The Surveyors of the Inca

The land where the condor soars between the towering peaks of the Andes would be the last place on earth to look for one of the world’s most productive agricultural societies. Yet more than half of all the varieties of crops that we eat were first cultivated in Peru, many of them on steep, terraced mountain slopes where the soil had to be hauled from the valley below. The equitable distribution of the preciously small amount of farm land appears to have been successful enough to keep the peace. Until destroyed by Spanish conquerors, Inca society was a success, and a major credit for that success must go to their surveyors.

As is customary in totalitarian regimes, the real estate belonged to the state, here represented by the Inca. Under no condition could a Peruvian buy or sell land; it could, however, be received as a gift from the Inca. All available land was divided into three, not necessarily equal, parts. One part belonged to the Sun, which cynics identify with the numerous members of the priesthood who maintained the temples. A second part was set aside for the support of the Inca and his court. The third part was held in common by the tribal villages and was annually distributed to the people.

When a Peruvian married, he received a dwelling and a tupu of land for himself and his wife. A tupu was an agrarian measure of somewhat elastic quantity, somewhere around two and a quarter acres, depending probably on local definitions. As the family grew in size, it received additional acreage, a tupu for each son, half that much for a daughter. Tribal leaders, government officials, widows and orphans each received a specified share that had to be cultivated for them by their neighbors. There were, however, no slaves. To pay taxes or render service meant to work on somebody else’s land—the Sun’s, the Inca’s or whoever else was entitled to such labor. Excess acreage was allowed to lay fallow rather than unfairly increasing somebody’s allocation. As may be imagined, a system of ever-changing allotments requires plenty of surveying.

Measurements were carefully made, using wooden rods and brass plumb bobs. For leveling they used clay bowls set on tripods and filled with sand. On top of the sand was set a second bowl that was partially filled with water and diametrically opposed peepsights cut into the sides. As long as the water level was equidistant below the sights, the line of sight was level. The success of that simple instrument in the layout of the world’s greatest system of irrigation canals was astounding.

The unit of lengths was called rikra, measuring about 5.3 feet. Marked stones monumented the boundaries. Anyone caught disturbing a monument was punished by having a heavy stone dropped on his shoulders from a height of about three feet, very likely breaking his back or otherwise crippling him for life. A second offense resulted in the death penalty. We may assume that Peruvian boundary markers lasted longer than ours.

The skill of the Peruvians surveyors to lay out irrigation systems is almost unbelievable. Rivers were dammed and canals were built over dozens of miles to irrigate tiny tracts of land. Often the channels had to be carved through solid rock, sometimes in zigzag fashion to slow the water down.

The Incas built a highway network of more than 15,000 miles of all-weather roads, connecting the extensive territories of the western hemisphere’s most rugged terrain. Many of the main roads were paved with stone and had mileposts set at intervals of about six miles, an indication that the routes had been measured.

Their names are lost to us because they had no written language, and their oral historians are in their graves. But the trained eye of the modern surveyor will recognize their work by the marks they left upon the land and will admire the competence of the surveyors of the Inca.