CREATION BY EVOLUTION
been carried to them by winds and currents. If this is true, the nature of the plants and animals of such an island must be determined by the antiquity of the island, its remoteness from land, and its position with reference to strong winds and marine currents. But even if these plants and animals reached the islands in the accidental manner described, might they not have remained unchanged and immutable? In that case there should be no particular relation between the remoteness of the islands and their geological date of formation, on the one hand, and the kind of creatures that inhabit them, on the other. But if species are mutable and subject to modification, then we ought to find that the islands had species that are peculiar to them, yet that would show more or less distinct relationship to those of the mainland from which the islands received the ancestors of their peculiar species. That this is the true solution of the problem is strongly indicated by the plants and animals of the Galapagos Islands, which first led Darwin to form his new views on the origin of species.
The Galapagos Archipelago is a group of five relatively large and ten small islands, all of volcanic origin, which rise steeply from great depths of the ocean. The one nearest to the coast of Ecuador is about 600 miles distant from it, and the islands lie almost on the Equator, in the zone of calms, in which strong winds seldom blow. The arrival of a new form from the mainland must be a very rare event; yet the islands contain many birds, reptiles, and insects, but no mammals. It is fortunate for our inquiry that no aborigines settled in the islands, which, when Darwin first visited them, were almost in a state of nature. Nearly all the animals and plants that inhabit the islands are peculiar to them; the species and many of the genera are found nowhere else in the world. This statement does not, of course, apply to the sea
[ 96 ]
