Transcript The Evolution of Evolution

Idea of Evolution
• Species of living
things change over
time
• Under the right
circumstances this
change can produce
new species of living
organisms from
existing ones
Before Darwin
Theology played a major role in thought. Christian
Bible accepted as literal truth and was used for
knowledge of the natural world.
All life, and existence itself, were a simultaneous
creation of a supernatural being (God).
Emergence of Evolutionary Thought
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Sequence of Fossil Types
Existence of Rudimentary Organs
Evidence of Common Underlying Plan
Facts of Animal & Plant Breeding
Struggle for Existence
Evidence of New Explorations
Sequence of Fossil Types
By 18th century fossils recognized as remains of critters that
had become extinct or still existed but in different forms. In
other words, living things changed.
Rudimentary Organs
If organisms were created "de novo," why do
they retain these vestiges?
Pelvis & femur in whales
Non-functional eye bulbs
In cave-dwelling salamanders
Check out the article on whale evolution at:
http://www.edwardtbabinski.us/whales/evolution_of_whales/
Common Underlying Plan
All mammals’
forelimbs are
constructed on a
similar anatomical
plan due to a
SHARED
ANCESTRY.
See Plate 1-6 in the Human Evolution Coloring Book
Animal & Plant Breeding
Starting with the ancestral rock pigeon
(middle), Darwin produced a wide variety of
morphologically distinct types in a few
generations by selective breeding.
Struggle for Existence
The elephant, one of the slowest breeders in the animal kingdom, could take over
the planet if it reproduced unhindered for long enough. Even if after only 500 years,
one pair would leave 15 MILLION descendants. So why aren’t there at least 15
million elephants?
Are you still paying Attention?
Evidence of New Explorations
None of these animals were mentioned in
the Bible. If Bible literal history, from where
had these animals come?
Ideas That Shaped Darwin’s Thinking
• Georges-Louis de Buffon (1707-1788):
Uniformitarianism
• James Hutton (1726-1797): Founder of
modern geology; geological forces worked
very slowly, thus earth very, very old
• Charles Lyell (1797-1875): Principles of
Geology; Formalized uniformitarianism;
Stimulated Darwin: if earth changed over
time, what about life?
Uniformitarianism
Mt Vesuvius
Mt. St. Helens
C.E. 79; last time 1944
15 eruptions in last 4000 years
Pinnacles
Began as a volcano that first erupted
about 195 miles south of its present
location. It has traveled northward along
the San Andreas Fault, and currently
moves at a rate of about 2 - 3 cm/year.
SF Quake
C.E. 1906
Oxbow Lakes
Geological Forces Work Slowly
Marine terraces north of
Santa Cruz.
Mt. Everest
Uplift: 10mm/yr
Coastal uplift: 5 mm/yr
Are you still paying Attention?
Pre-Darwin Explanation of Evolution
• Jean-Baptiste de Lamarck (1744-1829)
– Plants / animals adapted to their
environments
– When environment changes (as the
geological record shows), organisms must
change if they are to continue to exist
– Organisms change because they WANT or
FEEL A NEED to change
– Inheritance of Acquired Characteristics
Are you still paying Attention?
Acquired Characteristics
Darwin’s Explanation for
Evolution
• We’re not created equal (variations in phenotypes
& genotypes)
• Limited stuff (finite resources)
• Produce more offspring than finite resources can
support
• Struggle for existence
• Favorable vs. unfavorable traits (relative to the
environment)
• Inheritance
Not Created Equal
Over the past
200,000 years or so,
natural selection
favored subtle
variants allowing
different human
populations to adapt
to their different
environments.
Limited Stuff
Too Many Babies
Too Few Resources
Struggle For Survival
Favorable vs. Unfavorable Traits
Variants best adapted to conditions of
life are most likely to survive &
reproduce
Over time, favorable traits increase,
less favorable traits decrease
Are you
still
paying
Attention?
Darwin’s Conclusions
• Nature an open-ended process
of becoming: life continually
evolves
• Emergence of new species:
result of Descent with
Modification
• Evolution NOT a single line of
ascent but an irregularly
branching tree (adaptive
radiation)
Darwin vs. Lamarck
Descent With Modification
The Genetic
Code
• Life has the same
underlying genetic
code
• DNA sequences of
organisms are similar
Evolution
A change
in the relative frequencies of alleles
in a population
from one generation to the next
HOW DOES EVOLUTION WORK?
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Natural Selection
Mutation
Genetic Drift
Gene Flow