Unpack Natural Selection Step by Step

You want natural selection to finally click rather than stay a vague slogan. Pick an organism, finches, resistant bacteria, peppered moths, and it walks the four core parts: variation, heritability, differential survival, differential reproduction, each with a concrete example. Then it shows how the four combine to drive evolution, using the Feynman technique to keep it clear.

Walk me through Charles Darwin's theory of natural selection using the Feynman technique. Break it into its four core components: variation within a population, heritability of traits, differential survival, and differential reproduction. For each component, give a concrete real-world example involving {ORGANISM} (e.g., finches, antibiotic-resistant bacteria, or peppered moths). Then show how all four components combine to produce evolutionary change across generations. Address the common misunderstanding that evolution has a goal or a direction, or that organisms 'try' to adapt. My background is high-school biology: keep it clear and accurate but not patronising.