Evidence for Evolution
Describe the main types of evidence for evolution: the fossil record (change over time), comparative anatomy (homologous structures), and the geographic distribution of related species
What a learner can do afterwards
- Explains how fossils form and what they can tell us about past life
- Uses the fossil record as evidence that species have changed over time
- Describes homologous structures (e.g. pentadactyl limb) as evidence for common ancestry
- Explains why island species provide evidence for evolution (e.g. Darwin's finches, Galapagos)
The lesson
Evolution says that species change over long spans of time, and that different species share ancestors. Nobody can watch millions of years go by, so scientists rely on evidence instead. Three strong clues come from fossils, body shapes, and where animals live.
Look at a human arm, a bat wing, and a whale flipper. All three are built on the same five-bone pattern, called a pentadactyl limb, even though a human writes with it, a bat flies with it, and a whale swims with it. That shared pattern is strong evidence these animals descended from one ancestor long ago.
When you see closely related species with small differences, like Darwin's finches on separate Galapagos islands, look for what they share instead of what makes them different. Small differences often show how one ancestor species split as each island population adapted to its own food supply.
Fossils show change over deep time, shared body patterns like the pentadactyl limb show common ancestors, and related island species show one start with different paths.
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Where it sits
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Where this leads
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8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.