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George Peter Murdock
1897 — 1985

Professor of Anthropology, Yale University

Africa. Its Peoples and Their Culture History

New York. McGraw-Hill. 1959. 456 p.

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Explore also (a) the SemanticAfrica Peoples Vocabulary
(b) the Nilotes mind-mapping diagram

Part Nine
East African Pastoralism
— 43 —

At approximately the same time as the Eastern Cushitic peoples were evolving an independent pastoral mode of life, a parallel development was taking place to the west of them among the egroes of the tall, slender subrace known as the Nilotes (see Chapter 2). These people today occupy a large territory extending from the border of Kordofan in the northwest through southern Sudan, northern Uganda, and western Kenya to northern Tanganyika in the southeast, and from the edge of Ethiopia in the northeast to the border of the Belgian Congo in the southwest (see Map 15). They have had an extremely complex history, which will become more readily understandable if we begin with a linguistic and cultural classification of their component tribes.
All the Nilotes speak languages of the Eastern subfamily of the Sudanic stock. A few tribes in the northeast, on and near the Ethiopian border, belong to the Beir branch of the Eastern Sudanic subfamily and are therefore segregated from the rest as the Beir cluster. All other groups belong to the Nilotic branch of the same subfamily. The Nilotic languages proper fall into two subdivisions, of which one, called “Great Lakes” by Greenberg but “Nilo-Hamite” by most other authorities, differs from the other in reflecting an obvious Cushitic influence. Since the present writer dislikes geographical terms for language groupings and considers the term “Nilo-Hamitic” a linguistic monstrosity, he finds both names unacceptable. He prefers to call both groups Nilotes and to distinguish the one from the other, where necessary, as the “Cushitized Nilotes,” since they are characterized as strongly by cultural as by linguistic borrowings.
The Cushitized groups lie mainly in the east, where three distinct clusters are distinguishable, namely, from north to south, the Karamojong, Nandi, and Masai clusters. A fourth, or Bari, cluster extends westward and separates the tribes that reveal little Cushitic influence into a northern, or Dinka, and a southwestern, or Luo, cluster.

Beir Cluster

This cluster occupies the relatively inhospitable lowlands adjacent to the Sidamo peoples of southwestern Ethiopia. Its tribes exhibit a number of specific borrowings from the latter but seem otherwise to have remained comparatively static. They practice aariculture where geographic conditions permit but elsewhere are predominantly pastoral.

  1. Didinga (Birra, Dodinga, Karoko, Toi). This group, whose population is variously estimated at from 10,000 to 25,000, leads a seminomadic existence with seasonal migrations.
  2. Murie (Ajiba, Beir, Irenge, Merule, Mourle, Murule), embracing the Epeita (Boma, Epeta, Kapera), Longarim (Boya), and Pibor. They number about 30,000 and are seminomadic.
  3. Nyangiya (Nangiya), with the Arom and Niporen (Napore, Ngitaio, Nyipori). The specific linguistic affiliations of this sedentary group, numbering about 3,000, are as yet unknown.
  4. Suri (Churi, Dhuak, Dhuri, Dzuak, Kachipo, Kachuba, Kichepo, Ngachopo, Shuri, Thuri), with the Mekan (Men, Micken, Tishana), Murzu (Dama, Merdu, Meritu, Mourse, Murdhu, Muriru, Mursi, Mursu, Tama, Tdama), and Surma (Karoma, Korma, Makurma, Mokurma, Mursia, Nikorma, Nyikoroma). The Tid (Chach, Dolot, Tod), Tirma (Chima, Cirma, Dirma, Terema, Terna, Tilma, Turmu), and Zilmamu (Tsilmanu, Zelmamu, Zulimamu) are subtribes of the Surma. Tlus group, numbering about 25,000, subsists primarily by agriculture, with some terraced-field cultivation.

Dinka Cluster

In the northeast the peoples of this cluster adjoin the Anuak, Meban, and Shilluk tribes of the Prenilote province, to whom they are both linguistically and culturally akin. They differ, however, in being primarily pastoral rather than agricultural and in lacking the complex political institutions of the Prenilotes.

