Fire hydrant and stone tool: what they have in common

1. Step 1. Fire hydrant — is used in — Fire truck. Connection.
2. Step 2. Fire truck — evolved from — Fire pump. A pump on a motor-vehicle chassis.
3. Step 3. Fire pump — has part — Piston pump. A fire pump is a piston pump.
4. Step 4. Piston pump — works like — Syringe. A syringe is a hand-operated piston pump.
5. Step 5. Syringe — has part — Needle. A hollow needle.
6. Step 6. Needle — evolved from — Stone tool. Bone needles with an eye are part of the Palaeolithic toolkit.

Open Evothings