Food Historic Accomplishments History Science

Food Series: Domestication of Yam in 5000 BC, West Africa

All over the world, there are certain foods that not only serve for consumption and commercial purposes but also are part of the culture of a people. Yam is one of such crops in West Africa.

All over the world, there are certain foods that not only serve for consumption and commercial purposes but also are part of the culture of a people. Yam is one of such crops in West Africa.

 

Nigerian Garlic Mashed Yam (source)

Yam is the common name for the starchy vegetable root tubers of the Dioscorea genus family, the tubers are of different shapes and sizes, weigh up to over 130 pounds and can grow up to a length of 5 feet, they have a rough skin that varies in colour ranging from light pink to dark brown. The leaves of mature yams have different colours too like purple, pink, yellow or even white.

A major agricultural crop and a staple food source, it is just not food but has religious, cultural and social significance as well. Its significance varies across all the different regions where it is cultivated. It is most profound in West Africa.

Yams grow in tropical climates with moderate to high rainfall. When it comes to the cultivation of this crop, Africa has no rival, according to Washington International Food Policy Research Institute (IFPRI) West Africa accounts for 96% of the world’s total yam production. Out of which Nigeria contributes a whopping 66%[1], and as of 2017 the figure stood at approximately 48 million tonnes. Ghana comes a distant second at 8 million tonnes followed closely by Cote d’Ivoire with 7 million tonnes[2]. These figures make it obvious the popularity of Yam is highest in West Africa. Asia comes second in world production after Africa. Parts of South America, the Caribbean, and South Pacific islands also produce yams.

It is important to note that the name yam is often erroneously used for some other crop with some resemblance in countries like the USA, Japan, New Zealand, and even Malaysia. The culprit is usually but not restricted to potatoes, perhaps because of its similar physical resemblance even though they have no genetic similarity or maybe because of the many species of yam which number well over 600 that comes in different shapes and sizes. Although not all species of yam are edible.

The White yam (Dioscorea rotundata) and the Yellow yam (Dioscorea cayenensis) accounts for 90% of all the yams produced from West Africa, they are considered indigenous and are of the most significance to the region. An exception, however, is Cote d’Ivoire where the water yam (Dioscorea alata) accounts for a bulk of their total yam production, about 70%.

The White yam was domesticated by African farmers that discovered it growing wild[3]. It is cylindrical with a rough dark brown skin and white inner flesh. This particular variant was favoured over the rest of the wild yam population because of its good taste and superior nutritional benefits, and this drove its domestication. A 100g serving of cooked yam contains; 1.53g of protein, 0.17 g of lipid(fat), 27.88g of carbohydrate, 4.1g of fibre, 0.50g of sugar, 17mg of calcium, 0.54mg of iron, 21mg of magnesium and so many other nutrients.

In Asia however, the purple yam (Dioscorea alata) holds sway and is cultivated in southeast Asia. It is also of cultural significance and is a part of the tradition of the people.

The agricultural cultivation of yam has been practiced in West Africa as early as 5000BC[4]. Its domestication arose in the forest-savannah region of the eastern part of West Africa, particularly the present-day south-eastern Nigeria home of the Igbo people. The Igbo people are reputed to have the most advanced yam culture and sophistication in the world[5].

Although there was also wide-scale domestication and cultivation of this crop all over the Guinea Savannah and humid forest regions of the country which encompass Western, Eastern, Southern and Middle Belt Nigeria inhabited by the Yorubas, Igbos, Efiks, Tivs, and other smaller ethnic minorities respectively.

There is a popular proverb in the Igbo language that states ”önye ume ngwu anaghi ako Ji” which translates to “a lazy person cannot cultivate yam”. Yam cultivation is an exacting process, tedious and labour intensive.

It requires a special method of earthing up the soil to form mounds; this process makes the hoe an indispensable tool and mechanization difficult[6]. Portions of the tubers are planted in the moulds; this is usually at the start of the rainy season. The size of the moulds and provision of stakes or support for the vines are important and is a factor in determining the crop yield. The vines need support, and each plant requires its individual stake for maximum yield. A lengthy and hard task of cultivating yams takes about 7 months of activity that includes clearing the land, tillage, readying and preparing the yam setts and tubers for planting, staking and trailing the yam vines, weeding, harvesting, readying the yam barns and tying the yam tubers to the barn racks[7]. This is not easy and requires a certain amount of vigour, dedication and material resources. Families that accomplish these tasks convey the status of wealth and privilege. The difficulty associated with yam cultivation adds to its value in the region as a social, economic and cultural crop for the strong and serious-minded individuals and a symbol of social status and authority. Chinua Achebe, a world-renowned African novelist, couldn’t have stressed this better in his legendary multi-award-winning novel Things Fall Apart.

