Les grands voyages et les transferts intercontinentaux de plantes cultivées ont eu des répercussions extrêmement importantes sur le développement des civilisations par action directe sur la prospérité de leurs agricultures et sur leurs régimes alimentaires. Il n'est que de rappeler le rôle joué par la Pomme de terre dans les pays tempérés et par le Maïs dans la zone chaude, rôle de briseurs de famine et de disette.

After the end of the Pleistocene, sub-Saharan Africa seems to have been more receptive of than contributory to cultural progress in the Old World as a whole. By that time favourable localities in the subcontinent—the margins of lakes and watercourses, the sea coasts, the peripheral regions of the equatorial forest—were sometimes supporting nearly, or entirely, sedentary communities of hunting-collecting peoples who were enabled to live in this way due to the permanent presence of one or more staple sources of food: freshwater fish, water animals and plants, and sea foods; and forest foods (the Dioscoreas, Elaeis guineensis, and other oil-bearing plants), either perennial or capable of being stored. Evidence of such occupation is seen in the midden accumulations in both cave and open sites at this time. Populations could thus become more concentrated and an increase in density may be inferred, the limiting factor being the maximum that any one environment could support by intensified collecting methods (fig. I).

In his book, Africa; its peoples and their culture history, ethnographer G. P. Murdock has undertaken a tremendous interpretive task based upon a survey of the literature. Of consequence here is his thesis that

… agriculture was independently developed [at about 5000 B.C.] by the Negroes of West Africa. This was, moreover, a genuine invention, not a borrowing from another people. Furthermore, the assemblage of cultivated plants ennobled from wild forms in Negro Africa ranks as one of the four major agricultural complexes evolved in the entire course of human history … The invention of agriculture in Negro Africa is most probably to be credited to the Mande peoples around the headwaters of the Niger in the extreme western part of the Sudan, less than 1,000 miles from the shores of the Atlantic Ocean.

A recent generalization on cropping and cultivation in Africa reduces the variety of environmental types to two: ‘savannahs’ and ‘forest and woodland’. Another work simplifies West African anthropology by introducing two regions linguistic in origin: the West Sudan and the Guinea Coast. The latter, misleadingly shown as the western portion of a ‘yam belt’ or ‘corridor’, includes the ‘forest’ and a small southern portion of the ‘savannah’. Such regional generalizations invite critical assessment of the relationships displayed between crops, agriculture and the environments. It is proposed to take one of these last as termed above: the ‘forest and woodland’.

The Occupation of the earth by Man has always been limited and conditioned by the natural environment of the various climatic zones he inhabits. Modern technology is giving him an increasing control over that environment, but in most parts of Africa, where the results of this control are only beginning to become significant, the influence of the factors of natural environment are still very apparent in the patterns of human settlement and history. The waterless desert is still an almost impossible human habitat, and the tropical forest, where the lush vegetation inhibits agriculture and pests and parasites endanger the life of Man and his domestic animals, has been colonized cautiously and frequently only under pressure.

The conservation and study of the variation in indigenous crop plants is an integral part of a crop improvement programme. Investigation of the manner in which the ‘observed’ distribution of the variation has developed is also essential in understanding how to direct the further evolution of the crop in the desired direction.

Of geographical necessity the external culture contacts of Africa have been mainly by sea, and consequently in order to explain the areal differentiations apparent in the cultural history of the continent it would seem necessary to supplement research on the landward traditions of African societies by investigations into the cultural patterns of sea regions embracing the oceanic faces of the continent. In the macro-regional structure of Africa it is possible to recognize entities such as Mediterranean Africa, Atlantic Africa, and Indian Ocean Africa, which possess distinctive personalities that cannot be entirely understood by landward reference but find their true provenance in the cultural dynamics of wider maritime theatres of action. Thus many of the keys to the cultural history and character of the eastern face of Africa must be sought not in Africa itself but in the changing patterns of the Indian Ocean region of which this African zone forms an integral part. As a student of the historical geography of the Indian Ocean, I am concerned here with but one environmental element in the structure of this region and its significance to some aspects of pre-colonial African history.

This is note will not deal with the evidence from glottochronology, which is the subject of Professor Armstrong's paper, nor with the evidence from linguistic borrowings, but with the inferences which may be drawn from the general linguistic configuration of Africa. It consists of a few miscellaneous observations, which are not intended to do more than stimulate interest in this line of inquiry.

In a field like Africa it is reasonable to hope for some assistance from linguistic data for the general study of prehistory. In fact there is a real temptation to use material of this kind in such a way that the results cannot be verified, or, to put it more baldly, to make guesses that are no better than other guesses. Clearly the serious investigation of the prehistory of Africa demands something more than speculative hypotheses, and for this reason it is essential that any conclusions drawn from linguistic information shall be based on a firm basis of codified data.

