red-billed queleaMale (right) and female red-billed queleas (Quelea quelea).� Johan Swanepoel/Shutterstock.comAnimal life of particular interest to humans includes four main groups that are not mutually exclusive. They are: (1) species potentially or actually useful to humans as food (large ungulates), (2) dangerous or pest species that may have to be controlled or eliminated (locusts, tsetse flies, Quelea finches�which do immense damage to grain crops�and some ungulates or carnivores), (3) species that provide a spectacle and bring economic benefit (elephants, the larger plain ungulates, primates, or carnivores), and (4) endangered, rare, or unique species.

Much of the study of African wildlife has been addressed to the first two groups described above. For example, after it was learned that the feeding habits of domesticated livestock and wild ungulates are complementary, it became possible to incorporate the ungulates into pastoral and mixed-farming systems. This has happened on limited scales with the oryx (which was domesticated by the ancient Egyptians), the springbok (which has been run with cattle for decades in Southern Africa), and the African buffalo and eland. Similarly, much attention has been given to controlling pests. In the 1950s and �60s considerable progress was made in the control of mosquitoes and locust swarms, although these achievements have been partially lost by governmental instability and mismanagement and by warfare between states. Infestation by the tsetse fly remains as one of tropical Africa�s most critical problems, not only because the tsetse spreads disease but also because�by effectively restricting livestock farming�it denies relief of the chronic protein shortage of many African peoples. Control of the tsetse is possible, but it is complex and requires a coordinated effort within and between countries.

Much research has also been carried out on animals in the third and fourth groups. Studies of predators, such as the lion, for example, have shown that they do not generally control the numbers of ungulates to the same degree as do disease or starvation. It has also been established that the hyena is as much a potent predator as a scavenger. Intensive studies have been made of such primates as baboons, Ethiopian geladas (to which baboons are related), and especially chimpanzees and gorillas; of great interest has been learning what associations there are between human and other primate behaviour and psychology. Conservation

Many countries have now set aside large tracts as national parks, game reserves, or forest reserves. Of these parks, only some are large enough to be self-contained ecosystems, and most have been set aside to accommodate large mammals. In East Africa there are also sanctuaries for birds and marine organisms. The conservation of vegetation is undertaken mainly in forest reserves but also in national parks. In addition, a number of countries are attempting to conserve wildlife by refusing export licenses for certain kinds of skins, especially those of the leopard, cheetah, and zebra.

Conservation efforts in Southern Africa have been aided by the creation of transfrontier parks and conservation areas, which link nature reserves and parks in neighbouring countries to create large international conservation areas that protect biodiversity and allow a wider range of movement for migratory animal populations. One such park is the Great Limpopo Transfrontier Park (GLTP), where representative populations of most savanna species are maintained. The GLTP links one of Africa�s oldest and best-known national parks, Kruger National Park, with Mozambique�s Limpopo National Park and Zimbabwe�s Gonarezhou National Park. Another is Kgalagadi Transfrontier Park, which links South Africa�s Kalahari Gemsbok National Park with Botswana�s Gemsbok National Park; it conserves a tract of arid country with such associated types of antelope as springbok and gemsbok; smaller reserves and parks conserve particular species. Only one large mammal species, the blaubok (or blaauwbok), has become extinct, though several subspecies have nearly disappeared; one such subspecies�the quagga, a race of zebra�has vanished.

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East and central African countries have large national parks, which have been expanded in size or have increased in number as a result of the economic benefits of tourism. Kenya�s parks include Tsavo, one of the largest, with an area of more than 8,000 square miles, Lake Nakuru National Park for flamingos, several montane parks, and a marine park. Uganda has several national parks. Tanzania has the famous Serengeti National Park, with its unrivaled populations of plains ungulates, and the parks of Ngorongoro, Lake Manyara, Arusha, and others. Other countries with notable national parks and game reserves are Botswana, Malawi, Namibia, Zambia, and Zimbabwe. All parks in these countries preserve representative woodland, thornbush, grassland, and succulent-desert habitats and species.

Elsewhere the situation is less satisfactory. In the Democratic Republic of the Congo, national parks were all seriously depleted after independence. Congo now has several major national parks, including the Virunga National Park (3,100 square miles), but in the late 20th century many suffered from deforestation and poaching, as well as general human encroachment, due to conflicts and warfare in the region. Ethiopia has several parks developed largely during the 1970s, while Somalia has only a rudimentary system consisting mostly of game reserves and one area (Luc Badana) nominally a national park but failing to meet UN criteria for such parks. The �W� park is shared between Burkina Faso, Niger, and Benin, but most western African countries have only small national parks if any at all.

Animals not protected in parks are not necessarily threatened. Many large species are still plentiful in forest or game reserves or in controlled-hunting areas. Well-managed forest reserves in particular provide secure habitats for many smaller unprotected forms. Animals affecting land usage

Historically, the abundance of elephants and other large ungulates may have stimulated some individuals�notably western African hunters in the forests and Europeans in Southern Africa�to occupy certain areas. Trade routes were established and early hunter-explorers were influenced by the availability of elephants, whose ivory tusks slaves could carry.

Large and small animals now affect humans by competing with them or with their livestock. They may prey on people or on livestock or carry diseases affecting either. The bilharzia snail and the Simulium fly (host to an organism causing blindness), the tsetse fly, and the mosquito collectively affect human beings and their livestock far more than do such individually large or formidable species as lions or elephants.

The larger ungulates may compete with domestic livestock for forage, but they are more keenly resented and hunted by those agriculturists whose crops they eat. Pastoralists are much more concerned about lions that occasionally kill cattle than they are about locusts or rats, which, by depleting forage, indirectly cause the death of much livestock; such perceptions may hinder eradication or better control of these pests.

Danger to humans from large animals�carnivorous or otherwise�has been greatly exaggerated, but disease carried by living organisms has remained a serious problem. Diseases have reduced crop productivity, spoiled harvests, and acted as a curb on the better integration of land use and on the extension of pastoralism and mixed farming into underused areas. David N. McMaster People

Africa is now widely recognized as the birthplace of the Hominidae, the taxonomic family to which modern humans belong. Archaeological evidence indicates that the continent has been inhabited by humans and their forebears for some 4,000,000 years or more. Anatomically modern humans are believed to have appeared as early as 200,000 years ago in the eastern region of sub-Saharan Africa. Somewhat later those early humans spread into northern Africa and the Middle East and, ultimately, to the rest of the world.

Kenya: traditional clothingWomen in traditional clothing, Kenya, East Africa.� Goodshoot/Thinkstock

Africa is the most tropical of all the continents; some four-fifths of its territory rests between the Tropics of Cancer and Capricorn. As a consequence, the cultures and the physical variations of the peoples reflect adaptation to both hot, dry climates and hot, wet climates. Dark skin is the dominant characteristic of indigenous African peoples, but skin colour is not uniform. Skin colour shows a clinal variation from a light or tan colour in the northern fringe of the continent, which has a Mediterranean climate, to very dark skin in certain Sudanic regions in western and East Africa, where radiation from the Sun has been most intense. Africa has the most physically varied populations in the world, from the tallest peoples to the shortest; body form and facial and other morphological features also vary widely. It is the continent with the greatest human genetic variation, reflecting its evolutionary role as the source of all human DNA.

Throughout human history there have been movements of peoples (see human migration) within, into, and out of Africa along its northern coasts, across the Sinai Peninsula, along the Red Sea, and especially in the Horn of Africa and coastal areas as far south as Southern Africa. North Africa from the Strait of Gibraltar to the Nile River delta has been the site of conquests and movements of peoples for thousands of years. Along the east coast, trading cities arose and fell, cities that had overseas contacts during the past two millennia with peoples of southern Arabia and as far east as India and Indonesia. Internal movements during that time contributed to the heterogeneity and complexity of native African societies. The greatest movement of peoples out of the continent was a result of the Atlantic slave trade that lasted from the 16th to the 19th century and involved the transport of an estimated 10,000,000 people to the New World. Such a loss of people, together with the devastating warfare and raiding associated with it, was the major cause of the subsequent weakness and decline of African societies.

Whereas the majority of Africa�s peoples are indigenous, European colonial settlers constitute the largest majority of new peoples, with substantial numbers in Kenya, South Africa, Zimbabwe, Zambia, Namibia, and Mozambique. Dutch settlers first arrived in South Africa in 1652; their descendants now constitute the main Afrikaner, or Boer, population. The vast majority of European settlers arrived after the 1885 Berlin West Africa Conference and the resulting �scramble for Africa,� during which European leaders carved out spheres of influence. Attendant, but unassociated, with the scramble, French and Italian settlers also established new communities in North Africa and, to some extent, western Africa. Much earlier, in several waves of migrations beginning in the 7th century, Arabs spread across northern Africa and, to a lesser extent, into western Africa, bringing a new religion (Islam) and a new language (Arabic), along with some new cultural and political institutions. They also spread Islam southward along the east coast, largely through trading and kinship relationships. (More detail is given in the regional history articles North Africa, Central Africa, Southern Africa, Western Africa, and Eastern Africa.) The colonial era began to disintegrate in the 1950s. Culture areas

Although the precise number is unknown, there are several thousand different societies or ethnic groups in Africa. They are identified by their recognition of a common culture, language, religion, and history. But in some areas the boundaries among ethnic groups and communities (villages, towns, farm areas) may not always be clear to the outsider. Most Africans speak more than one language, and frequent migrations and interactions, including intermarriage, with other peoples have often blurred ethnic distinctions. There are an estimated 900 to 1,500 different languages, but many distinct political units share a common or similar language (as among the Yoruba, Hausa, and Swahili-speaking peoples). Complicating the situation in the 20th century was the creation of new �tribes� (such as the Zande [Azande] and Luo) that had not been distinct polities before the colonial era. Ethnic (cultural) identities in modern times have often been heightened, exacerbated, or muted for political reasons.

In their attempts to comprehend such a huge heterogeneous continent, scholars have often tried to divide it into culture areas that represent important geographical and ecological circumstances. Those areas reflect differences in the cultural adaptation of traditional societies to varying natural habitats. For the purposes of this discussion, the principal regions are northern, western, west-central, eastern, and Central and Southern Africa; Madagascar is also included. Audrey Smedley Northern Africa

Africa north of the Sahara is differentiated from the rest of the continent by its Mediterranean climate and by its long history of political and cultural contacts with peoples outside of Africa. It is physically separated from the rest of the continent by the Atlas Mountains and is inhabited primarily by peoples who speak languages that belong to the Afro-Asiatic group. Those peoples include, for example, the Imazighen (Berbers) of Morocco, Algeria, and Tunisia. The Berbers are most numerous in Morocco and least in Tunisia, where, as a result of culture contact and intermarriage, they have become largely assimilated with Arabs, who speak a Semitic language. The Arabs migrated into North Africa from Arabia in a number of waves; the first of those waves occurred in the 7th century ce. The distinctive nature of Maghrebian, or western Arab, culture resulted from that admixture. In the Sahara such Arab peoples as the Shuwa live side by side with such Berber peoples as the Tuareg. See also Islamic world.

