Galapagos: a Zoological Landmark

Abstract

IN September 1835 Charles Darwin landed on the Galapagos Islands, and twenty-four years later the “Origin of Species” was published. The two events are linked together, almost as cause and effect, in the history of the theory of evolution, for, according to Darwin himself, the conception of the “Origin of Species”, and all that it meant in revolutionizing the outlook of men, lay away back in that month's visit to the Archipelago. It was a touch of inspiration that suggested to William Hunter and David Lack that the sort of evidence which appealed to Darwin might be embodied in a cinematograph film of the Islands and their characteristic vegetation and animals. Their film, “Galapagos”, produced by the Dartington Hall School Film Unit, is a novel and notable instrument for bringing realism to many biological truths the evidence of which students often find it difficult to appreciate. The zoning of plants and animals is illustrated by the waterless and porous lava formations of the low grounds with xeprohytic vegetation and scanty fauna, and by the rain-forest of the misty uplands; the effect of isolation, by endemic animals showing various degrees of distinctiveness from their mainland ancestors. An outstanding example of adaptive radiation is illustrated by the ground-finches, six different types of which range from the normal seed-eater to the remarkable Cactospiza, which is seen digging insect larvæ from their lairs by means of a twig—a tool-using bird.