Dice

• 1. Introduction

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  Dice are one of humanity's oldest tools for conjuring chance. Somewhere beneath a site called the Burnt City in south-eastern Iran, archaeologists unearthed what may be the oldest known dice in existence, estimated to date from between 2800 and 2500 BCE. They were part of a backgammon-like game set, and they were already recognizably what we still use today. That continuity raises a striking question: how did a small cube of bone or stone become so central to human play, ritual, and even cryptography that it outlasted empires, religions, and entire languages?

  The answer starts long before that Iranian burial site. It threads through ancient Indian texts, Roman gambling dens, medieval Japanese parlors, and modern casino floors. Along the way, dice picked up unexpected roles as divination tools, password generators, and teaching aids for probability theory. The humble die turns out to be a device of remarkable depth, and its history is far stranger than any roll of six.

• 2. Ancient Origins

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  Before the first carved cube, there were knucklebones. Researchers hypothesize that dice developed from the practice of fortune-telling with the talus bones of hoofed animals. Native Americans of the Great Plains region are speculated to have used dice since at least 12,000 years ago, placing the practice around 10000 BCE. That timeline makes dice not merely old, but ancient beyond most categories of human technology.

  The Ancient Egyptian game of senet, played before 3000 BCE and as late as the 2nd century CE, used flat two-sided throwsticks to determine how many squares a player could move. Bone dice from Skara Brae in Scotland have been dated to 3100-2400 BCE. Across the world at roughly the same time, excavations at Mohenjo-daro, the Indus Valley civilization settlement, turned up terracotta dice from 2500-1900 BCE. At least one of those Indus Valley dice already had opposite sides that add up to seven, the same convention found in modern dice.

  Games involving dice appear in the ancient Indian Rigveda, Atharvaveda, and Mahabharata, as well as in the Buddhist games list. In ancient Greece, knucklebones evolved into a game of skill where the four sides of the bone were assigned different numerical values. The conceptual leap from fortune-telling bone to numbered game piece had already been made across multiple civilizations, independently and early.

• 3. Rome, China, and Japan

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  Roman society held a complicated relationship with the die. Gambling was illegal, yet many Romans were passionate gamblers who enjoyed a practice known as aleam ludere, or "to play at dice." Two distinct types circulated throughout the empire. Tali were large dice marked with one, three, four, and six pips on four sides. Tesserae were smaller with all six sides numbered from one to six. Twenty-sided dice appeared as far back as Ptolemaic Egypt in the 2nd century BCE and persisted into Roman times.

  In China, the story of dice took a different turn. Dominoes and playing cards both originated there as developments from dice. The transition from dice to playing cards coincided with the Tang dynasty, which ran from 618 to 907 CE, and happened alongside the technological shift from manuscript rolls to block-printed books. An object used for generating random values thus became entangled with the history of printing itself.

  Japan developed its own dice culture through a game called sugoroku, which existed in two distinct forms. Ban-sugoroku resembled backgammon and dates to the Heian period, 794-1185 CE. The second form, e-sugoroku, was a racing game. Meanwhile, a 13th century Spanish text called the Libro de los juegos records that King Alfonso X invented seven-sided dice specifically to speed up play in chess variants, suggesting that rulers were actively engineering new die shapes to solve specific game-design problems.

• 4. Words and Slang

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  The word "die" itself carries a surprisingly rich etymology. It descends from the Old French word dé, which in turn comes from the Latin datum, meaning "something which is given or played." A die, in its oldest linguistic sense, is literally a given thing, something handed over to fate.

  Specialist vocabulary built up around the die over centuries. The terms ace, deuce, trey, cater, cinque, and sice named the sides from one to six in a vocabulary drawn from Old French and Latin. Though largely obsolete today, some professional gamblers still use them. Ace traces to the Latin as, meaning "a unit."

  Rolling two dice at once generated its own slang. The term "snake eyes" describes a roll of one pip on each die; the Online Etymology Dictionary traces that phrase to 1919. "Boxcars," also called "midnight" in American usage, describes a roll of six pips on each die, named for the resemblance to a pair of freight train boxcars. The game of craps generated the richest vocabulary for specific roll combinations, a linguistic layer built entirely on the act of throwing two cubes.

