25 
dical but of natural selection. We must show, that is to say* 
bow circumstances may have arisen under wbicb these charac- 
teristics could not but have become perpetuated, even m spite 
of a desire to obliterate them. In other words, we must show 
how certain conditions of existence may possibly have acted 
upon man in an early period of the world's history by means 
of which Nature herself may have forced . forward selective 
breeding and in that manner may have indirectly brought 
about exactly the same results as those which would have 
been produced through methodical selection. 
47. For this purpose we must revert to those pre-historic 
periods of the human race in which its primary migrations 
commenced, and when the first physical varieties of man 
began to appear. Most of the simple varieties were, I doubt 
not, rapidly developed by means of climate, food, location, 
and all those other external forces, within the range of which 
the wandering hosts were driven ; exactly in the same sort ot 
way as certain natural varieties of the wild animals were 
originated. The tigers, for example, now so diverse m their 
characteristics, as met with in Bengal and Siberia, were con- 
fessedly produced by such means from one primeval species. 
In the same way we can easily conceive how, m the primary 
distribution of mankind, the Turanian, Indo-European, and 
Hamitic families gradually began to assume their present dis- 
tinguishing types. Nor would these first physical alterations 
of the aboriginal type of man require any excessive period ot 
time. Even Mr. Darwin says,* “ In some few instances a 
marked effect has been produced quickly on all [the italics are 
his own] , or nearly all, the individuals which have been exposed 
to some considerable change of climate, food, or other circum- 
stance. This has occurred, and is now occurring, with Furo- 
pean men in the United States, with European dogs in India, 
with horses in the Falkland Islands, with foreign oysters m 
the Mediterranean, and with maize grown in Europe from 
tropical seed.” 
48. Imagine, then, that soon after the commencement ot 
those migrations by which the great Hamitic family ultimately 
became distributed over the continent of Africa, and while, as 
yet, the originally coloured skin of man (though darkened m 
a measure by hotter suns or bilious climates) remained more 
or less definitely clear ; imagine that a woman . of some par- 
ticular place foremost in the van of that migration had unex- 
pectedly given birth to a boy, who soon became marked by a 
jet-black skin, and crisp wool-like hair, and was otherwise 
* Variation of Animals, Sc., vol. ii. p. 290. 
