Essay/Earth Science


Half of the Earth’s surface and seas must be dedicated to the conservation of nature, or humanity will have no future

Edward O Wilson

The Serengeti National Park. Photo by Medford Taylor/National Geographic

Edward O Wilson

is a professor emeritus in entomology at Harvard. Half-Earth concludes Wilson’s trilogy begun by The Social Conquest of Earth and The Meaning of Human Existence, a National Book Award finalist. 

3,300 words

Edited by Pam Weintraub

Republish - Licence Only

Unstanched haemorrhaging has only one end in all biological systems: death for an organism, extinction for a species. Researchers who study the trajectory of biodiversity loss are alarmed that, within the century, an exponentially rising extinction rate might easily wipe out most of the species still surviving at the present time.

The crucial factor in the life and death of species is the amount of suitable habitat left to them. When, for example, 90 per cent of the area is removed, the number that can persist sustainably will descend to about a half. Such is the actual condition of many of the most species-rich localities around the world, including Madagascar, the Mediterranean perimeter, parts of continental southwestern Asia, Polynesia, and many of the islands of the Philippines and the West Indies. If 10 per cent of the remaining natural habitat were then also removed – a team of lumbermen might do it in a month – most or all of the surviving resident species would disappear.

Today, every sovereign nation in the world has a protected-area system of some kind. All together the reserves number about 161,000 on land and 6,500 over marine waters. According to the World Database on Protected Areas, a joint project of the United Nations Environmental Program and the International Union for Conservation of Nature, they occupied by 2015 a little less than 15 per cent of Earth’s land area and 2.8 per cent of Earth’s ocean area. The coverage is increasing gradually. This trend is encouraging. To have reached the existing level is a tribute to those who have led and participated in the global conservation effort.

But is the level enough to halt the acceleration of species extinction? Unfortunately, it is in fact nowhere close to enough. The declining world of biodiversity cannot be saved by the piecemeal operations in current use alone. The extinction rate our behaviour is now imposing on the rest of life, and seems destined to continue, is more correctly viewed as the equivalent of a Chicxulub-sized asteroid strike played out over several human generations.

The only hope for the species still living is a human effort commensurate with the magnitude of the problem. The ongoing mass extinction of species, and with it the extinction of genes and ecosystems, ranks with pandemics, world war, and climate change as among the deadliest threats that humanity has imposed on itself. To those who feel content to let the Anthropocene evolve toward whatever destiny it mindlessly drifts, I say please take time to reconsider. To those who are steering the growth of reserves worldwide, let me make an earnest request: don’t stop, just aim a lot higher.

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I see just one way to make this 11th-hour save: committing half of the planet’s surface to nature to save the immensity of life-forms that compose it. Why one-half? Why not one-quarter or one-third? Because large plots, whether they already stand or can be created from corridors connecting smaller plots, harbour many more ecosystems and the species composing them at a sustainable level. As reserves grow in size, the diversity of life surviving within them also grows. As reserves are reduced in area, the diversity within them declines to a mathematically predictable degree swiftly – often immediately and, for a large fraction, forever. A biogeographic scan of Earth’s principal habitats shows that a full representation of its ecosystems and the vast majority of its species can be saved within half the planet’s surface. At one-half and above, life on Earth enters the safe zone. Within half, existing calculations from existing ecosystems indicate that more than 80 per cent of the species would be stabilised.

There is a second, psychological argument for protecting half of Earth. The current conservation movement has not been able to go the distance because it is a process. It targets the most endangered habitats and species and works forward from there. Knowing that the conservation window is closing fast, it strives to add increasing amounts of protected space, faster and faster, saving as much as time and opportunity will allow.

The key is the ecological footprint, defined as the amount of space required to meet the needs of an average person

Half-Earth is different. It is a goal. People understand and prefer goals. They need a victory, not just news that progress is being made. It is human nature to yearn for finality, something achieved by which their anxieties and fears are put to rest.

