Why do human babies have soft spots on their heads?

A newborn’s skull is made of several bones that have not yet fully fused. The soft spots, called fontanelles, let the skull compress slightly during delivery and help protect the brain during early growth. The bones gradually join together over time, with the anterior fontanelle usually closing around 18 months and the posterior one much earlier, often by a few months of age. This design balances birth, protection, and development. The open spaces are a normal part of healthy infant anatomy.