Why Are Human Babies Born With More Bones Than Adults? Hint: Evolution Left Us Unfinished On Purpose

Human babies start with many separate cartilage-based bone structures that fuse gradually over time.

This slow skeletal maturation is part of endochondral ossification, the process that turns cartilage into bone during growth.

The long development likely reflects an evolutionary trade-off: fitting a large brain through the birth canal while still allowing the body to grow.

That same trade-off leaves children and adolescents in a prolonged period of skeletal change and vulnerability.