a common
ancestor
• Suggested the Earth was
much older than 6000
years
• Revolutionary thinking for
this time!
Georges Cuvier-French naturalist
(1769-1832)
• Cuvier is the founder of
palaeontology
• 1769-1832 – Theory of
Catastrophism
• Explained that catastrophes
in the past caused the
extinction of local species
Georges Cuvier-French naturalist
(1769-1832)
Sir Charles Lyell
• 1797-1875 – geologist
• Uniformitarianism
• Geological processes are
slow & continuous rather
than catastrophic
• Inspired other scientists Can populations also
change in slow, subtle
ways?
Jean-Baptiste Lamarck (1744-1829) French naturalist
• 1809 – developed the
theory ‘the inheritance of
acquired characteristics’
E.g. Giraffe
• Environment plays a role
in use and disuse
Charles Darwin (1809-1882)
• At 16 was sent to medical
school… he thought it was
boring and found surgeries
disturbing, and left
• Became a clergyman &
naturalist
Charles Darwin (1809-1882)
• John Henslow, a professor of
botany, introduced Darwin to
Captain FitzRoy (HMS Beagle)
• On the HMS Beagle for 6 years
as the ship’s naturalist
• Mission was to chart the South
American coast
• Darwin would go ashore and
collect specimens of local
animals and plants, as well as
fossils of extinct animals
Voyage of the Beagle
Charles Darwin (1809-1882)
• The fossils led Darwin to
believe that existing animals
were descended from extinct
animals
• He wrote an essay on
‘Natural Selection’ in 1844
• Darwin was excessively
meticulous, and didn’t publish
his essay on Natural
Selection
On the Origin of Species
• 1856, Darwin had amassed more evidence
for evolution, that he re-opened his 1844
essay.
• In 1858, Darwin received a letter from
Alfred Russell Wallace. A naturalist
working in Indonesia, that described the
changing of species over time. 12 days
after reading the letter, Darwin read
Wallace’s letter and a portion of his 1844
essay to the Linnaean Society.
• On the Origin of Species by means of
Natural Selection was published in
November 1859. It was over 1000
pages long. It sold out.
Some people didn’t like it
Observations p. 329, Table 8.1
Observations p. 329, Table 8.1
Observations p. 329, Table 8.1
Natural Selection
 Organisms produce more offspring than can survive,
resulting in competition for limited resources.
 Individuals of a population vary, variation is heritable
 Individuals that are better suited to environment survive
to produce more offspring
 Processes for change are slow and gradual
Evolution = change over time, no set direction
To Do List
• Section 8.1 p. 327 #1 – 4, p. 331 #4-8, 11,
12, 14
• Read and make notes on ‘Evidence from
Embryology & Evidence from DNA’