The Future of Evolution
Norman Myers is a tropical ecologist and international consultant in environment and development, with emphasis on conservation of wildlife species and tropical forests. His research and consulting have taken him to 80 countries. A leading environmental expert, he has consulted for many development agencies and research organizations, including the U.S. National Academy of Sciences, the World Bank, the Organization for Economic Cooperation and Development, UN agencies, and the World Resources Institute. Among his many publications (see Further Readings on the website for this book) are The Primary Source: Tropical Forests and Our Future (1992), Ultimate Security: The Environmental Basis of Political Security (1996), Perverse Subsidies (with Jennifer Kent, 2001), and The New Consumers: The Influence of Affluence on the Environment (with Jennifer Kent, 2004).
Human activities have brought the earth to a biotic crisis. Many biologists have commented that this crisis will result in the loss of large numbers of species, possibly 25–50%, within the lifetime of students reading this book. However, surprisingly few biologists have recognized that in the longer term these extinctions will impoverish evolution’s course for several million years.
The future of evolution should be regarded as one of the most challenging issues humankind has ever encountered because currently we are the world’s greatest evolutionary force. We are conducting a planet-scale experiment, with little clue as to how it might turn out, except that it will prove irreversible and could severely reduce human well-being. We could get by without half of all mammals and other vertebrates. But if we lost half of all insects with their pollinating functions, let alone their many other ecological services, we would be in trouble in the first crop-growing season.
In addition, the mass depletion or extinction under way is the biggest of our environmental problems in terms of the duration of its impact and the numbers of people to be affected. All other environmental problems are potentially reversible. If we wanted to clean up acid deposition, we could do it within a few decades. We could push back the deserts, restore topsoil, and allow the ozone layer to be repaired within a century or so. We could probably restore climate stability in the wake of global warming within a thousand years. But once a species is gone, it is gone for good.
Of course, in the long run evolution will generate replacement species with numbers and variety to match today’s. But that is likely to take millions of years. We are witnessing severe reduction if not elimination of entire sectors of biomes, notably tropical forests, coral reefs, and wetlands, all of which may have served as powerhouses of evolution—centers of new speciation—in the prehistoric past.
Suppose, as has happened after the mass extinctions and depletions of the prehistoric past, that the bounce-back period lasts at least 5 million years. This would be 20 times longer than humans have been around as a species. Suppose that the average number of people on the earth during that period is 2.5 billion people, as opposed to the 6.5 billion today. Then the total number of people affected by what we do (or don’t do) to protect the biosphere during the next few decades will be about 500 trillion, in contrast with the 50 billion people who have ever existed! In short, we are engaged in by far the biggest decision ever made by one human community on behalf of future human communities. Yet the issue is almost entirely disregarded, whether scientifically, ethically, or otherwise. How often do you hear leading scientists or ethicists even mention the issue?
Despite our gross ignorance of what lies ahead, we can venture a few hypotheses about what is likely to happen as a result of the projected extinction spasm:
A temporary outburst of speciation. As large numbers of niches are vacated, there could be an outburst of speciation, although not nearly enough to match the extinction spasm.
A proliferation of opportunistic species such as cockroaches , rats, flies, and others that prosper when new niches open up. This proliferation will be enhanced by the likely elimination of species that naturally control such opportunistic species.
An end to large vertebrates.
An end to speciation of large vertebrates. Even if larger vertebrates were to survive the extinction spasm ahead, our largest protected areas will prove far too small for further speciation of elephants, rhinoceroses, apes, bears, and the bigger cats, among other large vertebrates.
What does this imply for our conservation efforts? By far the predominant strategy of conservationists is to save as many species as possible. But we now need to safeguard evolutionary processes as well. A prime goal is to look out especially for endemic species (found only in a particular place) or species confined to small habitats. Examples include the California condor, the black-footed ferret, the giant panda, and the gorilla.
However, the fossil record shows that endemic species often turn out to be evolutionary dead ends: Generally they do not throw off new species. So should we shift our conservation priority from endemic species to broader-ranging species in the hope that they have more genetic variability and thus more of a diversified resource stock on which natural selection can work its creative impact?
Similarly, should we devote more attention to protecting the evolutionary powerhouses such as the forests, coral reefs, and wetlands of the tropics? All these are in dire trouble and may be all but eliminated within a few decades. Do they deserve preferential treatment ahead of, say, temperate-zone woodlands and grasslands and boreal forests with their lack of species, ecological complexity, and evolutionary potential?
If within your lifetime we allow the current biotic crisis to proceed unchecked (which is what the recent record suggests), it is possible that your children will ask you a key question: “When the evolutionary debacle was becoming all too plain at the start of the 21st century, what did you do to help ward off this disaster?” I hope you will engage yourself in dealing with this crucial issue.
1. Do you agree or disagree with the thesis of this essay? Explain.
2. If you agree, list three things you could do to help prevent the outcomes described in this essay.
Copyright ©2005 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning is a trademark used herein under license.