The beginning of agriculture

1Archaeological, archaeobotanical, and epigraphical evidence suggests that early forms of food production in southern Arabia developed during the middle Holocene within each of several foraging systems, viz pastoral, maritime, and tropical, based upon the principal Saharo-Arabian biological resources.1 In fact, seasonal camp sites along the shores and coastal backwaters of southern Arabia were a constant feature since early Holocene times.2 Human occupation at ash-Shumah, located about 120 km south of Hudeidah, is radiocarbon dated to the 7^th millennium BC.3 By the late 4^th millennium BC, increasingly selective foraging strategies had driven Arabian hunters and fishermen to the domestication of camel and date palm. Whereas the palm trees combined with water works to create the artificial microclimatic conditions for intensive oasis farming, camel transport intensified collection of scarce desert plant resources.4 The camel was perhaps domesticated around the piedmont ecotone of Oman or Yemen in the contexts of proto-farming techno-complexes.5

2African sorghum and local edible wild plant species, along with marine resources and domesticated animals, formed the foundation for early agricultural developments across southern Arabia at least as early as the late 4^th millennium BC.6 Carbonized seeds and imprints of sorghum, wheat and barley together with the fruit stones of Ziziphus and date palm (Phoenix dactylifera) were identified at Hili 8, a site in the interior oasis of al-^cAin (late 4th millennium BC to late 3^rd millennium BC). Predominantly farming economies in highland Yemen appeared during the 3rd millennium BC in areas like Khawlân al-Tiyâl and Hadâ, in the great hydrological basin of the Wâdî Dhanah southeast of San^câ’.7 The paleobotanical study of plant impressions in potsherds from these Bronze Age sites reveals that already by the second half of the 3^rd millennium BC the central highlands supported agricultural communities exploiting fertile terrain near seasonal water courses. About 5167 potsherds from 15 sites provided 120 well-preserved and identifiable imprints. The numbers of potsherds, identifiable impressions, and identified plant species varied from site to site, with the best samples coming from al-Masannah, al-Raqlah and Wâdî Yanâ^cim.8 These three sites, and others in the area, occupied an ecosystem that was becoming progressively more arid, thus making it difficult to exploit land higher up and a long way from water.9 At al-Raqlah (radiocarbon dated to 406090 BP, 376080 BP), the well-preserved imprints belonged to emmer wheat (Triticum cf. dicoccum), wheat (Triticum sp.), cf. Sorghum sp., Cenchrus racemosus (a forage plant), and Phoenix sp.; numerous grinding stones and mullers accompanied these crops. The pottery imprints found in the Wâdî Yanâ^cim site (dated to 370080 BP) showed the contemporary presence of five principal grain crops, barley (Hordeum vulgare), Triticum sp., Sorghum sp., millet (Panicum miliaceum) and oats (Avena sp.), along with cumin (Cuminum cyminum). The pottery imprints at al-Masannah (dated 397080 BP and 389080 BP) belonged to glume wheat (Triticum monococcum/dicoccum), free-threshing wheat (Triticum aestivum/durum) and six-rowed hulled barley (Hordeum vulgare) along with other Gramineae. The pottery imprints of the site of Sarm al-^cAbâdilah belonged to two-rowed barley (Hordeum distichum). The site of al-Jabâhirah and al-Ma^claq produced imprints of Hordeum vulgare and oats (Avena sp.).

3Panicum miliaceum, Cenchrus sp., and Phoenix sp. are indigenous to Yemen, while the rest of these crops have African (Sorghum sp.) or West Asian (wheat, barley, oats, cumin) origins. In the central highlands, as at Hili 8, farmers cultivated crops in summer and winter seasons, resulting in high agricultural production. It seems probable that Yemeni farmers gathered for food the seeds of local Panicum miliaceum, the natural distribution of which includes southern Arabia, but that the farmers domesticated this species at a later date. Thus, they perhaps started agricultural innovation using this millet along with the wild/cultivated date palm. Farmers began to grow sorghum when they learnt that its productivity was higher than that of the local Panicum miliaceum. It goes to the credit of the Yemeni farmers that in the late 3^rd millennium BC they began to cultivate two crops in year, viz sorghum in summer season and wheat and barley in the winter season.

