evolution is science wade b. worthen biology dept. furman university greenville, sc 29613
TRANSCRIPT
Evolution Is Science
Wade B. Worthen
Biology Dept.
Furman University
Greenville, SC 29613
Evolution: An Excellent Example of the Process of Science
Evolution: An Excellent Example of the Process of Science
I. Science as a Way of Knowing
Evolution: An Excellent Example of the Process of Science
I. Science as a Way of Knowing
II. Evolution as Science
Evolution: An Excellent Example of the Process of Science
I. Science as a Way of Knowing
II. Evolution as Science
III. Scientific Theories
…people have always had lots of very important questions…
How can I grow more food?
…people have always had lots of very important questions…
How can I grow more food?
What happens when I die?
…people have always had lots of very important questions…
How can I grow more food?
What happens when I die?
Why is my daughter sick?
…people have always had lots of very important questions…
How can I grow more food?
What happens when I die?
Is it always wrong to steal?
Why is my daughter sick?
…people have always had lots of very important questions…
How can I grow more food?
What happens when I die?
Is it always wrong to steal?
Why is my daughter sick?
…when’s lunch?
…often there are several different questions wrapped up together …
Why is my daughter sick?
…often there are several different questions wrapped up together …
1) Is there a cause of her illness?
Why is my daughter sick?
…often there are several different questions wrapped up together …
1) Is there a cause of her illness?
2) Is there a purpose to her illness?
Why is my daughter sick?
…often there are several different questions wrapped up together …
1) Is there a cause of her illness?
2) Is there a purpose to her illness?
3) Is it "bad" that she is sick?
Why is my daughter sick?
…often there are several different questions wrapped up together …
Why is my daughter sick?
1a) Is there a physical cause of her illness?
1b) Is there supernatural cause of her illness?
2) Is there a purpose to her illness?
3) Is it "bad" that she is sick?
…and our questions can become even more specific …
…over time, we have created a process of inquiry for addressing the physical cause of physical events…
…over time, we have created a process of inquiry for addressing the physical cause of physical events…
This process is:
The Scientific Method
Observations: identify correlated variables and patterns in the physical world
The Scientific Method
Observations: identify correlated variables and patterns in the physical world
Hypothesis: propose a causal relationship between variables or patterns that leads to specific new predictions.
The Scientific Method
Observations: identify correlated variables and patterns in the physical world
Hypothesis: propose a causal relationship between variables or patterns that leads to specific new predictions.
Experiment: We TEST our predictions!
The Scientific Method
Observations: identify correlated variables and patterns in the physical world
Hypothesis: propose a causal relationship between variables or patterns that leads to specific new predictions.
Experiment: We TEST our predictions!
Conclusion: Were our predictions refuted or supported?
Here is all that science can do:Test causality between physical events
Physical Cause ?
Physical Event
Physical Cause ?
Physical Event
As we have seen, there are a lot of other interesting questions:
Here is all that science can do:Test causality between physical events
Physical Cause ?
Physical Event
As we have seen, there are a lot of other interesting questions:
Is there is supernatural cause?
Here is all that science can do:Test causality between physical events
Physical Cause ?
Physical Event
As we have seen, there are a lot of other interesting questions:
Is there is supernatural cause?
Is this “good” or
bad?
Here is all that science can do:Test causality between physical events
Physical Cause ?
Physical Event
As we have seen, there are a lot of other interesting questions:
Is there is supernatural cause?
Is this “good” or
bad?
Is there a “cosmic”
purpose for the event?
Here is all that science can do:Test causality between physical events
Physical Cause ?
Physical Event
As we have seen, there are a lot of other interesting questions:
Is there is supernatural cause?
Is this “good” or
bad?
Is there a “cosmic”
purpose for the event?
But these are not scientific questions…
Because they make no specific predictions about physical events – so there’s no way to test them
Here is all that science can do:Test causality between physical events
Key Points:
- science makes specific predictions about the physical world
- science tests these predictions by experiment
- science reaches a conclusion only after an experimental test
- there are many interesting questions that are not testable using this method.
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
“Common Sense” conclusions based on observations, alone:
Observation: Conclusion:
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
“Common Sense” conclusions based on observations, alone:
Observation: Conclusion:
The Earth looks flat The Earth is flat
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
“Common Sense” conclusions based on observations, alone:
Observation: Conclusion:
The Earth looks flat The Earth is flat
The sun moves through the sky The sun orbits the Earth
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
“Common Sense” conclusions based on observations, alone:
Observation: Conclusion:
The Earth looks flat The Earth is flat
The sun moves through the sky The sun orbits the Earth
Solid matter seems solid Solid matter is solid
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
“Common Sense” conclusions based on observations, alone:
Observation: Conclusion:
The Earth looks flat The Earth is flat
The sun moves through the sky The sun orbits the Earth
Solid matter seems solid Solid matter is solid
Can’t see continents move Continents don't move
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
“Common Sense” conclusions based on observations, alone:
Observation: Conclusion:
The Earth looks flat The Earth is flat
The sun moves through the sky The sun orbits the Earth
Solid matter seems solid Solid matter is solid
Can’t see continents move Continents don't move
Cats make cats and dogs make dogs Cats and dogs are unrelated
Science is NOT common sense. “Common sense” refers to conclusions we accept without rigorous testing. They are conclusions based on observation, alone (not observation, prediction, and experiment).
