Where The Phrase Why The Long Face Might Have Originated
You may have heard the joke: "A horse walks into a bar. The bartender asks him, 'Why the long face?'" While hokey, the joke's success hinges on our understanding of the idiom: "long face." An idiom, according to Merriam-Webster, is a phrase or group of words that mean something different than the sum of their parts. Common English idioms include "we're on the same page," "asleep at the wheel" — and of course, "long face," meaning sad, disappointed, serious, or melancholy (via Macmillan Dictionary).
But where did the idiom "long face" come from? According to the d, internet etymological sleuths (yes, that is a real thing) have attempted to dig beyond the dates cited by dictionaries as the first usage of "long face." While Dictionary cites 1780-90 as the approximated date for the first use of the term, Merriam-Webster offers a more precise date, 1747.
Per English Language & Usage Slack Exchange, Etymology investigator Sven Yargs posits that the phrase's origin is potentially much earlier. He identified the source text for the 1747 date as "The Crounian Lectures on Muscular Motion, Lecture II. Read Nov. 27, 1746," by James Parsons, a London-based physician and contributor to medical literature (included in "The Philosophical Transactions (from the Year 1745, to the Year 1750"). Yargs notes that the discrepancy between the year 1747 cited by Merriam-Webster and the 1746 date The Crounian Lectures were published initially may have to do with the fact that a second edition was published a year later (posted at the Hathi Trust Digital Library).
How to determine a word's first use
Etymologists attribute the first idiomatic use of the term "long face" to "The Crounian Lectures on Muscular Motion," a collection of medical documents that detail ailments, conditions, and treatments of the mid-1700s. The quote Sven Yargs identifies (at English Language & Usage Slack Exchange) uses "long face" as an idiom and comments on the phrase's "common use," suggesting that the phrase's origins are some time before the publishing date: "This gives occasion for the phrase commonly used, of putting on a long face, upon being sorrowful; and the relaxation mentioned causes the forlorn look."
Even though the text suggests that possibly English speakers used "long face" idiomatically years before its publishing date, dictionaries can safely keep the phrase's first use date as 1746. This is because dictionaries cite the first time a word or phrase is printed or written as the first use date. Merriam-Webster reminds its readers that first use dates are subject to change and do not reflect when words were first spoken.
Further digging by Yargs and etymological enthusiast Tom O'Bedlam (posted at English Language & Usage Slack Exchange) has uncovered several other written mentions of the term "long face," dating as far back as 1665 ("The Art of How to Know Men"). Still, the phrase is used as a physical description rather than an idiom, so 1746 remains long face's first-use date.
Why do we associate long faces with sadness?
An educated guess would pair the descriptor "long face" with a frown, much like the texts using "long face" to describe sad people, dating back to 1665. But why do we frown when we're feeling low? Our emotions and muscles could play off each other, explains Simon Rego, PhD, Director of the CBT [Cognitive Behavioral Therapy] Training Program at Montefiore Medical Center/Albert Einstein College of Medicine in New York to Everyday Health. He says, "In other words, there's a two-way street between emotions and facial expressions: Most people understand that they smile when they feel happy and frown when they feel sad. But few know that when the facial muscles that are used to create a smile are activated it can generate feelings of happiness. By the same token, when the facial muscles that are used to create a frown are activated it can generate feelings of sadness."
Furthermore, a study by Lawrence Ian Reed and Peter DeScioli, published in Evolutionary Psychology, suggests that "sad expressions function to increase the credibility of claims of loss." Essentially, physical expressions like frowns provide physical evidence backing up whatever we claim to feel. Imagine the central figure in Edvard Munch's "The Scream" telling you they are having a good day. The claim and the physical evidence wouldn't add up. In a sense, our expressions, from smiles to "long faces," provide a shorthand for the emotions we attempt to communicate.