Polyethylene layers and needle: what they have in common

1. Step 1. Polyethylene layers — is part of — Tetra Pak. Airtightness.
2. Step 2. Tetra Pak — is made of — Paper. Cardboard.
3. Step 3. Paper — is material for — Fire lance. The barrel of a fire lance is a paper or bamboo tube.
4. Step 4. Fire lance — evolved from — Spear. The fire lance was a spear with a tube of gunpowder — the first step to firearms.
5. Step 5. Spear — has part — Stone tool. Early spearheads were made of stone.
6. Step 6. Stone tool — evolved into — Needle. Bone needles with an eye are part of the Palaeolithic toolkit.

Open Evothings