Crop dispersal

4The geographic continuity of settlements along the southern Arabian coast, although the sites sometimes were simply small shell-middens, is a direct evidence for that conveyer-belt function between East African and northwest Indian shores that made possible the effective diffusion of plant resources, at least since the middle Holocene. Cultivated plant species of West Asian, African and Indian origins were introduced into southern Arabia, although it is not possible to pin-point exactly the date(s) of introduction during the proto-historic period for each species. Introduced and local cultivars/wild edible plant species formed the basis of early agricultural development in southern Arabia.

5Yemen historically and geographically extended far beyond its current national boundaries. In ancient times, it was the center of the Minaean, Sabaean, Himyarite, Qatabanian and Hadhrami states that had trade relations with African and Asian countries during pre-Islamic times, and also with Mediterranean countries from the 6^th century BC to the 2^nd century AD. Such trade relations also promoted the exchange of plant genetic resources. After 622 AD people passing through Yemen on the way to Mecca gradually introduced new crop plants. Europeans passing through Aden also introduced to Yemen several plant species of the New World origins. As a result the crops currently grown in Yemen have diverse origins:

Eco-geographic diversity

6The Republic of Yemen, covering around 537 000 sq. km., lies at the southwestern corner of the Arabian Peninsula, approximately between longitudes 43ºE and 56ºE, with Perim Island in the west and Socotra Island in the extreme east. Yemen physically comprises the dislocated southern edge of the great Arabian plateau. The whole Yemen plateau has undergone down-warping in the east and elevation in the west, so that the highest elevations (over 3 000 m) occur in the extreme west, with the gradual decline in the lower parts (under 300 m) in the extreme east. The whole of the southern and western coasts of Yemen were formed by a series of enormous fractures that produced a very flat but narrow coastal plain, rising steeply to the hill country a short distance inland. Wâdî Hadramawt runs parallel to the coast at 160 km. to 240 km. inland. In its upper and middle portions the valley is broad, and alluvial soil and intermittent flood water are available to support farming.

7Six eco-geographic regions may be distinguished in North Yemen,10 each forming a north-south belt (Tihâma, Tihâma foothills, lower escarpment, higher escarpment, highlands and high mountains, and eastern semi-desert and desert), while five main agro-ecological zones may be identified in South Yemen (the coastal strip, the Wâdî Hadramawt, the mid-altitude zone, the high altitude zone, and the mountains of Mahra and highlands of Dhofar).11 In both North and South Yemen these zones vary with respect to several agro-climatic factors (climate, altitude, rainfall, irrigation facilities, soil type), and also their land use and cropping patterns. While some crops are grown in several regions, others are cultivated only in a specific region.12 Crops are cultivated once a year (sowing dates may vary) at most areas, but a few crops are sown in more than one season in some areas.

Crop evolution under domestication

8Since the beginning of agriculture in Yemen, farmers have selected, rejected, adapted and conserved different races of crop species suited diverse agro-climatic conditions. We can get some ideas about the past and present variability of different crop species by comparing the varieties of cereals and other crops mentioned in the Bughyat al-fallâhîn, al-Ishârah fî al-^cimârah, Milh al-milâhah, written by Rasulid monarchs of the 13^th and 14^th centuries AD, and in Sifat Jazîrat al-^cArab of al-Hamdânî.13 These accounts mention different kinds of wheat (six varieties), barley (two varieties) and sorghum (12 varieties), but not of other crops (pearl millet, rice, finger millet, teff, sesame, cowpea, pea, cucumber, melon, pumpkin, etc.) cultivated in mediaeval Yemen. Thus it seems that only limited numbers of varieties of different crops were cultivated in mediaeval Yemen. Based on several plant germplasm collection trips undertaken in Yemen, the number of crop varieties currently grown in Yemen are significantly high: 15 varieties of wheat (eight of durum, one of emmer, six of bread wheat), ten varieties of barley, 75 varieties of sorghum, ten varieties of pearl millet, nine varieties of maize, seven varieties of coffee, 11 varieties of vine, and less than five each of several other crops. Several kinds of wheat (three varieties) and sorghum (15 varieties) mentioned in mediaeval texts could not be collected.

