Chapter 1 Notes – The Nature of Science and the Scientific Method

The Nature of Science

  • Science is both a body of knowledge (data) about the natural world and an evidence-based process for acquiring that knowledge.
    • It deals with aspects of the natural world that can be detected, observed, and measured.
    • It is based on evidence that can be demonstrated through observations and/or experiments.
    • It is subject to independent validation and peer review.
    • It is open to challenge by anyone at any time based on evidence.
    • It is a self-correcting enterprise.
    • Science cannot:
    • Tell us what is morally right or wrong.
    • Address the existence of God or other supernatural beings.
    • Tell us what is beautiful or ugly, which poems are most lyrical, or which paintings are most inspiring.

The Scientific Method

  • The practices that produce scientific knowledge are called the scientific method, or the process of science.
  • The steps typically include:
    • Gathering observations.
    • Forming a hypothesis.
    • Making predictions based on the hypothesis.
    • Designing experiments with appropriate variables, treatments, and controls.
    • Interpreting data collected during a study and drawing conclusions.
  • Key distinctions:
    • A scientific fact is a direct and repeatable observation.
    • A scientific theory is a well-supported explanation that results from substantial confirmation across diverse investigations and independent researchers.
  • Notable caution:
    • Hypotheses can be supported but never proven with complete certainty.
    • Advertisements often make exaggerated or inaccurate scientific claims.

Observations and Hypotheses

  • An observation is a description, measurement, or record of any object or phenomenon.
  • A scientific hypothesis is an informed, logical, and plausible explanation for observations of the natural world.
  • Example: Bick’s hypotheses about snail predation and shell color distribution:
    • First, Bick hypothesized that producing more offspring was responsible for enhanced predation survival.
    • P. hyalina’s broader distribution relative to P. clara led to a new hypothesis.
    • Bick hypothesized that the white shell of P. hyalina caused its greater distribution compared to P. clara with its brownish shell, perhaps because they heat up less in the sun.
  • A good scientific hypothesis must be:
    • Testable.
    • Falsifiable.
    • Precise enough to make predictions expressed as “if … then …” statements.
    • Example format: \text{Hypothesis: If } X \ ext{ occurs, then } Y \
      text{ occurs.}

From Observation to Hypothesis to Testable Prediction

  • Observations and Questions (e.g., rosy wolf snail vs Tahitian land snails):
    • Hypothesis: P. hyalina’s pale shell allows it to occupy sunnier areas, reducing predation.
    • Predictions:
    • If P. hyalina escapes predation by living in sunnier areas, then it should be found in areas with higher solar radiation.
  • Hypotheses can be supported but not proven with complete certainty.
  • Critical note: everyday claims in media often misrepresent scientific claims.

Types of Data and Approaches to Testing Hypotheses

  • Hypotheses can be tested through:
    • Observational studies:
    • Descriptive: reports data found in nature.
    • Analytical: looks for patterns and explains how/why they exist.
    • Experimental studies:
    • Involve a deliberate manipulation of one or more variables.
  • The approach can be multi-faceted:
    • Descriptive data (e.g., counts of snails in valleys).
    • Analytical data (e.g., solar exposure measurements).
    • Experimental data (e.g., behavioral responses to mucus trails).
  • Terminology:
    • Independent variable (IV): the variable deliberately changed by the researcher.
    • Dependent variable (DV): the variable that responds to changes in the IV.
    • Relationship: If the IV is the cause, then the DV is the effect.
    • Example prediction: Rosy wolf snails will follow mucus trails from snail species in their native range (Florida) but not from snails outside its native range.\text{Rosy wolf snails will follow mucus trails from snail species in their native range (Florida) but not from snails outside its native range.}

Experimental Design and Controls

  • An experiment is a repeatable manipulation of one or more aspects of the natural world, designed to test a hypothesis.
  • Variables:
    • Independent Variable (IV): the cause manipulated by the experimenter.
    • Dependent Variable (DV): the effect measured in response to IV.
    • Relationship: IV→DV\text{IV} \rightarrow \text{DV}
  • Controls:
    • Control group: maintained under standard conditions; the IV is not changed.
    • Treatment groups: the IV is manipulated; conditions otherwise match the control.
  • Example: Rosy wolf snail tracking behavior with multiple experimental groups following different mucus trails.

