Reminder The website for the course is http://www.bio200.buffalo.edu To watch the slides used in lecture: Username: BIO200 Password: darwin To listen to the lecture and see the slides: Go to UB Learns. Check into Bio200 course. Go to Classroom recordings

TopHat Questions for Bio200 class 339431

Clicker Question Have you used clickers before? Yes No 30

What is your intended career? 1) Health related profession 2) Business 3) Engineering 4) Science 5) None of the above 6) I don’t know 30

Huh? What is science?

an attempt to explain the natural world in terms of Science is an attempt to explain the natural world in terms of natural processes.

No supernatural explanations are permitted. Get it? Natural. No Supernatural Explanations

SCIENCE AS A WAY OF KNOWING “Science SCIENCE AS A WAY OF KNOWING “Science .... Is the organized, systematic enterprise that gathers knowledge about the world and condenses the knowledge into testable laws and principles.” E.O. Wilson Science is.... • a body of facts and principles about the physical world • a method of discovery

The Classical “Scientific Method” Ask a Question Form an Hypothesis Make Predictions Test Predictions: Experiment; collect data Draw a conclusion: compare your data to the hypothesis/prediction and draw a conclusion

What happens after Step 5? On the basis of the data make conclusions about validity of the hypothesis. DATA HYPOTHESIS HYPOTHESIS REJECTED SUPPORTED New Tests & New Hypotheses Science is self-correcting

Characteristics of Science 1. Claims are tested: repeatable observations and experiments 2. Law of Parsimony — “OCCAM” S RAZOR 3. Measurements are used. 4. Consilience is applied. Principles of many fields are used to see if they are consistent with a discovery How can we apply this method?

Characterization of DNA structure An Example: Characterization of DNA structure Question: What is the structure of DNA? DNA had been identified as possibly the genetic substance by Avery, Macleod and McCarty at the Rockefeller Institute in 1944, but its structure was unclear to anyone in 1950 DNA hypotheses: Crick and Watson hypothesized that DNA had a helical structure.

Conclusion: DNA’s structure is probably a helix DNA prediction: From earlier work on tobacco mosaic virus, Watson was aware of the significance of the possibility of a helix, so he predicted this shape & if this were true then a X-ray picture would show it. DNA experiment: Rosalind Franklin in another lab took an X-ray diffraction photo of DNA. Unknown to her, a colleague showed Watson the picture and he recognized it had a helical structure Conclusion: DNA’s structure is probably a helix

The Classical “Scientific Method” (Hypothetico—Deductive Method) Ask a Question Form an Hypothesis Make Predictions Test Predictions: Experiment; collect data Draw a Conclusion: compare your data to the hypothesis/prediction and draw a conclusion

Types of Reasoning Applying a set of general logic rules Deductive Reasoning General------- Specific Applying a set of general logic rules to a particular problem ****** Inductive Reasoning Specific----- General Generalizing on the basis of some observations

Notice the use of deductive reasoning: DNA hypotheses: Crick and Watson hypothesized that DNA was helical. Reasoning from general principles of chemistry and what was known about helical structure of proteins, they guessed a similar structure might be found in DNA. General principles  to a specific case So Watson & Crick predicted a helix based on deductive reasoning

Notice the use of inductive reasoning: DNA experiment: Rosalind Franklin in another lab took an X-ray diffraction photo of DNA. Unknown to her, a colleague showed Watson the picture and he recognized it was a helical structure Conclusion: DNA’s structure is probably a helix Specific Case General Principles So Watson & Crick generalized that DNA had a helical structure based on inductive reasoning

2. Consistent with known facts 3. Probable Characteristics of a Good Hypothesis 1. Simple 2. Consistent with known facts 3. Probable 4. Uses physical explanations 5. Stimulates research 6. Makes predictions 7. Testable

I have a fire-breathing dragon in my basement. Do you believe me? Yes No I don’t know 20

HOW DO WE DEAL WITH THIS KIND OF STATEMENT? This is an extraordinary claim. Extraordinary claims require extraordinary proof. What kind of proof would we want? Can we deal with this claim scientifically?

The Hypothetico-Deductive Method in action: Question: Is there a fire-breathing dragon in the basement? Hypothesis: There is a fire-breathing dragon in the basement Prediction: ? Test: ?

Suppose I counter every physical test you propose with a special explanation of why it won't work. Then what? What's the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? What should we conclude? ***

What is the major problem with the dragon in the basement hypothesis? Not simple No predictions are possible Doesn’t stimulate research Not consistent with the known facts Not testable 20

When do we accept an hypothesis? 1. When all attempts to falsify it (i.e. show it false) have failed. It is critical to repeat experiments! 2. When it is accepted by the scientific community as “true, beyond all reasonable doubt.”

From Hypothesis to Theory HYPOTHESIS THEORY (Guess) (Major Conceptual Framework) Speculative Certain Simple Elaborate Little Explanatory Power Great Explanatory Power

People should have 2 children per family Clicker Question WHICH OF THE FOLLOWING STATEMENTS IS A SCIENTIFIC THEORY? A camel is a mammal. People should have 2 children per family If the world’s population grows beyond 10 billion, then a massive natural die-off will occur. The cell is the basic unit of living organisms and is composed of the same basic subunits wherever it occurs. All living cells are derived from previous cells. Ozone molecules in the earth’s atmosphere are being broken apart by CFCs (chlorofluorocarbons). 30

WHICH OF THE FOLLOWING STATEMENTS IS A SCIENTIFIC THEORY? 1. A camel is a mammal. (FACT) 2. People should have 2 children per family. (OPINION) 3.If the world’s population grows beyond 10 billion, then a massive natural die-off will occur. (PREDICTION) 4. The cell is the basic unit of living organisms and is generally composed of the same basic subunits wherever it occurs. All living cells are derived from previous cells. (CELL THEORY) 5. Ozone molecules in the earth’s atmosphere are being broken apart by CFCs (chlorofluorocarbons). (FACT)

Asteroid/Comet Hypothesis of Dinosaur Extinction Let’s Look at the Asteroid/Comet Hypothesis of Dinosaur Extinction 1. Simple ? 2. Consistent with known facts ? 3. Probable ? 4. Uses physical explanations ? 5. Stimulates research ? 6. Makes predictions ? 7. Testable ?

Was Alvarez doing science? How do you know? Highlight all words and phrases that suggests that Alvarez was doing science.

The Classical “Scientific Method” Is this an adequate description of the fate of the Asteroid/Comet hypothesis? Ask a Question Form an Hypothesis Make Predictions Test Predictions: Experiment; collect data Draw a conclusion

Where on this diagram do we find the various events of the Alvarez journey?

explanation of what goes on. The Simple form of science in action Is powerful. But not an adequate explanation of what goes on.

Outline the steps in sequence of the Alvarez journey.

The Simple Hypothetico-Deductive Method in Action If this Then hypothesis is supported!

If this Then hypothesis is supported!

If this Then Hypothesis is falsified! (Rejected)

THE HYPOTHESIS IS SUPPORTED DATA FOR Typical BIO 200 CLASS THE HYPOTHESIS IS SUPPORTED

Data from 2016

NEW QUESTION

NEW QUESTION

AND THE DATA PLEASE

Conclusion? Hypothesis is supported

Come to Class Even if you’ve Gotta Crawl ! SO???? Come to Class Even if you’ve Gotta Crawl !