Tuareg man; camelA Tuareg man and a camel in the Sahara, Algeria, North Africa.� Claire.B/FotoliaWestern Africa

Western Africa contains a remarkable diversity of ethnic groups. It can be divided into two zones, the Sudanic savanna and the Guinea Coast. The savanna area stretches for some 3,000 miles (4,800 km) east to west along the southern Saharan borderland. Its vegetation consists of extensive grasslands and few forests, and little rain falls there. The savanna supports pastoralism and horticultural economies dependent on grain. In contrast, the Guinea Coast experiences heavy rainfall and is characterized by hardwood tropical forests and dense foliage. It produces primarily root crops (various yams).

Malinke villageMalinke village near Tambacounda, Senegal.N. Cirani/DeA Picture Library

Among the more important of the savanna peoples are the three main clusters known as Mande in Senegal and Mali and including the Bambara, Malinke, and Soninke; the Gur-speaking group in the savanna zone to the east that includes the Senufo, Lobi, Dogon, and Moore; and in northern Nigeria, Niger, and Cameroon the many small, mainly non-Muslim tribes of the plateau and highland areas. Throughout the region live the many groups of the Fulani, a cattle-keeping Muslim people who either have conquered indigenous peoples (such as the numerous Hausa) or live in a symbiotic relationship with agricultural peoples. In the Sahara fringe are the many Berber-speaking groups (collectively known as the Tuareg), the Kanuri of Lake Chad, and the Bedouin Arab peoples. Many of the kingdoms are successor states to those of Ghana and Mali.

The larger societies in the coastal zone are also mostly kingdoms. In Nigeria are the Igbo and Ibibio, organized into many autonomous polities; the Tiv; the Edo; and the several powerful kingdoms of the Yoruba. Westward are the Fon of Benin; the various peoples of the Akan confederacy, mostly in Ghana, the largest group being the Asante; the Ewe, Ga, Fante, and Anyi of the coast; the Mende and Temne of Sierra Leone; the Kru of Liberia; the Wolof, Serer, Dyula, and others of Senegal; and the Creoles of Sierra Leone and Liberia, descendants of freed slaves from the New World or of those who were on their way there. West-central Africa

West-central Africa may be considered as an eastern extension of western Africa: in the north are the savannas of Chad, the Central African Republic, Sudan, and South Sudan, stretching to the Nile River, and in the south is the largely forested area of the Congo River basin. The Congo area, in the centre of the continent, is an extension of the wet forestlands of the Guinea Coast; it extends to the lacustrine area of eastern Africa. That region is the largest area of secondary tropical forest in the world; only South America has more primary (i.e., undisturbed by humans) tropical forests. The vast majority of peoples speak related languages of the Bantu family. The Luba, Lunda, Fang, Mongo, Kuba, Songe, and Chokwe are among the larger ethnic groups of west-central Africa. The Bambuti (Pygmy) peoples live in the eastern forests, and smaller groups of Pygmy peoples live in the western forests of Gabon.

Ituri Forest: Efe campEfe camp in the Ituri Forest, Democratic Republic of the Congo. The Efe are one of the Bambuti (Pygmy) peoples of west-central Africa.Robert C. BaileyEastern Africa

Eastern Africa can also be divided into several regions. The northern mountainous area, known as the Horn of Africa, comprises Djibouti, Ethiopia, Eritrea, and Somalia. In the east is the arid Somali desert. The coastal area extends from Kenya to Southern Africa, where numerous trading cities arose beginning in the 10th century. The East African Rift System intersects eastern Africa, running from north to south. The region, particularly the areas of the East African lakes�Victoria, Albert, Tanganyika, and Nyasa (Malawi)�contains some of the most fertile land in Africa, and during the colonial period it attracted settlers from Europe and Asia. Vast areas of savanna support pastoralists and peoples with mixed economies.

Maasai menMaasai men in traditional attire, Kenya, East Africa.� Herby ( Herbert ) Me/Fotolia

Ethnically complex, eastern Africa includes the Eastern Sudanic-speaking pastoralists of the Nile valley (e.g., Shilluk, Dinka, Luo, and Lango), those of the central plains (Maasai, Nandi, and others), and the Somali and Oromo of the Horn of Africa, who speak Cushitic languages. In Ethiopia also are the Amhara, Tigre, and others who speak Semitic languages. Most of the remaining peoples of the region are Bantu speakers who, although they vary widely in other ways, are all subsistence farmers. Near the East African lakes are several formerly powerful Bantu kingdoms (Ganda, Nyoro, Rwanda, Rundi, and others). In the highlands of Kenya are the Kikuyu, Luhya, and others. On the coast are the various Swahili-speaking tribes, while in Tanzania are the Bantu-speaking Chaga (Chagga), Nyamwezi, Sukuma, and many more. There are also remnants of other groups: the hunting Okiek (Dorobo), Hadza, and some Pygmies. And on the coast are the remnants of the once politically powerful Arabs, formerly based on the island of Zanzibar. Central and Southern Africa

Central and Southern Africa may be considered as a single large culture area. Most of it consists of open and dry savanna grasslands: the northwest contains the edges of the Congo forests; the southwest is very arid; and the coastline of South Africa and Mozambique is fertile, most of it with a subtropical or Mediterranean climate.

Botswana: SanTwo San men in Botswana demonstrating the traditional method of starting a fire.Ian Sewell

The region was once populated by Khoisan-speaking peoples. The San are today restricted to the arid areas of southwestern Africa and Botswana, and most of the Khoekhoe are found in the Cape region of South Africa. The other indigenous groups are all Bantu-speaking peoples, originally from the area of Cameroon, who dispersed across the region some 2,000 years ago. The vanguard, known linguistically as the Southern Bantu, drove the Khoekhoe and San before them and adopted some of the typically Khoisan click sounds into their own languages. Over the past several hundred years, Bantu-speaking people who had mixed economies with large numbers of cattle began massive movements, mostly northward. A major cause of that displacement of peoples (which together with a series of related wars is known as the Mfecane) was the search for new grazing lands. A number of conquests resulted in the establishment of the states of the Zulu, Swazi, Tswana, Ndebele, Sotho, and others. Madagascar

The island of Madagascar forms a distinct culture area. The various Malagasy ethnic groups, of which the politically most important is the Merina, are mainly of Indonesian origin, following migrations across the Indian Ocean probably during the 5th and 6th centuries ce. The Malagasy language, spoken by virtually all of the island�s population, is classified as Austronesian. John F.M. Middleton John Innes Clarke Audrey Smedley Cultural patternsLanguages

The knowledge of most of the individual languages of Africa is still very incomplete, but there are known to be in excess of 1,500 distinct languages. Many attempts to classify them have been inadequate because of the great complexity of the languages and because of a confusion relating language, �race,� and economy; for example, there was once a spurious view of pastoralism as related to cultures whose members spoke �Hamitic� languages and were descendants of ancient Egyptians. One of the more recent attempts to classify all the African languages, prepared by the American linguist Joseph Greenberg, is based on the principles of linguistic analysis used for Indo-European languages rather than on geographic, ethnic, or other nonlinguistic criteria. The four main language families, or phyla, of the continent are now considered to be Niger-Congo, Nilo-Saharan, Afro-Asiatic, and Khoisan.

Africa: languages and peoplesMajor languages and peoples of Africa.Encyclop�dia Britannica, Inc.

Niger-Congo is the most widespread family and consists of nine branches: Kordofanian, Mande, Ijoid, Atlantic, Benue-Congo, Kru, Kwa, Gur, and Adamawa-Ubangi. Those languages cover most of Central and Southern Africa; they are found from Senegal to the Cape of Good Hope, with a geographically widespread extension due to relatively recent migrations. Kordofanian includes subgroups all spoken within a small area of southern Sudan. The most original point in that classification is the group called Benue-Congo, which linguistically subsumes all the Bantu languages found dispersed over most of eastern, Central, and Southern Africa. That dispersal is attributable to the rapid expansion of people from the area of the Bight of Benin from the beginning of the 2nd millennium ce onward: the vanguard, the Southern Bantoid speakers, had not reached the Cape of Good Hope when the Dutch arrived there in the 17th century. The close linguistic similarity among the Bantu languages points to the speed of that vast migration. Swahili, grammatically Bantu but with much Arabic in its vocabulary, is widely used as a lingua franca in eastern Africa; as the language of the people of Zanzibar and the east coast, it was spread by 19th-century Arab slavers in the hinterland as far as what is now the Democratic Republic of the Congo. Fula, an Atlantic language of the Niger-Congo family, also is used as a lingua franca in West Africa.

The Nilo-Saharan family classification is perhaps the most controversial�because of inadequate research�and the family is the most scattered. It comprises languages spoken along the savanna zone south of the Sahara from the middle Niger River to the Nile, with outlying groups among the pastoralists of eastern Africa. Its subgroups are Songhai, Saharan, Maban, Fur, Eastern Sudanic, Central Sudanic, Kunama, Berta, Komuz, and Kadu.

The Afro-Asiatic family includes languages from both Africa and the Middle East: Semitic (including Arabic, Amharic, and Tigrinya), Egyptian (extinct), Amazigh (Berber), Cushitic, Chadic (e.g., Hausa), and Omotic. It is found over much of northern Africa and eastward to the Horn of Africa. Arabic is both an official and an unofficial language in states north of the Sahara, as well as in Sudan. In many other countries it is the language of Islam. Amharic is one of the two principal languages of Ethiopia. Hausa also is spoken widely as a lingua franca along the northern fringe of sub-Saharan western Africa, a wide area that encompasses many ethnic and political boundaries.

The Khoisan family comprises the languages of the aboriginal peoples of Southern Africa, who now are limited largely to the arid parts of southwestern Africa, and perhaps of the outlying Hadza and Sandawe peoples of northern Tanzania.

The Austronesian language family is represented by the various languages of Malagasy in Madagascar.

There are many widespread trade languages and lingua francas in addition to those mentioned above. Some, including English and French, were imported and used by administrators, missionaries, and traders during the colonial period. Some of those languages have become the national languages of independent nation-states, and, with the spread of formal education, they are gaining greater acceptance. Between the Sahara and the Zambezi River, either English or French is widely understood. French is an official language in the states that formerly made up French West Africa and French Equatorial Africa, as well as in Madagascar (Malagasy is also an official language) and the Democratic Republic of the Congo. Similarly, English is the official language or is widely spoken in the states of western, central, and eastern Africa formerly under British administration and is also the official language in Liberia. Portuguese is used officially and otherwise in the countries formerly under Portugal. In South Africa, English and Afrikaans (which developed from 17th-century Dutch by way of the descendants of European [Dutch, German, and French] colonists, indigenous Khoisan-speaking peoples, and African and Asian slaves) are among the many official languages. Hindi, Gujarati, Urdu, and other languages of the Indian subcontinent are spoken in the Asian communities. In western Africa, forms of creole (Krio) and pidgin are widespread in the coast towns of very heterogeneous ethnic composition. In Southern Africa, Fanagalo, a mixture of English and local Bantu tongue (notably Zulu), is still spoken in some mining areas.