Case Study: Rosy Wolf Snails and Predation Trials

  • Experimental setup included several groups:
    • Control group: following a water trail.
    • Experimental group 1: following mucus trail of a small introduced trampsnail or a native Hawaiian snail.
    • Experimental group 2: following mucus trail of an introduced African snail or a native snail.
    • Experimental group 3: following mucus trails of a trampsnail or an African snail, both introduced.
  • Outcomes (illustrative results):
    • Rosy wolf snails showed clear preferences when tracking prey:
    • In 20 trials, following an African snail mucus trail occurred more often than following water for the control.
    • Experimental groups showed varying degrees of preference for native vs introduced trails (e.g., 7/20, 11/20, 15/20, 18/20 outcomes depending on the trail).
  • Summary: The experiment demonstrates that prey-tracking behavior is influenced by the type of mucus trail encountered.

Scientific Facts vs Theories

  • A scientific fact is a direct and repeatable observation of the natural world.
  • A scientific theory:
    • Is a hypothesis that has received substantial confirmation through diverse lines of investigation by independent researchers.
    • Often combines many hypotheses.
    • Differs from everyday usage of the word “theory.” In science, a theory has a high level of certainty and informs everyday actions.
    • Example: The theory of evolution, germ theory, plate tectonics (concepts with extensive supporting evidence).

The Peer-Review Process

  • Peer review: a process where a study is reviewed by several scientists who did not participate in the experiment.
  • Reviewers can request authors to address concerns and resubmit.
  • This is the main mechanism for policing bias and fraud in science.

The Biological Hierarchy

  • Biological hierarchy describes the multiple levels at which life can be studied, from small to large, showing how losing one type of organism can impact the entire system.
  • Levels (from smallest to largest):
    • Atoms
    • Molecule
    • Cell
    • Tissue
    • Organ
    • Organ system
    • Organism
    • Population
    • Community
    • Ecosystem
    • Biome
    • Biosphere
  • Notes:
    • An organism is a well-integrated unit with interacting components.
    • Tissues are groups of cells with related functions (e.g., eye tissue).
    • Organ systems network to perform wide ranges of functions (e.g., respiratory, circulatory).
    • Biomes are global-scale regions defined by climate and distinctive communities.
    • The biosphere encompasses all living things and the places they inhabit.

Mass Extinctions and the Sixth Extinction

  • The Sixth Extinction refers to a current period of elevated extinction rates caused largely by human activities.
  • Historical mass extinctions were driven by catastrophic environmental events: climate change, massive volcanic eruptions, sea-level changes.
  • Human activities accelerating extinctions include:
    • Dramatically altering habitats (farming, logging, mining, etc.).
    • Poaching.
    • Road and city expansion.
    • Pollution.
    • Global warming.
    • Introducing invasive species (e.g., rosy wolf snail).
  • Notable species that have gone extinct or are extinct in the wild since 1500 include:
    • Passenger Pigeon (extinct 1914, last wild 1900)
    • Xerces Blue Butterfly (last seen 1943)
    • Caribbean Monk Seal (last seen 1952)
    • Golden Toad (not seen since 1989)
  • Estimates of known extinctions by taxa since 1500 (illustrative counts):
    • Arachnids: 9
    • Crustaceans: 12
    • Reptiles: 22
    • Amphibians: 36
    • Insects: 58
    • Fishes: 71
    • Mammals: 79
    • Plants: 134
    • Birds: 145
    • Mollusks: 324

Saving Species: Real-World Interventions

  • Intensive conservation efforts have achieved some successes by:
    • Bans on hunting (e.g., humpback whales, elephant seals).
    • Bans on harmful chemicals (e.g., DDT).
    • Breeding programs for endangered species (e.g., peregrine falcons, bald eagles).
  • Case study: Partula snails in Polynesia
    • Fifteen American and European zoo curators bred 11 Partula snail species to reintroduce them into the wild.
    • Rosy wolf snail populations declined in Polynesia; since 2015, over 19,000 snails from 14 species have been reintroduced to their natural ranges, including predator-proof preserves on Tahiti.