Evolution of sorghum under domestication

9Sorghums have played an important role in the food security of rural Yemeni peoples. By trial and error farmers selected desirable traits (i.e. combinations of prefered economic attributes, multiple uses and culinary habits) adapted to specific environments and farming systems. One study of sorghum diversity in North Yemen14 showed that the many varietals belong to races durra, durra-bicolor, durra-guinea, durra-caudatum and daudatum, while few belong to the bicolor and kafir varietals. Caudatum and its derivatives seem more adaptable to high altitude areas, whereas the bicolor and guinea derivatives involving durra are more adapted to low altitude areas. Multi-cut/multi-purpose (grain, fodder, fuel and thatching) types mostly belong to bicolor, guinea and their derivatives, while most of the caudatum types are amenable to varying degree of defoliation. Durra derivatives have wide adaptability. Yellow endosperm varieties mostly belong to the caudatum and durra types (and one to bicolor also). This unique Yemeni germplasm needs to be protected under Intellectual Property Rights regimes. Local varietals exhibit high adaptability to local environments, and are generally preferred in the culinary preparations. Sometimes mixtures of two or more varietals with different water requirements are grown together in a risk-reduction strategy that increases the likelihood of some grain production occurring even in dry years. Farmers have also selected several pest resistant types, some of which are also highly productive in grain and/or fodder yield.

Summary and conclusions

10Initial agriculture in Yemen was based on the local plants Panicum miliaceum and date palm. Bronze Age farmers in the highlands started cultivating sorghum, wheat and barley as additional crops by the second half of the third millennium BC, and oats and cumin were taken into cultivation before the end of the third millennium BC. Farmers practiced cultivation in both summer and winter seasons, resulting in high agricultural productivity. Before the turn of the Christian era, several species of cultivated plants of West Asian, African and Indian origins were sown in a prosperous farming system. The pre-Islamic Minaean, Sabaean, Himyarite, Qatabanian and Hadrami states promoted plant exchanges, expecially through the maritime trade routes along the Arabian shores, the so-called “Sabaean Lane.” With the coming of Islam, peoples from many countries of the Old World further promoted the introduction of diverse germplasm of several crops during the annual pilgrimage to Mecca. With the discovery of the New World and the discovery of the sea route to India via the Cape of Good Hope, Europeans visited Yemen and introduced several plant species of the New World origins. Traditional farmers acclimatized, domesticated and selected cultivars of several crops suited to diverse climatic conditions of Yemen. Thus, varietals of sorghum, pearl millet and wheat developed under natural and human selection pressures.

11Although more varietals of several crops are available at present as compared to those of the mediaeval period, the genetic base of all crops is much poorer. Thus, systematic efforts are needed not only to introduce and evaluate elite germplasm of all economic plant species, but also crop improvement programs should be intensified to develop high yielding varieties/hybrids to increase agricultural production. At present improved varieties of several species of economic plants are being imported for cultivation, resulting in high expenditure of foreign exchange. Local plant improvement programs need to be intensified to make Yemen self-sufficient in seed stocks. Traditional cultivars of wheat, barley and sorghum are threatened by genetic erosion, while finger millet and teff are no longer grown on the mainland. The genetic erosion is increasing due to the introduction and spread of improved cultivars of bread wheat, crop substitution, changing farming systems, and availability of subsidized imported wheat and other crops. By restricting the import of vegetables and fruits, and by promoting the cultivation of adapted genotypes of several crops, the country is progressively becoming self-sufficient. Rain-fed agriculture based on traditional crops has sustained agriculture. This healthy situation needs to be maintained, by using traditional and modern agricultural technologies.

12Several Yemeni land races of sorghum, pearl millet, coffee, grapes and other fruit trees (root-stocks and scion sticks) have desirable attributes. National legislation should be enacted to protect the sovereign rights of the Yemeni nation over its genetic resources in the era of Intellectual Property Rights regimes. Several international missions have collected Yemeni plant genetic resources for the past few years. Efforts should be made to get back the germplasm from abroad. The traditional knowledge basis (agronomic practices, crop adaptability for specific agro-climatic conditions, land use pattern, and multiple uses of specific varietals of different crops) need to be documented, in order to formulate appropriate strategies for sustainable agricultural production and for seeking Intellectual Property Rights over genetic resources in the era of the liberalized global economy under the World Trade Organization.