Agriculture
Definition and Overview
Introduction :-
Agriculture is the most comprehensive word used to denote the many ways in which crop plants
and domestic animals sustain the global human population by providing food and other
products. The English word agriculture derives from the Latin ager (field) and colo (cultivate)
signifying, when combined, the Latin agricultura: field or land tillage. But the word has come
to subsume a very wide spectrum of activities that are integral to agriculture and have their
own descriptive terms, such as cultivation, domestication, horticulture, arboriculture, and
vegeculture, as well as forms of livestock management such as mixed crop-livestock farming,
pastoralism, and transhumance. Also agriculture is frequently qualified by words such as
incipient, proto, shifting, extensive, and intensive, the precise meaning of which is not selfevident. Many different attributes are used too to define particular forms of agriculture, such
as soil type, frequency of cultivation, and principal crops or animals. The term agriculture is
occasionally restricted to crop cultivation excluding the raising of domestic animals, although
it usually implies both activities. The Oxford English Dictionary (1971) defines agriculture
very broadly as “The science and art of cultivating the soil, including the allied pursuits of
gathering in the crops and rearing live stock (sic); tillage, husbandry, farming (in the widest
sense).” In this entry, we too use the term in its broadest, inclusive sense.
In the published literature on early agriculture, there is a tendency for the word agriculture and
many of its subsidiary terms to be used vaguely without precise definition, and sometimes their
connotations overlap, for example, proto/incipient and shifting/extensive. There is need to
clarify much agricultural terminology to avoid confusion (Harris 2007: 17-26), particularly
because the multidisciplinary nature of research on the subject leads to many concepts being
used that derive from disparate disciplines; principally archaeology, anthropology,
biogeography, genetics, linguistics, and taxonomy. In this entry, we cannot review
comprehensively all the typological terms currently used in discussions of the origins and early
development of agriculture. Instead we focus on the two most fundamental processes that led
to agriculture, cultivation and domestication (of plants and animals), and then comment on
some of the terms used to denote particular categories of agricultural production. In conclusion,
we return to agriculture itself as a process of landscape-scale food production.
This approach, leading from consideration of cultivation through domestication to agriculture
(Fig. 1), proposes that agriculture is a form of land use and economy that resulted from the
combination of cultivation (a bundle of human actions focused on preparing soil and planting,
tending, and harvesting plants) and domestication (a bundle of genetic and morphological
changes that have increased the ability of plants to adapt to cultivation). Cultivation and
domestication are related as cause and effect, a change in human strategy with consequences
in genetic adaptations of another organism, which increased the interdependencies of both. In
the next two sections, we explore the nature of and interaction between cultivation and
domestication over time in light of mainly archaeological evidence together with some genetic
data, including exploration of the concept of “pre-domestication cultivation.”
- Agriculture:
Definition and Overview, Fig. 1
An evolutionary model from foraging to agriculture, in which the transitions to cultivation,
domestication, and agriculture are separated and potential archaeological indicators are
suggested (Modified from Harris 1989 and Fuller 2007)
- Cultivation:-
Cultivation is an activity through which humans become directly involved in the management
of the lives and life cycles of certain plants. In abstract terms, this can be considered a change
from a largely extractive approach to subsistence (collecting) towards a highly regulative one
(Ellen 1994), with seasonal scheduling of labor for delayed returns and storable product. In
practice, cultivation involves manipulation of soil, water, and other components of the plant
environment. At its most basic, it involves sowing of seeds on soil which has been cleared of
other vegetation. In low-intensity systems, this may come about through burning of vegetation
(slash and burn) or by taking advantage of fresh deposits of silt by river floods
(e.g., décrue agriculture; Harlan & Pasquereau 1969). It usually involves preparation of the soil
by tillage. Tillage methods and tools vary from simple handheld devices (digging sticks,
spades, hoes) to team-employed tools, such as the Andean “foot-plough,” to animal-powered
ards and true ploughs (Steensburg 1986). Other important variables include the addition of
nutrients to the soil by such means as manuring, multiple cropping with nitrogen-fixing species
(usually legumes of the family Fabaceae), or using crop rotations with legumes or fallow
periods. This represents an important component of cultivation, i.e., scheduling the seasons of
sowing and harvesting and interannual patterns in crop rotation and fallowing.
