So, why do we lose our baby teeth anyway? I mean, they seem fine for a few years, then they just fall out! Why can’t we just keep the same ones forever? How does this whole tooth-replacement process work?
In: Biology
Our mouths, along with the rest of our bodies, grow a significant amount during our childhood and into adolescence. It shouldn’t be surprising that the set of teeth that we have as kids wouldn’t fit our mouths very well when we approach our full-size. So we evolved a system where throughout that period of growth, our bodies replace our smaller original teeth with larger ones to fit our larger mouths.
This also has the nice ‘side effect’ of giving us some new teeth a bit later in life that aren’t as worn-down and/or damaged as they would’ve been if we’d been using them since we were kids.
Lots of animals get new teeth through the course of their lives. You mentioned sharks, and they actually continually replace their teeth throughout their lives, not just once, and that’s because a combination of their tooth structure and their hunting/eating methods make tooth damage/loss much more likely throughout their lives.
We aren’t the only ones. Others do, too.
Our faces grow a lot from the time we are children to adulthood. Our teeth go through a lot. By the time our mouths are grown up, the space is bigger in the mouth, and baby teeth have been through a lot. We are designed to live 30-40 years. Having a second set that is nice and new and fits an adult mouth for the second half of life seems like a pretty good evolutionary advantage.
And note: humans are not the only ones who renew teeth.
Wait til you see a puppy’s ears morph from floppy to straight, right when their baby teeth are coming out. One side at a time!
As kids grow, their mouths and jaws get bigger. Baby teeth are just the right size for a smaller mouth, but as kids grow, they need bigger teeth to fit their larger mouths.
The jaws of humans grow quite significantly in proportion to the rest of their head. It’s *much* smaller at birth – I’d guess to reduce the overall size of the head to improve the chance of live birth and mother survival. But teeth, being not-quite-bone, doesn’t have the same growth as regular bone. So the evolutionary solution is to have two sets of teeth; one set when the human has very small jaws, and another set that emerges as the jaw continues to grow. The permanent teeth are fully formed adult sizes as they emerge, they just emerge in stages as more jaw space becomes available.
If you take a look at an X-Ray of a child’s skull before their permanent teeth has emerged, or even the skull of a child who passed away, you can see the teeth already fully formed in their skull, just waiting to emerge. It’s a very disturbing image – I have to warn you.
Underneath each baby tooth, adult teeth start to develop. These new teeth dissolve the roots of the baby teeth, causing them to become loose and eventually fall out.
Short answer: interlocking teeth evolved at the expense of our ability to constantly grow new ones.
Losing baby teeth is a sign that your mouth is transitioning to the adult phase. It’s part of the natural cycle of human development, ensuring you have a full set of teeth for your adult years.
We lose the baby teeth for two reasons
1. We are growing, which includes our jawbones. a new set of teeth that fit better serve us
2. Teeth cannot repair major damage. We have softer foods and brushing with fluoride toothpaste now to help, but that second set of teeth is very important to keep us healthy since teeth start to wear down or get cavities from plaque by the time we reach adults, and then our adult teeth are designed to keep us going up through our main reproductive years.
even then we are very primitive compared to some animals. quite a few animals regularly shed old teeth and grow new ones, and the front incisors of many rodents continue to grow outwards because they constantly gnaw on hard materials.
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