The Half-Earth solution does not mean dividing the planet into hemispheric halves or any other large pieces the size of continents or nation-states. Nor does it require changing ownership of any of the pieces, but instead only the stipulation that they be allowed to exist unharmed. It does, on the other hand, mean setting aside the largest reserves possible for nature, hence for the millions of other species still alive.

The key to saving one-half of the planet is the ecological footprint, defined as the amount of space required to meet all of the needs of an average person. It comprises the land used for habitation, fresh water, food production and delivery, personal transportation, communication, governance, other public functions, medical support, burial, and entertainment. In the same way the ecological footprint is scattered in pieces around the world, so are Earth’s surviving wildlands on the land and in the sea. The pieces range in size from the major desert and forest wildernesses to pockets of restored habitats as small as a few hectares.

But, you may ask, doesn’t a rising population and per-capita consumption doom the Half-Earth prospect? In this aspect of its biology, humanity appears to have won a throw of the demographic dice. Its population growth has begun to decelerate autonomously, without pressure one way or the other from law or custom. In every country where women have gained some degree of social and financial independence, their average fertility has dropped by a corresponding amount through individual personal choice.

There won’t be an immediate drop in the total world population. An overshoot still exists due to the longevity of the more numerous offspring of earlier, more fertile generations. There also remain high-fertility countries, with an average of more than three surviving children born to each woman, thus higher than the 2.1 children per woman that yields zero population growth. Even as it decelerates toward zero growth, population will reach between 9.6 billion and 12.3 billion, up from the 7.2 billion existing in 2014. That is a heavy burden for an already overpopulated planet to bear, but unless women worldwide switch back from the negative population trend of fewer than 2.1 children per woman, a turn downward in the early 22nd century is inevitable.

 And what of per-capita consumption? The footprint will evolve, not to claim more and more space, as you might at first suppose, but less. The reason lies in the evolution of the free market system, and the way it is increasingly shaped by high technology. The products that win are those that cost less to manufacture and advertise, need less frequent repair and replacement, and give highest performance with a minimum amount of energy. Just as natural selection drives organic evolution by competition among genes to produce more copies of themselves per unit cost in the next generation, raising benefit-to-cost of production drives the evolution of the economy. Teleconferencing, online purchase and trade, ebook personal libraries, access on the Internet to all literature and scientific data, online diagnosis and medical practice, food production per hectare sharply raised by indoor vertical gardens with LED lighting, genetically engineered crops and microorganisms, long-distance business conferences and social visits by life-sized images, and not least the best available education in the world free online to anyone, anytime, and anywhere. All of these amenities will yield more and better results with less per-capita material and energy, and thereby will reduce the size of the ecological footprint.

In viewing the future this way, I wish to suggest a means to achieve almost free enjoyment of the world’s best places in the biosphere that I and my fellow naturalists have identified. The cost-benefit ratio would be extremely small. It requires only a thousand or so high-resolution cameras that broadcast live around the clock from sites within reserves. People would still visit any reserve in the world physically, but they could also travel there virtually and in continuing real time with no more than a few keystrokes in their homes, schools, and lecture halls. Perhaps a Serengeti water hole at dawn? Or a teeming Amazon canopy? There would also be available streaming video of summer daytime on the coast in the shallow offshore waters of Antarctica, and cameras that continuously travel through the great coral triangle of Indonesia and New Guinea. With species identifications and brief expert commentaries unobtrusively added, the adventure would be forever changing, and safe.

The spearhead of this intensive economic evolution, with its hope for biodiversity, is contained in the linkage of biology, nanotechnology, and robotics. Two ongoing enterprises within it, the creation of artificial life and artificial minds, seem destined to preoccupy a large part of science and high technology for the rest of the present century.

The creation of artificial life forms is already a reality. On 20 May 2010, a team of researchers at the J Craig Venter Institute in California announced the second genesis of life, this time by human rather than divine command. They had built live cells from the ground up. With simple chemical reagents off the shelf, they assembled the entire genetic code of a bacterial species, Mycoplasma mycoides, a double helix of 1.08 million DNA base pairs. During the process they modified the code sequence slightly, implanting a statement made by the late theoretical physicist Richard Feynman, ‘What I cannot create, I do not understand,’ in order to detect daughters of the altered mother cells in future tests.