• 5. Construction and Precision

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  A standard die is most often 1.6 cm across, its six faces marked with round dots called pips. The rule that opposite faces sum to seven requires the faces numbered one, two, and three to share a single vertex. Whether those faces run clockwise or counterclockwise around that vertex determines handedness: counterclockwise makes a "right-handed" die, clockwise makes a "left-handed" one. Western dice are normally right-handed; Chinese dice are normally left-handed.

  The manufacturing process splits sharply between two tiers. Non-precision dice are made through plastic injection molding, often using polymethyl methacrylate. The pips are part of the mold. After injection, the die is submerged in paint, allowed to dry, then tumble-finished like a rock in a polisher. The abrasive scrapes off all surface paint while leaving color in the pip indents.

  Precision casino dice are made to a different standard entirely. They are cut from bars of extruded cellulose acetate, with pips drilled to 17 plus or minus 4 mil deep, then filled with opaque paint or epoxy matched in density to the cellulose so the die stays balanced. New Jersey specifies that a casino die may be no larger than 0.775 inches on a side, except for pai gow dice. Each precision die carries a serial number and the casino's logo to prevent substitution by cheaters. The transparency of the material makes internal weighting easy to detect.

• 6. Shapes Beyond the Cube

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  The modern tradition of non-cubical polyhedral dice began around the end of the 1960s, when such shapes grew popular among wargame players and then spread to role-playing games and trading card games. A standard role-playing dice set contains seven dice: one each of d4, d6, d8, d12, and d20, plus two d10s, one numbered 0-9 and the other in tens from 00 to 90.

  Five of the shapes in that set are Platonic solids, whose faces are all regular polygons. The tetrahedral d4 works differently from all others: because no face points upward when it rests, the result is read from the number at the upright vertex or at the base edges. The 10-sided die is not a Platonic solid but a pentagonal trapezohedron, each face a kite shape with two different edge lengths, three different angles, and two different kinds of vertices.

  The icosahedral d20 has a long history. Icosahedra dating to Roman and Ptolemaic times have been found, though whether they served as gaming dice is unknown. The 120-sided disdyakis triacontahedron sits at the extreme end of practical die design, each face a scalene triangle. At the other extreme is the Zocchihedron, a sphere containing another sphere with 100 facets, invented as a true d100 alternative to percentile dice; unlike standard dice, it is not isohedral, meaning some results are more likely than others. The seven-sided die appears in backgammon variants, and the 36-sided die is designed so that rows of spots above and below each number allow it to simulate two six-sided dice rolled simultaneously.

• 7. Chance, Divination, and Passwords

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  Dice acquired roles far beyond game tables. Using dice for divination is called cleromancy. Tibetan Buddhists practiced this method, and it is highly likely that the Pythagoreans used Platonic solids as dice, referring to them as "the dice of the gods" and connecting geometry in polyhedra to an understanding of the universe. Astrological dice form a specialized set of three 12-sided dice: the first represents planets, the Sun, the Moon, and the lunar nodes; the second represents the twelve zodiac signs; the third represents the twelve houses.

  A specialized icosahedron provides the answers printed inside a Magic 8 Ball, the toy conventionally used to answer yes-or-no questions. The same twenty-sided shape that helped resolve combat in Dungeons and Dragons also drives a novelty oracle.

  Modern cryptography found a use for dice as well. The Electronic Frontier Foundation describes a method for generating passphrases from dice rolls. The technique, called Diceware, involves repeatedly rolling five dice and selecting the corresponding word from a pre-generated list, producing passphrases that are both secure and memorable. Rolling a single six-sided die produces a uniform distribution where each face has equal probability; rolling two dice and summing the results shifts the distribution so that a total of seven becomes more likely than either two or twelve. That property has made dice a standard teaching tool for probability theory, a field of mathematics that dice helped bring into existence.