The question whether each race of mankind can live and reproduce itself—that is to say, become acclimatised—on any point of the globe will, evidently, only be resolved when attempts of this kind are undertaken by each race and pursued during several generations. Now there are no exact data on this subject except for the so-called white race and in some measure for Negroes. Without reckoning cosmopolitan peoples like the Jews and the Gypsies, it is certain that the majority of European peoples can as a race get acclimatised in the most diverse regions, in Canada (English and French) as in Brazil (Portuguese and Germans), Mexico (Spaniards), Australia (English), Southern Africa (Dutch Boers). The assumed failures of acclimatation are connected with countries where there has never been any European colonisation (India, Java), and where it is known that there are isolated cases of the collective acclimatation of several families.
According to Clements Markham and Elisée Reclus, the Englishman not only as an individual but as a race is able to live in the Cisgangetic peninsula.[138] Many generations of Englishmen have flourished in various parts of India. Numerous examples could be cited of children being acclimatised without detriment to their strength or health. According to Francis Galton, the mortality in 1877 of European soldiers in India (12.7 per 1000) was less than that of native soldiers (13.4) and Hindus in general (35). In the Dutch Indies the Dutch have kept themselves in good health for several generations.[139] We must leave out of the question certain unhealthy regions (like Lower Senegal) where the natives suffer almost as much as Europeans. On the whole, the so-called white race appears to have the aptitude of acclimatation in all countries, provided, of course, that it makes the necessary sacrifices for several generations.
If it be said of certain regions that they are not colonisable by Europeans, it is thereby implied that the sacrifices entailed by acclimatation are out of all proportion to the advantages to be gained by colonisation. As to Negroes, they thrive in temperate countries like the United States, where they multiply at the same rate as the Whites. By a strange anomaly they do not seem to thrive as well in Mexico, in the Antilles, and in Guiana—that is to say in the same isothermal zone (26°–28° C., or 70°–82° Fahr.) as their native country; nevertheless they live and reproduce there.
Upon the whole, if we consider (1) that the most mixed and most civilised races are those which are soonest acclimatised, (2) that the tendency of races to intermingle, and of civilisation to develop, goes on increasing every day in every part of the world, we may affirm without being accused of exaggeration that the cosmopolitanism of mankind, if it does not yet exist to-day in all races (which seems somewhat improbable), will develop as a necessary consequence of the facility of acclimatation. For it to become general is only a matter of time.
As to the fertility of acclimatised families, it has been established outside of hybridisation. Thus it has been possible to trace back certain English families in the Barbadoes for six generations.[140] As much may be said of the French in the islands of Mauritius and Réunion. In the Brazilian province of Rio Grande do Sul, between 25°–30° S. latitude—that is, in a sub-tropical region—it has been ascertained that there are three or four generations of German colonists, whose children enjoy very good health.[141] Lastly, in Matabeleland there are already two or three generations of Dutch.[142] It must be said that certain European races are more capable than others of becoming acclimatised in tropical countries. Thus it is universally acknowledged that people of the south of Europe—Spaniards, Italians, Provençals—become sooner acclimatised in Africa and equatorial America than the English and the Germans of the north.
But in spite of the facility of acclimatation, race-characters hardly seem to change in the new environment; the chemical constituents of the tissues having changed, the body adapts itself without change either in outward form or even colour.
The German colonists of Brazil and the Steppes of the Volga bear a perfect resemblance to each other after more than a century of separation from their race-brothers of Swabia or Franconia. It is the same after two or three centuries with the English of the Barbadoes, the French of Réunion, the Dutch of the Transvaal, etc.
The phenomena of hybridity are even less studied than those of the influence of environment; I shall speak of some of these in regard to different populations, but the facts are too isolated and disputed for any general conclusions to be drawn.
In reality, all that we know is that a great number of races produce half-breeds by crossing, but whether these half-breeds in so crossing produce a new race or revert to one of the ancestral types has not been demonstrated. Humanity appears to move in a confused medley of the most diverse and composite forms, without any one of them being able to persist; for the means of persistence, artificial selection or sexual selection, are wanting. The only selection which may have a decided influence on the predominance of the characters of a race in its interminglings is that which proceeds from the number of individuals of each of the races concerned in the blending and their respective fecundity, but this selection has hardly begun to be studied.