Washington, April 4 : Scientists have discovered that ancient Aztec mathematicians developed their own specialized arithmetic to measure tracts of taxable land.
According to a report by National Geographic News, by reading Aztec records from the city-state of Tepetlaoztoc, a pair of scientists has figured out the complicated equations and fractions that officials once used to determine the size of land on which tributes were paid.
The Aztec records include two ancient codices, written from A.D. 1540 to 1544, that have survived from Tepetlaoztoc.
They record each household and its number of members, the amount of land owned, and soil types such as stony, sandy, or "yellow earth."
"The ancient texts were extremely detailed and well organized, because landowners often had to pay tribute according to the value of their holdings," said co-author Maria del Carmen Jorge y Jorge from the National Autonomous University in Mexico City, Mexico.
According to Jorge y Jorge, the Aztecs recorded only the total area of each parcel and the length of the four sides of its perimeter.
"Officials calculated the size of each parcel using a series of five algorithms-including one also employed by the ancient Sumerians," she said.
The Aztec arithmetic included fractional symbols like hearts, hands, and arrows that seem unusual to modern eyes. But to the Aztecs, they likely had a relation to the familiar-the human body.
Jorge y Jorge takes the example of the heart.
"If you stretch out your left arm, that would be the measure from your heart to the tip of your finger. If you stretch both arms, the measure of the hand would be the distance between the tips of your two fingers," she explained.
"It's just very natural. Your body you carry with you all the time and it's very easy to refer whatever you want to measure to your body," she added.
The primary land unit was likely the distance from the ground to the tip of a finger on an adult's upraised right arm-about 8.2 feet (2.5 meters).
"I think the study is neat because it shows that this sort of math and science was pretty practical in orientation," said Michael Smith, an archaeologist and Aztec expert at Arizona State University.