Barbed harpoon head and boyle’s air pump: what they have in common

1. Step 1. Barbed harpoon head — is part of — Harpoon. Barbs keep the prey from slipping off.
2. Step 2. Harpoon — is made of — Bone. The oldest harpoons (Katanda, ~90,000 years ago) are carved from bone.
3. Step 3. Bone — is material for — Needle. The first needles with an eye were carved from bone.
4. Step 4. Needle — is part of — Syringe. A hollow needle.
5. Step 5. Syringe — has part — Piston. A plunger.
6. Step 6. Piston — is part of — Boyle’s air pump. A plunger.

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