The Quirks of Isolation

   Animals, like humans, develop special characteristics if they are isolated long enough on islands. Sometimes this is simply because the lack of other competitive animals gives them broader opportunities: a seed-eating bird may branch out and evolve subspecies that feed on insects, nectar or even fish. Sometimes a change in climate may result in the evolution of a new type, as in the case of a jay-sized, blue-black bird, a species of drongo, found exclusively in a wet, mountain evergreen forest in Ceylon. The difference between this drongo and its close relatives, which live in other parts of Ceylon, is that—isolated by climatic changes—it has lost the long, racket-shaped tail and head crest characteristic of the species.
   Sometimes islands even foster such curious developments as the long and flexible nose of the male proboscis monkey—an appendage which seems to have no relationship to what this animal eats or does, and is even inexplicable in terms of its rela­tives, the closest of which, in this case, probably live in China and have more normal noses. And tropical Asia, has one animal, the dragon of Komodo, which in isolation has turned into a giant—either from lack of any competition by other predators or perhaps because of a mutation of its genes which was perpetuated, unchecked, through the ages.