The Same Bones Keep Turning Up

You'll learnhow four separate lines of evidence, gathered by people who never spoke to each other, land on one family tree.

Open a human arm, a bat wing, a whale flipper and a bird wing and you find the same bones in the same order, doing four completely different jobs. That pattern is the first of four lines of evidence, and the last of them is a protein counted residue by residue. Twelve short steps; press Next for each one.

AP BIOLOGY · 12 STEPS · 6 QUICK CHECKS · ONE BONE PLAN · FOUR LINES · ONE TREE · v6

one bone plan · four lines of evidence · one tree

Before you start

What you're looking at

Four forelimbs, drawn as chains of coloured bones with one row per animal.

The question

Four animals, four different jobs — so why is the same set of bones inside every one of them?

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