outline of lectures 1 and 2: i.what is biology? ii.what is science? iii.context: ways of knowing...
TRANSCRIPT
Outline of Lectures 1 and 2:
I.What is Biology?II.What is Science?III.Context: Ways of KnowingIV.What Distinguishes Living Systems?V.The Evolution of Biology
I. What is Biology?
I. What is Biology?
Webster’s New World Dictionary: "the science that deals with the origin, history, physical characteristics, life processes, habits, etc. of plants and animals: it includes botany and zoology."
I. What is Biology?
Webster’s New World Dictionary: "the science that deals with the origin, history, physical characteristics, life processes, habits, etc. of plants and animals: it includes botany and zoology."
The scientific study of living systems.
I. What is Biology?
Webster’s New World Dictionary: "the science that deals with the origin, history, physical characteristics, life processes, habits, etc. of plants and animals: it includes botany and zoology."
The scientific study of living systems.
Begs two questions – “what is science?” and “What distinguishes living systems?”
II. What is Science?
A. Definition:
Webster’s: “systematized knowledge derived from observation, study, and experimentation carried on in order to determine the nature or principles of what is being studied. The systematized knowledge of nature and the physical world.”
II. What is Science?
A. Definition:
Webster’s: “systematized knowledge derived from observation, study, and experimentation carried on in order to determine the nature or principles of what is being studied. The systematized knowledge of nature and the physical world.”
II. What is Science?
B. Limitations:
- What is studied: the physical world /universe
A medieval, Ptolemeic view of the universe
II. What is Science?
B. Limitations:
- What is studied: the physical world /universe
- How it is studied (Method): empiricism
“of the senses”, but not “common sense”…
-Methodological Approaches:
1. REDUCTIONISM
Gaining an understanding of a system by describing its subsystems (components)
-Methodological Approaches:
1. REDUCTIONISM
Gaining an understanding of a system by describing its subsystems (components)
≠
“emergent properties”
Powerful Approach: living systems are very complex, so describing the STRUCTURE can give insights into FUNCTION.
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
The function of complex systems may be understood by comparing them with simpler systems (with fewer subsystems).
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
The function of complex systems may be understood by comparing them with simpler systems (with fewer subsystems).
How could a complex system like a camera eye, composed of mutually dependent parts, have evolved through a stepwise sequence?
Half an eye (lens) can’t work…
2. COMPARATIVE METHOD
The function of complex systems may be understood by comparing them with simpler systems (with fewer subsystems). Visual systems in molluscs: Half an eye
(retina) CAN work…
2. COMPARATIVE METHOD
Why is this method so powerful in biology? Is there a REASON why different organisms might have similar structures and functions?
2. COMPARATIVE METHOD
Why is this method so powerful in biology? Is there a REASON why different organisms might have similar structures and functions? Yes… common ancestry.
This is why the use of model organisms (E. coli, fruit fly, house mouse) illuminates the field of medicine
And the most dramatic examples of homology are in the hox genes, as well.
In fact, the homology is so good that lineages of eyeless flies lacking that hox gene can have the ability to grow eyes restored by adding the homologous gene from a mouse…and flies develop compound eyes with the mouse hox gene for eye development, even though mice have camera eyes…
HOW COOL IS THAT!?
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
Observe a pattern:“spiders occur on some Caribbean islands and not others”
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, there are no spiders”
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”GOAL: is this relationship causal?
GOAL: create a falsifiable (testable) causal hypothesis
Bring other observed facts to bear“They use similar habitats” (could live
together)
“Lizards eat spiders”
“Lizards and spiders eat other insects”
“They disperse differently” (so they may have gotten to different islands by chance)
“Hawks eat lizards but not spiders, so maybe it just happens that hawks and spiders are
together”
“Some warblers eat spiders and not lizards, and maybe it just happens that warblers and
lizards are together”
“Lizards run around and may break spider webs and starve them inadvertently”
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”GOAL: is this relationship causal?
GOAL: create a falsifiable (testable) causal hypothesis
Bring other observed facts to bear“They use similar habitats” (could live
together)
“Lizards eat spiders”
“Lizards and spiders eat other insects”
“They disperse differently” (so they may have gotten to different islands by chance)
“Hawks eat lizards but not spiders, so maybe it just happens that hawks and spiders are
together”
“Some warblers eat spiders and not lizards, and maybe it just happens that warblers and
lizards are together”
“Lizards run around and may break spider webs and starve them inadvertently”
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”GOAL: create a falsifiable (testable) causal hypothesis
Bring other observed facts to bear“They use similar habitats” (could live
together)
“Lizards eat spiders”
“Lizards and spiders eat other insects”
“They disperse differently” (so they may have gotten to different islands by chance)
“Hawks eat lizards but not spiders, so maybe it just happens that hawks and spiders are
together”
“Some warblers eat spiders and not lizards, and maybe it just happens that warblers and
lizards are together”
“Lizards run around and may break spider webs and starve them inadvertently”
You can envision many alternative causal hypotheses …and there are nearly a limitless supply…you can’t test them all (so scientific facts aren’t eternal truths or PROOFS)… test the simplest explanation first = “principle of parsimony” or “Occam’s razor”
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”GOAL: is this relationship causal?