The Importance of this crop in West Africa cannot be overemphasized. The White yam for instance when all of its resources are tapped can feed a community for a whole year, and many ethnic groups from the region are aware and have taken full advantage of this[8].

Consuming yam in its raw form is poisonous. It has to be eaten boiled, roasted, fried, pounded or can even be processed to make flakes, and yam chips. In Nigeria and some parts of Benin Republic, a very popular local delicacy known as Amala is produced from dried out pieces of yam that have been ground into powder and added to boiling water to form a thick paste which is then consumed with various local soups and sauces.

For the Igbo ethnic group in south-east Nigeria and indeed all the Yam producing regions in the country, yam is the most popular and favourite food, it plays significant roles in marriage ceremonies, thanksgiving ceremonies, burials, and traditional rituals. As cakes are an essential element to certain celebrations in Europe and America so is yam to the people of this region. These events must include yams in other for it to be complete. Annual yam festivals are held yearly throughout the region. In the rural areas of Ibibio lands, another ethnic group in south-south Nigeria the wealth of a man is determined by the quantity of yam he has stored in his barn. This culture also extends to most yam producing communities in Nigeria.

 

In some cases, coveted titles like “Ëzeji” are awarded to certain individuals with huge quantities of yam. To qualify for such title, you have to own hundreds of tubers of yam in your barn enough to feed the entire community for a few days. With such culture in practice it is therefore no wonder why Nigeria is the world’s largest producer of yam.

In other parts of the world, there are different uses yam serve as well. In China, Korea, and Japan for instance, it is used for traditional medicine and also used to make ice creams and the popular wagashi cakes in Japan. The mucilaginous tuber milk contains allantoin, a cell-proliferate which when applied to abscesses, ulcers, and boils speeds up healing. Yam decoction is also used to stimulate appetite and relieve bronchial cough[9]. In the Philippines, yam is used to make ice cream ingredient and can also be eaten as sweetened desserts like in Indonesia. In Vietnam, it is used to make soups.

Yam production is on a slow but gradual decline in Africa; this is caused mainly by urbanization which brings with it decreasing land availability for cultivation, migration from the rural to the urban cities in search of white-collar jobs; in turn giving rise to a dwindling yam farming population. Pests and diseases also contribute to its decline, as a result, the International Institute for Tropical Agriculture (IITA), is working on promoting healthy seed material and the conservation of important germplasm.

BIBLIOGRAPHY

  • J. Alexander, D.G. Coursey. The domestication of the yams
  • P.J. Ucko, G.W. Dimbleby (Eds.), The domestication and exploitation of plants and animals, Gerald Duckworth and Co, London, United Kingdom (1969), pp. 405-425.
  • G.O. Chukwu, M.C. IkwelleYam: threats to its sustainability in Nigeria
  • CGPRT Centre Newsletter, 17 (2000), pp. 1-14.
  • C.J. Korieh, Yam is king! But cassava is the mother of all crops: farming, culture, and identity in Igbo Agrarian economy
  • Dialect Anthropol, 31 (1-2) (2007), pp. 221-232
  • Journal of Ethnic Foods Volume 4, Issue 1, March 2017, Pages 28-35
  • Biodiversity and Domestication of Yams in West Africa: Traditional Practices Leading to Dioscorea rotundata Poir. By DumontR., DansiA., VernierP. and ZoundjihekponJ. Montpellier and Rome: CIRAD and IPGRI (2006), pp. 95. ISBN 9-782876-146327. – Volume 44 Issue 1
  • https://www.nutrition-and-you.com/yams.html
  • http://www.fao.org/faostat/en/#data/QC

CITATIONS

[1] According to the Food and Agriculture Organization of the United Nations (FAO).

[2] Food and Agricultural Organisation (FAO) of the United Nations Statistics Division

Report (2014) http://www.fao.org/faostat/en/#data/QC, Accessed 30 January 2019

[3] Burke 1939

[4] J. Alexander, D.G. Coursey, 1969.

[5] G.O. Chukwu, M.C. Ikwelle, 2000.

[6] C.J. Korieh, 2007.

[7] Journal of Ethnic Foods Volume 4, Issue 1, March 2017

[8] Dumont., Dansi A, 2006.

[9] https://www.nutrition-and-you.com/yams.html

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