Humans have developed the ability to observe and explore space, which raises an obvious question. What is the role of technology in the evolution of life? Technology is not an inevitable consequence of the evolution of intelligence. Yet the experience of our planet is that the highest functioning organisms — humans — have developed the tools to modify the environment. However, this ability is very recent. For most of the past 500,000 years, roving tribes of humans left no mark on the planet. It is the same story for most of the 6,000 years of fixed civilizations. One thousand years ago, the only trace of human activity that would have been visible from a high Earth orbit was the scar of the Great Wall of China. The surge of technology began 250 years ago with the Industrial Revolution and rapid population growth. It has accelerated in the last 50 years with the development of mass-production techniques, nuclear power, and electronics. We live in a time where we can decisively change our global environment, for better or worse.
The development of technology could actually end civilization on Earth and potentially on other worlds. As Pulitzer Prize-winning naturalist Rene Dubois points out, we are umbilically connected to the Earth. If we alter our planet too much before acquiring an ability to leave it, we are finished. Past wars did not threaten our whole species, because most conflicts were local, and weapons had limited destructive capability. Today's nuclear, biological, and other types of weapons, however, could potentially engulf the whole world. A sufficiently massive nuclear exchange could devastate not only civilization but also future forms of life, whose genetic pool would be exposed to high radiation levels for decades. Just as a large meteor impact can cause climate change, nuclear weapons could put a large enough amount of debris in the upper atmosphere to cause blanketing of the Sun's radiation. For most of the 70 years of the nuclear age, human civilizations have lived in a kind of uneasy peace. Recent years have given cause for optimism, as the nuclear arsenals of the United States and the former Soviet Union have begun to shrink. However, the corresponding proliferation of nuclear weapons in smaller and often less stable countries is a cause for concern. Our planetary culture could wipe itself out by conscious design of weapons, as irrational as that may seem.
Disasters can also happen inadvertently. As our technology reaches planetary scale, our accidents can involve large regions of the planet. Problems as diverse as nuclear power, acid rain, and aerosol cans illustrate the issue. Although we have been around less than 0.1% of the age of our planet, we are already beginning to have brushes with global disaster. Global warming has become an established fact, with consequences for the climate that we do not yet fully understand. One sobering truth stands behind our discussion of the future of humanity — extinction has been the fate of 99.8% of the species on this planet.
By exercising a bit of intelligence and caution, humanity can recognize these dangers and avoid them. There is a cultural hurdle that we must surmount: the transition from scattered, competing nation-states to stable global or interplanetary societies of intelligence and imagination. We face a race between the good side of our technological abilities, which make civilization possible (plumbing, electricity, stereos, and space travel), and the dark side of technology, which threatens civilization (carcinogenic byproducts, pollution, and hydrogen bombs). It is possible to break out of our muddle of competitive strife over resources and ideological space on a finite planet. Perhaps some alien cultures have crossed this cultural hurdle and spread to many planets, ensuring their survival against ecological disaster on any one planet. Such cultures might last and be detectable for millions rather than thousands of years.