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...