The more than six billion humans living on earth at the beginning of the twenty-first century were almost exclusively dependent upon a narrow range of domesticated foods produced on some thirty-eight percent of the world's total land surface. More than three quarters of our annual global harvest is cereal-based, the bulk of which is composed of as few as four species. Although humans and their ancestors have inhabited the earth for several million years, food production is relatively recent, spanning the Holocene epoch or last ten to eleven millennia. The two thousand or more species of plants and animals that humans domesticated during this relatively brief period represent only a tiny fraction of the earth's biota, and with some recent exceptions of minor exotic or luxury foods, most of the important dietary items were domesticated relatively early on.
From the beginning of the Holocene, plants and animals have been selectively bred to provide food and medicine, clothing and companionship, draft and transportation, tools and weapons, and fertilizer. Domestication can increase the efficiency and reliability of food procurement, which can further facilitate an increase in human population size and density. While some hunter-gatherers are highly sedentary and many farmers somewhat mobile, food production often provides the necessary foundation that enables larger populations to live in fixed settlements for longer periods of time.
Domestication is not a discovery but a process by which humans modify plants and animals by selectively encouraging certain characteristics that they want. In time, the domestication process can so genetically alter a population that it is no longer capable of flourishing in the wild. This dependency is usually bidirectional as humans and domesticates become reliant upon each other for survival. The process of domestication can be deliberate or unintentional as humans select for specific qualities of interest. Certain plants and animals are somewhat preadapted to domestication. Seed plants, for example, often thrive as weeds that colonize sunny clearings exposed by human occupation. Over time, subtle and important changes in the original population structure can be encouraged by inadvertently dropping or intentionally planting selected seeds in and around these open areas.
What characteristics do humans select? Domesticated plants mature simultaneously and lack the botanical ability to self disperse, attributes which are controlled by and for human consumers. Rapidly germinating plants that produce seeds with greater initial reserves and thincoats are desired. Self-pollinating plants that readily adapt to the conditions of human settlement are also favored. Preferred animals include: fast growing herbivores that can be economically raised and consumed; docile taxa that can be bred in captivity; and herding species with a natural dominance hierarchy that humans can readily commandeer. Characteristically, many of the earliest domesticated plants were locally exploited and rapidly growing self pollinators that produced high yields of readily storable edible seeds. Early domesticated animals included locally available generalists that were placid, gregarious, and amenable to confinement.
The Geography of Early Domestication
Where and when were certain plants and animals initially domesticated? The Swiss botanist and geographer Alphonse De Candolle (1779-1841) was the first to document the geographical origins of cultivated plants, a subject that was greatly elaborated by the Russian botanist and geneticist Nikolai Vavilov (1887-1943?), who suggested that the area of origin for a domesticate was likely centered in regions where it is presently most diverse. Currently, with the aid of genetics and molecular techniques, archaeologists, biologists, and geographers attempt to delineate the area in which a plant or animal may have been first domesticated by defining the present geographical distribution of its known wild progenitor and studying its subsequent development therein.
The early history of food production is an interdisciplinary undertaking which combines the techniques and methods of archaeology, botany, and zoology. Primary data are often recovered using specialized techniques and methods like flotation devices and pollen corers, and include preserved seeds, pollen, starch grains, phytoliths or mineral impressions of plant cell walls, bones, teeth, horns, and hair. Inferences are also drawn from tools, agricultural infrastructure, cultural implements, artistic portrayals, and written accounts. We can estimate how old our primary evidence is by radiometrically dating associated materials or the preserved organics themselves. Nevertheless, the entire endeavor hinges on the vagaries of sampling, luck of preservation, and intensive fieldwork. As a result, we understand the early origins of food production better in some areas than we do in others.
Much of the earliest evidence for food production comes from sites in arid areas. This may be simply because our primary data preserve better in these settings; however, the bulk of our major contemporary crops appear to have originated in regions with protracted dry seasons. We can identify some relatively circumscribed regions in which a core founder population of local plants and/or animals was originally domesticated. In other areas, the pattern of domestication was likely more diffuse. We can also recognize regions into which all or a few of the founder domesticates were introduced, after which local species were domesticated. Often it is difficult to know precisely whether or not the introduction was through indigenous adoption or direct population invasion from outside. Currently, we can recognize some five to nine early areas of independent food production, from where domesticates, people and their domesticates, and/or the idea of domestication may have spread to other regions.
