Earthlings

Landslides, earthquakes, eruptions, floods, storms, and other cataclysms have wrought many changes in the complexion of the planet's face during the past millennium. Still, despite some significant local alterations, the overall physiognomy of the Earth is not so very different from what it was in AD 1000. In contrast, change in the composition and distribution of the world’s living communities has been almost universal. The catalyst of this transformation of life on Earth is our own species. That people should have such a profound influence on the rest of the world’s creatures and their habitats isn’t surprising. We are, after all, very large. We dwarf well more than 99 percent of other animal species, most of which are insects. Furthermore, the number of people is astonishing. In October of 1999, the global human population passed 6 billion. Such staggering numbers of such large animals can hardly fail to affect other species and the environment we share. The human population explosion is very recent. There were about 200 million people in the world 1,000 years ago. By the end of the 2nd millennium, a single country, China, had six times that many people. India had five times that number. Every year the world grows by 80 million people—40 percent of the entire population of the globe in AD 1000! As recently as 1800 there were still fewer than 1 billion people, but soon after that a combination of improvements in agriculture, hygiene, and medicine enabled more people to survive infancy and live comparatively long lives. Owing to depressed death rates and increased numbers of reproducing adults, the world population began to swell rapidly. Demographers believe that the number of people in AD 2050 will stand at 8.9 billion, almost half again as many as are alive today. The problems that beset the Earth and its inhabitants are still daunting, of course. We can only hope that these examples and others like them are harbingers of a saner, sounder, and more enlightened millennium to come.