The expression “long in the tooth” is an idiom that refers to old people, particularly when their age makes them too experienced or too seasoned for a particular thing, event, or role. When people use this phrase they are generally implying that the subject is past his or her prime. For example, if someone calls an actress too long in the tooth for a role, he or she means that the actress is too old to play the part convincingly.
Origins
An idiom is basically a phrase or statement that has figurative meaning apart from its literal translation. This expression usually has nothing to do with how physically long a person’s teeth are. Rather, the imagery is meant to suggest age. People today often simply know this implication without understanding its origin, but centuries age the connection between teeth and old age likely made more sense to the common person since horses can often be quickly aged by looking their teeth — and when horses were a hot commodity and a common mode of transportation, their aging processes and signs were often much better known.
Horses’ teeth tend to actually gain length with age, which doesn’t usually happen in people. Additionally, their gum lines often recede into late adulthood. One way to informally measure a horse’s age is to look in its mouth and guess or measure how long its teeth are. The longer the tooth, the older it is likely to be. It was common practice for merchants to examine horse teeth before formalizing a purchase to avoid buying an animal that was too old to do the work of pulling a carriage or plowing a field, and this was a way to quickly check or verify the seller’s representation of how old the animal really was.
English Usage and Adoption
There is evidence of Latin variations of the phrase that date to the 1600s, though the earliest recognized example in English appeared in 1852, in a novel by William Makepeace Thackeray. That novel, The History of Henry Esmond, used the phrase “long in the tooth” to describe a woman who was also described as “of more than middle age, and had nobody's word but her own for the beauty which she said she once possessed.”
It is quite possible that this descriptive saying evolved independently in the English language without any reference to the Latin versions. There is a gap in years between examples of the phrase in common use, so some historians suggest that the Latin phrases went out of vogue before they were picked back up again in England and the English colonies of the time. The English phrase may have come into being on its own in the 1800s because of how common it was then to check a horse’s teeth to determine its age.
Examples and Contexts
The phrase is almost always used for people, particularly others who are seen to be engaging in activities that they may actually be too old for. One could say, for example, “He’s getting a bit long in the tooth to be dressing that way”; it’s also common in sports, theatre, and social engagements. Basically any time a person is acting younger than he or she is the phrase makes sense — it’s like a horse being marketed as being younger and more vibrant than its teeth show.
The connotations aren’t always negative, though. People sometimes use the expression on themselves, often as a way to of owning their age while still showing some degree of savvy; a phrase like “I may be long in the teeth, but I know what’s going on here” is just one example. Though it’s less common, the idiom can also be applied to inanimate things, like appliances or home goods that are past their prime and are no longer functioning properly, particularly if they appear fine at first glance.
Similar Expressions
At least one other English idiom, don’t look a gift horse in the mouth, shares the same roots of horse merchants examining animals’ mouths to check for age and overall quality. This expression usually means that people should be grateful for things they receive as gifts without trying too hard to scrutinize their quality. Getting something for free is better than not having it at all, or so the logic goes; examining it to make sure that it is in top condition is often seen as rude or ungrateful.