Why Babies Have More Bones Than Adults

Humans are born with about 300 bones, but many fuse together as we grow, leaving us with 206 bones as adults. The skull alone is made up of several plates that merge over time—one reason why baby heads feel a bit soft at first.

At birth, our skeletons are made up of around 300 bones. But many of those aren’t fully formed yet—they’re actually separate pieces that later fuse together as we grow.

It’s especially noticeable in the skull.

A baby’s skull is made of several bony plates with soft gaps between them called fontanelles. These flexible areas help the baby’s head squeeze through the birth canal and allow the brain to grow quickly in the first few years.

By the time most kids are around 2 years old, those plates have gradually fused into a solid skull. It's nature’s version of a construction project—one that adapts as the brain develops.

The same kind of fusion happens elsewhere in the body, too.

The bones in our spine, hips, and even fingers start off in multiple pieces and gradually unite to form the stronger, fewer bones of adulthood.

So while it may seem like we “lose” bones over time, it’s really just our skeleton getting more efficient as we grow.