Why do they not heal back like a bone or soft tissue? We just have one pair and that’s it…
In: Biology
Well typically we have two pairs, we lose our baby teeth and grow in adult teeth in late childhood.
But anyways, natural selection really only cares about surviving long enough in life to reproduce and then raise our next generation so that our genetics can continue. Any life beyond that is just bonus for us personally, as far as evolution is concerned.
Through most of humanity’s existence, we’ve tended to start reproducing by our mid teenage years, and by the time we hit 30, our children would be having kids of their own. So not too long after that, we’d no longer be particularly relevant in regards to evolutionary purposes. Whatever happens to us after that doesn’t matter so much.
Basically even without much in the way of active healing, our teeth would’ve tended to last long enough to get us through our reproductive “purposes”, so there wasn’t any evolutionary pressure to evolve teeth that could heal themselves. Our teeth are good enough as far as natural selection is concerned.
well we actually have two sets – milk teeth that then fall out and are replaced with your adult teeth.
the reason they can’t heal themselves is that unlike bones and soft tissues, enamel does not have blood vessels running through it. without blood, it has no access to oxygen or other nutrients that enable regeneration.
Teeth can heal. They use nutrients in your spit. Here is a [link](https://www.researchgate.net/publication/291997217_Recommendations_for_using_fluoride_to_prevent_and_control_dental_caries_in_the_United_States) if you’d like to learn more.
because our teeth aren’t living tissue. bone is made of proteins, minerals with their own blood vessels. enamel isn’t, its just a super hard covering over our teeth.
In adult teeth, outermost layer of enamel is unable to replenish, as the cells that form enamel undergo programmed cell death after the tooth erupts into the open. The layer underneath enamel, dentin, is able to be replenished by a different type of cell than what makes enamel.
Good news is there’s a Japanese research team that is in the process of enabling us to grow new teeth like sharks, with positive results in lab mice. Hoping to be on the market in next 10 to 15 years.
In short: they didn’t need to.
The reasons they didn’t need to are more multifaceted.
Before humans had modern diets, our teeth likely did not break down as often as they do now. There was a question posed here before asking why small tribal groups of people seem to often have such nice, white teeth. And that’s largely related to diet. Modern diets are very sugary and acidic, and break down our teeth faster without proper dental care.
We are also living longer. That gives more time for not just teeth, but every part of our body to break down.
There just doesn’t seem to have been (or currently exist) sufficient evolutionary pressure for us to have evolved the ability to heal teeth. We got by just fine with the two sets we get, and they break down or fall out under stress over time.
Latest Answers