Although the actual age can not be determined by bones, the approximate age of the individual can be.
For age determination, different parts of the skeleton are more useful at different age ranges. The different age ranges include perinatal, neonate, infants and young children, late childhood, adolescence, young adult, and older adult.
The age of perinatals, those that are not yet born, can be determined by looking at bone size. This is because outside factors such as malnutrition on the mother's part is not going to affect the fetus' growth as much. During periods of low food intake the mother's body will give nutrients to the fetus, shorting the mother of nutrients.
Neonates, babies who have not gotten their teeth yet, are very difficult to accurately determine the age of because of individual variation of development. As a group, the neonates have no teeth, many areas of the skeleton have not fused together (especially the cranium and pelvis), and they have very small bones.
Infants and young children will usually have some of their teeth in. The formation of teeth is often used in age determination for this group. Permanent teeth start to form at birth, thus the formation of permanent teeth is a relatively good age determinant. Some ossification has begun in the bones at this age, this means that soft parts of the bones become hard. However, this is not as good a determinant.
Late childhood is when the permanent teeth begin to come in. More bones begin to ossify.
Adolescence shows increased long bone length and fusion of the ends (or cap) to the shaft. This fusion is a particularly useful age technique. Each cap, or epiphysis, fuses to the shaft, or diaphysis, at a particular age range.
Young adults and older adults have several methods of age determination: closure of the cranial sutures; morphology of rib-ends, auricular surface and pubic symphysial; microstructure of bone and teeth; wear on teeth, incremental layers of cementum; and finally the 'Complex Method'.
Cranial sutures (non-movable joints in the head) slowly fuse together, becoming obliterated in time. Although this has been known for many years, there has only been a weak association established between age and closure.
The morphology of rib-ends changes through age. Ribs are connected to the sternum by cartilage. The rib ends that meet with the cartilage are relatively flat at first, but during the aging process the ends become ragged and the cartilage becomes pitted. The irregularity of the rib ends has been found to relate to age at death.