These, as the fittest, survive and tend to absorb the new-comers, pointing to hybridization as the simplest solution of the problem of tropical colonization.
[Sidenote: The relation of geography to history.] The more the comparative method is applied to the study of history--and this includes a comparison not only of different countries, but also of successive epochs in the same country--the more apparent becomes the influence of the soil in which humanity is rooted, the more permanent and necessary is that influence seen to be.
Geography's claim to make scientific investigation of the physical conditions of historical events is then vindicated.

"Which was there first, geography or history ?" asks Kant.

And then comes his answer: "Geography lies at the basis of history." The two are inseparable.
History takes for its field of investigation human events in various periods of time; anthropo-geography studies existence in various regions of terrestrial space.

But all historical development takes place on the earth's surface, and therefore is more or less molded by its geographic setting.

Geography, to reach accurate conclusions, must compare the operation of its factors in different historical periods and at different stages of cultural development.