Setbacks -- Constructive Extinctions
The possibility that humanity may not pass the test facing it cannot be overlooked. The pathways to failure are both numerous and diverse. We are facing a range of environmental dangers -- and there are probably many more of which we are still unaware. The stress of ever-increasing change could also have disastrous consequences -- remember, 80 percent of accidents are caused by human error. Nor can we ignore the dangers of war. As resources become less plentiful and social tensions increase, wars of one kind or another become ever-more likely; and the weaponry now at our disposal can destroy ecosystems as easily as people.
Any catastrophe -- natural or otherwise -- that destroyed the infrastructure of contemporary civilization could send humanity into a new Dark Age. Serious as that might seem to us, it would be a relatively minor setback for the rest of life.
The consequences would be much more serious if, for instance, the greenhouse effect were to become a runaway effect. It would not be just coastal cities and farmlands that were ruined; the regional ecologies critical for the survival of millions of species would be destroyed. This could result in evolution being set back millions of years.
Worse still, if a significant proportion of the ozone layer were destroyed, then, as we saw earlier, the ultraviolet light that streamed in from space could make the land uninhabitable. Once again life would be confined to the sea -- a setback of half a billion years or more.
The Demise of the Dinosaur
Such setbacks are not new to evolution. A major disaster occurred 66 million years ago when the dinosaursreign came to an abrupt end. And it was not just the dinosaurs that died; millions of other species, both plant and animal, suddenly became extinct.
Exactly what caused this catastrophe is still not certain. That it was some form of environmental disruption is pretty clear. The sedimentary rock that forms the boundary between the time of the dinosaurs, the Cretaceous Era, and the Tertian Era that followed consists of a thin layer of clay. Samples of this clay taken around the world show between a hundred and ten thousand times the normal level of soot. This suggests a colossal, planet-wide fire, during which a major proportion of the planets forests went up in smoke. Supporting evidence comes from the unusual abundance of nitrogen isotopes in this layer; these could have come from heavy acid rain. Another consequence of a planet-wide fire would have been a sudden increase in carbon dioxide, perhaps triggering a greenhouse effect.
Clues as to how such a fire might have started can be found in the high levels of iridium in this clay. Iridium is a rare element on Earth; but is not so rare in meteors. This, along with the discovery that mineral grains in this layer show signs of intense shock, suggests that a large meteor, perhaps several miles in diameter, struck the Earth -- and there is strong evidence for a very large impact occurring around that time, 66 million years ago, in the Yucatan Peninsula in Mexico.
As well as starting widespread fires, such an impact would have produced massive clouds of dust. The result could have been very similar to a nuclear winter. Many plants would have been eliminated, destroying important elements in the food chain -- at the top of which sat the dinosaurs.
Other researchers have proposed that volcanoes were the cause. Volcanic dust contains high levels of iridium and produces similar layers of clay. And there is geological evidence of an intense period of volcanic activity around that time, which could well have thrown huge plumes of fiery ash and gases into the upper atmosphere.
It is very possible that both these hypotheses are correct. The impact of a very large meteor could have smashed a hole through the Earths crust, triggering a series of massive volcanic eruptions.
Or perhaps some other series of events was to blame. During the million or so years immediately preceding the dinosaursdemise the climate seems to have undergone a series of significant changes. Possibly some phenomenon that we do not yet know about was the trigger -- remember that only fifty years ago we knew nothing of the greenhouse effect. All that is certain is that seventy-five per cent, or more, of the Earths species suddenly disappeared.
The end of the Cretaceous Era was but one of a series of mass extinctions. Scientists believe there have been at least seven other occasions when the number of species fell suddenly and dramatically. Two hundred and thirteen million years ago the Triassic Era came to an abrupt end -- again with signs of intense shock. (At around the same time a large meteor created the forty-mile Manicouagan crater in Quebec.)
Two hundred and forty-eight million years ago another mass extinction resulted in the loss of 90 percent of all species then living, ending the Permian Era of Earths history.
A hundred million years before that the Devonian Era ended in a mass extinction of marine life. (Again the sedimentary rock from around that time shows an unusually high level of iridium.)
Around 440 million years ago three close periods of extinction associated with major glaciation and lowering of the sea level brought an end to the Ordovician Era. Other major extinctions are thought to have occurred 500, 570, and 630 million years ago. And there may well have been others of which scientists are as yet unaware.
Mass Extinction Now
Today we are experiencing the start of another mass extinction. This time, however, it is not meteors or volcanoes that are responsible but one of the Earths own creatures.
Before the appearance of humanity there were more species on the planet than at the time of the dinosaurs -- a remarkable recovery whose significance we shall return to shortly. But with the advent of human beings things began to change. In our early days we hunted to extinction some of the large animals in North America, and parts of Africa and Asia. Later we eradicated many species simply because they were in our way. And more recently we have destroyed many more through sheer lack of care.
