Archeologists often have described the Tucson area’s prehistoric residents as totally at the mercy of the climate, unable to move away from the rivers or sites of permanent water.
But new evidence suggests that these people, called the Hohokam, cultivated large tracts on the dry bajadas, or the land at the foot of the mountains, where now only a few cattle graze.
“We certainly can appreciate their ingenuity and engineering ability more than we did in the past,” said Suzanne K. Fish of the Arizona State Museum. She is one of four archeologists who recently confirmed that the Hohokam, who lived here until about AD 1300, farmed large tracts of agave.
The Hohokam were irrigation-using farmers who flourished in central and southern Arizona for several centuries and then mysteriously disappeared just before the arrival of the conquistadors.
It is not that archeologists did not know that agave was important to native Americans in the Southwest. The Apache and others were heavily dependent on it. The Hohokam used it for food, fiber to weave into mats and baskets, spines to be used as sewing needles and construction materials for wall frames and roofing shingles.
But what is new is the idea of cultivation--as opposed to foraging for wild plants--and the extent of that cultivation, said Paul R. Fish, curator of archeology at the Arizona State Museum. Paul and Suzanne Fish and archeologists Charles Miksicek and John Madsen have found that agave farming was a major industry here between 1100 and 1300.
The archeologists have surveyed about a 60-square-mile area near suburban Marana and found that the major political and religious site for the community was not along the river, as might have been expected.
Instead, this site got its water from a canal several miles long that probably was excavated with stone and wooden tools, Suzanne Fish said.
Paul Fish said the Hohokam put approximately 1,200 acres (about two square miles) under agave cultivation at Marana and farmed a slightly smaller area near Tumamoc Hill. Both sites included extensive use of terraces and rock piles.
Agaves grow better in rock piles because the rocks trap moisture and mulch and provide protection against rodents that tunnel in to eat the young plants, Paul Fish said.
The team also has uncovered several roasting pits where agave hearts were baked for 24 to 48 hours, yielding a food that tastes something like a fibrous sweet potato, he said. Some of these pits are huge, up to 115 feet in diameter.
The impressive scale of the large bajada rock-pile fields is illustrated by the 42,000 rock piles and 393,700 feet of terraces and dams found.
The archeologists estimate that an initial investment of 50 man-years was needed to construct these fields and that 102,000 plants were under cultivation at one time. About 10,200 agaves would have been harvested each year, supplying the annual calorie requirements of 155 people and the protein requirements of 110. Such a food source--not to mention all the craft material available as byproducts--would have added significantly to the Hohokam diet and economy, Paul Fish said.
Suzanne Fish said the team had suspected that agave was cultivated here. But the real clincher was finding artifacts in the fields that were used for harvesting agave, she said. These are broad, flat volcanic stone tools sharpened by chipping and grinding.
Since agave grows well in rocky soil, it could be grown in marginal areas, leaving arable land for other crops such as corn, he said. Additionally, it may have had special value in that it would survive in the harshest conditions after other crops had failed, he said.
The archeologists speculate that several different species were cultivated. But they added that the Hohokam did not grow the large species found today in Tucson.
“Agave was one of the more important crops cultivated,” Paul Fish said. “There is a growing list of plants that the Hohokam cultivated, which is really very impressive.