Paper machine and hammer: what they have in common

1. Step 1. Paper machine — has part — Belt drive. The wire moves on belts and rolls.
2. Step 2. Belt drive — is part of — Combine harvester. Belt drives.
3. Step 3. Combine harvester — evolved from — Sickle. The machine replaced reaping by hand.
4. Step 4. Sickle — evolved from — Stone tool. The first sickles had flint inserts.
5. Step 5. Stone tool — evolved into — Hammer. The first hammer was a stone in the hand.

Open Evothings