Current estimates suggest that species are disappearing at the rate of one an hour or perhaps faster! At this rate more than half of the Earths plant and animal species will have been eliminated within the next few hundred years. But, given that our destructive potential accelerates along with our technological progress, we will probably reach this point much sooner.
But the curve need not plummet further. We have not yet entered a full-blown greenhouse effect. The ozone layer is still intact. Not all the forests have been destroyed. We need not become, like the dinosaurs, a species that suddenly disappeared -- a mere geological relic. There is still hope. We still have the opportunity to redeem ourselves.
Even if another mass extinction were to occur, all would not be lost. Evolution would still continue. Indeed, if the past is anything to go by, it would leap ahead.
Hard-bodied organisms only began to flourish after the mass marine extinction that ended the Pre-Cambrian Era. Amphibians only began to colonize the land after the Devonian extinction 365 million years ago. And it was the major extinction of 248 million years ago that preceded the appearance of the first dinosaurs.
The catastrophe that ended the dinosaursreign led in turn to the evolution of mammals. Small, rodent-like mammals did already exist, but had not evolved very fast. The fact that some of them lived in burrows probably helped them survive whatever environmental catastrophe befell those times. Afterwards, they evolved very rapidly, diversifying into the wealth of mammal species that we now know -- including ourselves.
The reason for this sudden burst of evolutionary activity is easy to understand. Before the catastrophe the ecological system would have been in a stable state; most species would have had plenty of time to become well adapted to their environment. There would have been little pressure for evolutionary change.
After a mass extinction things would have been very different. The living matrix of the biosphere would have changed profoundly. Most species that survived would have found themselves in circumstances to which they were not so well suited -- sources of food might have disappeared, the climate might have changed, new dangers might have emerged. In this new ecological context, life would have been under renewed pressure to evolve. New adaptations would establish themselves fast and new species would proliferate.
In short, the curve of evolution would have leapt upward once more.
The Upside of Extinction
Mass extinctions can therefore have a positive side. If the dinosaurs had not disappeared when they did, mammals might have remained as rodents and human beings would never have been born. In this respect we have good reason to be thankful for the disaster of 66 million years ago.
And, should it turn out that humanitys activities do result in another decimation of the planets species, who is to say what new evolutionary opportunities this might create? The dinosaurs would never have guessed that mammals, human beings, and civilization would follow them. Who knows what phoenix could arise from our ashes?
Whatever form they might take, the species that followed our demise might be very thankful to us for having set the stage and for creating the evolutionary opportunity they needed.
Who knows, they might even thank us for the genetic modifications that our nuclear and biological industries leave in their wake.
Knocking on Heavens Door
After such a setback, evolution would resume its steady march towards greater complexity and higher order. It would also resume its steady acceleration, though initially at a much slower pace.
If we were to set ourselves back fifty thousand years to some New Stone Age, our progress would be slowed considerably. However, as we once again strived to improve our lot, each new advance would serve as a platform for further advances, leading, as before, to an increasing rate of development.
Moreover, although such a calamity might set us back considerably in our material progress, our internal progress would not be so badly affected. It seems probable that we would retain some of the knowledge, understanding, learning, and awareness that we have accumulated, giving us a head start over our Stone Age predecessors. We could then find ourselves entering a new technological age in centuries rather than millennia -- though hopefully with more wisdom than before.
Even if some environmental holocaust were to wipe us out completely, biological evolution would continue. Inevitably, but slowly, new species would emerge. Novel qualities and abilities would appear, each serving as platforms for further evolutionary advance. Slowly but surely evolution would continue its inexorable acceleration.
Given the evolutionary trend towards higher orders of information processing, it is very likely that creatures with large and complex nervous systems would again emerge. Eventually beings with an intelligence similar to, or surpassing, our own might appear. Such beings might develop symbolic language through which to share their discoveries, and if they had hands, or some other way of manipulating their environment, they could develop technology.
If they remained stuck in a self-centered mode of consciousness, life on Earth would again come under increasing pressure. The planet would be in another crisis -- another crisis of consciousness. And, if this species could not raise its level of awareness, evolution might again be thrown back another fifty thousand, or even fifty million, years.
Then, once more, it would resume its relentless climb towards higher levels of organization, and higher rates of change. And once more it would face an inner challenge.
Again and again life would be confronted by the same challenge, the same intelligence test. Again and again it must answer the same crucial questions. Is this a being that can awaken to its inner world as fully as it has to the physical world? Is this a species that can make the leap into conscious evolution, and a higher order of intelligence?
That is the question facing us today: Are we ready to make that leap? Can we use our gifts of understanding, creativity, and choice in our true self-interest? Can we use our growing freedom from physical constraints to liberate our minds from outdated attitudes and beliefs? Can we develop a new, more enlightened, mode of consciousness?
And if we do, what lies ahead? It turns out that it may not be quite what we expect. Indeed, it may be very different from anything we have ever dared imagine.
Date created: 3-Oct-03