xxx Prehistoric Eras to 600 C.E 5000 b.c.e and later became the staple food for much of Asia By 3000 b.c.e the Chinese had invented the plow, and by 400 b.c.e., iron-clad farming implements The agricultural revolution occurred along the Indus River valley before 5000 b.c.e., where farmers cultivated wheat, barley, peas, and other crops Farming became common across Europe by 3500 b.c.e., but for centuries afterward, farmers worked a piece of land until the soil wore out, then simply moved on to virgin fields Such practice is roughly the same as the “slash and burn” farming of seminomadic communities in Africa, Asia, and the Americas, still in use to the present day A remedy for soil depletion was crop rotation: One plant replenished what another plant took from the soil the previous season This method was practiced first in Europe around 1400 b.c.e In the Western Hemisphere the agricultural revolution began first in Mexico, perhaps around 5000 b.c.e The “three sisters” of diet in this part of the world—maize, beans, and squash—provided a balanced diet and source of nutrition for the indigenous people, and they required little labor to produce Beasts of Burden The first beasts of burden to be domesticated were the donkey, the buffalo, and the camel, all by 3000 b.c.e The llama was used in the Andes Mountains in South America Animal husbandry lagged behind in the Americas because horses died out early in this part of the world and were only reintroduced by Europeans after 1500 c.e Over the centuries people as far separated as the Celts and Chinese adopted the horse to great advantage However, at first the horses were mainly used to pull war chariots; later for cavalry, and not commonly for agricultural labor Human diet throughout the world largely consisted of cereal grains, beans, vegetable oils, fresh vegetables and fruits, dairy products, occasional fresh meat, and fermented beverages made from either fruit or grains Consumption of cereals came in many forms, but in Europe, the Near East, and the Americas mainly through coarse bread White bread, made of fine wheat flour without the germ, was most highly prized throughout the Roman Empire and beyond In 350 b.c.e a new strain of wheat suitable for such bread was cultivated in Egypt, and Egypt and North Africa thereafter became a granary for the Mediterranean peoples Fruits and vegetables were consumed locally Trade and migrations introduced new plants across Eurasia and Africa and resulted in great improvements in food production Sub-Saharan Africa produced food surpluses with the introduction of the banana by the Malay peoples (of present-day Indonesia) Because of this fortuitous event, in the fourth century b.c.e the city-states of Nigeria were able to flourish Another revolutionary product, sugarcane, was cultivated in India and the East Indies from 100 b.c.e., but its dissemination to Europe waited for the discovery of a process of refinement Instead, honey and concentrated fruit were used for sweetening throughout much of the ancient world The New World offered a variety of plants not available in the Old World, most important maize, but also cacao, papaya, guava, avocado, pineapple, chilies, and sassafras Several of the more common foods today originally come from the Americas: peanuts, potatoes, and tomatoes The relationship between abundant food and community development was readily apparent in this hemisphere: Where farming flourished (Mesoamerica and South America), city-states and civilizations abounded; but where farming lagged (North America), population centers were few and less organized The “discovery” of the Americas by Western explorers had an enormous impact on diet and nutritional resources throughout the world SCIENTIFIC AND TECHNOLOGICAL DEVELOPMENTS Many ancient cultures were fascinated with the movement of the heavenly bodies because people thought that they exerted influence on earthly events The ancients carefully observed astral rhythms and computed how the seasons fit this schedule Sumer, one of the earliest Mesopotamian cities, left behind the first calendar (354 days) by 2700 b.c.e China had developed a calendar system very similar to the modern one by 1400 b.c.e In Central America the Maya developed an amazingly accurate calendar that could predict eclipses and planetary conjunctions that mirrored the modern way of calculating years, based on a commonly