Learn on PengiAmplify Science (California) Grade 8Chapter 2: Investigating Body Structure Differences

Lesson 3: Explaining Differences

Key Idea.

Section 1

The Paradox of Similarity and Difference

Key Idea

We can now explain why a whale looks so different from a wolf, yet has the same bones.

  • Similarity (Unity): Comes from Inheritance. They share the "1-2-Many" bone structure because they are related.
  • Difference (Diversity): Comes from Natural Selection.

Section 2

Environment Sculpts the Form

Key Idea

Evolution modifies the form to fit the function required by the environment. The environment acts as a sculptor.

It takes the clay (the inherited ancestral body plan) and reshapes it to survive in a specific habitat. But it never throws the clay away—the core material (skeletal structure) remains the same.

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

The Paradox of Similarity and Difference

Key Idea

We can now explain why a whale looks so different from a wolf, yet has the same bones.

  • Similarity (Unity): Comes from Inheritance. They share the "1-2-Many" bone structure because they are related.
  • Difference (Diversity): Comes from Natural Selection.

Section 2

Environment Sculpts the Form

Key Idea

Evolution modifies the form to fit the function required by the environment. The environment acts as a sculptor.

It takes the clay (the inherited ancestral body plan) and reshapes it to survive in a specific habitat. But it never throws the clay away—the core material (skeletal structure) remains the same.