Transcript Darwin and Evolution - Woodstown

Darwin and Evolution
Charles Darwin
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Son of Robert Darwin, a physician and
grandson of Erasmus Darwin, also a
physician
Was to study medicine, stomach not strong
enough
Studied Theology, loved natural science
Darwin’s Voyage
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1831 - 1836
Naturalist on the HMS Beagle
Looking for a biblical account of creation
Many specimens collected (hares, tortoise,
finches) and observations made that
contradicted creationism
Put his ideas into an essay, but sat on it for
20 years for fear of being discredited as a
scientist
Pre - Post Darwinian Views
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Earth is young
Fixity of species
Adaptation due to
creator variationimperfections
Observations should
confirm view
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Earth is old
Species related by
descent
Adaptation = random
variations in
environmental
conditions
Observations used to
test hypothesis
Evolution versus Creationism
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Descent with
modification- as
descent occurs through
time – so does diversity
Explains the unity and
diversity of life
Living things share
common characteristics
because they are
descended from a
common ancestor
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Higher being created
the species
Fixity of species
Each species has ideal
structure and function
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Mid-18
century contributions
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Carolus Linnaeus – taxonomy, scala naturae –
ladder of life: simple to complex (humans)
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Count Buffon – French naturalist, work support
DWM
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Erasmus Darwin – grandfather – physician,
naturalist, work eluded to DWM
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All these men’s work opened the door to the
thought of evolution but still supported fixity of
species
Late
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18
century contributions
Georges Cuvier –
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comparative anatomy for classification, founded
paleontology
Fixity of species supporter
Tried to explain strata of earth was due to
catastrophes/mass extinction
Cont.
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Jean Baptist LaMarck –
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First to believe evolution occurs
Inheritance of Acquired traits – use it or lose it –
environment brings about change
Phenotype does not result in genetic changes
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Giraffe neck length
Suntan, muscles…
Darwin’s Theory of Evolution
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Influenced by Charles Lyell’s Principle of
Geology
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James Hutton – geological changes occur slowly
over time, natural process: EARTH IS OLD
Contradicts Cuvier – due to catastrophes
Natural Selection
Charles Darwin and Alfred Wallace
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Idea that those organisms that are best suited to
their environment will reproduce and pass on their
traits
Alfred Russell Wallace – sent Darwin essay on
Natural selection before he published his own
Variations (mutations) are essential to natural
selection process ex. Independent assortment
Natural Selection
Thomas Malthus – socio-economist –
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human population increase faster than food
supply: struggle for existence
Each generation of organisms have same
reproductive potential, but not all will survive to
reproduce
Natural selection
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Fitness – ability to survive and reproduce in
its environment relative to others
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Usually has most resources
Survival of the fittest
Artificial selection – characteristics are selected
for and select organisms to reproduce.
Natural Selection
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Adaptation – trait that helps organism be
better suited for its environment
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Flippers – water, wont help on land
Natural selection occurs because certain
members of a population happen to have a
variation (mutation) that allows them to
survive and reproduce.
Darwin’s Theory of Evolution Evidence
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Biogeography – study of range and
geographic distribution of life forms on earth
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Darwin reasoned related species could be
modified based on their environment (ex.
Tortoises)
Observed geographical changes 1st hand and
collected fossils to support his theory that species
are not fixed, but change over time.
Evidence of Evolution
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Biochemical evidence
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Darwin was not aware of biochemical evidence
Amino acids- cytochrome c (used in electron
transport)
DNA/RNA/enzymes – similarities
Introns (junk DNA)
Fossils
Evidence of Evolution
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Anatomical structures
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Homologous structures - similar in structure but
have different function
Vestigial structures – features that are fully
developed in one group of organisms but are
reduced and may have no function in similar
groups
Embryological development – look at dorsal rod
(notochord), pharyngeal slits (gills)…
Theory of Evolution
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Unifying theory in biology
Large number of observations
have not yet been found lacking or disproven