The English word “puzzle” is unusual, according to Marcel Danesi, a professor of semiotics at the University of Toronto. Embracing everything from riddles and logical conundrums to mathematical problems and optical illusions, he notes that “it has no equivalent in any other language.”

That might seem to make sense — this constellation of brainteasers doesn’t obviously share much in common. But at the most basic level, all puzzles (jigsaws, crosswords, or detective novels) have a question-and-answer structure that taps directly into what Danesi calls The Puzzle Instinct.

“If you don’t get that answer, you feel a kind of void,” he says, “and when it’s finally filled you feel an intellectual catharsis.” In other words, we’re born suckers for a cognitive challenge.

The origin of this problem-solving compulsion is unclear, and we’re unlikely to pinpoint the precise moment when our ancestors started puzzling. But what we do know is that as soon as a historical record appears, puzzles start popping up around the world. Here are some of the most famous.

## 1. The Ishango Bone

In 1950, on the shore of Lake Edward in what is now the Democratic Republic of the Congo, a Belgian geologist named Jean de Heinzelin unearthed what may be the oldest known puzzle. At a glance it seems like no such thing — just a bone with random tally marks, or a bit of junk from the 11,000-year-old fishing settlement of Ishango. But the harder you look, the more meaningful those etchings become.

They’re separated into three columns, each unified by what looks like a mathematical theme. One revolves around the idea of doubling numbers: A cluster of 3 lines followed by a cluster of 6, 4 followed by 8, 10 followed by two sets of 5. Another column dances around multiples of 10, the all-important core of our modern decimal system: 11, 21, 19, 9. The third column lists four numbers which, incredibly, all happen to be prime: 11, 13, 17, 19.

Coincidence? De Heinzelin thought not. In his view, these marks represented “an arithmetical game of some sort,” and one that would have been surprisingly advanced for the Paleolithic period. If he was correct, popular mathematics writer Dominic Olivastro notes in his book Ancient Puzzles, “this is certainly the most ancient puzzle.”

## 2. The Sphinx’s Riddle

Whatever the Ishango bone’s true nature, the bona fide granddaddy of all puzzles is the Sphinx’s Riddle, best known from Oedipus Rex, a tragic play by the Greek poet Sophocles. In this story, the Sphinx is a merciless hybrid creature — head of a woman and body of a lion — that stands guard over the gate to Thebes, posing an enigmatic question to all who try to enter the city:

“What goes on four legs in the morning, two in the afternoon, and three in the evening?”

The monster swiftly devours those who get it wrong. But Oedipus alone grasped the correct answer: a human being, which crawls on all fours as a baby, walks on two legs as an adult, and uses a walking stick in old age. The riddle is in fact an allegory for life’s journey, one that may be familiar to modern readers.

“You never think of metaphor as being a riddle because you’re so used to it,” Danesi says. But it’s easy to imagine a Greek theater audience racking their brains for the solution.

## 3. The Stomachion

You’re probably familiar with tangrams. They’re dissection puzzles made up of seven polygons that together form a square and can also be arranged into all sorts of shapes, from birds to houses to sailboats. But long before this popular modern game was invented (likely in China in the late 1700s), it had an ancient predecessor in Greece.

The Greek mathematician Archimedes likely designed the Stomachion (also known as the Loculus), which was a tangram cranked up a few notches. With twice the number of geometric figures, it could be scrambled and reassembled into more complex shapes, like intricate gladiators and warships and elephants.

By creating a meaningful picture from abstract shapes, the game serves as “the blueprint for Legos, jigsaw puzzles, and tangrams,” Danesi says.

In some versions, the goal may have been to piece the figures back together into a square, a process that was more like jigsaw puzzling. In 2003, mathematician Bill Cutler determined there are 536 unique ways to form a square, excluding solutions that are identical by rotation or reflection.

## 4. The River Crossing

By the Middle Ages, puzzles were on their way to becoming a pastime. Around A.D. 800, the English clergyman Alcuin of York published Propositiones ad Acuendos Juvenes (“Problems to Sharpen the Young”), a work Danesi calls “puzzledom’s first masterpiece.” It contained some 50 problems, and the most renowned was the river crossing puzzle, which spawned a whole genre.

The classic version goes like this: You must cross a river with a wolf, a goat, and a head of cabbage, but the boat is only big enough to carry you and one other item at a time. You can’t leave the wolf alone with the goat, or the goat alone with the cabbage, since you’d like all your cargo intact on the other side. How do you proceed? (Hint: Which combo won’t end with someone/something getting gobbled?)

Based on one of Alcuin’s letters to Charlemagne, Olivastro suggests the scholar may have composed his puzzles for the amusement of the first Holy Roman emperor. If you consider Wordle a non-negotiable after-work diversion, imagine trying to decompress when your job involves conquering all of Europe.

## 5. The Knight’s Tour

Around the same time, chess (or rather an early form of the game called chaturanga) was taking off in India. These days, chess was an essential part of any serious player’s diet, and apparently that was true back then as well. One move stands out: the knight’s tour, in which you try to move a knight to all 64 squares on the board without landing on any square more than once.

The earliest solution comes from Rudrata, a 9th-century Kashmiri poet. In Kavyalankara, a Sanskrit work on poetics, he uses the knight’s route (albeit covering only half the board) to compose a charmingly bizarre form of verse — each of the 32 syllables corresponds to a square, and their order is the same whether you read from left to right or by following the path of the knight.

If you think these are dusty old puzzles devoid of relevance, think again. During the 2010 World Chess Championship, in a game between defending champion Viswanathan Anand and Veselin Topalov, Anand made 13 consecutive knight moves; online commentators reportedly joked that he was trying to solve the knight’s tour.

## 6. The Rabbit Puzzle

The Italian mathematician Leonardo de Fibonacci is widely known for his namesake number sequence, in which each number is the sum of the previous two: 0, 1, 1, 2, 3, 5, 8, 13, 21, etc. The Fibonacci sequence grew in fame as biologists discovered examples of it across the natural world — the spiral patterns in pinecones, flower petals and nautilus shells all reflect its formula.

What’s less commonly known is that he stumbled upon the sequence after devising a completely arbitrary puzzle about rabbit breeding. It starts with a pair of rabbits, male, and female. Every month, each pair produces a new pair, and the new pairs start producing in their second month of life. How many rabbits will you have at the end of the year?

Fibonacci couldn’t have known how extraordinary the answer would prove to be. As the numbers increase, the ratio between them approaches the golden ratio (roughly 1.618), which Leonardo da Vinci and other artists have used as a model for ideal proportions in their work. This abstract mathematical concept turns up again and again not only in aesthetics, but also in organic life. In the words of mathematician Ian Stewart “simple puzzles could open up the hidden depths of the universe.”

## Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

Professor of semiotics at the University of Toronto. Marcel Danesi

Scientific American. Ishango

World Book Encyclopedia. Mythic Monday: The Riddle of the Sphinx

Cornell University. Archimedes’ Stomachion

Jorge Nuno Silva - Associação Ludus. Propositiones ad acuendos iuvenes by Alcuin

Britannica. Chaturanga

The Fibonacci Quarterly. Why Do Fibonacci Numbers Appear in Patterns of Growth in Nature?

An Anthropology of Puzzles. Puzzles in Mind and History

Cody Cottier is a contributing writer at Discover who loves exploring big questions about the universe and our home planet, the nature of consciousness, the ethical implications of science and more. He holds a bachelor's degree in journalism and media production from Washington State University.