The great majority of African languages have no indigenous forms of writing. Several of them, however, were transcribed in the 20th century by missionary linguists, native speakers, and others. Many African languages (such as Swahili) have for centuries been written in Arabic script. The best-known exceptions to the Arabic writing system are those of the Vai of Liberia and Sierra Leone, the Mum of Cameroon, and the Tuareg and other Berber groups of the southern Sahara, all of whom invented their own scripts. Religions

In general, the peoples of northern Africa adhere predominantly to Islam and those in Southern Africa largely to Christianity, although their distributions are not discrete. For example, the Coptic church is found in Egypt and Ethiopia, and Islam is common along the coast of eastern Africa and is expanding southward in western Africa. Many of the Sudanic peoples�such as the Malinke, Hausa, Songhai, and Bornu�are Islamized, and the religion has also achieved substantial gains among such Guinea Coast people as the Yoruba of Nigeria and the Temne of Sierra Leone. Much conversion to Christianity also has occurred, most notably to Roman Catholicism and in the coastal regions of sub-Saharan Africa.

Dejenn�, Mali: mosqueMosque at Dejenn�, Mali, designated a UNESCO World Heritage site in 1988.� jean claude braun/Fotolia

In most of the rest of sub-Saharan Africa the people practice a variety of traditional religions, which have certain common features. All of those known include the notion of a high or creator God, remote from humans and beyond their comprehension or control. That God typically is not attributed a gender but in some cases is male or female; often God is given an immanent and visible aspect as well. The most important �spiritual� powers are usually associated with things or beings with which people have day-to-day contact or that they know from the past. Thus, there may be many kinds and levels of spirits of the air, of the earth, of rivers, and so on. There may be ancestors and ghosts of the dead who have achieved a partial divinity, or there may be mythical heroes who led the people to their present land and founded their society as it is known today.

Yoruba in Nigeria performing a dance in honour of the god Shango.Frank Speed

The ritual functionaries found in most African societies include priests, lineage and clan elders, rainmakers, diviners, prophets, and others. Very few of those people are specialists; typically they hold ritual authority by virtue of age, genealogy, or political office and are primarily responsible for the ritual well-being only of the members of the social groupings that they head; their congregations consist of their joint families, lineages, clans, local village communities, chieftaincies, or the like. Their ritual authority is thus a sanction for their secular and domestic authority.

A central element of every indigenous African religion is its cosmology�which tells of tribal origins and early migrations and explains the basic ideological problems of any culture, such as the origin of death, the nature of society, the relationship of men and women and of living and dead, and so on. Social values are typically expressed in myths, legends, folktales, and riddles; the overt meanings of those various oral statements frequently conceal sociological and historical meanings not easily apparent to outsiders.

In the past, witchcraft and sorcery were given widespread credence and served to explain or control the misfortunes of people who were aware of their lack of mastery and understanding of nature and society. Travelers� tales of African people living in fear of witchcraft, however, were, of course, grossly exaggerated; the colonial powers usually assumed (incorrectly) that witch doctors were socially harmful and prohibited them. Although belief in witchcraft is receding, it is still important in both rural and urban areas, often serving as a means of explaining the misfortunes that beset urban dwellers and labour migrants who find themselves in new and confusing social milieus. There have been many cases in modern times of �epidemics� of beliefs in witches, and there have arisen a number of evanescent religions led by various kinds of prophets and evangelists. Such manias arise in periods of radical change and their resultant uncertainty and stress.

Social and religious changes in Africa have often been accompanied by the appearance of prophets who advocate the expulsion of the Europeans or the eradication of epidemic diseases threatening the traditional ways of life. More recently, also, the spread of Christianity and, to a lesser extent, Islam has given rise to Christian prophets and to leaders of separatist movements repudiating European-controlled mission churches for nationalistic, tribalistic, or racial reasons. Such prophets lead their own groups and establish their own churches, typically gaining new political power sanctioned by their presumed direct links with God. The new churches have been reported in almost all parts of the continent. Domestic groupings

The forms of the family found in Africa are consistent with the forms of economic production. Throughout most of the rural areas the typical domestic group is the joint or extended family consisting of several generations of kin and their spouses, the whole being under the authority of the senior male. The size of the group varies, but it typically consists of three to five generations of kin. It provides a stable and long-lasting domestic unit able to work as a single cooperative group, to defend itself against others, and to care for all of its members throughout their lifetimes. Polygyny is traditionally widespread as an ideal, its extent depending on the status and wealth of the husband: chiefs and rulers need many wives to give them a mark of high position and to enable them to offer hospitality to their subjects.

In most of Africa those residential groups are based on descent groups known as clans and lineages, the latter being segments of the former. The significance given to descent groups varies, but they are important in providing for heirs, successors, and marital partners.

In the second half of the 20th century that pattern began to change�rapidly in the urban and poverty-stricken areas, more slowly in those areas less affected by economic and political development. In cities and in major labour-supplying areas, such as most of Southern Africa, the joint or extended family gave way to the independent nuclear family of husband, wife, and children. There is also a tendency toward the breakdown of family structure because of labour migration�the younger men moving to the cities, leaving women, older men, and children in the impoverished homelands. John F.M. Middleton John Innes Clarke The Editors of Encyclopaedia Britannica Demographic patterns

Africa has the most rapidly expanding population of any region in the world, even though the continent�s birth and death rates are also the world�s highest. There was some decline in overall death rates in the latter half of the 20th century, but infant and child mortality rates remained high, and average life expectancy at birth actually declined somewhat during the 1990s. On average, Africa�s population is increasing at about 3 percent per annum, and that growth rate is associated with an increasingly youthful population: in nearly every African country more than two-fifths of the population is younger than 15 years of age.

The great majority of the working population is still engaged in subsistence agriculture and in the production of cash crops. In most countries the proportion of the total population dependent on agriculture is at least three-fifths.

The remainder of the working population is divided mainly between a rapidly growing service sector (including civil servants, members of the armed forces, police, teachers, health workers, and those engaged in commerce and communications) and an increasing number of mining and industrial projects; in only a few countries, however, do those latter activities employ more than one-tenth of the workforce. Underemployment, particularly in the agricultural sector, is widespread, and unemployment has risen, especially in urban areas.

Participation in labour by women varies considerably from country to country. There are generally fewer women in paid employment than men, though a large proportion of women in sub-Saharan countries are engaged in subsistence agriculture�if only part of the time. Women are also employed in the civil service, trading (especially in western Africa), domestic service, and to an increasing extent in light industry. Population distribution

Africa has more than one-eighth of the total population of the world, distributed over a land area representing slightly more than one-fifth of the land surface. Such desert areas as the Sahara, Kalahari, and Namib, however, have reduced the amount of habitable land, and such factors as climate, vegetation, and disease have tended to limit the evolution of densely populated areas where agriculture is practiced. With the advent of the colonial era, the African continent was divided into small geographically and politically based units that took little or no account of ethnic distribution. Those political boundaries persisted, and the continent continued to be characterized by a large number of countries with predominantly small populations.

Population density of Africa.Encyclop�dia Britannica, Inc.

Wide variations in density occur from country to country in Africa and within countries. In general, the most densely populated areas are found bordering the lakes, in the river basins (especially those of the Nile and Niger), along the coastal belts of western and North Africa, and in certain highland areas, while settlement is the most sparse in the desert and savanna areas. Thus, Rwanda and Burundi, situated in the East African highlands, are the most densely populated countries in Africa, while Western Sahara, Mauritania, and Libya in the Sahara and Botswana and Namibia in the Kalahari and Namib are the least densely populated. Settlement patterns

Traditional African patterns of settlement vary with differences in landscape and ecology, communications, and warfare. The most widespread pattern has been that of scattered villages and hamlets�the homesteads of joint and extended families�large enough for defense and domestic cooperation but rarely permanent because of the requirements of shifting cultivation and the use of short-lived building materials. Large mud-adobe villages are traditional in much of the western African savanna, but over most of Africa housing consists of mud and wattle with roofs of thatch or palm leaves.

Mauritania: hutMud-and-thatch hut, Mauritania, West Africa.� Kirsz Marcin/Shutterstock.com

Large towns were not widespread in the continent until the 20th century. Towns dating from precolonial times are found mainly along the Nile valley and the Mediterranean fringe of North Africa�where many date from Classical times (e.g., Alexandria, Egypt) and the late 18th century (e.g., F�s, Morocco)�and also in western Africa, in both forest and savanna zones, where they were the seats of governments of kingdoms. Timbuktu (Mali), Ile-Ife (Nigeria), Benin City (Benin), and Mombasa (Kenya) all date from the 12th century, while the Nigerian city of Kano has prehistoric origins. Two other Nigerian cities, Ibadan and Oyo, became important cities only in the 19th century.

The more-traditional towns differ in form, function, and even population characteristics from the many towns and cities established under colonial rule as administrative, trading, or industrial centres and ports. The latter cities are found throughout Africa and include Johannesburg, Lusaka, Harare, Kinshasa, Lubumbashi, Nairobi, Dakar, Freetown, Abidjan, and many others; often, as in the case of Lagos or Accra, they are built onto traditional towns. Typically the focus of in-migration from an impoverished hinterland, they are ethnically heterogeneous. Many have grown to become the largest cities in their respective countries, dominating their national urban hierarchies in size as well as in function.

Mostly rural for centuries, Africa has rapidly become more urbanized. Although it is still the least urbanized of the continents, Africa has one of the fastest rates of urbanization. Thus, the total population living in towns�which was only about one-seventh in 1950�grew to about one-third by 1990 and about two-fifths in the year 2010. Generally, the level of urbanization is highest in the north and south, and it is higher in the west than in the east and nearer the coasts than in the interior.

The largest cities include Cairo, Alexandria, and Al-Jīzah, Egypt; Kinshasa, Democratic Republic of the Congo; Lagos, Nigeria; Casablanca, Morocco; Johannesburg, South Africa; Addis Ababa, Ethiopia; and Algiers, Algeria. Many other large cities are seaports along the coasts or central marketing towns, linked by rail or river with a coast. Examples of seaports are Accra, Ghana; Lagos; and Cape Town, South Africa. Examples of large inland cities are Ibadan and Ogbomosho, Nigeria; Nairobi, Kenya; and Addis Ababa.

Cape Town, South Africa.� Digital Vision/Getty ImagesMigrations

There have been many movements of population within the African continent, from outside into the continent and from the continent outward. The major movement within the continent in historic times has been that of the Bantu-speaking peoples, who, as a result of a population explosion that is not fully understood, spread over most of the continent south of the Equator.

Maison des Esclaves (�Slave House�), Gor�e Island, Senegal.� GoLo/Fotolia

The major movements into the continent in the past few centuries have been of European settlers into northern Africa and of European and Asian settlers in Southern Africa. The Dutch migrations into Southern Africa began in the mid-17th century. Originally settling on the coast, the Dutch�or Boers�later moved inland to the Highveld region, where a series of military conflicts occurred between them and the Bantu speakers in the 19th century. Other European settlement took place mainly in the 19th century: the British particularly in what is now KwaZulu-Natal province of South Africa but also inland in what are now Zambia and Zimbabwe and in the East African highlands, the Portuguese in Angola and Mozambique, and the Germans in what is now Namibia.

