Knife-edge pivot and sickle: what they have in common

1. Step 1. Knife-edge pivot — is part of — Balance scale. A low-friction pivot for the beam.
2. Step 2. Balance scale — is made of — Stone. Weights were hewn from stone.
3. Step 3. Stone — is material for — Adze. The blade of an adze was ground from stone.
4. Step 4. Adze — evolved from — Stone tool. Neolithic adzes were stone.
5. Step 5. Stone tool — evolved into — Sickle. The first sickles had flint inserts.

Open Evothings