Here's why:
* Give birth to live young: Pigs don't lay eggs. They give birth to live piglets.
* Nurse their young: Piglets drink milk from their mothers' mammary glands.
* Warm-blooded: Pigs maintain a consistent internal body temperature, unlike reptiles.
* Have hair: While piglets have fine hair, adult pigs have bristle-like hair.
* Breathe air: Pigs have lungs and breathe air, not through gills like fish or skin like amphibians.
Reptiles, on the other hand, lay eggs, have scales, are cold-blooded, and breathe with lungs.