We find our earliest and so far best evidence in a 2000 km arc of southwest Asia, bounded to the north by higher forested terrain and to the south by desert. This Fertile Crescent stretches from the eastern shores of the Mediterranean north of the Negev desert, around present day Syria and Turkey, and into the plains of the Tigris and Euphrates where it is bordered in the east by the Zagros mountains of present day Iran. Here, climatic amelioration at the end of the Pleistocene created local conditions suitable for large stands of wild grasses with abundant forage for various grazing herbivores. This topographically and floristically diverse region was rich in large-seeded and self-pollinating annuals adapted to seasonal rainfall and protracted dry seasons. It also supported a diverse population of mammals which, apart from the dog (Canis familiaris ), included the world's earliest domesticated animals.
Around 10,000 b.p. (before the present) we find evidence for domesticated barley, first as a two-rowed (Hordeum vulgare ditichum ) and somewhat later as a sixrowed (H. v. hexastichum ) variety, along with emmer (Triticum turgidum dicoccum ) and einkorn (T. monococum ) wheats. Possibly after 9000 b.p., sheep (Ovis aires ) and goat (Capra hircus ) were domesticated in the north and east respectively, with the subsequent additions of domesticated pig (Sus scrofa ) and cattle (Bos taurus ) from present day Turkey. At roughly the same time, the early menu was supplemented with domesticated pulses, especially lentil (Lens culinaris ), pea (Pisum sativum ), chickpea (Cicer arietinum ), and bitter vetch (Vicia ervilia ), along with flax (Linum usitatissimum ) for oil and fiber. The protein rich cereals provide an excellent source of carbohydrates but lack an essential amino acid for the manufacture of animal protein. This is provided by the pulses, which can also fix nitrogen into soils when planted alongside cereal crops. Flax was used for textiles and oil, while animals provided a reliable protein source, and were eventually used for dairying, clothing, traction, and transport. Together, this balanced package formed an important founder population of domesticates that variably spread into other world regions.
Archaeological evidence tracks the rapid diffusion of Neolithic food production to the African and European shores of the Mediterranean by 8000 b.p., and a little later into Italy, Greece, and the Balkans. Farming spread quickly throughout temperate Europe after 7000 b.p., reaching Scandinavia and England by around 5000 b.p. We also see the appearance of southwest Asian food production in the Nile Valley by 6500 b.p., and farther abroad into Ethiopia and the Indus Valley. Western domesticates reach China by 3300 b.p.
In most cases, we don't know whether these patterns represent foreign food producers who migrated into new regions, local populations that adopted farming due to external stimulus, or a mix of both. We do know that many important cultivars were subsequently domesticated. A list of some of the more popular and their possible region of origin includes: faba bean (Vicia faba ), olive (Olea europaea ), grape (Vitis vinifera ), fig (Ficus carica ), and date (Phoenix dactylifera ) in the Near East and Fertile Crescent; bread wheat (Triticum aestivum ), rye (Secale ), hemp (Cannabis sativa ), lettuce (Lactuca sativa ), and horse (Equus caballus ) in western Asia; dromedary camel (Camelus dromdarius ), and coffee (Coffea arabica ) in Arabia; Old World cotton (Gossypium ) in the Indian subcontinent; oat (Avena sativa ), and poppy (Papaver somniferum ) in Europe and the Mediterranean; and, donkey (Equus asinus ) in Egypt.
An early center of cereal based food production is found along the Huang Ho (Yellow) River in northern China. Transitionally located between semi-arid uplands to the west and forested plains to the east, prehistoric farmers cultivated foxtail (Setaria italica ) and broomcorn (Paniscum miliaceum ) millet by at least 7500 b.p. Although the area was likely warmer and wetter at the time, both plants are somewhat drought resistant. Shortly thereafter, diet was supplemented by domesticated chicken (Gallus gallus domesticus ) and pig. Although pigs were possibly present in southern China a thousand years earlier, either claim can support an ancient introduction from western Asia or independent domestication. Some later domesticates from north China include soybean (Glycine max ), hemp (Cannabis ), popular tree fruits like Chinese pear (Pyrus pyrifolia), peach (Prunus persica ), apricot (P. armeniaca ), varieties of apples (Malus domestica ), species of cherry (Prunus spp.), and silk worm (Bombyx mori ), along with many local derelict cultivars that survive today as weeds.
To the south, wet rice agriculture developed by 8000 b.p. along the Chang Jiang (Yangtze) River. Early evidence comes from the middle and lower reaches of this wet and marshy region, where varieties of long-grained (Oryza sativa var. indica ) and short-grained (var. japonica ) rice may have been domesticated at a time when temperatures were warmer than today. Some two thousand years after possible pig domestication in south China, water buffalo (Bubalus bubalus ) is recorded south of the Chang Jiang delta, along with bottle gourd (Lagenaria siceraria ) and cultivated aquatic plants including water caltrop (Trapa spp.) and fox nut (Euryale ferox ). Other no-table domesticates from south China include water chestnut (Eleocharis tuberosa ), Asian arrowroot (Sagittaria sinensis ), red bean (Vigna angularis ), and duck (Anas platyrhynchos ).