Water is a key input into any cultivation system, and in some regions it had a central role in the
origins of agriculture. For example, control of water levels was essential in the development of
early rice cultivation in China (Fuller & Qin 2009). Successful cultivation of the perennial
ancestor of japonica rice involved extending shallow and wetland-margin habitats by clearing
competing vegetation, as use of these slightly less-watered microenvironments would have
increased grain production. The earliest preserved field systems for rice cultivation consist of
small (1–2 m diameter) fields interconnected to each other and to frequent deep water pits that
served to drain water from the growing rice.
Cultivation represents an important change in human strategy as people start to manipulate the
soil and the composition of plant communities to enhance yields of particular plants later. This
has led many researchers to infer that morphological domestication came about through
unconscious selection. In other words, people did not set out to domesticate plants but to
manipulate productivity through cultivation. The new environment created by cultivation can
cause unintended domestication, as the cultivated species adapts to these new circumstances.
In recent years, archaeobotanical research has aimed to identify the practices of cultivation
prior to the emergence of domesticated species. Such evidence for pre-domestication
cultivation can be inferred from the presence of arable weed assemblages, which may be
demonstrated by the statistical composition of wild-seed assemblages or by the modern
ecological characteristics of species that recur archaeologically but have little or no known
human uses (Willcox 2012). As is well known from later agricultural periods, archaeobotanical
assemblages are made up predominately of crops and weeds, together with some gathered fruits
and nuts, and this pattern begins to emerge by the earliest Pre-Pottery Neolithic in Southwest
Asia and in the middle Neolithic in parts of China (Fuller & Qin 2010). This approach draws
on the well-developed tradition in European archaeobotany of using weed-seed assemblages to
infer the cultivation ecology of fields (Jones 1988).
- Domestication:-
Domestication is most clearly defined as a biological phenomenon, that is, by traits in crops
that result from adaptation to cultivation and by which they differ from close wild relatives.
Several recurrent “domestication syndromes” can be recognized as sets of characters that
define domesticated crops and characterize domestication as a form of convergent evolution
under cultivation (Fuller 2007). The domestication syndrome differs for different kinds of crop
plants, according primarily to how they are reproduced, by seed or by cuttings, and what plant
organ is the target of selection (grain, fruit, tuber).
The best defined domestication syndrome is that for grain crops, including cereals, pulses, and
oilseeds. While all of these traits are the product of cycles of harvesting and sowing from such
harvests, the actual selection pressures seem to come from two different aspects of cultivation.
First are some traits selected for by harvesting and the crops’ growing reliance on humans for
seed dispersal. Second are traits that relate to soil conditions, as tilled fields are essentially
early successional communities on empty soil, which is generally loose and allows deeper
burial of seeds. Although there are six essential syndrome traits in seed crops, only the first
four have some chance of archaeobotanical preservation in some species.
First (1) is the elimination of natural seed dispersal, such as through non-shattering rachis in
cereals and non-dehiscent pod in pulses and oilseeds. This is often regarded as the single most
important domestication trait as it makes a species dependent upon the farmer for survival. It
also means that human labor must be used to thresh crops and separate seeds, pods, or spikelets
instead of natural dispersal occurring at maturity (Fuller et al. 2010). This trait can only evolve
under conditions of harvesting, such as uprooting, use of sickles, or harvesting when crops are
mature rather than green. This trait is readily identifiable in cereal rachis or spikelet-base
remains, and has been studied in rice, wheats, barley, pearl millet, and maize, but is less evident
in the preserved remains of many other crops. However, not all harvesting methods necessarily
select for this, which means there are conceivable systems of “non-domestication cultivation”
(Hillman & Davies 1990), or there may be weak selection leading to very protracted evolution
of this trait within populations (Fuller 2007; Allaby 2010). It is worth noting that any individual
plant, or archaeological specimen, either has wild-type or domesticated-type dispersal, but
domestication is working on populations, and therefore domestication status should be
determined for assemblages as representative of past populations. Recent archaeobotanical
evidence tends to suggest relatively weak selection for this trait (Fuller et al. 2010).
