Not all bones grow at the same rate and the individual growth rate of a bone changes over a lifetime, therefore periodic growth marks can take irregular patterns. This indicates significant chronological events in an individual's life. The use of bone as a biomaterial is useful in investigating structure-property relationships.
The fact that bones don't all grow at the same rate and their growth patterns change over time means that periodic growth marks can exhibit unusual patterns. This suggests that there were important events in an individual's life, making bone a useful material for investigating how its properties are related to its structure.