Why Do We Get Long in the Tooth?

(Last Updated On: October 17, 2021)

Things getting old are sometimes called “long in the tooth,” which is strange when the phrase is occasionally applied to people. After all, most people don’t really have teeth one would describe as “long.” So what’s up with that? Why do we say things get long in the tooth?

Actually Long Teeth

While your teeth might not get longer over time, many animals do have teeth that elongate as they age. Horses have long since had their age determined by the length of their teeth. The practice dates so far back that it serves as an origin for the phrase “don’t look a gift horse in the mouth.” That phrase has been in modern English since the 1500s, so the practice of measuring horse teeth probably dates that far back.

Anyway, that’s not the point. The point is that some animals do get teeth that can grow dangerously long. The babirusa boar is known for having tusks that grow through the top of its mouth. You’d know this can be a problem if you have a pet rabbit–notable for how their teeth literally never stop growing. Without grazing to file down their teeth (or humans clipping them), rabbit teeth can grow so long they go back into the heads of the rabbit. 

This is not a good time for the rabbit.

First Uses

Latin phrases dating back to the 16th century seem to allude to the idea of longer teeth. However, the phrase didn’t make its first written English appearance until the 1800s. Specifically, 1852. 

In William Makepeace Thackeray’s 1852 The History of Henry Esmond, we see one of the first written records of being “long in the tooth.”

“His cousin was now of more than middle age, and had nobody’s word but her own for the beauty which she said she once possessed. She was lean, and yellow, and long in the tooth…”

In Thackeray’s book, he’s not referring to a horse though. He’s referring to a person, which suggests that at some point “long in the tooth” made its way from describing horses to being a euphemism for people without a strong written record. The jump was probably assisted by people’s receding gums, which can make it appear as if the teeth are getting longer. Kind of like how dead bodies have receding cuticles, which gives the illusion of the nails still growing after death. 

Speaking of teeth, see how well you know them here.

About the Author:

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Kyler is a content writer at Sporcle living in Seattle, and is currently studying at the University of Washington School of Law. He's been writing for Sporcle since 2019; sometimes the blog is an excellent platform to answer random personal questions he has about the world. Most of his free time is spent drinking black coffee like water.