The presence of large settler populations delayed the achievement of self-government by the African peoples of South Africa, Namibia, Zimbabwe, Angola, and Mozambique and resulted in much bitterness between the indigenous peoples and settlers. In North Africa, by contrast, where the extensive settlement of Europeans from France, Italy, and Spain occurred, the growth of Arab nationalism and the emergence of independent states such as Morocco, Algeria, and Tunisia led to the return of between one and two million colonists to their homelands in the late 1950s and early 1960s and to the political dominance of the indigenous peoples.

The greatest outward movement of people was that of Africans�particularly from western Africa and, to a lesser extent, Angola�to the Americas and the Caribbean during the period of the slave trade from the 16th to the 19th century. (For further discussion of the phenomenon, see slavery.) Earlier estimates that between 15 and 20 million Africans were transported across the Atlantic have been revised to a figure of 10 million, which appears more realistic. While their contribution to the development of the New World was of crucial importance, the effect of the loss of manpower to the African continent was considerable and has yet to be satisfactorily analyzed. The slave trade was also active on the east coast of Africa, where it was centred on the island of Zanzibar.

There were few permanent population movements in Africa during the 20th century, although an extensive settlement of Hausa from northern Nigeria took place in what is now Sudan. Warfare produced some significant population displacements, usually of minority groups fleeing the dominant majority. In 1966 the Igbo people of northern Nigeria, for example, returned en masse to their homeland in eastern Nigeria, the number of refugees being estimated at more than 500,000. The conflicts in the Horn of Africa since the 1960s have caused similar displacements. Indeed, Africa has millions of refugees. Such refugees are among the poorest and most vulnerable people in the world, and their numbers are substantially augmented by those fleeing drought and famine. The countries to which those people flee often find it extremely difficult to cope with them.

Somali refugeesSomali refugees in Ethiopia, 2011.Carola Frentzen�DPA/Landov

Most movement occurs across uncontrolled borders and between people of the same tribal groups. Much is seasonal, in any case, and is restricted to migrant labourers and nomadic herdsmen. Controlled immigration and emigration are generally negligible; contemporary examples, however, include the employment of mine workers in South Africa, the forced emigration of Asians from East Africa, and the expulsion of people from neighbouring western African states caused by such actions as the enforcement of the Alien Compliance Order of 1969 in Ghana. Robert K.A. Gardiner Davidson S.H.W. Nicol John F.M. Middleton John Innes Clarke The Editors of Encyclopaedia Britannica Economy

With the exception of South Africa and the countries of North Africa, all of which have diversified production systems, the economy of most of Africa can be characterized as underdeveloped. Africa as a whole has abundant natural resources, but much of its economy has remained predominantly agricultural, and subsistence farming still engages more than 60 percent of the population.

Until the beginning of the 20th century this system of farming relied on simple tools and techniques, as well as on traditional organization of the family or community for its labour. Because of poor transport and communications, production was largely for domestic use. There was little long-distance trade, and wage labour was virtually unknown. The small size and vast heterogeneity of polities at that time also made exchanges very limited. There were, however, notable exceptions, especially in western Africa, where for many centuries societies had engaged in long-distance trade and had elaborate exchange and craft facilities, communications, and a political infrastructure to maintain their trade routes.

Africa experienced considerable economic development during the 20th century, and, while this provided many benefits, it also gave rise to a number of serious problems. The first significant changes occurred under colonial rule in the first half of the century: wage labour was introduced, transportation and communications were improved, and resources were widely developed in the colonial territories. The legacy of this, however, has been that the export of two or three major agricultural products or minerals�such as peanuts, petroleum, or copper�has come to provide most of the foreign-exchange earnings for nearly all African countries. Fluctuations in the prices of these commodities have made the economies of these countries vulnerable and fragile. The situation has been exacerbated in countries in the marginal dryland zones, where the increasing frequency of drought conditions have undermined agricultural productivity.

The second major change was the vigorous promotion of industrial development, often with foreign assistance, that took place in the two decades (1960�80) following the political independence of most African countries. The political fragmentation of the continent, however, also became a major constraint to industrial growth, because it created numerous small markets. Consequently, most African countries became saddled with excess industrial capacity, coupled with enormous foreign debts incurred in large part to build this capacity.

In nearly all African countries a poor economic situation has been aggravated by rapid population growth, which has kept per capita gross domestic product low or in some cases caused it to decline. Thus, any hope for improving economic conditions in most of Africa rests on two factors: population control within individual countries to give their economies the chance to grow; and the organization of groups of states into regional economic blocs in order to create internal markets large enough to sustain growth. ResourcesMineral resources

Africa�s known mineral wealth places it among the world�s richest continents. Its very large share of the world�s mineral resources includes coal, petroleum, natural gas, uranium, radium, low-cost thorium, iron ores, chromium, cobalt, copper, lead, zinc, tin, bauxite, titanium, antimony, gold, platinum, tantalum, germanium, lithium, phosphates, and diamonds.

Major deposits of coal are confined to four groups of coal basins�in Southern Africa, North Africa, the Democratic Republic of the Congo, and Nigeria. Proven petroleum reserves in North Africa occur in Libya, Algeria, Egypt, and Tunisia. Exploration has been concentrated north of the A�r�Ahaggar massifs; there may also be major Saharan reserves to the south. The other major oil reserves are in the western coastal basin�mainly in Nigeria and also in Cameroon, Gabon, Equatorial Guinea, and the Republic of the Congo�and in Angola and South Sudan. Natural gas reserves are concentrated in basins of North Africa and coastal central Africa.

Southern Africa is said to be one of the world�s seven major uranium provinces. In South Africa the unusual degree of knowledge of reserves derives from the joint occurrence of uranium with gold, a condition that also decreases the cost of production. Other countries with significant uranium deposits are Niger, Gabon, the Democratic Republic of the Congo, and Namibia. Metallic deposits

In North Africa reserves of iron ore are concentrated in the Atlas Mountains and in the western Sahara. Egypt, however, has medium-grade reserves, of which the most important are at Al-Baḥriyyah Oasis. The ore deposits in Morocco and Tunisia, which were once of considerable importance, have been severely depleted. Africa�s most significant iron reserves are to be found in western and Southern Africa. It is the sedimentary Precambrian rocks, particularly in western Africa, that have proved the basis of Africa�s role as a major world producer of iron ore. The most significant deposits are in Liberia in the Bomi Hills, Bong and Nimba ranges, and Mano valley; in the extension into Guinea of the Nimba�Simandou ranges, where hematites have been located; in Nigeria and Mauritania, which have large deposits of low-grade ore; and in Gabon, where extensive reserves are present in the northeast. In Southern Africa most iron ore reserves lie in South Africa itself. The chief deposits are at Postmasburg, in the Bushveld Complex, at Thabazimbi, and in the vast low-grade deposits of Pretoria. There are also substantial reserves in Zimbabwe.

Africa�s reserves of minerals used as ferroalloys in the steel industry are even more striking than its enormous share of world iron ore reserves. This is particularly true of chromium. Almost the entire world reserve of chromium is found in Southern Africa and, to a much lesser extent, in western and northeastern Africa. The highest concentrations are found in Zimbabwe, at Great Dyke. South Africa contains the largest deposits of chromite. As compared with these two sources, reserves elsewhere in Africa are relatively small.

Manganese reserves are also considerable. In South Africa reserves of contained manganese are found in the Kalahari Manganese Field and elsewhere. The Mouanda deposit in southeastern Gabon is thought to be among the largest in the world. Ghana is another important source of manganese, having both low-grade and high-grade reserves. Elsewhere in western Africa, manganese deposits are situated in Burkina Faso and C�te d�Ivoire, as well as in the Democratic Republic of the Congo and in Cameroon. In North Africa manganese is found in Morocco and Algeria.

Africa�s contribution to world resources of other ferroalloys is, by comparison, insignificant. Nickel is of some importance, occurring in other metalliferous ores in Southern Africa.

Most of Africa�s copper is contained in the Central African Copperbelt, stretching across Zambia and into the Katanga (Shaba) area of the Democratic Republic of the Congo. Accompanying minerals vary with the geologic layer, but cobalt dominates. Outside the Copperbelt a number of countries have lesser but still significant reserves of copper.

Only Nigeria, the Democratic Republic of the Congo, and South Africa contain tin reserves of any significance. Although it is difficult to consider Africa�s reserves of lead and zinc separately, of the two, lead ores are considerably more widespread. North Africa is the largest traditional producing region. African reserves of zinc metal are located along the Moroccan-Algerian frontier, in the Copperbelt in the Democratic Republic of the Congo, in Nigeria, in Zambia, and in Namibia.

Africa has about one-fourth of the world�s reserves of bauxite, the chief aluminum ore. Virtually all of this occurs in a major belt of tropical laterite stretching some 1,200 miles from Guinea to Togo. The largest reserves are in Guinea.

Half of the world reserves of cobalt can be found in the Democratic Republic of the Congo. A continuation of the geologic formation into Zambia gives the country sizable reserves of cobalt content. The only other deposit of any importance is found in Morocco.

The titanium ores, ilmenite and rutile, are widely distributed in Africa but are rarely considered as minable reserves. A major source is the Sherbro deposit in Sierra Leone. Almost all of Africa�s antimony resources lie in the Murchison Range of South Africa. The major concentrations of beryllium are in Madagascar, Mozambique, the Democratic Republic of the Congo, Zimbabwe, Rwanda, Uganda, and South Africa. The principal sources of cadmium are in Namibia and the Democratic Republic of the Congo. Deposits of mercury are restricted to North Africa, notably to Tunisia and, more particularly, Algeria.

Gold and allied metals are widely disseminated, reaching their greatest concentrations in South Africa, where reserves of gold probably constitute about half of the world total. Gold is also found in Zimbabwe, in the Democratic Republic of the Congo, and in Ghana. There are numerous alluvial sources of gold in Burundi, C�te d�Ivoire, and Gabon. South Africa has the most important deposit of platinum of the world�s market economies. Silver reserves of the continent are not important.

Africa contains a major share of world reserves of tantalum, and the Democratic Republic of the Congo has most of these reserves. African reserves of niobium (columbium; a steel-gray metallic element resembling tantalum in its chemical properties that is used in alloys) are relatively small. Nigeria, however, is an important world producer.

One of Africa�s many sources of zirconium (a metallic element resembling titanium chemically) is the Jos Plateau in Nigeria. Greater reserves, however, are contained in deposits on the Senegal coast; on the east coast of South Africa; in Madagascar; at Sherbro, Sierra Leone; and in the Nile delta.

Another rare metal of which Africa contains a majority of world reserves is germanium, concentrated in the Democratic Republic of the Congo and in Namibia. Africa also has large deposits of lithium, the largest of which are found in the Democratic Republic of the Congo. Nonmetallic deposits

Clays are widespread and are found in North Africa, where brick and pottery clays occur in Algeria and Morocco; in western and central Africa, where clays are located in Togo (ceramic), the Central African Republic, and C�te d�Ivoire (ceramic); and in East and Southern Africa.

