Overview
This lecture covered the concepts of evolution, natural selection, and the scientific method, focusing on definitions, examples, and how scientific inquiry operates.
Descent with Modification & Natural Selection
- Descent with modification means offspring differ slightly from parents but share common traits.
- Natural selection acts on variations; individuals best suited to their environment survive and reproduce.
- Too many offspring and environmental factors create competition, leading to evolutionary adaptations.
Evolution Defined & Examples
- Evolution is a change in the genetic sequence (DNA) of a population over time.
- Evolution can be observed (e.g., changes in Pomeranian size, German Shepherds created in 1899).
- Crops like modern corn were derived from wild ancestors (e.g., teosinte) through selective breeding.
- Classic natural selection example: darker insects survive on dark backgrounds due to predation.
- Adaptations include camouflage (geckos, seahorse), and genetic behaviors (mating dances in birds).
- Individual organisms cannot evolve; evolution occurs in populations.
Evolution vs. Natural Selection
- Evolution is genetic change in a population; natural selection is the mechanism driving it.
- De-evolution does not exist; evolution has no inherent direction.
Scientific Method
- Science questions and revises assertions about the natural world; nothing is "settled."
- Steps: observations, questions, hypothesis, predictions (if-then), controlled experiments, report findings.
- Hypotheses must be testable and falsifiable; they are answers to questions, not if-then statements.
- Scientific theories are broad, supported by evidence, but always open to revision and cannot be proven.
Hypotheses & Theories
- Hypothesis: specific, testable, falsifiable answer to a question; no data needed beforehand.
- Theory: broad, supported by large amounts of evidence; different from everyday use of the word.
- Scientific laws and theories are not "proven," unlike mathematical proofs.
- Supernatural and faith-based explanations are outside scientific inquiry since they cannot be tested or falsified.
Key Terms & Definitions
- Descent with modification — Passing traits from parent to offspring, with slight differences.
- Natural selection — Process where organisms better adapted to their environment survive and reproduce.
- Evolution — Genetic change in a population over time.
- Hypothesis — Testable, falsifiable answer to a scientific question.
- Theory — Well-substantiated explanation backed by evidence; broader than a hypothesis.
Action Items / Next Steps
- Review concepts of hypothesis vs. prediction vs. theory.
- Prepare for Chapter 2 on Tennessee.
- Think of examples of testable and non-testable hypotheses.