  1. Dinka (Denkawi, Jang) . Together with the Padang, they number about 500,000.
  2. Jur (Djur, Gour, Luo, Lwo), with the Bor (Baer, Behr, Boor, Mberidi, Mverodi), Dembo (Bodho, Bwodho), Fujiga, Kamum, Manangier (Manangeri), Shatt (Cat, Thuri), and Shilluk-Luo. This group, numbering about 20,000, subsists largely by agriculture today. It was shattered, dispersed, and depopulated by Azande invasions and Arab slave raids during the nineteenth century.
  3. Nuer, with the Atwot. They number about 300,000.
  4. Padang. They are a detached branch of the Dinka, from whom they separated about two centuries ago.
  5. Pari (Beri, Berri, Bori, Fari, Feri, Fori). These people, numbering about 7,000, are a branch of the Anuak, from whom they split off about ten generations ago.

Luo Cluster

The tribes of this cluster, who subsist primarily by agriculture, inhabit northern Uganda, but the Alur extend into the Belgian Congo and the Luo into Kenya.

  1. Acholi (Atscholi, Gan, Gang, Mandschuru, Shuli). They number nearly 250,000.
  2. Alur (Aioro, Alua, Alulu, Lour, Lur, Luri). They number about 200,000.
  3. Labwor (Tobur). They number about 5,000 and are closely akin to the Acholi.
  4. Lango (Umiro). They number about 275,000 and are about equally agricultural and pastoral.
  5. Luo (Jaluo, Luwo, Nilotic Kavirondo, Nyifwa), with the detached Gaya (Girange, Vageia) and Jopadhola (Dama). They number about 800,000.

Note. Tom Mboya (1930-1969), a leading independence activist, and one of the founding fathers of the Republic of Kenya, former U.S. President Barack Obama, actress Lupita Nyong'o, among others, are of patrilineal Luo descent. Tom Mboya organized the 1960s “airlift” program which allowed hundreds of Kenyan students to enroll at American universities; the recipients included Barack Hussein Obama, Sr., Wangari Maathai (1940-2011), environmentalist and Nobel Peace Prize laureate, etc. (Source: David Remnick. The Bridge: The Life and Rise of Barack Obama., New York, 2010) — T.S. Bah

Bari Cluster

These tribes, wedged between the Dinka cluster on the north and the Luo cluster on the south, extend into the Belgian Congo. In addition to being Cushitized, they reveal considerable intermixture with, and acculturation to, their Central Sudanic neighbors on the west.

  1. Bari. These people, numbering about 35,000, were primarily pastoral until Arab depredations in the nineteenth century fo rced them into greater dependence upon agriculture.
  2. Fajulu (Fagdelou, Fajelu, Fedgelu, Pojulu), with the Kakwa (Kakuak), Ligi, and Nyangbara (Nyambara). They number about 90,000 and are primarily agricultural.
  3. Kuku, with the Nyepu (Nieffu). This tribe, numbering about 30,000, is predominantly agricultural.
  4. Loruko (Laruka), with the Koriuk, Lafit (Lofit, Lopit), Lango, Lokoiya (Leria, Oghoriok), Lomya, and Lowudo (Laudo). In this group, numbering about 70,000, agricultural and pastoral activities are evenly balanced.
  5. Mondari (Mandari, Mundar), embracing the Bori, Boronga (Tali), and Sere (Kir, Shir). This group, numbering about 36,000, was predominantly pastoral until the Arab depredations of the nineteenth century.

Karamojong Cluster

This Cushitized group resides east of the Bari and Luo clusters in northwestern Kenya and an adjacent strip of Uganda. Most have pastor al economies characterized by transhumance. Among them live a few Teuso r emnants of the indigenous hunting population.

