Why can't babies sit up?

Babies can't sit up on their own initially because their muscles and motor skills are still developing. At birth, their neck and back muscles are weak, making it difficult for them to support their own weight. Typically, babies begin to gain the strength and coordination needed to sit up between 4 to 7 months of age, as they develop better muscle control and balance. Additionally, their overall physical development, including core strength, plays a crucial role in achieving this milestone.