Ancient bone dice reveal 12,000-year history of gambling in America

Research led by Colorado State University Ph.D. student Robert J. Madden shows that dice, gambling, and games of chance have deep roots in Native American culture, stretching back at least 12,000 years. The earliest examples come from Late Pleistocene Folsom-period sites in Wyoming, Colorado, and New Mexico. These artifacts are more than 6,000 years older than comparable dice found in the Old World.

"Historians have traditionally treated dice and probability as Old World innovations," Madden said. "What the archaeological record shows is that ancient Native American groups were deliberately making objects designed to produce random outcomes, and using those outcomes in structured games, thousands of years earlier than previously recognized."

What Ice Age Dice Looked Like

The oldest specimens identified in the study date to roughly 12,800-12,200 years ago. Unlike modern six-sided dice, these objects were two-sided pieces known as "binary lots." They were carefully shaped from bone into small, handheld forms that were flat or slightly rounded, often oval or rectangular, and designed to be tossed together onto a surface.

Each piece had two distinct faces, marked by differences in color, texture, or added designs, similar to heads and tails on a coin. One side served as the "counting" face. When thrown, each piece would land showing one side or the other, producing a binary (two-outcome) result. Players cast multiple pieces at once, and the outcome depended on how many landed with the counting face up.

"They're simple, elegant tools," Madden said. "But they're also unmistakably purposeful. These are not casual byproducts of bone working. They were made to generate random outcomes."

A New Method to Identify Ancient Dice

To move beyond guesswork, the study introduces an attribute-based morphological test, a structured checklist of physical characteristics used to identify dice in archaeological collections. This method is based on a comparative analysis of 293 sets of historic Native American dice recorded by ethnographer Stewart Culin in his 1907 Bureau of American Ethnology monograph, Games of the North American Indians.

Using this framework, the study revisits artifacts that had previously been labeled as possible "gaming pieces" or ignored entirely. By applying consistent criteria, Madden was able to determine whether these objects fit the definition of dice.

In many cases, the items had been known for decades but were never evaluated within a broader pattern. With this new approach, the study identifies more than 600 hundred diagnostic and probable dice from sites covering every major period of North American prehistory, from the Late Pleistocene through and after European contact.

"In most cases, these objects had already been excavated and published," Madden said. "What was missing wasn't the evidence, it was a clear, continent-wide standard for recognizing what we were looking at."

The earliest examples were also examined directly in museum collections at the Smithsonian Institution, the University of Wyoming Archaeological Repository, and the Denver Museum of Nature and Science.

Rethinking the Origins of Probability

Dice games are often considered humanity's earliest structured interaction with randomness, laying the groundwork for probability theory, statistics, and scientific reasoning. Until now, scholars believed these practices originated in complex Old World societies around 5,500 years ago.

The new findings point to a much earlier and more widespread origin.

"These findings don't claim that Ice Age hunter-gatherers were doing formal probability theory," Madden said. "But they were intentionally creating, observing, and relying on random outcomes in repeatable, rule-based ways that leveraged probabilistic regularities, such as the law of large numbers. That matters for how we understand the global history of probabilistic thinking."

A Long-Lasting Cultural Tradition

The research also highlights how widespread and enduring dice games have been in Native American cultures. Evidence of dice appears at 57 archaeological sites across a 12-state region, spanning Paleoindian, Archaic, and Late Prehistoric periods, and reflecting a wide range of cultural traditions and lifestyles.

Madden suggests that this long history points to the important social role of games of chance. "Games of chance and gambling created neutral, rule-governed spaces for ancient Native Americans," he said. "They allowed people from different groups to interact, exchange goods and information, form alliances, and manage uncertainty. In that sense, they functioned as powerful social technologies."

About the Study

The article, "Probability in the Pleistocene: Origins and Antiquity of Native American Dice, Games of Chance, and Gambling," will appear in American Antiquity, published by Cambridge University Press on behalf of the Society for American Archaeology.