Kaolin (china clay) occurs in Algeria. Outside North Africa it is widespread. In western Africa it occurs most notably in Nigeria�s Jos Plateau, as well as in Mali, Ghana, and Guinea. Similar deposits occur in central and East Africa, as well as in Southern Africa.

Bentonite (a clay formed from decomposed volcanic ash, which is able to absorb large quantities of water and to expand to several times its usual size) is found in the Moroccan Atlas Mountains and in Tanzania, Kenya, and South Africa. The continent�s principal reserve of fuller�s earth (an absorbent clay) is in Morocco.

Economically important mica deposits occur primarily in Southern Africa (South Africa, Zimbabwe, and Tanzania) and in Madagascar.

Africa has none of the world�s major reserves of sulfur. It reaches economic concentrations only in South Africa�s Witwatersrand, in Zambia�s Copperbelt, and in Morocco. Large quantities of sodium deposits remain to be evaluated. Sodium chloride is the principal salt, the largest deposit being in the Danakil Plain of Ethiopia. The principal sources of salt in Africa, however, are inland or coastal basins, from which it is extracted by the evaporation of salt water. Major coastal reserves of this type lie along the North African Mediterranean coast and along the Red Sea and Indian Ocean coasts of East Africa and Madagascar. Inland, the chief reserves are in the Oran Sebkha, a salt pan region in Algeria; in Botswana around Lake Makarikari; and in Uganda.

Another important sodium mineral is natron, or sodium carbonate. Natron is more limited in occurrence, but Africa contains several significant deposits. It is found in Lake Magadi, Kenya, and in Lake Natron, Tanzania, as well as in western Africa, where beds have been deposited from the waters of Lake Chad.

North Africa has been a traditional exporter of phosphates, and western Africa has large reserves. Morocco and Western Sahara together have vast reserves. The R�o de Oro region in Western Sahara contains huge deposits, and a major development at Bu-Craa has been established. Algeria and Tunisia also have reserves. To the east, phosphate-bearing sediments outcrop on the Red Sea coast. The Thi�s deposit in Senegal is of particular interest in constituting the world�s only source of aluminum (as opposed to calcium) phosphate. Other phosphate deposits occur in Togo, Nigeria, Tanzania, Uganda, and Malawi.

The potash deposits in the Republic of the Congo are the largest in Africa. The other large reserve is in Ethiopia.

Madagascar has the world�s largest known accumulation of flake graphite deposits. Continuations of these high-quality deposits in Mozambique and southeastern Kenya contain further reserves of graphite.

While deposits of low-grade sand suitable for construction and engineering work are widely distributed, reserves of sands with a sufficiently high silica content for glass manufacture are more localized. There are deposits in western Africa (C�te d�Ivoire, Liberia, Nigeria, and Ghana), East Africa (Uganda and Tanzania), and South Africa. Glass sands are also found in Egypt.

Kyanite (cyanite), a mineral aluminum silicate used as a refractory, occurs most typically in Southern Africa. Apart from South African reserves, there are deposits in Kenya, Malawi, Ghana, Cameroon, and Liberia.

Of the abrasive substances, industrial diamonds are most closely associated with Africa. The continent contains some 40 percent of the total world reserves. The stones are found in a number of major belts south of the Sahara. The principal known reserves of diamonds in their primary form are in the South African Vaal belt. Elsewhere in Africa, primary deposits are found in Tanzania, Botswana, and Lesotho.

Another major belt of diamondiferous rocks encircles the Congo River basin and includes the world�s largest deposit, located in the Democratic Republic of the Congo, which contains the majority of Africa�s reserves of industrial diamonds. The same belt has secondary deposits that occur elsewhere in that country as well as in the Central African Republic and Angola. In western Africa known reserves are located primarily in alluvial gravel fields. They are found in Sierra Leone, Guinea, C�te d�Ivoire, Liberia, and Ghana.

A considerable proportion of the world reserves of corundum (a common mineral, aluminum oxide, notable for its hardness) is located in Southern Africa. The principal deposits are in Zimbabwe, South Africa, Mozambique, Madagascar, and Malawi.

Pumice is found in areas of volcanic activity such as the Atlantic islands, the coastal Atlas Mountains of northeastern Morocco, and the East African Rift System, notably in Kenya, Tanzania, and Malawi. Joint reserves, however, constitute only a small percentage of the world total.

Reserves of building materials are characterized by their wide distribution, to such an extent that the commercial status of such deposits depends more on their location relative to areas of development than on their extent and quality. While almost all African countries have reserves of building materials, knowledge of such reserves is strictly related to the country�s level of development, and no meaningful estimate of the size of reserves can be made.

Granite is located in Morocco and Nigeria, and there are vast reserves in Burkina Faso. Quartzite (a granular rock, consisting essentially of quartz) is important as a building stone in Uganda and the Democratic Republic of the Congo. Dolerite (a coarse-grained basalt) is produced in South Africa and basalt, which is crushed for use in road construction, in Senegal. Marble is found in Mali, Togo, Nigeria, and South Africa.

Limestone is important because of its use in the cement industry, and deposits are fairly widespread. North Africa is a particularly important source. In western Africa a belt of limestone runs from the Central African Republic to the Atlantic coasts, with major outcrops in northern Nigeria, Niger, Burkina Faso, and Mali. Elsewhere there are deposits in Nigeria, Benin, Togo, and Ghana. East African deposits include those in Kenya, Tanzania, Uganda, and Zambia; there are also deposits in South Africa.

North Africa has major reserves of gypsum on the Mediterranean coast, as well as in outcrops along the Gulf of Suez and the Red Sea. Somalia has one of the largest known deposits. Eastern Africa and Madagascar have further reserves, and in western and Southern Africa superficial deposits are particularly important�for instance, north of Nouakchott, Mauritania.

Many of the major deposits of the most important commercial gem mineral, the diamond, have already been described above in the discussion of industrial diamonds. One major deposit, however�that of Namibia�consists almost entirely of gem diamonds.

There is no other gem mineral in Africa of comparable importance to these diamond reserves. Deposits of a number of such stones are found, however, especially in Southern and eastern Africa, where diamond fields contain beryl, garnets, amethyst, rose quartz, topaz, opal, jasper, emeralds, and other stones. Madagascar contains a large deposit of garnet. Tourmaline is found in Madagascar and Namibia. Agate is particularly associated with the volcanic areas of eastern and Southern Africa and malachites with the Katanga Copperbelt, while sapphires are found with diamonds in Ghana.

Africa contains no major world deposits of talc, but the mineral is found in Morocco, Nigeria, Sudan, Zimbabwe, and South Africa. Reserves of asbestos are much more important, and Southern Africa has a number of deposits of world significance.

Major deposits of fluorite, or fluorspar (a common mineral, calcium fluoride, used as a flux in metallurgy), are particularly associated with deposits of lead and zinc. In South Africa the chief deposit is in the northeastern part of the country. North African reserves lie primarily in Tunisia and Morocco.

Africa produces a very small share of the world supply of diatomite (a fine siliceous earth, used as an abrasive). The most important deposit is in Kenya. Water resources

In general, the seasonal distribution of river flow in Africa reflects the seasonal rainfall pattern; the amount of groundwater entering the river channels during the dry season is comparatively small. Important modifications in the flow of some rivers are caused by the presence of large lakes and swamps, which act as natural storage reservoirs, by the construction of dams on their courses, and by the incidence and severity of drought. Surface water

Although the surface area of Africa is about one-fifth of Earth�s land surface, the combined annual flow of African rivers is only about 7 percent of the world�s river flow reaching the oceans.

North Africa�s few perennial rivers originate in the mountains of the Maghrib, and their water is used extensively for irrigation. The large number of wadis, or ephemeral watercourses, to be found throughout the Sahara and the eastern Mediterranean coastal lands become filled with water as a result of the rare and erratic storms that occur over mountainous areas; otherwise they remain dry.

From the relatively well-watered areas of western and equatorial Africa, the S�n�gal, the Niger, the Logone�Chari, and the Nile rivers flow through the drier inland zones. Of these, the Niger River, originating in the Fouta Djallon region of Guinea, is retarded in the lake and swamp area south of Timbuktu in Mali, and the Logone�Chari feeds Lake Chad.

The Nile, the world�s longest river, receives more than 60 percent of its water from the Ethiopian Plateau, although its source is much farther south in the mountains of Burundi. Since the completion of the Aswan High Dam, only a small proportion of the river�s total flow reaching Egypt enters the Mediterranean Sea.

A number of rivers flowing in a more or less southerly direction into the Atlantic Ocean drain the southern part of western Africa. Many flow rapidly over bedrock before entering the coastal plains, draining into the system of lagoons and creeks along the coast. During the dry season the upper reaches of these rivers are without water, but in Guinea, Sierra Leone, and Liberia, where the dry season is fairly short, the rivers flow throughout the year.

In the well-watered western part of equatorial Africa the total average annual flow of the Congo River is enormous: some 44 trillion cubic feet. River flow at the lower end of the basin has two maxima: one that corresponds with the rainy season north of the equator, the other with the rainy season that occurs when it is summer in the Southern Hemisphere. The waters in the lower reaches of the river are slightly acid after traversing the large swamps situated in the centre of the basin.

East Africa�s many lakes stretch along the East African Rift Valley from the Red Sea to the mouth of the Zambezi River. Evaporation from most of them exceeds their surface rainfall, and in consequence their outflow is less than the quantities brought in annually by their tributaries. They often govern river flow by acting as storage reservoirs�decreasing the flood flow and increasing the dry-season flow. A number of the rift valley lakes are situated in closed basins and contain high percentages of dissolved salts. The largest of these are Lakes Rudolf (Turkana), Natron, and Eyasi.

Rainfall over much of Southern Africa is small, and the majority of the rivers originating there have an intermittent flow. Some large perennial rivers (e.g., the Okavango, the Zambezi, and the Orange) flow from areas of abundant rainfall into the drier zones. Groundwater

The conditions under which groundwater is found and the quantity and quality of groundwater reserves are closely related to geologic structure. Large inland depressions in Africa�s basement rock, having been filled with sedimentary layers of continental origin, sometimes form important groundwater reservoirs, notably those in the Taoudeni�Niger region, in the central Sahara between the Atlas and Ahaggar mountains; in the Libyan Desert; and in Chad, the Congo basin, the Karoo area of South Africa, and the Kalahari.

The East African plateaus usually contain little or no quantities of groundwater, and aquifers (geologic formations containing water)�generally of local importance�are found only in humid areas where the crystalline rock is weathered or fractured.

The chalky shales (rocks of laminated structure formed by the consolidation of clays) and dolomitic limestones (those containing calcium magnesium carbonate), which sporadically cover the basement rock, may contain important aquifers; those in Zambia and South Africa are major sources of water.

