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BIOL 101 Lecture 2

BIOL 101 Lecture 2. Methods & Beliefs in Science. The nature of science. Science : A systematic process for learning about the world and testing our understanding of it The accumulated body of knowledge that results from a dynamic process of observation, testing, and discovery

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BIOL 101 Lecture 2

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  1. BIOL 101 Lecture 2 Methods & Beliefs in Science

  2. The nature of science Science: A systematic process for learning about the world and testing our understanding of it The accumulated body of knowledge that results from a dynamic process of observation, testing, and discovery Science is essential: To sort fact from fiction Develop solutions to the problems we face

  3. Six Criteria of Science • Consistent • Observable • Natural • Predictable • Testable • Tentative Steven Dickhaus (1989)

  4. Pseudoscience Appears scientific, but…. • Uses scientific sounding jargon • Appears to conduct research • Usually more rhetoric than data: questions • Fails to follow scientific methods • Often faults “established scientific community” or claims a conspiracy against revealing “the truth.” What are we hiding?

  5. Pseudoscience Pseudoscience is not necessarily fraud; just bad science. • Extraordinary claims • Claims usually lack substance • Practices bias confirmation • Often pushes particular agenda • Ignores contrary data • Value of data often exaggerated

  6. Vaccines cause autism Jenny McCarthy Twenty-five percent of parents believe vaccines could cause developmental problems Fact or Fiction?

  7. Shark Cartilage Cures Cancer

  8. Global Warming Fact or Fiction?

  9. Scientists test ideas Two Primary Approaches to Science Hypothesis-driven or experimental science. Discovery or observational science.

  10. Hypothesis-Driven Studies

  11. Discovery/Observational Studies

  12. Discovery/Observational Studies One current view of hominid evolution. Some Scientific Questions Can’t Be Answered By Experimentation Discovery or observational science is still science; falsifiable hypotheses based on natural phenomenon are proposed to best account for observations.

  13. What is Science? A way of investigating the world in order to form general rules about why things happen. Science is a way of knowing based on experimental or observational evidence and its interpretation. Science is a discipline largely defined by its primary method – the scientific method.

  14. Science as a Way of Knowing Pure Science- pursuit of knowledge Applied Science- search for practical uses of scientific knowledge Pain relief in terminal cancer patients tetradoxin

  15. Characteristics of Scientific Explanations Science is empirical. It relies on observation and experience. The phenomenon studied must be measurable. Phenomenon that cannot be measured: Is this painting beautiful? Does God exist? It must be consistent with known natural laws and well-established, well-documented existing theories. It must be derived objectively from independently confirmable observations. All scientific knowledge must be regarded as tentative.

  16. Scientific statements must be testable and reproducible (i.e., valid & reliable). Hypothesis: Overfishing Antarctic Krill has an effect on the Antarctic food web. Hypothesis: The fibropapilloma virus causes tumors in green sea turtles. Hypothesis: Cigarette smoking causes lung cancer. Hypothesis: Infants who are breast fed are smarter than infants who are given formula. Hypothesis: Exercise makes people happy.

  17. What Kind of People Are Scientists? The Textbook Case Scientists are dispassionate and always reasoned in their approaches to their discipline and the world around them. Reality: Scientists can be egocentric, emotional nutcakes at least as well as anyone.

  18. One Human Side of Science

  19. One of many recent examples of “good” biology. What Does Biology Offer Society? Lot’s in terms of medicine, agriculture, maintaining a healthy environment, and basic understanding of ourselves and our world.

  20. How Does Society Understand Biology and Biologists? Science and scientists of all kinds are poorly understood by the public and scientists tend to poorly understand the public

  21. The Scope and Limitations of Science Science acquires knowledge through examination of falsifiable hypotheses based on natural phenomena. This sets a limit on science; science cannot speak directly to such issues as morality or religion. The domain and limit of science are often misunderstood.

  22. The Scope and Limitations of Science Are More Than An Academic Issue

  23. The Scope and Limitations of Science Are More Than An Academic Issue

  24. The Scope and Limitations of Science Are More Than An Academic Issue Summary points of the December 20, 2005 Kitzmiller v. Dover Area School District ruling: Is this the final word on evolution and alternatives in the classroom? Hardly.

