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The oldest records of
domesticated material come from the Middle East dated at 7 - 8000 BC. These include wheats
(Triticum
spp.), barleys (Hordeum
spp.), flax (Linum
usitassimum) and lentil
(Lens orientalis and L. culinaris). In the Americas, common, kidney, navy,
string and wax bean (Phaseolus
vulgaris) might and squashes, pumpkins and some gourds (Cucurbita
spp.) do date back to around the same time. Recently, the earliest date for maize has been
revised to about 4700 years ago from the original radiocarbon date of ~5000 BC. The earliest dates of domestication are also the dates of the start of
agriculture. An invention made independently in different parts of the world, probably by
women, that marked a profound change from hunter-gathering to a more
settled existence. |
| Modern maize from Latin America |
Other early domestications, a few
millenia BC, include rice (Oryza sativa),
sorghum
(Sorghum bicolor), soybean
(Glycine max) and
sugarcane (Saccharum officinarum). Sugar
beet (Beta vulgaris)
was developed in eighteenth century Europe. Rubber
(Hevea spp.) and oil
palm (Elaeis
guineensis) were domesticated at the end of the nineteenth century. All three, the
result of deliberate policy decisions.
More recently, the last three decades have seen the domestication of Ipil-ipil (Leucaena
leucocephela). This crop
can be used as animal fodder, fire-wood, timber, green fertilizer and for soil erosion
control. It has been dubbed the "saviour of the tropics".
Domestication is an ongoing process, reflecting the ever-changing demands of human
societies for new and improved agricultural products.
New domestications have proceeded alongside extinction. The original domesticate is
replaced by another species better able to supply the product or by advances in
technology, e.g. indigo (Indigofera
tinctoria) by aniline dyes. Also, there is the potential of speciation of the
domesticate and extinction of the ancestor.
Table 1 summarises the data on the time of domestication of 127
"major" crops, classified by type and region. N.B. Simmonds' age classes
are not of equal duration. From this table, the rate of domestication has been fairly
constant since the start of the early (E) period.
Every crop originated somewhere. The russian scientist Vavilov (1951) concluded that our
major crops originated/ were domesticated in centres of diversity.
However, these "centres" are known to coincide with early areas of settled
agriculture e.g. the Mediterranean and Mexico. Also, many crops evolved with man in his
migrations. The wild ancestors were obviously grouped together because this was the point
of departure of the migrants.
Thus, there is no necessary geographical connection between the source of wild ancestors,
area of domestication and area of evolutionary diversification. Sometimes, two or more of
these coincide.
The very wide diffusion of domestication through the continents is shown in Table 1.
Until very recently, Australia lacked settled agriculture. But, Australia has recently
domesticated the native Macadamia nut (Macadamia
integrifolia and M. tetraphylla). Orchard plantings of both species were begun
in eastern Australia about 1860.
Also in Australasia, the kiwifruit
(Actinidia chinensis), a native of southeastern China, has been domesticated in New
Zealand. Seed was sent from China sometime early this century and by 1910 some vines were
fruiting in the North Island.
| Barbados can claim the
grapefruit (Citrus paradisi)
- a natural hybrid between C. grandis (Pummelo, Pamplemousse, Shaddock) and C.
sinensis (Sweet or Valencia Orange) that occurred about 1750. Interestingly, C.
sinensis is a hybrid of the pummelo and the mandarin (C. reticulata). Modern
grapefruit cultivars are believed to have come from this single bajan hybrid (Sauer, 1993). |
 |
Until about 200 years ago, crop
evolution was in the hands of farmers and it still is today for many crops in poorer
countries. Probably, the total genetic change achieved by farmers over the millenia was
far greater than that achieved by the last hundred or two years of more systematic
science-based effort.
The current phase of crop evolution is rapidly passing into the hands of professional
plant breeders. This has seen the development of, for example, hybrid maize, F1 cabbage,
and more recently molecular breeding.
At the level of domestication, the same is true: sugar beet, rubber and pyrethrum all owed
their origins as crops to state-supported research workers.
More web pages that
you might wish to consult -
This page last updated February 25, 2005
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1997-2001 by L.E. Chinnery. All rights reserved.
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