Babies are less bony for a good reason; if they were fully “hardened”, it would make delivery almost impossible. Infants’ bodies need to be extremely soft and limber so that they can be born in the first place! Babies are born with more cartilage (than bone), but it gradually turns into bone over a period of time through a process called endochondral ossification. This is a vital part of the developmental stages of a fetus and leads to the creation of bone tissue in the body. As the baby grows, cartilage is replaced by bone matrices. Calcium salts (that babies get from their diet) are laid to form hardened bones. This is the reason why adults have fewer bones than babies because, for babies, many small bony segments fuse together to form a single bone.
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