A second connected trait (2) is reduction in aids to wild seed dispersal. Plants often have a
range of structures that aid seed dispersal, including hairs, barbs, awns, and even the general
shape of the spikelet in grasses. Thus domesticated wheat spikelets are less hairy, have shorter
or no awns, and are plump, whereas in the wild they are heavily haired, barbed, and
aerodynamic in shape. Varieties of wild rice are always awned and heavily barbed, while many
cultivars are awnless and those with awns have fewer barbs. Rather than being positively
selected by harvesting, this comes about by removal of natural selection for wild-type dispersal
adaptations, and therefore under domestication, such traits require less metabolic expenditure.
This trait may sometimes be visible in archaeobotanical material but is rare and non-diagnostic
and does not provide a definitive means of identifying domestication archaeologically. Because
this trait shifts gradually and non-diagnostically, it can be regarded as indicating
“semidomestication.”
Two additional traits of the domestication syndrome may be widespread, but they are not
recoverable archaeologically: (3) synchronous tillering and ripening, sometimes including a
shift from perennial to annual. Planting at one time and harvesting at one time will favor plants
that grow in synchronization. Another trait (4) is a more compact growth habit with apical
dominance, such as a reduction in side branching and denser spikes or seed heads. In some
species, such as in several pulses, this involved a shift from a climbing habit to self-standing.
Harvesting methods, like those that select for non-shattering types, can also favor plants with
single and compact parts to be harvested.
Two more important traits are thought to relate primarily to an aspect of soil conditions, i.e.,
planting seeds into more deeply tilled soils. These are traits that relate to rapid germination and
early growth. On the one hand (5) is the loss of germination inhibition. In the wild, many seeds
will only germinate after certain conditions have passed – conditions of day length and
temperature – or after the seed coat is physically damaged. In wild legumes, for example, this
may mean that 90 % of seeds will fail to germinate. By contrast, crops tend to germinate as
soon as they are wet and planted. This is simply selected by planting as those seeds that do not
germinate will fail to contribute to the next harvest and subsequent crops planted from it. This
is regarded as a key domestication trait, especially in pulses and pseudo-cereals
(e.g., Chenopodium spp.) This change is often signalled by changes in the seed, such as thinner
and less ornamented seed coats. On the other hand it is a trait, widely studied in archaeobotany,
that can be regarded as a “semidomestication” trait. Trait 6 is increasing seed/fruit size. This is
likely to be selected for by open environments and deep burial in disturbed soils. This has the
added advantage of increased seed weight which tends to increase harvest yields from a given
number of crop plants. Comparative studies, for example, between related species, show that
larger seeds germinate more quickly and effectively than smaller seeds, and thus this should be
selected for by tillage and cultivation generally. As seeds readily preserve, archaeological
populations of them can be measured to track changes in average sizes and size ranges, to trace
this trait over time. In the case of cereals, selection seems to be focused on seed
thickness/breadth rather than length (Fuller et al. 2010).
While for seed crops, predominance of the above traits marks domestication, the end of a
process of biological evolution, the determination of domestication sequences is much more
difficult in vegetatively cultivated plants such as roots and tubers (Hildebrand 2003, and see
the section below on Vegeculture). Because harvest of tubers focuses on a starchy storage
organ rather than a reproductive organ, harvesting practices by humans are unlikely to pose
strong selective pressures on the next generation. In addition, because tuber plants tend to be
perennials, the harvested individual will tend to grow back, reducing the potential to select for
improvements across generations. In many cases, cultivation practices may induce the useful
part of the plant – the starchy organ – to exhibit phenotypic alteration without changes in its
genotypic makeup, such as the improved tuber size produced by yams in loosened, prepared
soil as opposed to harder unprepared soils (Chikwendu & Okezie 1989). Thus tuber crops can
be cultivated for long periods and on an extensive field scale without undergoing
morphological domestication. In addition, archaeologically recovered tuber fragments
(parenchyma) tend to preserve few morphological attributes relevant to phenotypic or
genotypic change. There is some research which suggests that micro-remains such as starch
grains have increased in size with tuber domestication (Piperno 2012). As a result of these
factors, the study of early vegecultural systems tends to focus on establishing the presence of
potential crop species and inferring practices of landscape modification and management, such
as soil mounding, ditch digging, and vegetation burning (see, e.g., Denham 2007).
