Breastfeeding requires active work from a baby: the tongue has to perform rhythmic, wave-like movements to draw milk from the breast — quite different from bottle-feeding, where the liquid often flows with little effort or even on its own. This active movement trains exactly the muscles that are later responsible for jaw growth, swallowing patterns, and lip closure. This doesn’t mean bottle-fed babies inevitably develop problems — but it does explain why, with bottle-feeding, the right teat shape and targeted exercises are especially important to make up for this missing “training.”