Why do we grow two sets of teeth ?

Have you ever wondered why we get two sets of teeth ? Do other animals, especially mammals, also have two sets of teeth ? As i was searching for answers to these questions, i came to know some interesting facts about human teeth, that i am going to share here.

On the basis of teeth sets, mammals can be divided into two categories :

• Monophyodont : These mammals have just one set of teeth in a lifetime.
• Diphyodont : These mammals get two sets of teeth in a lifetime. Humans come under this category.

There are some exceptions among mammals, such as elephants, kangaroos, and manatees which have multiple sets of teeth. Their teeth grow in the back of their mouth and then migrate forward.

Another exception among mammals are rodents and rabbits, as their teeth grow continuously, just like out nails. So these exceptional animals need to keep biting and grinding their teeth in order to keep them short, else their own teeth can tear their jaws. 

Why do we grow two sets of teeth ?

As a baby our mouth and jaws can't accommodate 28 or 32 teeth. So we get just 20 as the initial milk teeth. In most of the cases milk teeth emerge as the baby gets older than 6 months, if they emerge before that time then it may harm the mother when they feed milk to baby. If you are healthy, then every change in our body happens for a reason at a particular time.

Our teeth don't grow in size with our age. They may appear bigger in old age people, due to gum recession. 

Our permanent teeth are bigger and tougher than milk teeth, while milk teeth are usually more whiter than permanent teeth.

Why do some people grow Wisdom teeth while some don't ?

Most of the people live with just 28 teeth while some grow a third set of molar. This last set of molar is not available in every person, and may completely get extinct after few thousand years of evolution. It was necessary when humans need to eat raw (uncooked) food and needed some more strength to grind and chew the food. Only those people who eat raw and tight food items in early childhood, grow these extra wisdom teeth. If you are one of those who think that people with wisdom teeth are more intelligent than others, then you are mistaken.

Wisdom teeth is named so because it grows in adulthood when a person is considerably wiser than a child.

Dentist often advise to get the wisdom teeth pulled out as it may cause complications in old age as it is an extra burden on our jaws, but some people consider it as a luck charm.