- Specialized Types of Livestock Management and Crop Production
In this section, we examine briefly several distinctive types of agriculture that developed over
time into specialized systems focused on the production of food and often also secondary
products such as hides, hair, wool, building materials, and many other useful items.
Mixed Crop-Livestock Farming
- Mixed Crop-Livestock Farming
One of the most significant variables in the historical differentiation of agricultural systems is
whether domestic livestock were fully integrated with the processes of crop cultivation as
beasts of burden and agents of soil fertilization as well as producers of food. Such systems of
“mixed farming” or “agropastoralism” developed early in only a few regions. They did so most
comprehensively in Southwest Asia (and later in Europe) where domesticated herd animals –
cattle, sheep, goats, and pigs – were raised in close conjunction with wheat, barley, and other
cereal and pulse crops as producers of meat, milk, hides, hair, wool, and dung and as traction
animals used for ploughing, load-bearing, and other purposes (Harris 2002). A comparable
system of mixed farming evolved in East and Southeast Asia where water buffaloes became an
integral component of the system of wet-rice (padi) cultivation (Hoffpauir 2000), although this
may have been millennia after rice had spread throughout China and much of Southeast Asia
(Fuller et al. 2011).
In other regions of early agriculture where domestic herd animals were present, they were not
fully integrated with crop cultivation as providers of food, fertilizer, and traction. Thus, in
northern tropical Africa, cattle, camels, sheep, and goats, and in the Andean region of South
America camelids (llama and alpaca), were not fully incorporated into indigenous systems of
cereal, pulse, and root-crop cultivation.
- Pastoralism :-
The full incorporation of domestic herd animals into systems of mixed farming requires
permanent facilities such as barns, sheds, stalls, fenced fields, and other enclosures for
confining the animals and controlling their movements. This contrasts with pastoral systems
that are characterized by more mobile methods of management. The term pastoralism derives
from the Latin pastor, meaning a herdsman or shepherd, and it applies to mobile systems in
which the herd animals, principally sheep, goats, cattle, horses, donkeys, camels, llamas,
alpacas, and reindeer, are raised to provide food and other products and as pack and riding
animals. The essence of pastoralism is that people move with their animals. The spatial and
temporal scales of their movements range from short daily movements of flocks and herds to
and from pastures near their owners’ settlements (diurnal grazing) to longer seasonal
movements by part of the local community with their animals to higher and/or more distant
pastures (transhumance), to the most fully mobile system in which families migrate from
pasture to pasture with their herds throughout the year and from year to year (nomadic
pastoralism). Nomadic pastoralists own and largely depend on their animals, although they
have historically obtained some of their food and other supplies by trading with or raiding
settled agricultural communities. In fact, all nomadic pastoralists depend to some degree on
crop products for their food and often also for supplementary fodder for their animals.
Few if any fully nomadic pastoral groups still exist in the modern world, but in the historical
and prehistoric past, this way of life was followed extensively in the deserts of northern and
eastern Africa and southwestern and central Asia. The pastoralists’ herds consisted mainly of
sheep and goats, with the roles of horses and camels varying from region to region, and in the
high latitudes of Eurasia a variant form of reindeer pastoralism became established
(Ingold 1980).
- Horticulture:-
Horticulture has two contrasted connotations in the literature on traditional agricultural systems
and the origins of agriculture. The first relates directly to the origin of the word from the
Latin hortus, meaning garden (juxtaposed to ager, field), and in this literal sense it refers to the
cultivation of plots of land adjacent or quite close to the houses of the cultivators. Such gardens
are normally smaller than fields, which are usually located farther from their associated
settlements. A greater variety of plants, especially perennial shrubs and trees, tend to be
cultivated in gardens than in fields, which are commonly devoted to one or only a few types of
crop. Also, whereas most fields are cultivated in seasonal cycles, gardens are usually tended
continuously, especially in the tropics where long growing periods favor year-round
production. Another distinctive feature of house gardens is the presence in them of many
adventitious wild and weedy plants. They add to the floristic and structural diversity of the
plant community and enhance its ability to provide a great variety of edible, medicinal, and
other products such as flowers, fibers, dyes, containers, and construction materials (see, e.g.,
Coomes & Ban 2004).
