A fully developed adult human will typically have 206 bones in their body. These bones work well together and provide the rigid, yet mobile, structure that your body needs to perform everyday tasks.

Interestingly, however, when you were born, you had far more bones than you do today. Newborn babies generally have between 275 and 300 bones (depending, at least in part, on how developed they were at birth).

This begs the question: why do babies have more bones, and where do they go?

Babies are born with a larger number of smaller bones. Many of those bones are made with cartilage rather than normal bone tissue because it is softer and more flexible. This is needed because the baby needs to be able to squeeze (or, more accurately, be pushed) through the narrow birth canal.

The most well-known example of extra bones in babies comes with their skull. While an adult human skull is one hard bone, the baby skull is made up of multiple separate bones. This is why babies have the ‘soft spot’ (fontanelle) at the top of their heads. The skull bones haven’t fused together yet, leaving a soft area that can squish and move in order to allow the baby’s brain to pass through the birth canal safely.

Dr. Matthew Badgett from the Cleveland Clinic commented on this, saying:

“Babies are born with five major skull bones that allow the skull to mold during delivery. The fontanelle is a space between these skull bones. It gradually closes within the first year or two of life as the baby develops a solid, hard skull.”

After a baby is born, their bones continue to grow and develop throughout their infancy and childhood. Part of this process is known as ossification, which is when many of the soft bones made of cartilage will solidify. This is also when multiple smaller bones (such as those in the skull) will fuse together to make one larger bone.

While all of this is going on, the child’s bones will also be growing in length in a process that will continue until sometime in their teenage years.

Making bones takes a lot of energy, and with babies having to make new bones, solidify existing bones, fuse together different bones, and make them all grow at the same time, it is no surprise that these little humans eat and sleep so much.

If you found that story interesting, learn more about why people often wake up around 3 AM and keep doing it for life.