A study by anthropologist Robert Madden from Colorado State University may have identified the oldest known dice, dating back over 12,000 years. The game pieces were used by Native American hunter-gatherers near the end of the last ice age, making them thousands of years older than previously known artifacts. The study used a test to identify four features that all had in common, such as wood or bone, and the right size and shape for players to hold several of them in their hand. Of the artifacts, Madden identified 565 that fit all four criteria for being dice, with an additional 94 objects deemed probable dice. The findings suggest that dice, games of chance, and gambling have been a significant feature of Native American culture for at least 12 years.