“Common Sense” conclusions based on observations, alone:
Observation: Conclusion:
The Earth looks flat The Earth is flat
The sun moves through the sky The sun orbits the Earth
Solid matter seems solid Solid matter is solid
Can’t see continents move Continents don't move
Cats make cats and dogs make dogs Cats and dogs are unrelated
Some traits look "designed" Some traits are "designed"
II. Evolution as Science
Question: Where do species come from?
II. Evolution as Science
Question: Where do species come from?
This is a question about the physical world
II. Evolution as Science
Question: Where do species come from?
This is a question about the physical world
Science can test for physical causes
II. Evolution as Science
Question: Where do species come from?
This is a question about the physical world
Science can test for physical causes
- using the scientific method
The Scientific Method
I. OBSERVATIONS OF CORRELATED PATTERNS:We observe a physical pattern, and note other physical patterns that correlate with our pattern of interest...
The Scientific Method
I. OBSERVATIONS OF CORRELATED PATTERNS:We observe a physical pattern, and note other physical patterns that correlate with our pattern of interest...
Human limbs have a particular set of bones
The Scientific Method
I. OBSERVATIONS OF CORRELATED PATTERNS:We observe a physical pattern, and note other physical patterns that correlate with our pattern of interest...
Human limbs have a particular set of bones
Cat limbs have the same set of bones
The Scientific Method
I. OBSERVATIONS OF CORRELATED PATTERNS:We observe a physical pattern, and note other physical patterns that correlate with our pattern of interest...
Human limbs have a particular set of bones
Cat limbs have the same set of bones
Whale limbs have the same set of bones
The Scientific Method
I. OBSERVATIONS OF CORRELATED PATTERNS:We observe a physical pattern, and note other physical patterns that correlate with our pattern of interest...
Human limbs have a particular set of bones
Cat limbs have the same set of bones
Whale limbs have the same set of bones
Bat wings have the same set of bones
The Scientific Method
I. OBSERVATIONS OF CORRELATED PATTERNS:
We observe a physical pattern, and note other physical patterns that correlate with our pattern of interest...
Human limbs have a particular set of bones
Cat limbs have the same set of bones
Whale limbs have the same set of bones
Bat wings have the same set of bones
Correlated patterns
organisms are only produced from other organisms
The Scientific Method
I. OBSERVATIONS OF CORRELATED PATTERNS:
We observe a physical pattern, and note other physical patterns that correlate with our pattern of interest...
Human limbs have a particular set of bones
Cat limbs have the same set of bones
Whale limbs have the same set of bones
Bat wings have the same set of bones
Correlated patterns
organisms are only produced from other organisms
Biologically related organisms (like members of a family) share characteristics
II. HYPOTHESIS OF PHYSICAL CAUSALITY:
Species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
Human limbs have a particular set of bones
Cat limbs have the same set of bones
Whale limbs have the same set of bones
Bat wings have the same set of bones
Correlated patterns
organisms are only produced from other organisms
Biologically related organisms (like members of a family) share characteristics
II. HYPOTHESIS OF PHYSICAL CAUSALITY:
species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
II. HYPOTHESIS OF PHYSICAL CAUSALITY:
species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
IF this hypothesis is true, then we predict:
II. HYPOTHESIS OF PHYSICAL CAUSALITY:
species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
IF this hypothesis is true, then we predict:
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
II. HYPOTHESIS OF PHYSICAL CAUSALITY:
species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
IF this hypothesis is true, then we predict:
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species
II. HYPOTHESIS OF PHYSICAL CAUSALITY:
species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
IF this hypothesis is true, then we predict:
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species
3) Species that are closely related should have similar DNA
II. HYPOTHESIS OF PHYSICAL CAUSALITY:
species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
IF this hypothesis is true, then we predict:
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species
3) Species that are closely related should have similar DNA
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Prediction….
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
Fish Amphibians
Should Be Here
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Prediction….
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
Fish Amphibians
Should Be Here
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Ichthyostega
- feet (amphibians)
- gill covering (fish)
- fins with 'struts' (fish)
IS HERE
CONFIRMATION:
Prediction….
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
Reptiles Birds
Should Be Here
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Prediction….
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
Reptiles Birds
Should Be Here
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
IS HERE
CONFIRMATION:
Archeopteryx
- feathers (birds)
- teeth and fingers (reptiles)
Prediction….
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
Reptiles Mammals
Should Be Here
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Prediction….