The Sixth Extinction (Continued) and Data Visualization

  • The slide deck includes a historical overview of extinct species and current extinction risk indicators, highlighting the scale of biodiversity loss across taxa.

Practice Questions and Quick Checks (Clicker Questions)

  • Clicker Question 1: Which of the following is NOT an appropriate topic to study using the scientific method?

    • a) Do women make the same amount of money for the same job as men?
    • b) Is Anne really in love with Andy?
    • c) Does drinking coffee raise blood pressure?
    • d) Do Lucky Strike cigarettes contain fewer carcinogens than other brands?
    • Answer: (not provided in transcript)

  • Clicker Question 2: If tomato plants are exposed to more sun, they will grow more tomatoes. Based on this prediction, what is the hypothesis?

    • a) Does increased sun exposure lead to more tomatoes?
    • b) Increased sun exposure leads to more tomatoes.
    • c) Amount of sun exposure affects tomato quantity.
    • d) Either B or C could be the hypothesis.
    • Answer: (not provided in transcript)

  • Clicker Question 3: A controlled experiment is one that must:

    • a) proceed very slowly.
    • b) include experimental and control groups.
    • c) be supervised by an experienced scientist.
    • d) keep both the dependent and the independent variable constant.
    • Answer: (not provided in transcript)

  • Clicker Question 4: Your friend says, “I have a theory that Kristi failed her exam because she waited until the day before the exam to study.” In this case, what is the best scientific word to use in place of the word “theory”?

    • a) Theory
    • b) Observation
    • c) Hypothesis
    • d) Guess
    • Answer: (not provided in transcript)

  • Clicker Question 5: Dr. Jones conducted an experiment. She divided sixty people into three groups: cycling 20 minutes daily, stretching 20 minutes daily, and no exercise. Heart rate was measured weekly. What is the independent variable in this experiment?

    • a) Heart rate
    • b) Time length of exercise
    • c) Type of exercise
    • d) Number of people
    • Answer: (not provided in transcript)

  • Note: The transcript provides the questions and options, followed by slides labeled “Answer,” but the actual answer choices are not shown in the provided content. Use these as practice prompts and verify answers with the course resources when available.

Connections to Foundational Principles and Real-World Relevance

  • The material connects:
    • Foundational scientific reasoning: observations, hypotheses, predictions, and controlled experiments.
    • The role of data types (descriptive, analytical, experimental) in building support for hypotheses.
    • The ethical and practical limits of science (morality, religion, aesthetics) and the importance of peer review for maintaining scientific integrity.
    • The hierarchical organization of life and how disruptions at one level (e.g., species loss) ripple through ecosystems, affecting biodiversity and ecosystem services.

Key Formulas and Notation

  • Hypothesis format (logical structure):
    Hypothesis: If X occurs, then Y occurs.\text{Hypothesis: If } X \text{ occurs, then } Y \text{ occurs.}
  • IV and DV relationship:
    Independent Variable (IV)→Dependent Variable (DV)\text{Independent Variable (IV)} \rightarrow \text{Dependent Variable (DV)}
  • General causal relationship statement:
    If IV is the cause, then DV is the effect.\text{If IV is the cause, then DV is the effect.}

Quick Reference: Core Terms

  • Science
    • Body of knowledge, evidence-based process, peer review, self-correcting, limitations on moral or metaphysical claims.
  • Hypothesis
    • Testable, falsifiable, precise with if-then format.
  • Prediction
    • Derived from hypothesis; testable expectation about DV given IV.
  • Independent Variable (IV)
    • Deliberately changed by the experiment.
  • Dependent Variable (DV)
    • Measured outcome influenced by IV.
  • Control Group
    • Standard conditions; no change in IV.
  • Treatment Group
    • Same conditions as control except IV is changed.
  • Fact vs Theory
    • Fact: direct, repeatable observation.
    • Theory: well-supported, comprehensive explanation with substantial evidence.
  • Biological Hierarchy
    • Atoms → Molecule → Cell → Tissue → Organ → Organ system → Organism → Population → Community → Ecosystem → Biome → Biosphere
  • Mass Extinction
    • Past events driven by climate change, volcanism, asteroids; current event largely driven by human activity.
  • Saving Species
    • Hunting bans, pollution controls, breeding programs, habitat restoration, predator-proof preserves, reintroductions.