The contrasts in size and floristic diversity between gardens and fields are widely recognized
in the literature on early agriculture, for example, in the terms “fixed-plot horticulture” and
shifting or “swidden” cultivation and the German gartenbau and ackerbau. Small,
continuously tended plots close to dwellings have been proposed as probable arenas of early
plant domestication (Harris 1973: 398-401), but very little archaeobotanical research on past
garden cultivation has as yet been undertaken.
Secondly, the terms horticulture and gardening have been used to denote agricultural systems
that combine field cultivation of annual root and/or seed crops with growing mainly perennial
tree, shrub, and herbaceous plants in gardens – a mixed cropping system that, when trees are a
major component, is sometimes alternatively described as agroforestry. This connotation of
horticulture has been used particularly in descriptions of traditional, and by implication early,
systems of cultivation in Melanesia and the Pacific Islands, but this usage tends to obscure the
useful distinction between field and garden cultivation.
- Arboriculture :-
The term arboriculture, from arbor the Latin for tree, is used to specify agricultural systems
focused exclusively or largely on the cultivation of trees and shrubs for the production of fruits
and seeds and, in some species, also for ancillary products such as wood for construction and
leaves for thatch, fiber, etc. The term, which is sometimes equated with agroforestry (see
above), refers mainly to the specialized cultivation of fruit- and nut-bearing trees and shrubs in
single- or mixed-species orchards and plantations. It can refer also to plantations of trees for
timber production, although this process is more usually described as forestry.
Arboriculture differs from horticulture in that the plants are grown in less floristically diverse
communities on larger landholdings. Traditional systems of arboriculture include oil-palm
plantations in tropical West Africa and olive, almond, and walnut orchards in the circumMediterranean region. Arboriculture has attracted much less attention in the literature on the
beginnings and early development of agriculture than the cultivation of cereal, pulse, and root
crops, and fruit- and nut-bearing trees are likely to have been a much more important source of
food among many hunter-gatherer groups than among early farmers (Harris 2012: 37-9). It
tends to be difficult to differentiate specialized arboriculture from more floristically mixed
traditional systems of horticulture, and it is seldom possible to do so on the basis of
archaeobotanical data alone (see, e.g., Gosden 1995 and Latinis 2000). At present, most of
what can be inferred about arboriculture in premodern times comes from historical and
ethnoecological evidence.
- Vegeculture:-
The word vegeculture is used to describe agricultural systems that produce mainly root and
tuber crops with underground storage organs consisting of starch-rich roots, root and stem
tubers, corms, and rhizomes. The crops are reproduced asexually by planting pieces of a parent
plant such as parts of tubers, stem cuttings, or sprouts, rather than being grown from seed.
Vegetative reproduction made possible the domestication of tuberous plants by replicating the
characteristics of parent clones and then selecting and multiplying useful phenotypic variations
that arose in planted stock, such as unusually large or smooth-skinned tubers. The process did
not involve directional genotypic change from wild progenitor to domesticate as occurred in
seed-crop domestication. Root and tuber domestication has taken place within the limits of
phenotypic variation determined by an unaltered genotype, but morphological changes under
domestication have nevertheless been substantial, for example, decreased flowering and in
tubers changes towards greater size and starch content and reduction in bitterness and in the
numbers and length of thorns.
Although root and tuber and seed crops are often cultivated together, vegeculture is the
traditional mode of agricultural production in many parts of the humid and seasonally dry
tropics. Until recently, little macrobotanical evidence of vegeculture had been found because
the soft tissues of root and tuber crops are seldom preserved (except in very dry or waterlogged
archaeological contexts), but advances in microbotanical techniques for identifying remains of
tuberous plants in the form of phytoliths (silicified particles of plant tissues), parenchyma
(vegetative storage plant tissues), and starch grains preserved in sedimentary deposits are now
beginning to illuminate the prehistory of vegeculture in several regions of the tropics
(Hather 1994; Fullager et al. 2006; Piperno 2012).
- Agriculture as Landscapes of Food Production :-
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