Here's why:

* Composition: Human hair is primarily made of protein called keratin. This protein is rich in carbon, hydrogen, nitrogen, and oxygen. Synthetic hair, on the other hand, is usually made from materials like nylon, polyester, or acrylic.

* Flammability: Keratin, the protein in human hair, is relatively flammable. Synthetic fibers, while they can burn, have lower flammability due to their different chemical compositions.

* Ignitability: Human hair is easier to ignite because it has a lower ignition temperature than synthetic hair. This means it requires less heat to start burning.

Therefore, if you were to set both human hair and synthetic hair on fire, the human hair would burn faster and more intensely.