  1. Jie (Ajie, Egye, Giye, Gye, Jibbeh, Jiwe, Jiye, Kum, Kumi, Negye, Ngie, Nigye, Njie), with the Dodoth (Dodoso). They number about 40,000.
  2. Karamojong, with the Tepes (Entepes, Tepeth). They number about 60,000.
  3. Teso (Bakedi, Bateso, Iteso, Kedi, Kedo, Kidi, Wakedi), with the kindred Kumam (Akum, Ikokolemu, Lango) and Itesyo (Elgumi, Wamia). They number about 560,000.
  4. Topotha (Dabosa, Tabosa, Taposa), wirh the Donyiro (Burna, Burnie, Dongiro, Idongiro, Iynahatom, Nyangatom, Orogniro), Jiye, and Magoth (Magois, Magos). They number about 45,000.
  5. Turkana (Elgume), witt the Ngamarak, Nibelai (Billai, Ngebellai), and Nittir (Nyissir). They number about 80,000.

Nandi Cluster

This strongly Cushitized group lives in the mountainous section of western Kenya northeast of Lake Victoria and on the slopes of nearby Mount Elgon. Except for an occasional subtribe living in an unfavorable habitat, all its members practice an intensive agriculture, characterized in some places by irrigation on terraced mountain slopes. Most of them reveal evidences of admixture with a Caucasoid racial element.

  1. Keyu (Flgeyo), with the Kamasya (Tuken). They number about 110,000.
  2. Kipsigi (Lumbwa, Sikisi), with the kindred Buret and Sotek. They number about 160,000.
  3. Nandi, with the Terik (Nyangori, Tiriki). They number about 115,000.
  4. Sabei (Basabei, Mbai, Sabaot, Sapaut, Sapei), with the Bambe, Kipsorai (Kipsorak, Sore, Sorek), Kony (Eigonyi), Ngomakek (Wangoma), and Pok (Lako, Walako). They number about 50,000.
  5. Suk (Bawgott, Pakot, Pokot, Pokwur, Sukku), with the Endo (Chebleng, Ndo), Kadam (Debasien), and Marakwet (Maragwetta). They number about 90,000, of whom the central core are sedentary tillers in the hill country. To the east and west of these live about 40,000 pastoral nomads, the Plains Suk.
  6. Tatoga (Oatoga, Mangati, Taturu), with the Barabaig. This detached group, shattered in wars with the Masai, live in northern Tanganyika. They number about 20,000 and were primarily pastoral until their dispersion.

Masai Cluster

These Cushitized people reside east of the Karamojong and Nandi clusters and extend southward across Kenya into northern Tanganyika, where they form a wedge deep into Bantu territory. Except for the Arusha and small dispossessed groups elsewhere, they subsist exclusively by animal husbandry. Scattered among them, as well as among the adjacent Nandi, live the Dorobo, a remnant group of hunters and gatherers.

  1. Arusha (Warush). Numbering about 62,000, they resemble the Masai except for their dependence upon agriculture.
  2. Masai (Massai), with the dispersed Kwafi (Kuavi) and Lumbwa (Bumba, Ilumpua). They number in excess of 100,000.
  3. Samburu (Sambur), with the Elburgu, Elmolo (Ngaboto), Leikipiak (Koikop, Leikipia, Leukop, Oikop), Mogogodo (Mokogodo), and Njamus (Eljemasi, Enjemasi, Iltiamus, Njemps). Closely akin to the Masai, this group numbers about 12,000 today but was formerly much more numerous.

