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Wisdom teeth are the worst, aren’t they? They just pop up out of nowhere, bringing pain and sensitive gums with them. Only eventually they decide they’ve had enough of the world inside your mouth and they start hurting until you get them removed. But why do they appear in the first place? Because of evolution, of course. Attempting to better understand the evolution of our teeth, a team of researchers reveal that prehistoric teeth evolved according to inhibitory cascade.
More and bigger teeth
After attempting to find the reason behind our teeth’s evolution for over a decade, scientists have finally figured out that the answer is much simpler than they had anticipated. It has to do with an evolutionary trend instead of something particular to humans, but I’ll get into that a bit later.
Our wisdom teeth, also known as the third molars, are often very small and underdeveloped in humans despite the fact that they bring a lot of pain with them. However, previous hominid species had much bigger molars. They were so big, in fact, that they used to chew on surfaces up to two or four times those we are used to.
For a long time, this was believed to be the cause of a particular change the hominids partook in, like a shift in dietary habits, a shift in culture, or even something resulting from intermingling. But it turns out that the answer is far less exciting.
The inhibitory cascade
Since teeth can tell us a lot about the lives of our ancestors, researchers used fossilized teeth of both humans and animals and came to the humbling discovery that we did nothing special – or more like nothing at all – in order for our teeth to change so much.
As humans, we are animals. Mammals to be more specific. And this is exactly what triggered the change. We’re not the only ones to suffer such a huge transition at the level of our chewing surfaces. In fact, almost all mammals went through the same change. And it’s owed to something called the inhibitory cascade.
A hypothesis on molar evolution, the inhibitory cascade refers to the fact that there is always a balance between the molar-derived inhibitors and the mesenchymal activators which determines the size of the immediately posterior molar. That molar, in its turn, determines the size of the one next to it, and so on, eventually determining the size of all of our teeth.
Image source: Wikimedia
