LS 15 Notes:Lecture 1: 1/07/14What is the Scientific Method?-organized-empirical (based on observations)-methodical-structured way of finding information about observable events in nature-enables us to reject hypotheses about how the world worksQ.) Is maze running ability in mice genetic? How might you apply the scientific method?-what observations would you makeStep 1: make observationsStep 2: formulate hypotheses-Is it testable? Is it refutable?Step 3: Make a prediction:-If my hypothesis is true, when I do “x” then “y” will occurStep 4: Conduct an experiment: Control all variables but one-randomized? Double blind?Q.) Is eyewitness testimony infallible? How could you answer this with certainty?-Eyewitness reliability depends on how the susceptiable are presented (sequential viewing vs standard line up)Take-home message: scientific method: observation, hypothesis, prediction, test, concluson, is an efficient pathway to understanding the world.Q.) The more firefighters present at the fire, the greater the damage that the fire does.-One is Seven Fathers conclusion: not represetative of all fathers.Lecture 2: 01/09/14:What is scientific thinking?1. we make observations2. we formulate hypotheses3. we make predictions (based on the hypotheses)4. we devise & carry out experiments (to test hypotheses & alternatives)5. we draw conclusions, modify hypotheses (and continue the process)-Scientific method is too rigid, not creative enough.-Scientific thinking will tell you when to change your mind, abandon old thoughtsThe “critical experiment”-putting a hypothesis to the test-the results can decisively determine whether a hypothesis is correct.At the core of scientific thinking is the ability to imagine a “critical experiment.”How can you increase your experiment’s power?1. Randomize (subjects across control and experimental groups)2. Control your study. (Must be NO underlying differences between the two groups used)3. Use a Double-Blind design.Observation-a certain chemical may fight the aids virus-which experimental tests of this are better, those done in a lab or those done in the “real world” why? Neither one is better, different. The better control there is though, the more confidence we have in its results (But as experiments are better-controlled they often are poorer models of the situation of interest.)Q.) Why is “randomized, controlled and double-blind” a redundant phase?-scientific thinking is powerful, but can be costly, time-consuming, and difficult (attention to detail, careful thought.)- pseudoscience or anecdotes are appealing, but should not influence our beliefsEx: “9 out of 10 doctors recommend brand x”Questions to ask: how many doctors did they ask? How were they selected? What was the alternative?Always ask: How do you know what you claim you know?From anecdotal to scientific: Testable predictions of the “vaccines cause autism” theory:Lecture 3: 1/14/14Prep U Code: phelan20425Evolution and Natural Selection:1. the evolution of starvation resistance2. what is evolution3. what is natural selectionHow long can a fly live without food? Can we increase the average time to starvation in a population?What if you let only the “best” flies reproduce? (top 20% of starvation resistance)-after 1 generation, average was 21 hours-after 10 generations, average was 28 hours-after 60 generations, average was 160 hoursTHM#1: species are not immutable. We can watch them change in nature or even cause them to change.We can use the same experimental approach (used with the rats) to change other populations-Why are anti-bacterial soaps dangerous?What is evolution:in everyday life, a gradual process which is something changes into a different and usually more complex or better form-in biology, a change in allele frequencies within a population-gene- section of DNA instructing how to produce a trait-allele- one variant of a gene (several may exist)-you have 2 copies of every instruction set/gene, one from each parent.-Sometimes the alleles are the same (BB or bb) sometimes they are different (Bb)We can measure the frequency of “B” and “b”Charles Darwin:-bio: lazy teenager, med school drop out, transferred to Cambridge to study theology, 1831-36: has beagle trip around the world, provocative observations w/ years of thinking, almost scooped by Alfred Russel Wallace, published his total triumph book “Abstract.”His observations:1. Finch variation:-Each island had unique species-Island species resembled mainland species (maybe they used to be same species)2. Similiarity between fossils of extinct species and the living species in an area:-extinct glyptodonts looked like GIANT armadillosSome common thins in Nature, Darwin observed:--offspring overproduction--competition for scarce resources--the inheritance of traitsDarwin concluded that is a “struggle for existance”:Organisms better suited to an environmeny have a greater proble of surviving the struggle and the will leave more offspring.Through evolution, organisms may become better matched with their environment.--THM #3: Even slacker students in poor health can change the worldDarwin’s dangerous idea was for a mechanism of evolution: Natural selection:1. Variation – all offsprings vary, not all individuals look the same.2. Heritable- offspring resemble their parents3. Differential Reproductive Success-some leave more offsping than others depending on which variant of the trait they have--THM #4: If the 3 conditions (listed above) are fulfilled, evolution by natural selection is occurring.Types of selection:1. Directional selection (milk production),2. Stabilizing selection (birth weight),3. Disruptive selection (body weight)--THM #5: Persistent selection can dramatically change the morphology, behavior, and physioogy of the inidividuals in a population.Q: How is medical technology today undoing the work of natural selection in optimizing birth weight?Aka glassesDiscussion Notes:Scientific Thinking:- a hypothesis must be testable and repeatable.Prediction: If our hypothesis x is true, when we perform y, z should happen.Pseudoscience-when people make scientific-sounding claims, but they are not backed up by any evidence.Lecture 4:Q: Why is the phrase “survival of the fittest” a misnomer?-Critical to assessing fitness is understnading that it is measured:-relative to other genotypes/phenotypes in the population.-in a specific environmnent.-by reproductive successThere is no absolute