If our minds are to break free and dwell in the far more interesting universe of reason triumphant over superstition, it will be through advances in biology

The textbook example of elementary artificial selection of the past 10 millennia is the transformation of teosinte, a species of wild grass with three races in Mexico and Central America, into maize (corn). The food found in the ancestor was a meagre packet of hard kernels. Over centuries of selective breeding it was altered into its modern form. Today maize, after further selection and widespread hybridisation of inbred strains that display ‘hybrid vigour’ is the principal food of hundreds of millions.

The first decade of the present century thus saw the beginning of the next new major phase of genetic modification beyond hybridisation: artificial selection and even direct substitution in single organisms of one gene for another. If we use the trajectory of progress in molecular biology during the previous half century as a historical guide, it appears inevitable that scientists will begin routinely to build cells of wide variety from the ground up, then induce them to multiply into synthetic tissues, organs, and eventually entire independent organisms of considerable complexity.

If people are to live long and healthy lives in the sustainable Eden of our dreams, and our minds are to break free and dwell in the far more interesting universe of reason triumphant over superstition, it will be through advances in biology. The goal is practicable because scientists, being scientists, live with one uncompromising mandate: press discovery to the limit. There has already emerged a term for the manufacture of organisms and parts of organisms: synthetic biology. Its potential benefits, easily visualised as spreading through medicine and agriculture, are limited only by imagination. Synthetic biology will also bring onto centre stage the microbe-based increase of food and energy.

Each passing year sees advances in artificial intelligence and their multitudinous applications – advances that would have been thought distantly futuristic a decade earlier. Robots roll over the surface of Mars. They travel around boulders and up and down slopes while photographing, measuring minutiae of topography, analysing the chemical composition of soil and rocks, and scrutinising everything for signs of life.

In the early period of the digital revolution, innovators relied on machine design of computers without reference to the human brain, much as the earliest aeronautical engineers used mechanical principles and intuition to design aircraft instead of imitating the flight of birds. But with the swift growth of both fields, one-on-one comparisons are multiplying. The alliance of computer technology and brain science has given birth to whole brain emulation as one of the ultimate goals of science.

From the time of the ancient human-destined line of amphibians, then reptiles, then mammals, the neural pathways of every part of the brain were repeatedly altered by natural selection to adapt the organism to the environment in which it lived. Step-by-step, from the Paleozoic amphibians to the Cenozoic primates, the ancient centres were augmented by newer centres, chiefly in the growing cortex, that added to learning ability. All things being equal, the ability of organisms to function through seasons and across different habitats gave them an edge in the constant struggle to survive and reproduce.

Little wonder, then, that neurobiologists have found the human brain to be densely sprinkled with partially independent centres of unconscious operations, along with all of the operators of rational thought. Located through the cortex in what might look at first like random arrays are the headquarters of process variously for numbers, attention, face-recognition, meanings, reading, sounds, fears, values, and error detection. Decisions tend to be made by the brute force of unconscious choice in these centres prior to conscious comprehension.

Next in evolution came consciousness, a function of the human brain that, among other things, reduces an immense stream of sense data to a small set of carefully selected bite-size symbols. The sampled information can then be routed to another processing stage, allowing us to perform what are fully controlled chains of operations, much like a serial computer. This broadcasting function of consciousness is essential. In humans, it is greatly enhanced by language, which lets us distribute our conscious thoughts across the social network.

What has brain science to do with biodiversity? At first, human nature evolved along a zigzag path as a continually changing ensemble of genetic traits while the biosphere continue to evolve on its own. But the explosive growth of digital technology transformed every aspect of our lives and changed our self-perception, bringing the ‘bnr’ industries (biology, nanotechnology, robotics) to the forefront of the modern economy. These three have the potential either to favour biodiversity or to destroy it.

