Question
Today in my anatomy class, I asked my teacher "If fetal skeletons of catilage turn to bone, what is it that prevents our noses and ears from doing the same?"  She didnt kno, but she said if I find out I'll get extra credit on our exam, So...do you kno why?

Answer
Hi James,

From the time of conception, each cell is assigned a specific function...some are destined to be contractile tissues found in the heart, some are destined to become bone, some to be organs, etc.  The softness of the bones at birth serves many purposes...primarily to allow the baby to be born without breaking the bones.  The cartilage between the joints never hardens and neither does the cartilage in the nose or ear, and the reason is because it is never "instructed" to do that by the genetic code found in the DNA.  It was instructed to stay soft.  

Of course, there are diseases and conditions that can mess up those instructions (genetic disorders, myositis ossificans, or sclera derma, for examples).

Hope this helps!  Good luck with the extra credit:)

Jenny