  25. Scientific Method A way to answer questions Must be testable & repeatable, i.e., validity and reliability • Deductive Reasoning- general to specific • reasoning from general theories to account for specific experimental results • (theory-data collection-analysis) • Inductive Reasoning- specific to general • reasoning from specific observations and experiments to more general theories • (data collection-analysis-theory)

  26. Lost at Sea January1992 in the North Pacific

  27. Rubber Duckies and Ocean currents. • Jim Ingram (NOAA scientist)- offered a reward • He graphed and studied the data as it came in. • Hypothesis: ocean currents were moving the ducks in about the same speed and direction that the currents were going!

  28. Toy trek Researchers expect some 29,000 bath toys lost at sea in 1992 to make the ice-covered trek over the North Pole and to the North Atlantic by this summer.

  29. Population cycles in Snowshoe Hares vs. Lynx.

  30. Population cycles in Snowshoe Hares vs. Lynx • Scientists collected data between 1850 to 1930 on the population of hares and lynx. • Data was from # of pelts sold by trappers to the Hudson Bay Company! Scientists observed an oscillation of population density

  31. As the population of Snowshoe Hare increased or decreased, the population of Lynx increased or decreased too. • Hypothesis: the populations of Snowshoe Hare and Lynx depended upon each other. • Scientists made inferences from their observations (Inductive reasoning).

  32. However, further observations failed to support the current hypothesis. • New data showed that populations of Snowshoe hare on islands without Lynx had similar population changes as those with Lynx! • This means the Snowshoe hare population is not dependent upon the Lynx population. (However, the Lynx may be dependent upon the amount of Snowshoe Hare.) • Thus the data was accurate, but the hypothesis wasn't.

  33. Scientific Method Observations Question Formulate Hypothesis Conduct Experiment to test Hypothesis Analyze Results Conclusions Discussion

  34. Observation: The car won’t start when I turn the ignition. Question: Hypothesis: Test hypothesis: Analyze Results: Draw Conclusion: New hypothesis:

  35. Ben Franklin & the Gulf Stream Observation: Question: 1786 Hypothesis: Test hypothesis: Analyze Results: Draw Conclusion: 1996

  36. Scientific Method • Observations • Suggest questions to investigate • Question • Why does something happen • Hypothesis • An educated guess • A testable explanation for an observation

  37. Scientific Method • Conduct Experiment • Process of testing a hypothesis or prediction by gathering data under controlled conditions • Control vs Experimental Group Control group: a group that has not been exposed to some factor (variable) Experimental group: a group that has been exposed to the factor (variable) Independent variable (IV): the variable you manipulate that you believe will affect the DV Dependent variable (DV): the outcome variable, i.e., variable you measure

  38. Scientific Method • Collect, organize, analyze data • Determine whether data is reliable • Determine whether data supports or does not support the hypothesis or prediction • May use statistics • Compare data from other studies • Determine relationships • Determine experimental error

  39. Scientific Method • Theories • Unifying explanations for a broad range of observations • Based on testing a collection of related hypotheses • The solid foundation of science • Can be revised given new evidence

  40. Scientific Method • Drawing Conclusions • To understand something not previously understood • To produce a model • Construct a representation of an object, a system, or a process to help show relationships given the data • A model is an explanation supported by data • Use the model to generate new hypotheses or predictions

  41. Experimental Design Confounding factors Biased sampling Method for Reducing Bias: Randomization Replication

  42. Experimental Design Sample Size: A larger sample size tends to give you a closer estimate of the true population mean.

  43. Coral Reef Benthic Habitat Point and Area Assessments Kaneohe Bay, HI • Large sample size • Random sampling

  44. Do sponges affect mangrove root growth? Mangrove Study

  45. Mangrove Study Select a large sample size Randomly divide the sample into 2 groups Treat the groups equally in all ways but one Observe or make measurements Compare results

  46. Select a large number of appropriate subjects Randomly divide the subjects into 2 groups Treat the groups equally in all ways but one Observe or make measurements Compare results

  47. What is difference between hypothesis, theory & law? Hypothesis - “an educated guess”; a tentative explanation of phenomena. Theory - a widely accepted explanation of natural phenomena; has stood up to thorough & continual testing. Law - a statement of what always occurs under certain conditions.

  48. Theories Cell Theory Evolution

  49. Laws Physics, Chemistry, Math- Lots!!!! Biology: Mendelian Inheritance

  50. The Blind Men and the Elephant

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