GOAL: create a falsifiable (testable) causal hypothesis
Hypothesis: Lizard predation causes a reduction in spider abundance on Caribbean Islands
Other observations
You have just used Inductive logic , using specific observations to formulate a general principle
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”GOAL: is this relationship causal?
GOAL: create a falsifiable (testable) causal hypothesis
Hypothesis: Lizard predation causes a reduction in spider abundance on Caribbean Islands.
Alternative Hypothesis: Lizard predation does not cause a reduction in spider abundance… (maybe competition does or maybe it is just a correlated effect of something else…)
Other observations
Here is a another critical element of a scientific hypothesis – it must be falsifiable – you must be able to envision data collected from the physical universe that would prove
your hypothesis is wrong.
Hypothesis: Lizard predation causes a reduction in spider abundance on Caribbean Islands
Alternative Hypothesis: Lizard predation does not cause a reduction in spider abundance… (maybe competition does or maybe it is just a correlated effect of something else…)
Conduct an experiment in which data supporting either hypothesis is possible.
IF: - lizard predation is responsible for low spider abundance
AndIF: - I add lizards to specific islands and remove lizards from others, with appropriate controls for the manipulations,
THEN: - Spider abundance should decline where I add lizards and increase where I remove lizards, and spiders should be a major component of lizard diets (gut content analysis).
To do this, you use deductive logic (general to specific case). IF my general principle (hypothesis) is true, THEN I can predict a specific outcome in my particular experiment.
IF: - lizard predation is responsible for low spider abundance
AndIF: - I add lizards to specific islands and remove lizards from others, with appropriate controls for the manipulations,
THEN: - Spider abundance should decline where I add lizards and increase where I remove lizards, and spiders should be a major component of lizard diets (gut content analysis).Then you do it and see!!! And you generalize from your specific experiment to nature (inductive logic). You use logic and evidence from the physical world to reach a conclusion about how nature is and how it works.(Usually by statistical inference…which we will demonstrate in lab…)
Then you do it and see!!! And you generalize from your specific experiment to nature (inductive logic). You use logic and evidence from the physical world to reach a conclusion about how nature is and how it works.
Many lines of independent evidence…
Then you do it and see!!! And you generalize from your specific experiment to nature (inductive logic). You use logic and evidence from the physical world to reach a conclusion about how nature is and how it works.
Many lines of independent evidence…
can support a single general explanation
Then you do it and see!!! And you generalize from your specific experiment to nature (inductive logic). You use logic and evidence from the physical world to reach a conclusion about how nature is and how it works.
Many lines of independent evidence…
can support a single general explanation…
These Explanations are THEORIES. They are supported by experimental results and they can be tested by subsequent experiments
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
4. METHODOLOGICAL MATERIALISM
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
4. METHODOLOGICAL MATERIALISM
Philosophical materialism – the material is all there is.
Methodological materialism – the material is all we can test.
II. What is Science?
A. Definitions
B. Limitations
C. Theories
- tested, explanatory models of how the physical universe works
II. What is Science?
A. Definitions
B. Limitations
C. Theories
- tested, explanatory models of how the physical universe works
Physics: “Atomic Theory”
Chemistry: “Chemical Bond Theory”
Astronomy: “Heliocentric Theory”
Biology: “Evolutionary Theory”
III. Context: Ways of Knowing
A. Why You Know - Searching for Truth
1. Faith: Webster’s – “unquestioning belief not requiring proof or evidence”
III. Context: Ways of Knowing
A. Why You Know - Searching for Truth
1. Faith: Webster’s – “unquestioning belief not requiring proof or evidence”
2. Logic: “the science of correct reasoning; science which describes relationships among propositions in terms of implication, contradiction, contrariety, conversion, etc.” Evidence is a "clean argument“, but it does not have to describe a physical reality.
III. Context: Ways of Knowing
A. Why You Know - Searching for Truth
1. Faith: Webster’s – “unquestioning belief not requiring proof or evidence”
2. Logic: “the science of correct reasoning; science which describes relationships among propositions in terms of implication, contradiction, contrariety, conversion, etc.” Evidence is a "clean argument“
3. Science: Logical argument and physical evidence.
III. Context: Ways of Knowing
A. Why You Know - Searching for Truth
B. Different Problems, Different Tools
“If the only tool you have is a hammer, you tend to see every problem as a nail.”
– Abraham Maslow, American Psychologist
Is abortion right?
How old is the Earth?