But with homodonts, it doesn’t matter if they lose a tooth, because the new one is going to be the same shape as the old one.
Have you ever wondered why sharks have an infinite supply of teeth while humans have to rely on fillings? It turns out that the reason has an evolutionary history that’s quite interesting.
Not all teeth are created equal - some animals have homodont teeth, meaning that every tooth in their mouth is more or less the same shape, while other animals have heterodont teeth, with a variety of different shapes. Humans are heterodonts, which is why anthropologists can find a single tooth and tell where exactly it went in its owner’s mouth.
Sharks, being homodonts, constantly regrow their teeth on a cycle that results in an alternating pattern of old and new teeth. This means that if a shark loses a bunch of teeth all at once, there’s a fresh set just under the gumline ready to pop up.
Heterodonts have the benefit of having specialized teeth for specific tasks, such as molars for crushing and canines for slicing. Carnivores have a pair of teeth called carnassial teeth that act like nature’s scissors, and certain primates have C-P3 honing complexes to keep their canines sharp for fighting.
Mammals’ teeth gained complexity over time, but in doing so, lost the ability to regenerate. This is why humans have to rely on fillings, while sharks can continuously regrow their teeth. Nobody likes a broken comb, and if you’re waiting for a tooth to grow in, that’s what you’re stuck with. Most mammals have specialized tooth shapes, meaning the ability to grow more than one set of teeth had to be sacrificed. However, there are some mammals who have managed to find workarounds to the one set of adult teeth thing, such as elephants and silvery mole-rats. Elephants have huge molars that look like car batteries, and as they use them to chow down, the front part of the tooth wears down and falls out of the elephant’s mouth. They have around six or seven molars in each quadrant of their mouth, and as the first one wears down, the next one moves forwards like a conveyor belt. Silvery mole-rats, on the other hand, grow new molars at the back of the mouth as the ones at the front wear out, with no apparent limit on how many they can grow.
The reason why mammals can’t regrow teeth is the same reason why you can bite a chunk off of an apple with your front teeth and crunch it to bits with your molars. For those who enjoy listening to smart people discuss the merits of regrowing teeth, SciShow Tangents has an entire tooth-related comedic deep dive. It has games, poetry, and most importantly, every episode will contain at least one butt-related fact.