There have been many movements of population in human history, and almost as many reasons for them. But all of them have one feature in common. They arose as a result of a change either in the external circumstances confronting a society or a section of it, or in the reactions of the people to their external circumstances. Migrations have always involved preferences, and occurred when preferences have changed. Perhaps the reception area has improved. Perhaps the other area has worsened. Perhaps both processes have occurred simultaneously. Whatever the causes of the change in relative preferences, whether it be the development of racial, political, or religious persecution, the occurrence or threat of war, the discovery of new continents or new sources of wealth, the effect of new medical techniques in enabling the opening up of hitherto uninhabitable countries, or the decline in fertility in the occupied area, it is the change that precedes the movement.

African land tenure is a subject so vast that in dealing with it one hesitates to commit oneself to statements of general application lest particular instances should be found to controvert them. Yet, when it is considered from the point of view of culture change, it is possible to discern a number of general trends, the nature of which is similar because their cause is the same–the impact on African society of the commercial economy of Western Europe with its infinite range of forms of wealth and possibilities of acquiring them. Though other forces too are active in the modern process of culture change, this is the most pervasive, and its influence can be traced in the development of every institution. In the case of land rights, closely bound up as they are with systems of production, the influence is direct and obvious.

Nigeria is not only a recent creation, but it can with justice be called an artificial creation with a heterogeneous population. This is the reason why the social system of Nigeria is fraught with problems of which the first and foremost is the problem of integrating many divergent elements in social, religious, political, and economic life, of selecting what is good from each of these elements, and reconciling them with the culture of an invading and stronger civilization.

A Great many criticisms have been made of South Africa's treatment of her native population. Many of these have been well founded, but at the same time it is well to remember that it is not easy, in a country where over three-quarters of the population is living at a totally different historical level from the rest, to decide what Professor Julian Huxley calls the optimum rate of advance for the more backward people. Undue haste results in the detribalization of people who have not yet had time to adjust themselves to western modes of life. The gold-mines of the Rand, for example, have been responsible for the growth of the evil of migrant labour, which drains the native reserves of their able-bodied men, and creates huge urban populations of Natives who have lost touch with tribal customs and sanctions, and have not had time to acquire the western ideas which should take their place.