I Shall not attempt to repeat or even to summarize the excellent discussion of glottochronology by Dr D. H. Hymes (Current Anthropology, I, I, January 1960), but shall to some extent base my remarks on it. It seems to me that glottochronology is one method of analysis among many. It sheds a certain light of its own which is most useful when related to other kinds of study. The method of common innovations, for example, gives a much more precise picture of the genetic relations of a set of languages, and it does not depend on so many controversial assumptions. But the chronology which it gives is always a relative one. Furthermore, it depends for its success on quite deep studies of the languages in question, since it is always hazardous to say that a particular form or construction is not present in a language. Further study may often reveal it. It is, of course, also true of glottochronology that it depends for its full success on the deep study of the languages under consideration and of their cognate interrelations. It appears that we shall have to wait quite some time for those conditions to be satisfied in African studies, and field workers have had to go ahead and use these methods as best they can in order to make some kind of sense out of the vast mass of data before them. It seems to me that this is legitimate if all the conclusions of such exploratory ventures are firmly held to be subject to change without notice. We can at least get some idea of the time depths with which we are dealing. Language relationships which are recent enough to be of historical interest are fairly easy to handle even with crude methods. It is with respect to the older relationships that technique is stretched to its uttermost limits. Even here glottochronology can establish a ground against which recent borrrowings, containing the traces left by historical process, can be more readily distinguished.

In this paper an attempt will be made to set out the basic facts about the blood groups and other genetical characters in so far as they apply to anthropology.

In very few regions of Africa are the blood group distributions known in detail—even for the ABO system—and the maps must therefore be treated with reserve. Small-scale maps are useful for showing general trends, such as the rise in O frequency from the Middle East to Central Africa, but they cannot do justice to the considerable local fluctuation which detailed surveys have revealed (especially in Liberia and in the Eastern Congo).

It frequently happens that the only information available on interrelationships and former movements of African peoples lies in their oral traditions and myths. In the myths it is difficult to disentangle symbolic from historical events and personalities, while, fascinating though it is to listen to an old man recounting the movements of his ‘ancestors’ countless generations earlier, one frequently wishes that there were some independent line of evidence against which his statements could be checked. Such an independent line of evidence is provided by the steadily accumulating data on the genetic Constitution of African peoples. The Nilotes provide an illustration of its usefulness, of its limitations, of the type of additional information required to extract the maximum from the data, and of the postulates necessary to do so.

Since African Political Systems, edited by Fortes and Evans-Pritchard in 1940, many monographs have been published on particular political organization of pre-colonial Africa. Some attempts have been made to synthesize these data in order to constitute a typology of African political organizations; for instance the segmentary type has been studied in Middleton's Tribes Without Rulers (1958), and the absolute monarchies have been given an important place by Murdock in his Africa (1959) and by others (e.g. P. Hadfield: Traits of Divine Kingship in Africa, London, 1949). Typological research falls within the historian's province if he is interested in the problem of uniformities in history.

Between 1959 and 1961 I worked with an Ethiopian research student, Gētāčaw Takla Māryām, on the constitutional history of Ethiopia from the Aksumite period (first to fourth centuries A.D.) to the end of the seventeenth century. So far as could be discovered, no serious attempt has yet been made to deal with this subject by means of strict documentation. The first step therefore has been to collect from printed Ethiopic material (mainly written in Ge‘ez) and from Ge‘ez manuscripts a body of documents and charters which will ultimately form the basis of a constitutional history. The aim has been to produce something like Stubbs's Select Charters, for some such basis is an essential preliminary in a field in which be one of the resultes of our study. For place-names the position is a little better, since Conti Rossini produced many years ago an index to names in material published up to 1894; and not long ago I compiled one for the historical texts published in the Corpus Scriptorum Christianorum Orientalium (CSCO).The work on constitutional history, which is still in progress, has involved the study and translation of four categories of document written in Ge'ez; these are:

(1) The early Ge'ez (and Greek) inscriptions of the Aksumite period.

(2) The Lives of the Ethiopian saints (gadla qedusān) of the sixth, thirteenth, fourteenth, fifteenth, and sixteenth centuries, including the Synaxarium (senkesār) or general collection of lives of saints.

(3) The land charters and other documents in the Book of Aksum, from the tenth to seventeenth centuries, with a few attributed to kings from the fourth to ninth centuries.

(4) The Chronicles, now mostly available in printed form, either in the CSCO, or published individually; some are to be found in periodicals.