Taken out of their native habitats, most plants and animals wither and die. But some really thrive in new climes, freed from predators, food limitations, diseases and other factors that stifle growth in their home territory. Take the water hyacinth from the Amazon, for example. In India, it chokes every waterway that it lands in and devastates aquatic life by depleting oxygen from the water and blocking out life-giving sunlight. This alien onslaught replaces native species and does not contribute to the local food chain. Such malicious foreigners are called 'invasives' by ecologists.
Tim Flannery, author of "The Future Eaters," views man as an invasive species. We evolved in Africa and that's where we truly belong in the ecological sense. Soon after 'invading' the Pacific islands, people killed scores of hapless species which had never before seen humans, with no thought of tomorrow. In New Zealand, ovens full of baked moa drumsticks were opened by archaeologists, hundreds of years after they were cooked. The rest of the carcasses, sometimes entire ones, with plenty of edible meat, were just thrown away. Such wastefulness led many species such as moas (gigantic flightless birds like ostriches), giant wallabies, takahe (a giant swamp hen), elephant seals and sea lions to extinction within a few years of contact with man.
The mysterious civilisation of Easter Island went one step further and self-destructed. At one time, the island was thickly forested with a population of 6000 to 8000 people (although ecologist, Jared Diamond estimates 15,000) but by 1877, it was bereft of all trees and down to 111 starving souls. Improbable as it sounds, trees were cut down (to the last one) to roll giant stone carvings from the quarries in the interior to the beaches where they were propped up. With no tree roots to hold the soil, erosion set in and the exploding population could no longer support itself. The islanders splintered into rival clans, killing and eating each other. In a final act of irony, they even pulled down each other's statues, the cause of all the devastation. {Read on}