Although domesticated rice is found in India and Southeast Asia as early as 5000 b.p., east Asian domesticates dispersed less quickly into Europe and western Asia. Rice was unknown to much of the West before Hellenistic times, and many domesticates were only introduced through merchant voyaging in the past five to six hundred years. It is unknown whether or to what extent the introduction of rice agriculture into Southeast Asia supplanted an indigenous domestication of root and tree crops, which included yam (Dioscorea spp.), bananas and plantains (Musa spp.), citrus (Citrus spp.), mango (Mangifera indica ), breadfruit (Artocarpus spp.), and various spices. Tantalizing evidence hints at the possibility of early agriculture in Papua New Guinea around 9000 b.p. Many plants were domesticated in the Pacific islands, including sugarcane (Saccharum officinarum ), coconut (Cocos nucifera ), taros (Alocasia, Cyrtosperma, Colocasia ), sago (Metroxylon ), kava (Piper methysticum ), and numerous spices. We can trace a relatively early spread of southeast Asian food production into nearby islands, beginning in Taiwan as early as 7000 b.p. and subsequently spreading to Borneo by 4500 b.p. Subsequent colonization into Polynesia between 3500 and 2500 b.p. introduced fowl, dogs, pigs, and various root and tree crops.
Before west Asian farming arrived in the Nile Valley, the Sahara was inhabited by nomadic pastoral groups that herded indigenous domesticated cattle along with sheep or goat introduced from the Mediterranean. The southern boundary of this early "pastoral neolithic" was controlled by tsetse fly infestation in the forests and savannas of sub-Saharan Africa, where nagana disease wasted domestic livestock. Early evidence for indigenous African plant domestication in savanna and Sahel regions south of the Sahara include native grains like sorghum (Sorghum bicolor ) around 4000 b.p. in Niger, pearl millet (Pennisetum glaucum ) after 3000 b.p. in Mauritania, and African rice (Oryza glaberrima ) after 2000 b.p. in Mali. Other important African domesticates with possible savanna origins include cowpea (Vigna ungulata ) and African yams (Dioscorea spp.). Finger millet (Eleusine coracana ) and tef (Eragrostis tef ) were locally domesticated in the highlands of eastern Africa, as were ensete (Musa ensete ), noog oil (Guizotia abyssinica ), and narcotic chat (Catha edulis ).
Forest zones contributed oil palm (Elaeis guineensis ), kola nut (Cola nitada ), and guinea fowl (Numida meleagris ) in the west, and okra (Hibiscus esculentus ) and robusta coffee (Coffea canephora ) in equatorial Africa. The somewhat misnamed Arabian variety (C. arabica ) actually originated in mountain forests of southern Ethiopia and Sudan. Desertic regions contributed cantaloup (Cucumis melo ), watermelon (Citrullus lanatus ) possibly after 3000 b.p. in Mauritania, and perhaps date (Phoenix dactylifera ). The house cat (Felis catus ) may have been domesticated in Egypt, where we also see early evidence for bottle gourd around 5500 b.p. Archaeologists have traced the later diffusion of pastoral groups into southern Africa as they reached the Cape coast by the time of Christ.
Early evidence for a nutritionally balanced founder population of domesticated squash, beans, and maize is found in Mesoamerica. Orange pumpkin squashes (Cucurbita pepo ), that today include acorn and zucchini varieties, appear around 10,000 b.p. in Mexico. Ancient farmers may have selected squash for their seeds rather than pulp, later adding winter (C. moschata ), cushaw (C. argyrosperma ), and fig leaf cultivars (C. ficifolia ). The chayote (Sechium edule ) was more recently added, while ancient evidence for the bottle gourd suggests that it may have rafted across the Atlantic from Africa. The common bean (Phaseolus vulgaris ) was independently domesticated twice, once in Mexico as early as 6000 b.p., and later joined by members of the same genus including tepary (P. acutifolius ), runner bean (P. coccineus ), and botil (P. polyanthus ). Maize (Zea mays ) was likely domesticated from a wild teosinte in southwestern Mexico. Direct dating of maize remains suggests its earliest appearance around 5500 b.p., after which it spread rapidly throughout the hemisphere. The common chile pepper (Capsicum annum ) is also found very early in Mesoamerica. Later domesticates of note include grain amaranths (Amaranthus spp.), tomatillo (Physalis philadelphica ), tree crops like cacao (Theobroma cacao ) and sapote (Pouteria sapota ), hairy cotton (Gossypium hirsutum ), various species of Agave for hennequen and sisal fiber, as well as fermented drink, and a domesticated bird, the turkey (Meleagris gallopavo ).
