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Science

Evidence for Evolution

Overview

Students move beyond the basic mechanism of natural selection to evaluate the diverse evidence that supports evolution as the explanation for biological diversity.

Learning Objective
Students can evaluate and compare multiple lines of evidence that support the theory of evolution by natural selection.

Resources needed

  • None

Lesson stages

0 / 7 done
  1. 1 Ask: how do we know that life on Earth has changed over time? List possible types of evidence.
  2. 2 Introduce fossil evidence: fossils show organisms that no longer exist and gradual changes over time. Transitional fossils (e.g. Tiktaalik — between fish and land vertebrates) show intermediate forms.
  3. 3 Introduce comparative anatomy: homologous structures — same underlying structure, different functions (human arm, whale flipper, bat wing, horse leg). All have the same bones. Why, if not shared ancestry?
  4. 4 Introduce molecular biology: DNA sequences of related species are more similar than those of distantly related species. The genetic code is universal — the same codons mean the same amino acids in all living things.
  5. 5 Introduce direct observation: antibiotic resistance, Galápagos finch beak changes, peppered moths — evolution observed in real time.
  6. 6 Introduce biogeography: species distribution matches continental drift. Australia's unique marsupials reflect long isolation.
  7. 7 Ask: does any of this evidence prove evolution? (Science does not prove — it provides evidence that supports or challenges explanations. Evolution is supported by more evidence than almost any other scientific theory.)

Tap a step to mark it as done.

Variations

  • Examine and compare limb bone structures across vertebrates — identify the homologous bones.
  • Research the evidence from DNA comparison between humans and chimpanzees (approximately 98.7% identical DNA).
  • Discuss the difference between a scientific theory and an everyday use of the word theory.
More information

Teach: fossil, transitional, homologous, vestigial, biogeography, molecular evidence, universal genetic code. The distinction between proof and evidence is a key scientific literacy concept — all scientific knowledge is provisional.

Focus on two or three types of evidence in depth rather than surveying all six superficially.

Can students describe three independent lines of evidence for evolution and explain why each is convincing? Can they explain what a scientific theory is and why it is not mere speculation?

No resources needed. The lesson is discussion and concept-based. Drawings of comparative anatomy can be made in soil.

Students often think evolution is just a theory as if this means it is uncertain. A scientific theory is a well-tested, well-supported explanation of natural phenomena. Evolution is one of the most strongly supported theories in all of science.

The evidence for evolution spans geology, genetics, comparative anatomy, and direct observation. No other explanation accounts for all this evidence. Understanding the variety of evidence is essential for scientific literacy.

Activity details
Secondary Challenging 25 minutes no prep Whole Class, Small Group Indoor & Outdoor
Topics
Evidence For Evolution Fossil Record Comparative Anatomy