The linguistic and cultural distributions summarized above, coupled with the various fragments of other evidence presented in earlier chapters, enable us to reconstruct the culture history of the Nilotic province with a fair degree of assurance. We shall attempt to tell a connected story without belaboring the obvious fact that parts of it are highly tentative.
Prior to the introduction of agriculture, the eastern and southern portions of the province were occupied by Bushmanoid hunters with cultures of the Stillbay type, and the northern and western portions by Negroid peoples who also were still at the hunting and gathering level of economic development. The Negroes almost certainly spoke languages of the Sudanic stock—Eastern Sudanic in at least the northeastern fringe of the area now occupied by the Dinka cluster, and Central Sudanic in at least the present territory of the Bari cluster. Bushmanoids inhabited the country of the present Beir, Karamojong, Masai, and Nandi peoples. The precise boundary between the Negroid and Bushmanoid hunters must await determination through archeological research.
Sometime around 3000 B.C. Sudanic agriculture, diffusing eastward, reached the northern border of the province, where the adjacent and kindred Prenilotes, as we have seen (Chapter 21), transmitted it to highland Ethiopia. It doubtless penetrated the northern part of the Nilotic province to a certain extent, and it almost certainly enabled the Beir linguistic group to expand eastward into former Bushmanoid territory as far as the edge of the Ethiopian plateau. Diffusion to the south, however, may well have proceeded only gradually, partly because of the unfavorable character of much of the terrain and partly because of the unsuitability of the West African crops to low latitudes and high humidity. Indeed, the dominant position held by durra and eleusine in the present roster of food plants suggests that agriculture may actually first have reached many parts of the province from Ethiopia rather than from the northwest.
Archeological and other evidence already adduced (Chapter 25) shows that, by about 1000 B.C., Megalithic Cushites had descended from the Ethiopian highlands into favored sections in the east of the province, especially in the present territory of the Nandi cluster, and that a Sidamo people, at an as yet undetermined date, similarly moved southwest across the province into Uganda. We may reasonably ascribe to them the introduction of the Ethiopian food plants.
A century or two before the advent of the Christian era, the Malaysian crops acquired by the Cushites on the Azanian coast passed westward through Uganda and the Central Sudanic province (see Chapter 28). They exerted only a modest effect on Nilotic culture, however, although the tribes of the Luo and Bari clusters still cultivate them to a limited extent.
Five or six centuries after the time of Christ the Bantu, having wrested the tropical-forest region of the Congo Basin from the Pygmies, arrived in Uganda and encircled Lake Victoria, completely occupying its shores. The account of their conquest and its results will receive our attention in Chapter 45. What is important in the present connection is that the people they found in possession of the country were not Nilotes of the Luo cluster, who hold portions of it today, but Cushitic descendants of the Sidamo immigrants. At this period the Nilotes seem to have been a relatively backward agricultural people occupying only a fraction of their present territory. In the entire eastern section, the present habitat of the Karamojong, Nandi, and Masai groups, there still lived only Bushmanoid hunters and, in well-watered districts, dispersed settlements of Cushitic tillers.
Within two or three centuries, however, the Nilotes had developed a full-fledged pastoral complex, which they could either combine with their traditional agricultural pursuits or detach from the latter and practice independently where the geographic environment did not permit extensive cultivation. Whether they made the discovery by themselves or borrowed it from the Eastern Cushites or from the Beja by way of the Prenilotes we do not know. We assume, however, that it depended upon the late acquisition of the technique of milking their domestic animals.