I believe they will favour it, by moving the economy away from fossil fuels to energy sources that are clean and sustainable, by radically improving agriculture with new crop species and ways to grow them, and by reducing the need or even the desire for distant travel. All are primary goals of the digital revolution. Through them the size of the ecological footprint will also be reduced. The average person can expect to enjoy a longer, healthier life of high quality yet with less energy extraction and raw demand put on the land and sea. If we are lucky (and smart), world population will peak at a little more than 10 billion people by the end of the century followed by the ecological footprint soon thereafter. The reason is that we are thinking organisms trying to understand how the world works. We will come awake.

Silicon Valley dreamers of a digitised humanity have failed to give much thought at all to the biosphere

That process is already under way, albeit still far too slowly – with the end in sight in the 23rd century. We and the rest of life with us are in the middle of a bottleneck of rising population, shrinking resources, and disappearing species. As its stewards we need to think of our species as being in a race to save the living environment. The primary goal is to make it through the bottleneck to a better, less perilous existence while carrying through as much of the rest of life as possible. If global biodiversity is given space and security, most of the large fraction of species now endangered will regain sustainability on their own. Furthermore, advances made in synthetic biology, artificial intelligence, whole brain emulation, and other similar, mathematically based disciplines can be imported to create an authentic, predictive science of ecology. In it, the interrelations of species will be explored as fervently as we now search through our own bodies for health and longevity. It is often said that the human brain is the most complex system known to us in the universe. That is incorrect. The most complex is the individual natural ecosystem, and the collectivity of ecosystems comprising Earth’s species-level biodiversity. Each species of plant, animal, fungus, and microorganism is guided by sophisticated decision devices. Each is intricately programmed in its own way to pass with precision through its respective life cycle. It is instructed on when to grow, when to mate, when to disperse, and when to shy away from enemies. Even the single-celled Escherichia coli, living in the bacterial paradise of our intestines, moves toward food and away from toxins by spinning its tail cilium one way, then the other way, in response to chemosensory molecules within its microscopic body.

How minds and decision-making devices evolve, and how they interact with ecosystems is a vast area of biology that remains mostly uncharted – and still even undreamed by those scientists who devote their lives to it. The analytic techniques coming to bear on neuroscience, on Big Data theory, on simulations with robot avatars, and on other comparable enterprises will find applications in biodiversity studies. They are ecology’s sister disciplines.

It is past time to broaden the discussion of the human future and connect it to the rest of life. The Silicon Valley dreamers of a digitised humanity have not done that, not yet. They have failed to give much thought at all to the biosphere. With the human condition changing so swiftly, we are losing or degrading to uselessness ever more quickly the millions of species that have run the world independently of us and free of cost. If humanity continues its suicidal ways to change the global climate, eliminate ecosystems, and exhaust Earth’s natural resources, our species will very soon find itself forced into making a choice, this time engaging the conscious part of our brain. It is as follows: shall we be existential conservatives, keeping our genetically-based human nature while tapering off the activities inimical to ourselves and the rest of the biosphere? Or shall we use our new technology to accommodate the changes important solely to our own species, while letting the rest of life slip away? We have only a short time to decide.

The beautiful world our species inherited took the biosphere 3.8 billion years to build. The intricacy of its species we know only in part, and the way they work together to create a sustainable balance we have only recently begun to grasp. Like it or not, and prepared or not, we are the mind and stewards of the living world. Our own ultimate future depends upon that understanding. We have come a very long way through the barbaric period in which we still live, and now I believe we’ve learned enough to adopt a transcendent moral precept concerning the rest of life.

Reprinted from ‘Half-Earth: Our Planet’s Fight for Lifeby Edward O Wilson. Copyright © 2016 by Edward O Wilson. With permission of the publisher, Liveright Publishing Corporation. All rights reserved.

For a critical response to this essay, read Robert Fletcher and Bram Büscher’s opinion here.

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