Human Skeleton under Different Situations (Use your Headphone) Humans have around 270 bones at birth, but they fuse together as we grow old. By the time we reach adulthood, the number of our bones goes down to 206 bones. The bones in our skeletons reach their maximum density around age 21. Our bones do not only help us move, they provide us with structural support, protect our organs and help us produce red blood cells. They also act as a storage area for minerals, particularly calcium. | Hashem