In the Sahara a rock stratum called the Continental Intercalary series, which dates from the early Cretaceous Period and which includes the Nubian sandstones of southern Egypt, is the most important water-bearing layer. It extends over very large areas and reaches a thickness of more than 3,000 feet; in Egypt and Algeria it is a major source of artesian water. In Sudan it sometimes lies directly on the Precambrian bedrock and contains underground water layers of local importance. Overlaying the Continental Intercalary series, but generally separated from it by a thick marine deposit, is a younger Tertiary layer called the Continental Terminal, which is the second largest aquifer in this area. Both these layers contain �fossil� water�i.e., water that entered the layers when rainfall in and around the Sahara was much more abundant than today. Near the surface, aquifers are found in such geologically recent deposits as alluvial deposits and sand dunes.

In the coastal areas of Senegal, C�te d�Ivoire, Ghana, Togo, Benin, Nigeria, Cameroon, Gabon, the Republic of the Congo, Angola, Mozambique, the East African countries, and Madagascar, aquifers are found in sandstone, limestone, and sand and gravel sediments. Intensive exploitation, however, may result in saltwater intrusions.

The Jurassic limestones of the mountainous area of the Maghrib are much more abundant in water sources than are dolomitic limestones. Around the cape in South Africa, sandstones and limestones contain very little water.

Yields from aquifers with good porosity, such as coastal sedimentary rocks or alluvial deposits, vary from a few cubic feet per hour in the fine-grained sands found in many parts of the continent to 35,000 cubic feet (990 cubic metres) per hour in the coarse gravels of the Nile delta. The capacity of wells in the Continental Terminal is generally somewhat lower, and those in the Continental Intercalary and the Karoo formations can also deliver moderate to high yields.

In North Africa limestones containing many cracks and fissures may yield thousands of cubic feet of water per hour, while in the Democratic Republic of the Congo, Zambia, and South Africa large yields are drawn from dolomitic limestones.

The harder sandstones, sandy shale, and quartzites of Precambrian and Paleozoic age are not generally very porous, and water is obtained only from fractured or weathered deposits. Western African, Angolan, and Tanzanian wells in these formations produce only a few cubic feet per hour. Crystalline and metamorphic rocks are almost impermeable except where fractured or weathered. Volcanic rock, especially the basalts, may yield up to 1,060 cubic feet per hour.

Most of the exploited groundwater is generally fit for consumption, because the dissolved minerals in water from shallow wells, particularly in the sandy aquifers of western Africa, are quite low. Groundwater from deeper marine layers, however�such as occurs in parts of North Africa, Mozambique, Ethiopia, and South Africa�may have a high content of dissolved salts. In moist tropical countries the water from Precambrian rocks generally contains only small amounts of dissolved minerals, whereas in the volcanic areas of East Africa groundwater may have so high a content of fluorine as to make it unfit for human consumption. There, and elsewhere in Africa, hot (possibly medicinal) springs with high mineral contents occur. Availability for human use

The pronounced seasonal character of rainfall and the fact that many rivers stop flowing during the dry season have necessitated the development of groundwater for human use, and the tapping of local aquifers has become important in many parts of the continent.

Large-scale irrigation has long been practiced mainly in North Africa, Egypt, Sudan, South Africa, Mali, Zimbabwe, and Mozambique. Medium-scale irrigation projects have been operated in Madagascar, Senegal, Somalia, and Ethiopia. In C�te d�Ivoire, Burkina Faso, Kenya, Nigeria, Ghana, and Zambia, medium- to small-scale projects have been constructed.

More than 50 river and lake basins are shared by two or more countries, and the development of their resources requires the cooperation of the basin states and several intergovernmental agencies�such as the Organization for the Development of the S�n�gal River, the Niger Basin Authority, and the Lake Chad Basin Commission.

Several large reservoirs were built in the late 20th century, such as the Aswan High Dam, Roseires, and Khashm al-Qirbah reservoirs in the Nile basin, Kainji on the Niger, Akosombo on the Volta, Kariba on the Zambezi, Cahora Bassa on the Zambezi in Mozambique, Kossou on the Bandama in C�te d�Ivoire, Kafue on the Kafue in Zambia, and Inga I and II on the Congo River in the Democratic Republic of the Congo. At a number of man-made lakes, research centres have been set up to study resettlement problems, the full use of ecological conditions, and the control of health hazards that sometimes occur. Biological resources

Africa�s naturally occurring biological resources�its immensely varied vegetational cover, vast insect life, and diverse animal life�have been described above. When combined with cultivated crops and domestic animals, these resources represent the great bulk of the continent�s economic wealth. Botanical resources

The two most economically important types of vegetation are forests and grasslands. Among the forested areas, the tropical forests contain much of the valuable timber. The vast equatorial lowland rainforest has the greatest variety of tree species, but the species most commercially in demand are found in the zones of broad-leaved woodlands and tropical highland forests. The true value of the forested areas, however, cannot be ascertained exactly, as original forests are progressively being converted to farming areas, and few governments have undertaken comprehensive land-use surveys to determine their present extent.

A large proportion of the land surface of Africa bears vegetation in which grass is an essential feature. This abundance of grass has made possible the continent�s enormous and varied populations of herbivorous mammals, both wild and domesticated. The tall and fibrous invasive grasses in forest environments and in large tracts of wooded grasslands are seldom very palatable to livestock, but, in those parts of the continent where good forage grows naturally or has been introduced, livestock raising is of great economic importance.

The Albida acacia tree of the �farmed parkland� areas of western Africa is of special economic importance. Unlike almost all other dry woodland trees, whose leaf shedding normally occurs at the onset of the dry season, the Albida appears to have a period of partial dormancy during the rainy season and springs to life only at the beginning of the dry season. At such periods its foliage is abundant and�being a palatable leguminous species�is much prized as browse for sheep, goats, and cattle. The smaller leafy branches are frequently fed to stock. The tree flowers and produces fruits, which are harvested, dried, and fed as a protein concentrate to stock at the height of the dry season. Animal resources

Water buffalo, oxen, horses, mules, donkeys, and camels are used primarily as draft, pack, or riding animals in Africa, and they also provide milk, meat, hides, or skins. Because of its intractability and wild nature, however, the African elephant�unlike the Asian elephant�is not used for draft or haulage purposes.

The water buffalo is an offshoot of the Asiatic buffalo (Bubalus bubalis); it arrived in Africa in relatively recent times and is now found almost exclusively in Egypt. The domesticated African water buffalo is used to cultivate irrigated land (mainly in the Nile delta) and to provide milk and meat.

Oxen are widely used in Africa for agricultural purposes, especially for plowing and cultivation; they are also trained to thresh grain, pump water, and act as pack animals. Bullock (castrated oxen) plowing is well developed in the countries of North Africa, in Ethiopia and Sudan, and farther west in Chad, in northern Nigeria, and in the savanna climatic zone of western Africa. Plowing and cultivation by oxen is also well developed in areas of eastern and Southern Africa that are free of the deadly tsetse fly. Females used for work may also be milked. Work oxen are often used for meat and to provide hides.

Horses and ponies are principally found in Morocco, Algeria, Tunisia, Chad, Ethiopia, Mali, Niger, Nigeria, Senegal, Burkina Faso, Egypt, South Africa, and Lesotho. Horses are used as riding or pack animals and in a number of areas are bred with donkeys to produce mules. Few are kept in areas where tsetse flies are present. Five main types of horses inhabit Africa: the Darfur pony, the Dongola horse, the Ethiopian-Galla horse, the Somalia pony, and the South African horse (including the Basuto pony). In North Africa, types also have evolved as a result of selection and crossing with exotic Arab, Barb (Barbary), and Thoroughbred horses. Arab and Thoroughbred influence may also be noted in Southern Africa.

The distribution of the ass roughly corresponds to that of the horse, except that it also extends into the livestock areas of eastern and central Africa. Mules are found in Algeria, Ethiopia, Morocco, Somalia, South Africa, and Tunisia, where they provide farm draft power and are used as pack animals and for riding. The ability of mules to perform work in hot, dry climates is superior to that of most other farm animals.

The Arabian camel, or dromedary, is widely dispersed in the drier regions of northern and eastern Africa. Although used principally as a pack animal, it also is used for land cultivation, water pumping, and human transportation. The camel is essentially a bush browser and, if reasonably well fed and watered, may produce about 11 to 13 pounds (5 to 6 kilograms) of milk daily, in addition to that fed to the calf. The milk is prized by the camel herders and their families. Camel meat and camel hides find a ready market among Muslim communities.

Cattle provide hides, and sheep, goats, and pigs provide skins. Skins of the Maradi, Sokoto, and Kano red goats from Niger and Nigeria are greatly prized by the Morocco leather trade. In the areas north and south of the tropical zone, African sheep are covered with wool, but in the tropics they are hairy. In elevated areas, such as Ethiopia, where temperatures are modified by altitude, some sheep may be partially wooled, at least on the back and buttocks. The wooled sheep of North Africa are largely of the woolly Barbary type, which was originally introduced to Africa from the Middle East.

The great herds of wild African herbivores include the principal game animals. African antelope have been important throughout human history as sources of meat and such by-products as hides and bone, and they, along with other large mammals, became prized by trophy hunters. For centuries African elephants were sought for the ivory in their tusks, but the severe reduction of their numbers by the late 20th century led to a total ban on hunting them in most African countries.

The most economically useful fishes found in African waters include many freshwater species. Important among the marine fishes are flounder, halibut, sole, redfish, bass, conger, jack, mullet, herring, sardine, and anchovy. Crustaceans are important for local consumption and for export, as are oysters (for pearls), trochus shells, corals, and sponges. The most economically important aquatic mammal is the Southern, or Cape, fur seal. Agriculture

Agriculture is by far the single most important economic activity in Africa. It provides employment for about two-thirds of the continent�s working population and for each country contributes an average of 30 to 60 percent of gross domestic product and about 30 percent of the value of exports. Nonetheless, arable land and land under permanent crops occupy only about 6 percent of Africa�s total land area.

Except for countries with sizable populations of European descent�such as South Africa, Zimbabwe, and Kenya�agriculture has been largely confined to subsistence farming and has been considerably dependent on the inefficient system of shifting cultivation, in which land is temporarily cultivated with simple implements until its fertility decreases and then abandoned for a time to allow the soil to regenerate. In addition, over most of Africa arable land generally has been allocated through a complex system of communal tenure and ownership rather than through individually acquired title, and peasant farmers have had rights to use relatively small and scattered holdings. This system of land ownership has tended to keep the intensity of agricultural production low and has inhibited the rate at which capital has been mobilized for modernizing production. A number of countries have made efforts to raise productive levels by selecting better varieties of seeds and planting materials, using tractors and other mechanized equipment, or increasing the use of mineral fertilizers and insecticides. Such measures, however, have been relatively limited, and they have raised concerns about their part in accelerating soil erosion and desertification. In areas of cash crop production, land has become private rather than community property, and cultivation is intensive.

The persistence of relatively low-productivity agricultural systems over large parts of the continent also stems from a lack of integration between crop production and animal husbandry. Traditionally, sedentary cultivators like the Hausa in Nigeria and the Kikuyu in Kenya live apart from their nomadic herdsmen neighbours (the Fulani and Maasai, respectively), with the result that over large areas of the continent farmers do not have access to animals for draft power or to manure for fertilizer. The incidence of such insect pests as the tsetse fly also discourages mixed farming in many areas.

