agriculture: The Americas plantings that included raised fields, terracing, canals, and other irrigation systems The raised fields and the canals were constructed together; when the farmers dug out the canals, they dumped the excess dirt onto the fields This provided the crops with a steady source of water and kept them away from floods The canals were a valuable food source, too; farmers allowed wild turtles and fish to live in them and caught them for meat The Mayan priests maintained a complex calendar that helped farmers keep track of the solar year This calendar told farmers when to plant their crops and when to harvest them It helped farmers plan their year so they could produce the best possible crop Despite the fact that about 70 percent of the Mayan people worked as farmers, Mayan farming never produced the vast surpluses of grain that farmers in other areas achieved The damp climate made it difficult to store corn for more than a year The Maya had no domestic animals to help them plow and instead had to all their work by hand Corn, the largest crop, contains little protein, and the Mayan diet had few other protein sources; as a result, most people were malnourished THE ANDES: QUINOA, POTATOES, LLAMAS, GUINEA PIGS AND People living in the Andes mountains of Peru developed their own crops and domestic animals suited to their dry climate and high altitude They cultivated two crops not grown elsewhere, the potato and the grain quinoa They also domesticated three animals: the llama, the alpaca, and the guinea pig Andean Americans ate many types of wild potatoes; there is fossil evidence that people consumed wild potatoes as early as 10,000 b.c.e in Chile Potatoes were domesticated between 2000 and 1200 b.c.e The people of the Andes cultivated four types of potatoes, one of which became the common potato eaten all over the world today People of the Andes also cultivated the sweet potato Archaeologists have found evidence of domestic sweet potatoes dating to about 2000 b.c.e The sweet potato spread throughout the tropical portions of the Americas and was a staple of the Caribbean diet by the time Columbus arrived Quinoa is a grain that produces edible seeds People began cultivating it from 2000 to 3000 b.c.e It grows well in dry soils at high elevations and is quite hardy Quinoa contains a complete set of amino acids, which meant that people did not have to combine it with a legume to get their necessary protein It also contains fiber, iron, magnesium, and phosphorus People boiled it like rice and ate it as a cereal Llamas and alpacas are four-legged animals related to camels Their wild ancestors, the guanaco (for the llama) and the vicuña (for the alpaca), lived in herds with dominance hierarchies, making them easy for humans to domesticate The process of domestication occurred gradually between 5000 and 2500 b.c.e People used llamas and alpacas for both wool and meat They also used llamas as pack animals on the high mountain paths Historians believe humans may have 47 domesticated llamas and quinoa simultaneously Llamas eat wild quinoa and pass the seeds onto the ground in their manure When people began herding wild llamas and shutting them in enclosures at night, the llamas’ manure would have contained both seeds to grow quinoa and natural fertilizer to help them germinate After a successful crop of quinoa started growing, the farmers would move the llamas to another corral The quinoa grew inside the enclosure, safe from grazing llamas The guinea pig was the third domesticated animal of the Andes Hunter-gatherers between 5500 and 10,000 b.c.e consumed a great deal of wild guinea pig meat Between 2500 and 5000 b.c.e people began keeping guinea pigs in their settlements to save the trouble of hunting them and ensure a steady supply of meat Guinea pigs were ideal candidates for in-home domestication They reproduce rapidly and prolifically, they eat table scraps, and they like to live in close quarters SOUTHWESTERN UNITED STATES Agriculture fi rst appeared in the southwestern region of the present-day United States about 1000 b.c.e People living in caves in the mountains of New Mexico were growing corn and squash around 800 to 1200 b.c.e Beans arrived slightly later, around 400 b.c.e The tools and pots found with the fossilized remains of corn and squash indicate that the cave dwellers were not colonists from Mexico but instead local hunter-gatherers who made occasional trips south of the Rio Grande and returned home with seeds Once agriculture arrived in the region, southwestern Americans adopted it quickly Some historians believe these people had already domesticated some local seed crops such as little barley, amaranth, or chenopod, which prepared them for larger-scale agriculture with corn Scholars agree it was certainly possible that foragers had discovered these local seeds and begun growing them deliberately, but so far no one has found changes in the forms of these local seeds that would indicate domestication The people of the Southwest managed to create farming practices that succeeded in a variety of environments and at different elevations, adapting their agriculture to local landscapes and wild animals Early southwestern farmers lived in circular houses in small settlements They kept their corn in underground storage pits and spent much of their time tending crops and grinding corn, which became an increasingly important portion of their diet as the centuries went by Nevertheless, they continued to gather such wild plants as cactus, mesquite, grasses, pinyon, and agave They hunted mountain sheep, mule deer, and pronghorn antelope Agriculture did not become the primary means of sustenance for southwestern Americans until about the fi rst century c.e One reason this transformation took so long was the problem of irrigation The southwestern United States has little rainfall, and it was a constant challenge to keep crops alive in the