Why animals have even number of legs?

Animals typically have an even number of legs due to evolutionary advantages related to balance and stability. An even number of limbs allows for symmetrical movement and better weight distribution, which is crucial for locomotion. Invertebrates like insects, which often have six legs, and vertebrates like mammals, which commonly have four, exemplify this trait, as it enhances their ability to navigate different environments effectively. This symmetry also aids in the coordination of movement and reduces the risk of injury during locomotion.