Why do babies have more bones than adults?
Babies are born with about 270 to 300 bones, while adults have 206. Many of a baby's bones are partly made of cartilage and fuse together as the child grows.
At birth, much of the skeleton is still soft cartilage, which gradually hardens into bone in a process called ossification. Several separate bones join together over time. For example, a baby's skull is made of separate plates with soft spots called fontanelles, which allow the head to squeeze through the birth canal and the brain to grow quickly.
The skull bones fuse during childhood. The sacrum, at the base of the spine, starts as five separate vertebrae that fuse by early adulthood. The tailbone, or coccyx, is made of three to five small vertebrae that fuse. Long bones like the femur have growth plates that fuse after puberty.
Done by adulthood
By about age 25, bone fusion is complete, leaving the typical adult total of 206 bones. The exact number varies slightly between people, who may have an extra rib, small extra bones in the hands or feet, or extra bones in skull joints.
Did You Know?
More than half of the adult body's 206 bones are in the hands and feet.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.