Spear-thrower shaft and elevator: what they have in common

1. Step 1. Spear-thrower shaft — is part of — Spear-thrower. A lever that extends the arm.
2. Step 2. Spear-thrower — uses — Spear. It throws darts.
3. Step 3. Spear — evolved into — Harpoon. A spear with barbs.
4. Step 4. Harpoon — has part — Rope. A line connects the head to the hunter.
5. Step 5. Rope — is used in — Pulley. A rope runs over the pulley.
6. Step 6. Pulley — is part of — Elevator. The rope runs over a pulley.

Open Evothings