The need to sharply increase food production to meet the demands of a rapidly growing population, however, has remained paramount. Intense research at such centres as the International Institute of Tropical Agriculture in Ibadan, Nigeria, has been directed at developing high-performing varieties of crops and designing more appropriate cropping systems. One product of such research is a genetically improved strain of corn (maize). Corn is not in itself a balanced food, being deficient in some amino acids, but a scientific breakthrough in the mid-1960s resulted in an increase of the amino acids lysine and tryptophan in certain new varieties of corn called opaque, or high-lysine, strains. These varieties initially produced low yields, were more prone to disease and vermin, and had a soft texture that was not desirable. Breeding programs, however, corrected these defects, and the new strains began to improve the nutritional value of diets in Africa (which consist mainly of corn preparations). Principal cropsCereals and grains

Africa produces all the principal grains�corn, wheat, and rice�in that order of importance. Corn has the widest distribution, being grown in virtually all ecological zones. Highest yields per acre are recorded in Egypt and on the Indian Ocean islands of R�union and Mauritius, areas where production is under irrigation. Millet and sorghum are also produced but principally in the savanna regions of the continent. Rice production and consumption have become increasingly important and are closely associated with areas of rapid urbanization. The most important rice-producing countries are Egypt, Guinea, Senegal, Mali, Sierra Leone, Liberia, C�te d�Ivoire, Nigeria, Tanzania, and Madagascar. Wheat production was once restricted to South Africa, the countries of North Africa, and the highland zones of Ethiopia and Kenya, but new varieties have extended cultivation (under irrigation) to countries in the savanna region such as Nigeria. Legumes and fodder

Fodder crops are not widely grown except in subtropical areas of North Africa and the highland zones of East and Southern Africa, where pure stands of alfalfa (lucerne) are raised. Berseem (a type of clover used for forage) is also grown in Egypt and Sudan under irrigation. Protein-rich legumes are produced widely, usually sown together with other crops. They include velvet beans, cowpeas, soybeans, and lablab (hyacinth beans). In North Africa broad beans and vetches are also produced. Peanuts (groundnuts) are grown widely in western Africa, both for domestic consumption and for export. Tubers and root crops

Cultivation of the hardy cassava has expanded tremendously, particularly in western and central Africa; it has displaced the cultivation of yams in many areas and has ceased to be regarded as just famine reserve. Potatoes are cultivated in the higher elevations of such countries as Ethiopia, Kenya, and Madagascar, as well as in areas of Mediterranean climates in North and South Africa. Sweet potatoes have a more tropical and subtropical distribution, while the plantain is grown extensively in the tropical forest zones. Fruits and vegetables

Among the important fruits are bananas, pineapples, dates, figs, olives, and citrus; the principal vegetables include tomatoes and onions.

The banana is well distributed throughout tropical Africa, but it is intensively cultivated as an irrigated enterprise in Somalia, Uganda, Tanzania, Angola, and Madagascar. Also widely cultivated is the pineapple, which is produced as a cash crop in C�te d�Ivoire, the Congo basin, Kenya, and South Africa.

A typical tree of desert oases, the date palm is most frequently cultivated in Egypt, Sudan, and the other countries of North Africa. The fig and olive are limited to North Africa, with about two-thirds of the olive production being processed into olive oil.

The principal orange-growing regions are the southern coast of South Africa and the Mediterranean coast of North Africa, as well as Ghana, Swaziland, Zimbabwe, the Democratic Republic of the Congo, and Madagascar. The largest yields are produced in countries where basin irrigation is practiced. South Africa is the largest producer of grapefruit, followed by Sudan.

Tomatoes and onions are grown widely, but the largest-producing areas border the Mediterranean. Large vegetables, such as cabbages and cauliflowers, are grown in the same region, from where it is possible to export some quantities to southern Europe. Important vegetables of tropical Africa include peppers, okra, eggplants, cucumbers, and watermelons. Beverage crops

Tea, coffee, cocoa, and grapes are all grown in Africa. Kenya, Tanzania, Malawi, Zimbabwe, and Mozambique are the largest producers of tea, while Ethiopia, Uganda, C�te d�Ivoire, Tanzania, and Madagascar are the major producers of coffee. Cocoa is essentially a tropical forest crop. Its cultivation is concentrated in western Africa, with the principal producers being C�te d�Ivoire, Ghana, Nigeria, and Cameroon. All these crops are largely grown for export. Sharp price fluctuations caused African countries to form international cartels with other producing countries in an effort to regulate the market and negotiate better prices. Grapes are produced in northern Africa and in South Africa, essentially for the making of wine for European markets. Fibres

Large areas of Africa raise cotton for textile manufacture. The principal producing countries include Burkina Faso, Nigeria, Egypt, Zimbabwe, and Mali. Sisal production is also important, especially in the eastern African countries of Ethiopia, Tanzania, Kenya, and Madagascar, as well as in Mozambique, Angola, and South Africa. Some countries, notably Nigeria, promote the cultivation of kenaf (one of the bast fibres). Other cash crops

The oil palm, producing palm oil and palm kernels, grows widely in secondary bush in the tropical forest zones. There are large plantations in Nigeria, C�te d�Ivoire, and the Democratic Republic of the Congo. Coconuts are important in the Comoros, Ghana, C�te d�Ivoire, Mozambique, Nigeria, and Tanzania. Kola nuts are grown principally in the forested regions of Nigeria, Ghana, C�te d�Ivoire, Sierra Leone, and Liberia. The cashew tree is grown to a limited extent in East Africa and to a lesser extent in the coastal countries of western Africa. Rubber is produced principally in Nigeria and Liberia. Tobacco is widely cultivated as an export crop in Zimbabwe, Malawi, Tanzania, Nigeria, and South Africa. Sugarcane is also widely grown but largely for domestic consumption. Major producers include South Africa, Egypt, Mauritius, and Sudan. Livestock and fishing

Cattle, sheep, and goats form the bulk of livestock raised. Except in South Africa, most of these animals are raised essentially for meat. Sheep in the north and south are also kept for their wool; South Africa alone produces half of the entire continental production, much of the clip from Merino or crossbred Merino sheep. In the tropical areas, however, other livestock products include hides and skins. It is estimated that the annual output of hides is in the range of 10 percent of the total population of cattle, while that of sheepskins and goatskins is approximately 25 percent. The number of game hides and skins processed and sold annually is not accurately known. Except in South Africa, Zimbabwe, and Kenya, production of milk and milk products is grossly insufficient to meet domestic needs. Poultry production, however, has increased tremendously, and everywhere stocks have nearly doubled since the 1960s. Nigeria, Ethiopia, Morocco, South Africa, and Sudan are the countries with the largest poultry stocks.

Fishing is important on the local level in all countries bordering the sea or inland bodies of water. Commercial ocean fishing is practiced most widely by the countries near the rich fishing grounds of the west coast�South Africa, Namibia, Angola, Nigeria, Ghana, Senegal, and Morocco. Herring, sardines, and anchovies contribute most to the ocean catch, followed by jack, mullets, sauries, redfish, bass, and conger in tropical waters and cod, hake, haddock, tuna, bonitas, and bullfish in northern and southern waters. Inland countries with well-developed fisheries include Malawi, Uganda, Chad, C�te d�Ivoire, and Mali; tilapia and other cichlids constitute the largest catch in inland waters. Some countries, such as Nigeria, have developed both marine and freshwater fishing industries. A number of commissions have been established to monitor and control fishery development on the continent. Industry

The countries of North Africa, unlike those of the rest of the continent, have wide-ranging and ancient traditions of manufacture. At the end of the 19th century, however, Africa as a whole was regarded solely as a potential source of raw materials or as a natural market for Europe. In the course of time, limited industrialization tended to converge around the relatively large expatriate settlements, where technical considerations operated in favour of the industrialization of some areas and transport costs constituted the dominant development factor in others. Though World War II led to acceleration in the process of industrial development, by 1950 the total factory output of manufacturing industries (excluding South Africa) still remained small.

After 1950 output rapidly increased. The substantial increase and its range were attributable to such factors as increased demand, the substitution of home-produced for imported goods, the encouragement of manufacturing by individual African administrations, and an influx of development capital and petrodollars. Major weaknesses nevertheless were evident, among them high capital costs, the political division of Africa into more than 50 countries, which inhibited mass production and mass marketing, and a scarcity of skilled personnel.

Despite its expansion since about 1950, the relative significance of manufacturing remains considerably smaller than in the more-advanced countries and smaller also than in continental Asia and in Latin America. Furthermore, the share of manufacturing in the gross domestic product varies widely in different African countries. At the lower end of the spectrum are countries such as Equatorial Guinea, Guinea, and Niger, and at the upper end of the spectrum are countries such as Egypt, Algeria, and South Africa. The total output of manufacturing in South Africa alone, however, is nearly 50 percent of the output in the remainder of the continent.

Manufacturing in Africa tends to concentrate on comparatively simple items and on those where some special advantage is available to the African producer, although the range of products has widened. Industrial production includes electric motors, transport equipment, and tractors, while airplanes are also assembled. The leading heavy industries are chemical and petroleum, coal, rubber, and metal manufacture. Most industrial plants, however, are of the relatively simple kind, being engaged in food processing or in manufacturing textiles, leather products, and cement or other building materials.

The mining industry is an increasingly significant source of national income, foreign exchange, and raw materials for the development of local processing industries. The industry is very unevenly distributed: more than half of mineral earnings came from North Africa alone, and nearly one-fourth came from Southern Africa.

Except in South Africa, iron and steel are used mostly for construction rather than for engineering. There are integrated iron and steel plants in Algeria, Tunisia, Egypt, Zimbabwe, and South Africa, while smaller production facilities�often based on the transformation of scrap�exist in several other countries.

Petroleum-refining capacity is based on domestic crude oil output in a few cases and on imported crude oil in others. In some countries the development of the petrochemical industry followed the establishment of refineries. In 1965 there were only three major petrochemical complexes in Africa�in Zimbabwe, Egypt, and South Africa. By the late 20th century several more countries had large refinery capacities, including Algeria, Ghana, Kenya, Libya, Morocco, Nigeria, Senegal, Sudan, and Tunisia.

Most of the textiles are processed in bleaching, dyeing, and printing establishments that form an integral part of composite spinning and weaving units. With the exception of Egypt, producers have concentrated on the home market and on the manufacture of cotton textiles. Although African countries export textiles, their imports are usually larger. Rayon�synthetic and woolen materials are, for the most part, imported. Ready-made clothing, both domestic and imported, has emerged as a major market factor.

Most African countries have cement plants, the leading producers being South Africa and Algeria. The transport costs of cement make its price variable. Prices are lowest on the North African coast, somewhat higher on the west and east coasts, and highest in the inland countries.

