A study by archaeologist at Colorado State University has revealed that Native Americans invented dice over 12,000 years ago, giving archaeologists the world's oldest evidence of gambling and possibly the oldest use of probability. The study looked at more than 600 sets of Native American dice from 45 prehistoric archaeological sites in the western U.S. from 13,000 to 450 years ago. The dice were present at Indigenous sites on both sides of the Rocky Mountains throughout this period. This discovery precedes any evidence of dice in the Old World by 6,000. The three earliest dice were found from sites in Wyoming, Colorado and New Mexico dating to nearly 12,900 years ago and were identified by anthropologist David Madden. The discovery indicates that dice games may have been invented as a "social technology of integration" or an icebreaker for strangers seeking information or information.