Once the Nilote had learned to subsist primarily by pastoral nomadism with only auxiliary dependence upon agriculture, they expanded with explosive force. They marched southward and occupied all the territory now held by the Dinka and Luo clusters, probably wresting much of it from their Central Sudanic cousins, and they even penetrated Bantu country on the northeastern shores of Lake Victoria. The powerful states of the Interlacustrine Bantu, however, blocked their further progress southward and deflected them to the southeast, where they infiltrated the territory of the Megalithic Cushites, who were politically less well organized. With their superior economic adjustment the Nilotes easily wrested the uncultivated savanna country from the Bushmanoid hunters, leaving only the Dorobo and Teuso as vanishing remnants. They encircled and engulfed the scattered agricultural settlements in the mountainous sections, intermarried with the Cushitic tillers there, and in time largely absorbed them. There thus resulted a mixed population speaking a Nilotic language with strong Cushitic increments and exhibiting a culture which combined ilotic and Cushitic elements. Those of Cushitic derivation predominate today in the hilly and more strongly agricultural regions, notably the area inhabited by the Nandi cluster. Elsewhere, as in the Karamojong and Masai regions, Nilotic physical and cultural traits prevail more strongly, although the language has become unquestionably Cushitized.
The Bantu, who had previously replaced the Megalithic Cushites in southern Kenya, here lacked the military and political strength of their cousins in Uganda and were thus no better prepared than the Cushites to withstand the aggressive Nilotes, whose spearhead, the Masai, had penetrated well into Tanganyika by the time the first Europeans arrived in East Africa. One group of the Cushitized Nilotes reversed their course and moved westward across Uganda into the country previously occupied by the Central Sudanic peoples. Merging with the latter as they had previously done with the Cushites, they produced there the mixed population and culture of the Bari cluster.
In summary, the Negroid Nilotes and Bantu have constituted, respectively, the upper and nether millstones that in the last millennium or so have crushed and obliterated the Caucasoid Cushites of theMegalithic branch who had previously dominated much of northeastern Africa and had played there a culture-historical role of the utmost significance. Recent European settlement in highland Kenya may thus be regarded as a relatively feeble, and perhaps temporary, reversal of a long historical trend.
Nilotic agriculture consists primarily in the cultivation of cereal grains, with sorghum of the durra variety, eleusine, and millet, in this order, ranking as the staples. The more strongly pastoral tribe grow little else, but those that depend substantially on tillage supplement the African cereals with ambary, cotton, cow peas, earth peas, gourds, okra, and se ame from the Sudanic complex; gram beans, hemp, hyacinth beans, Jew's mallow, and pigeon peas from the Indian complex; bananas and yams from the Malaysian complex; and cucurbits, maize, manioc, peanuts, sweet potatoes, and tobacco from the merican complex.
Animal husbandry ranks on a parity with, or surpasses, agriculture everywhere except in the Luo cluster and among the Teso. The principal domesticated animals are cattle, goats, and sheep, though dogs are widely used for hunting. Most group also keep chickens, and cats and bees occur sporadically. The tribes of the Beir, Karamojong, Masai, and Nandi clusters keep donkeys. Camels, introduced about a century ago, are reported for the Karamojong, the Suk, and epecially the Turkana. Milk constitutes a dietary staple in nearly all groups. Most of them also make butter, and the Bari and Fajulu prepare a kind of cheese. The peoples of the Masai and Nandi clusters observe dietary regulations, forbidding the consumption of milk and meat on the same day. Since we shall find this custom again among some of the Interlacustrine Bantu, it may well reflect an ancient Cushitic practice. All the eastern peoples—those of the Beir, Karamojong, Masai, and Nandi clusters—drink quantities of fresh blood drawn from the necks of their cattle by means of a miniature arrow. This specifically Cushitic custom also appears, though only sporadically, among the tribes of the Bari and Dinka clusters in the northwest.