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record
Reptiles Mammals
Should Be Here
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Therapsids
- mammalian skeleton
- scales (reptiles)
- intermediate ears
IS HERE
CONFIRMATION:
Mammals from the Jurassic (185 mya)
Pelycosaur Reptiles of the Carboniferous (300 mya)
Therapsids from the Permian (280 mya) to the Triassic (200mya)
Hippos
Whales
Prediction….
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Hippos
Whales
Prediction….
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Mesonychids
Ambulocetus
Rodhocetus
Basilocetus
Chimpanzee
Human
Homo sapiens
Prediction….
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Chimpanzee
Human
Homo sapiens
Australopithecus afarensis
Australopithecus africanus
Homo habilis
Homo erectus
CONFIRMATION:
Prediction….
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Prediction….
3) Species that are closely related should have similar DNA
CONFIRMATION:
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
Prediction….
3) Species that are closely related should have similar DNA
Human Chimpanzee Gorilla Orangutan
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record - CONFIRMED
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species - CONFIRMED
3) Species that are closely related should have similar DNA - CONFIRMED
IV. CONCLUSION: Is hypothesis refuted or confirmed?
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record - CONFIRMED
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species - CONFIRMED
3) Species that are closely related should have similar DNA - CONFIRMED
IV. CONCLUSION: Is hypothesis refuted or confirmed?
Species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
III. EXPERIMENT: TEST THESE SPECIFIC PREDICTIONS!!
1) 'Intermediate’ fossils should exist, and exist in a particular place in the fossil record - CONFIRMED
2) 'Intermediate’ fossils should exist in sequences, with more recent species more like existing species - CONFIRMED
3) Species that are closely related should have similar DNA - CONFIRMED
IV. CONCLUSION: Is hypothesis refuted or confirmed?
Species are morphologically similar BECAUSE they are biologically related and have inherited these traits from common ancestors. Species come from shared ancestors. HYPOTHESIS OF COMMON ANCESTRY - EVOLUTION
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
THEY ARE NOT UNTESTED "IDEAS"..... (those are hypotheses...)
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
The theory of evolution has been tested and supported by:
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
The theory of evolution has been tested and supported by:
experiments in physics (radioactive decay) - the Earth is OLD
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
The theory of evolution has been tested and supported by:
experiments in physics (radioactive decay) - the Earth is OLD
experiments in geology (fossils) - sequences of intermediates
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
The theory of evolution has been tested and supported by:
experiments in physics (radioactive decay) - the Earth is OLD
experiments in geology (fossils) - sequences of intermediates
experiments in anatomy - similarities among existing organisms and continuity with fossil species
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
The theory of evolution has been tested and supported by:
experiments in physics (radioactive decay) - the Earth is OLD
experiments in geology (fossils) - sequences of intermediates
experiments in anatomy - similarities among existing organisms and continuity with fossil species
experiments in genetics - confirm relatedness among species
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
The theory of evolution has been tested and supported by:
experiments in physics (radioactive decay) - the Earth is OLD
experiments in geology (fossils) - sequences of intermediates
experiments in anatomy - similarities among existing organisms and continuity with fossil species
experiments in genetics - confirm relatedness among species
experiments in ecology - confirm that change occurs by Natural Selection
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
BUT....
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
BUT....
Theories are incomplete....we don't know everything!!!!
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
BUT....
Theories are incomplete....we don't know everything!!!!
Incomplete? But how can they work? How can we accept them as descriptive models if they aren’t complete?
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
BUT....
Theories are incomplete....we don't know everything!!!!
Incomplete? But how can they work? How can we accept them as descriptive models if they aren’t complete?
The heliocentric theory was accepted as TRUE:
- without knowing how planets were made - without knowing what stars are made of - without knowing how stars are made - without knowing when the solar system formed
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
BUT....
Theories are incomplete....we don't know everything!!!!
Incomplete? But how can they work? How can we accept them as descriptive models if they aren’t complete?
We don’t have to know EVERYTHING about a topic before claiming that we know SOMETHING.
And new research applies our theories to new questions, and new results make our existing theories more precise…
III. Scientific Theories
Scientific theories are broad, tested, predictive explanations for how the physical universe works, supported by experiments from a variety of scientific disciplines.
BUT....
Theories are incomplete....we don't know everything!!!!
So, with respect to evolutionary theory, we still don't know....
How and where did life on Earth arise?
- at surface?
How and where did life on Earth arise?
- at surface?
- at hydrothermal vents?
How and where did life on Earth arise?
- at surface?
- at hydrothermal vents?
- fed by chemicals on meteors that hit the Earth?
What genetic changes made us uniquely human?
What genetic changes made us uniquely human?
We have now sequenced the human and chimp genomes – what are the differences? What do these differences do?
These are questions about the physical world, and SCIENCE is the best way to address these questions!
...OF COURSE there are things we don't know.... but this DOES NOT INVALIDATE what we DO know... LIKE OTHER SCIENTIFIC THEORIES...