The human skeleton begins to develop 13 to 16 weeks after conception. At birth, a baby has about 300 bones and cartilage elements, almost a third of which eventually fuse together to form the 206-bone skeleton of an adult. The malleable nature of cartilage allows for a baby's easier passage through the birth canal.
During childhood, the cartilage grows and is slowly replaced by bone, so that by the time you are about 25, this process will be complete - the bones are as big as they will ever be.
In order to make sure you maintain your strength, mobility and flexibility through the years, it's important to keep in mind that taking care of your bones it's vital. Whatever your age, gender or level of fitness, a rich diet in a range of minerals, proteins and fats is needed to preserve bone mass.