Masai Drawing Blood from a Cow's Neck with a Miniature Arrow.
Masai Drawing Blood from a Cow's Neck with a Miniature Arrow.
(Courtesy of British Information Services.)

Masai Dwelling and Its Equipment
Masai Dwelling and Its Equipment.
(Courtesy of British Information Services.)

Hunting and gathering, though rarely important, often add a modest supplement to the daily fare, as does fishing among the Murle and Suri and many tribes of the Bari, Dinka, and Luo clusters. The Didinga tribe and all members of the Karamojong, Masai, and Nandi groups, however, observe the characteristic Cushitic taboo against eating fish. Only the Suri have developed commerce to any considerable extent, trading lion and leopard pelts, ivory, honey, and slaves to the highland Ethiopians.
The men do the hunting, fishing, and land clearance. They also perform all agricultural work among the Tatoga, but this task is shared by both sexes among most tribes of the Dinka and Luo clusters and is assigned mainly, and sometimes exclusively, to women everywhere else. Sex participation in milking reveals an interesting regional contrast. Women do all or most of the milking in the Dinka, Karamojong, Masai, and Nandi clusters as among most North and East African pastoralists, notably the Arabs, the Berbers, and the Afar, Galla, and Somali. Among the Didinga and all tribes of the Bari and Luo clusters, on the other hand, cattle are strictly taboo to adult women, and only men and children can milk. We have hitherto encountered the assignment of milking to the male sex only among the Beja and the Central Sudanic peoples. Since the latter are immediate neighbors, we can reasonably ascribe to them the origin of the ritual separation of women and cattle. This could have been acquired by the invading Bari peoples, who coalesced with them, and then transmitted to the neighboring Luo cluster and thence to the adjacent Interlacustrine Bantu. In any event, the widespread assumption that this taboo is a “Hamitic” trait lacks any factual support.
Marriage everywhere in volves a substantial bride-price in livestock, and in the Bari and Beir clusters usually a period of agricultural bride-service as well. Incest taboos prevent unions with any first cousin and commonly also with remoter relatives. General polygyny revails, nearly always in the nonsororal form, and each wife is established in a separate dwelling. Though residence is uniformly patrilocal, the Lotuko and Nuer commonly observe an initial matrilocal period. Small extended families occur in the majority of tribes, but independent polygynous families predominate in the Masai and Nandi clusters.
Descent is invariably patnlineal, with segmemary lineage systems among at least the Luo, Mondari, Nuer, and Tatoga. Exogamy extends to all members of the father's patrisib in all tribes except the Kipsigi and Nandi, and in most groups to the mother's sibmates as well. Localized clans tend, in general, to be present in the western clusters but absent in the eastern ones. Cousin terminology conforms basically to the Omaha pattern among the Acholi, Bari, Lango, Masai, Nandi, and Suk; to the Iroquois pattern among the Kipsigi and Lotuko; to the descriptive pattern among the Dinka, Luo, Nuer, and Turkana; and to the Hawaiian pattern among the Teso.
The Masai and Samburu tribes are full nomadic and wander in bands throughout the year. The Didinga, Mondari, pastoral Suk, Tatoga, and most tribes of the Dinka and Karamojong clusters are seminomadic, living in temporary camps only during the dry season. Although the Acholi, Labwor, Lango, Pari, and the tribes of the Beir cluster inhabit compact and usually stockaded villages, the prevailing settlement pattern, among seminomadic and sedentary peoples alike, is a neighborhood of dispersed homesteads or small hamlets, each surrounded by a fence, a thorn hedge, or a palisade. Dwellings characteristic of adjacent areas have penetrated a few of the marginal tribes, notably the central Tanganyikan tembe among the Tatoga and the beehive hut of the Interlacustrine Bantu among the southeastern Alur and formerly among the Teso, but two other house types dominate the area as a whole. Round huts with conical thatched roofs and walls of wattle and daub prevail in the Bari, Beir, Dinka, Luo, and Nandi clusters and in the permanent settlements of some of the Karamojong tribes. In the temporary camps of the Nuer and of all tribes of the Karamojong cluster and in the wet-season settlements of some of the latter, however, the house type approaches that of the pastoral Galla and was probably borrowed from the preexisting hunting population. Hemispherical in shape, it consists of a frame of bent poles fastened together at the top and covered with interlaced branches, grass, reed mars, or skins. The dwellings of the Masai represent a variant of this pattern; they are elongated rather than round, and both top and sides are smeared with a mixture of mud and dung.
Exceptfor wealth distinctions, inevitable among people for whom livestock are so important, the Nilotes are remarkably egali tarian. They completely lack any hereditary aristocracy, and even slavery occurs only among the Dinka, Jur, and Padang of the Dinka cluster and the Alur, Lango, and Teso of the Luo cluster. Most tribes of the Bari group, however, have a class of hereditary serfs, called dupi. These are of alien stock and are presumably descended from the subjected Central Sudanic indigenes of the region. Depressed and endogamous castes of smiths occur throughout the Bari, Masai, and andi clusters of Cushitized Nilotes, and hunters constitute a comparable group among the Bari, Masai, and Suri.
