Sharp stone edge and radio: what they have in common

1. Step 1. Sharp stone edge — is part of — Stone tool. An edge made by knapping.
2. Step 2. Stone tool — evolved into — Hammer. The first hammer was a stone in the hand.
3. Step 3. Hammer — includes — Reflex hammer. A hammer.
4. Step 4. Reflex hammer — is made of — Vulcanized rubber. A rubber head.
5. Step 5. Vulcanized rubber — is material for — Weather balloon. The envelope is rubber or latex.
6. Step 6. Weather balloon — has part — Radio. A radiosonde.

Open Evothings