Maize appears in the American Southwest by 3500 b.p., but becomes a major staple with squash and beans much later. By 2000 b.p. maize eventually enters the southeast, where independently domesticated squash (Cucurbita pepo ), sunflower (Helianthus annuas ), marsh elder (Iva annua macrocarpa ), and goosefoot (Chenopodium berlandieri ) were all already under cultivation, possibly by 4500 b.p. Some 2000 years later, erect knotweed (Polygonum erectum ), maygrass (Phalaris caroliniana ), and little barley (Hordeum pusillum ) assume greater dietary significance, but only after roughly 1000 b.p. does maizecentered agriculture dominate eastern North America.
An early complex of domesticates that may have developed by 5000 b.p. in highland areas from south-central Peru to Bolivia, eventually dispersed throughout the ancient Andean world by the time conquering Spaniards arrived. Included were quinoa (Chenopodium quinoa ), kaniwa (C. pallidicaule ), and kiwicha (Amaranthus caudatus ), all high altitude pseudocereals that provide flour for baking, soups, and beverages. Indigenous tuber crops like oca (Oxalis tuberosa ), mashua (Tropaeolum tuberosum ), ullucu (Ullucus tuberosus ), and potato (Solanum tuberosum ) are also adapted to the cold conditions of high elevation.
The only native New World mammalian domesticates, llama (Lama glama ), alpaca (L. pacos ), and cuy or guinea pig (Cavia aparea porcellus ) round out the highland package. Direct dating of archaeological specimens indicates that domesticated South American common (Phaseolus vulgaris ) and lima (P. lunatus ) beans were added somewhat later, possibly at slightly lower elevations in the southern highlands. Other Andean domesticates included roots like maca (Lepidium meyenii ), and arracacha (Arracacia xanthorrhiza ), and tree crops as pepino (Solanum muricatun ) and tree tomato (Cyphomandra betacea ).
Phytolith evidence could suggest the appearance of maize around 7000 b.p. in northern neotropical lowlands; however, others argue a more recent introduction around 4000 b.p. in accordance with Mesoamerican data. Early lowland contexts also reveal domesticated jack beans (Canavalia plagiosperma ), cotton (Gossypium barbadense ), and the root crops achira (Canna edulis ), leren (Calathea allouia ), and arrowroot (Maranta arundinacea ). Phytolith evidence also supports early use of bottle gourd and squash; indigenous domesticated squash include the hubbard (Cucurbita maxima ) originally from Argentina, and possibly the relict C. ecuadorensis of southwestern Ecuador. Many domesticates come from areas of the lowland neotropics, including: manioc (Manihot esculenta ), cocoyam (Xanthosoma spp.), yam (Dioscorea trifida ), sweet potato (Ipomeoea batata ), peanuts (Arachis hypogaea ), capsicum peppers (Capsicum spp.), various drug and medicinal plants, tree and palm crops like cashew (Anacardium occidentale ), avocado (Persea americana ), guava (Psidium guajava ), and peach palm (Bactris gasipaes ), and the muscovy duck (Cairina moschata ).
Ancient agriculturalists customarily attributed their origins to an act of divine intervention. As scientists began to seek alternative explanations for the beginnings of food production, they persisted in the teleological assumption that domestication was initially a discovery. Cultural innovation took place especially in areas where resources were concentrated, either naturally or as unintended consequence of human behavior. It is, however, reasonable to assume that humans everywhere possessed, from earliest times, a sophisticated understanding of the plants and animals that surrounded them. This is easily confirmed in the detailed knowledge of hunter-gatherers who, moreover, actually spend less time procuring food than their agricultural brethren. Bioarchaeological study of skeletal assemblages also indicates that early agriculturalists may have suffered poorer health than hunter-gatherers. So, why bother to produce food? Causation came to be viewed as a response to stress or disequilibrium; humans began to produce food in order to keep up with unceasing population growth and/or as an adaptation to their changing environment. Some view the adoption of food production as the product of rational economic decisions in which optimizing foragers weighed costs against benefit. Others seek social origins for early agricultural, suggesting that early cultigens were originally prestige items used in specific, highly politicized contexts.
Whatever the ultimate cause, it appears that food production antedated the appearance of sedentary village life. It likely took place in settings where populations were neither internally nor externally threatened, and evolved out of a lengthy mutualistic association between plants, animals, and humans. The distinction between domesticator and domesticated is simply a matter of perspective, as food and food producers eventually launched a trajectory that would irreversibly change the way we live.
See also Agriculture, Origins of ; American Indians: Prehistoric Indians and Historical Overview ; Food Archaeology .
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Peter W. Stahl