No Nilotic people has a complex political organization. A handful of tribes, notably the Alur, Labwor, and Suri, acknowledge perry paramount chiefs over small districts, but the rest reveal no secular integration transcending the level of the village or neighborhood. A fair number of these, however, have ritual experts who exert an influence over a group of neighboring settlements, notably rainmakers in the Bari cluster and diviners capable of predicting success in offensive warfare among the tribes of the Masai and Nandi clusters. Particularly interesting in this category are the spear chiefs of Dinka subtribes. These act as rainmakers, sacrificial priests, and peacemakers in feuds. Each possesses special insignia of office, such as a stool, a string of ostrich-eggshell beads, and a sacred war spear. Like the divine kings of the hilluk, of whom their status is clearly a pale reflection, the spear chiefs are ceremonially killed when too old to perform their ritual functions.
The Cushitic practices of circumcision and clitoridectomy have spread only to the Masai and Nandi clusters. With occasional exceptions, all othe tribes adhere to the ancient initiatory rite of the Sudanic-speaking peoples and extract the two lower front incisor teeth in one or both sexes. The Masai peoples, indeed, have not abandoned this custom despite their adoption of genital mutilations. either cannibalism nor headhunting occurs among the Nilotes.
Organized age-grades constitute the most distinctive feature of Nilotic social organization and are lacking only in the peripheral Alur, Fajulu, Jur, Kuku, and Luo tribes. Despite differences, all systems have in common the fact that they are entered by initiation, usually during adolescence, and that the boys or young men who are initiated together form a closely knit age-set. In nearly all of them, moreover, initiations occur at specified intervals, normally ranging from four to ten years, and one or more sets, forming an age-grade, constitute the warrior class of the society. The great majority of tribes have grades of the linear type, which succeed one another indefinitely. The tribes of the Nandi cluster, however, resemble the Galla and the Megalithic Cushites in possessing age-grades of the cycling type. In a cycling system there are a limited number of named grades, and when the last grade is preempted, the next one takes again the name of the first in the series.
A relatively simple type of linear system occurs widely in the Bari, Beir, Dinka, and Luo clusters. Here the age-set and the age-grade are commonly identical. A new set is formed most typically every fourth year, though the interval is six years among the lurle and ten among the Acholi, Nuer, and Suri. From one to fom of the junior sets form the society's body of warriors. A number of tribes, e.g., the Didinga and Murle, do not allow a man to marry until his age-set either has attained the status of senior warriors or has graduated to the status of elders.
The Masai have a somewhat similar system but with a normal interval of fifteen years. During this time there are two periods, of four to six years each, during which boys may be circumcised; when they subsequently enter the grade of junior warriors, they form a “right-” and a “left-hand” division thereof. Promotion of the preceding age-set to the grade of senior warriors does not occur, however, until several years later, and in the meantime members of two completely different age-sets occupy the same grade. After about fifteen years as enior warriors, an age-set advances to the status of junior elders; after fifteen more, to that of senior elders; and so on at like intervals as long as the set has living members. Between circumcision and their formal initiation as junior warriors, boys wander in bands all over the Masai country. After initiation they sleep in special bachelor huts with the unmarried girls. Only when thhey become senior warriors are they permitted to marry.
The pastoral Suk and the tribes of the Karamojong cluster reveal a still more complex type of linear system, of which that of the Jie may serve as an example. Here an age-grade is composed exclusively of men of the same genealogical generation. Each grade is divided into about three ageclasses, and each class into three or four age-sets. A new age-set is initiated every one to three years, but no man may be initiated until all those senior to him, according to a strict traditional definition of seniority, have already entered an age-set. In the most favorable case he will be eighteen or twenty years of age when he becomes eligible, but he may be as old as forty. When all the men of a generation have finally been initiated, they are formally constituted into an age-grade by the surviving oldsters of their grandfathers' grade, and the sets of the new grade are grouped into classes on the basis of relative age. One man in each grade inherits from his paternal grandfather the title of chief of his generation for the entire Jie tribe.
All the tribes of the Nandi cluster except the pastoral Suk and the Tatoga possess systems of the cycling type, of which that of the Kipsigi may be taken as representative. Seven named age-grades succeed one another in regular rotation every fifteen years, a single full cycle being completed every 105 years. Initiation into an age-set, however, occurs every fifth year, three such se ts forming a grade. The junior grade at a given time constitutes the warriors o f the society. Every fifteen years the warriors as a body advance to the status of elders, and the first set of the next warrior grade is initiated. Whatever his actual age, however, no man can enter the warrior grade until his father graduates from the status of elder to that of an old man, i.e., thirty years later. As among the Masai, the warriors live apart in special bachelor houses, where they are visited by the uninitiated girls.
The Nilotes unquestionably acquired their age-grade systems through fusion with, or imitation of, the Eastern Cushites. The reason for the spread of these systems must lie in their survival value. They clearly promoted military strength and social integration and thus doubtless served to offset in large measure the disadvantages inherent in a minimal development of political organization.

Selected Bibliography