By far most of Africa�s wood output is used for fuel. Sawmills, however, are distributed throughout the continent. Plants for the manufacture of plywood, particleboard, and fibreboard have a considerable amount of excess capacity. The pulp and paper industry is concentrated in North Africa and in Southern Africa, although a number of small paper mills have been established in other parts of the continent. The main products of the paper industry proper comprise newsprint, printing and writing papers, paper and paperboard, and industrial paper. The bulk of the output of all paper products is directed to national markets. Power

A spectacular development in the use of electric energy took place in the second half of the 20th century, partly because of the growth of the petroleum industry and partly because of the establishment of large hydroelectric plants and some thermoelectric plants. The increased quantity and quality of electric energy gave rise to problems of transmission and distribution. Unlike thermoelectric plants, which may be sited where the consumer demand is greatest, sites of hydroelectric installations are not flexible, and the type of transmission lines in use has therefore changed. Although in the 1950s it was common practice to use lines with transmission voltages of less than 220 kilovolts, transmission lines were later built that could handle higher voltages. In Nigeria, for example, 330-kilovolt lines were strung; similar lines were used in Zimbabwe�s system, which feeds Harare and Bulawayo in Zimbabwe, as well as the Copperbelt in Zambia. This same system is interconnected in the north with the large Katanga (Shaba) region hydroelectric power stations in the Democratic Republic of the Congo. The construction of high-tension lines to supply power to the Katanga Copperbelt was completed in 1982. Much of the power for Egypt�s population centres is supplied by lines from such hydroelectric power stations as that at the Aswan High Dam. Construction of 533-kilovolt lines to transmit power from the Cahora Bassa hydroelectric station in Mozambique to South Africa was completed in 1974. The possibility of supplying landlocked states with energy from the large hydroelectric plants in the coastal states is more likely to be considered in the future.

A number of steam power stations are located in ports and cities near the coasts. The largest installations of this kind operate in Tunis, Tunisia; Casablanca and Oujda, Morocco; Dakar, Senegal; Abidjan, C�te d�Ivoire; and Lagos, Nigeria. Steam power stations using coal are by far the most common, especially in South Africa.

Electric energy consumption in large urban centres, especially when they are near coastal towns and mining areas where industrial activity has taken shape, has increased considerably. Although some countries have extended networks to the rural areas or increased the numbers of isolated low-powered stations and independent networks, progress in rural electrification has not been especially noteworthy. TradeInternal trade

Intra-African trade records frequently understate the amount of trade�partly because of the lack of adequate statistics and partly because of the high rate of smuggling, which allows a substantial amount of traditional border trade to continue unrecorded. Apart from this, commerce between African states has been handicapped by a tendency for trade to remain concentrated within the common-currency areas and trade zones that developed among African countries during the colonial era, by the often inadequate means of transport and communication, by the lack of complementary agricultural or other products, and by the limited development of manufacturing industries.

Much of the intra-African trade consists of consumables�food, drinks, tobacco, sugar, cattle, and meat. The growth of industrialization in some countries, however, has been accompanied by an increase in the trade of durable and nondurable manufactured goods. There has also been a large amount of reexport trade between the coastal and inland states, especially in machinery, transport equipment, and spare parts.

Common-currency and trade zones that have evolved through the granting of preferences or the operation of common currencies inherited from former colonial powers include: the Economic and Monetary Community of Central Africa (CEMAC), which comprises Cameroon, Gabon, the Central African Republic, Equatorial Guinea, Chad, and the Republic of the Congo and is part of the larger Economic Community of Central African States (CEEAC), which also includes Angola, Burundi, the Democratic Republic of the Congo, and Sao Tome and Principe; the Economic Community of West African States (ECOWAS), consisting of Benin, Burkina Faso, Cape Verde, C�te d�Ivoire, The Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Niger, Nigeria, Senegal, Sierra Leone, and Togo; the Common Market for Eastern and Southern Africa (COMESA), consisting of Burundi, Comoros, the Democratic Republic of the Congo, Djibouti, Egypt, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Malawi, Mauritius, Rwanda, Seychelles, Sudan, Swaziland, Uganda, Zambia, and Zimbabwe; the East African Community, comprising Kenya, Uganda, Tanzania, Rwanda, and Burundi; the Southern African Development Community (SADC), comprising Angola, Botswana, the Democratic Republic of the Congo, Lesotho, Madagascar, Malawi, Mauritius, Mozambique, Namibia, Seychelles, South Africa, Swaziland, Tanzania, Zambia, and Zimbabwe; and the Arab Maghreb Union (UMA), grouping Algeria, Libya, Mauritania, Morocco, and Tunisia. External trade

Since the outbreak of World War II there has been a considerable expansion in Africa�s overall external trade. The growth compares favourably with that of the other developing regions, such as Latin America. The value of imports, however, has outweighed exports for some time, resulting in huge trade imbalances for most African countries. The large expansion in African exports is generally attributed to the increase in the demand for primary commodities during World War II and in the immediate postwar reconstruction period. Subsequently the attainment of independence by a large number of African countries, especially in the early 1960s, followed by a bid for economic development, strengthened the export-expansion drive. Another reason for the rapid growth in African exports was the temporary increase in the price of primary commodities, although subsequently the general trend, except for petroleum, has been toward depressed commodity prices. The persistence of this situation has been part of the reason the economies of many African countries have become crippled by huge foreign debts. Exports

An important factor that influenced the growth of African exports was the discovery of petroleum in several countries, notably Libya, Algeria, Nigeria, Gabon, Angola, the Republic of the Congo, and Cameroon, and the dramatic price increases brought about by the Organization of Petroleum Exporting Countries (OPEC) in the 1970s. Other factors include the discovery and the increased exploitation of minerals that are in high demand, such as diamonds�especially in Sierra Leone, the Republic of the Congo, the Central African Republic, and the Democratic Republic of the Congo�and the exploitation of other minerals, such as uranium ore.

Since achieving independence, many African countries have made attempts to diversify external trade relations. The record of achievement has been poor, however, because Africa�s trade patterns continued to reflect the influence of traditional links with the countries of western Europe. These links were further consolidated through a series of agreements, collectively called the Lom� Conventions, that guaranteed preferential access to the European Economic Community (precursor to the European Community and, later, the European Union) for various export commodities from African states and that provided European aid and investment funding. Nonetheless, a significant export trade developed with the United States and Japan.

In most African states one or two primary commodities dominate the export trade�e.g., petroleum and petroleum products in Libya, Nigeria, Algeria, Egypt, Gabon, the Republic of the Congo, and Angola; iron ore in Mauritania and Liberia; copper in Zambia and the Democratic Republic of the Congo; cotton in Chad; coffee in Burundi, Uganda, Rwanda, Ethiopia, Madagascar, Kenya, and C�te d�Ivoire; and sugar in Mauritius. Imports

The tremendous increase of Africa�s import trade has meant that the import bill of most African states has exceeded their export earnings; in consequence, many governments have established import restrictions or subsidized many of the required imports. The bulk of imports comes from western Europe, especially countries of the European Union, with strong trade ties persisting along former colonial lines. There has, however, been a substantial increase in imports from the United States, Japan, and South Africa. Imports are needed primarily to develop manufacturing industries and are, therefore, confined for the most part to mineral fuels, industrial goods, machinery, transport equipment, and durable consumer goods. Transportation

There were highly developed transport networks in many parts of Africa in precolonial times, and, during the colonial era that followed, these networks were restructured to penetrate into the interior from the seaports and, in the main, to serve the commercial and administrative needs of the colonial powers. Their fragmentation, which led to interregional links being but thinly developed, resulted from the juxtaposition of varied and difficult terrains, the economic artificiality of certain national frontiers, the lack of a developed intra-African trade, and the strong orientation of commodity trade with the administering countries. All of this was further complicated by the existence of vast unpopulated areas lying between the main centres.

The emergence in the 1960s of independent African governments who recognized the need to lift economies from their generally very low levels and, above all, to develop agriculture and embark on industrialization heralded improvements in economic planning, the development of transport networks, and the introduction of cheaper freight rates. But there remained a serious shortage of qualified African labour to plan and manage transport systems at the national or multinational level and, simultaneously, to keep up with the rapid development of transport technology outside Africa. Animal transport

There is some evidence that before the arrival of the camel, which was introduced into Africa via Egypt at the time of the Arab conquest, bullocks were used either as pack animals or to draw carts from the northern countries across the Sahara to the gold-producing areas of the ancient Sudan. From the 16th century onward the Portuguese developed transport inland from the coast at Mozambique, and from the 17th century first the Dutch and then British settlers from the Cape trekked northward and northeastward with their wagons. Except in such highland areas as Ethiopia, where pack animals were and still are used, the tsetse fly often prevented the use of animal transport. With the steady progress in the development of transport infrastructure in many African countries, the use of bullocks in Southern Africa, donkeys in western and North Africa, horses in northern Nigeria, and camels in western and North Africa and the Horn of Africa has been reduced, but the extent of this reduction cannot be accurately gauged. Motor transport

The arrival and rapid development of the internal-combustion engine in the 1920s transformed the collection and distribution of goods and personal travel. Roads were built, particularly in North and Southern Africa but also in parts of the west and east. World Bank loans since the 1950s, supplementing contributions to road and highway development from national budgets, have financed the building and improvement of road networks in many African countries. Rail transport

The early railways were constructed partly to facilitate the administration of interior regions and to bring supplies from ports to central consumption or distribution points and partly�especially in the south�to enable valuable minerals or commodities to reach the coast for export. In Africa, as in Europe and North America, the major period of railway development extended from the end of the 19th century to the end of World War I. This expansion, however, was not coordinated: railways with different gauges of track were built and were operated with rolling stock of different braking and coupling systems. Thus, the colonizing powers left a difficult and costly legacy for independent African countries who wished to link themselves together. As with roads, rail networks have been improved considerably since the 1960s and, as a result, there has been a lowering of transport costs. Air transport

Air transport is well suited to Africa�s geographic vastness, and it has become the primary means of international and sometimes of national travel in Africa. During the late 1940s and the �50s, as great advances were made in the extension and improvement of rail and road services, a new transport factor emerged in the introduction of internal and international scheduled air services. The rapid development of air transport increased the movement of goods and people and began to open up the hitherto largely closed interior of the continent. Transport became much quicker and usually cheaper. Since then, internal air services have steadily increased, and intercontinental air transport, especially of passengers, has developed greatly. The largest international airports include those at Casablanca, Morocco; Las Palmas, Canary Islands; Cairo, Egypt; Dakar, Senegal; Abidjan, C�te d�Ivoire; Lagos, Nigeria; Douala, Cameroon; Addis Ababa, Ethiopia; Nairobi, Kenya; and Johannesburg, South Africa. Navigation

Historically, throughout the vast interior between the Sahara and the Zambezi River, people or goods were transported by canoe or boat on the great river systems of the Nile, S�n�gal, Niger, Congo, Ubangi, and Zambezi rivers and on the few but very large lakes. Where conditions allowed, engine-powered craft later supplemented or displaced canoes, but further development of water transport has been slight. Also notable were the construction of lake ports and the installation of rail ferries across Lake Victoria.

Meanwhile, on the coasts, artificial harbours have been developed. New berths have been added to established port facilities, and a number of ports have been constructed. In planning new ports, the choice of site, probable costs, and the possibilities of using containers or other unitized loads have been taken into consideration. Robert K.A. Gardiner Akinlawon Ladipo Mabogunje