The earliest evidence for what we might describe as measurement comes in the form of animal bones carved with notches. These metrological relics include the Ishango Bone, a baboon fibula between 18,000 and 20,000 years old, and the Wolf Bone, older still at roughly 33,000 years in age.1 Reading their meaning is like any augury, indefinite and intuitive, but archaeologists think the ordering of marks on these bones might make them tally sticks: the first formal measuring tools.
