Inheritors of the Earth

by Chris D. Thomas

  It follows that everything that we, as humans, obtain from those forests has also arrived recently: the beasts of the chase, the fruits we harvest and the forest-dwelling fungi. These trees gave us somewhere to live by providing timber for the construction of our houses and furniture, food by developing the continent’s soils, which we subsequently turned into cultivated fields, means of storing our food in wooden granaries and barns, and wooden bowls to eat it off, and materials to corral our domestic livestock in wooden stables and behind fences. They provided our transport system and means of cultivation: wheels, carts, ploughs and ships. And they gave us our heating and ability to cook. Less gloriously, they provided the materials of war: wooden spikes and fortresses to keep out the enemy, the shafts of spears and handles of swords, and the bows of archers.

  Converted to charcoal, the trees not only allowed our ancestors to cook food, but enabled Stone Age people (‘Wood Age’ might be more accurate) to smelt the first copper seven thousand or more years ago. A thousand years later, charcoal was used to heat alloys of copper, tin and arsenic, ushering in the Bronze Age, followed by iron and steel smelting in the last three to four thousand years. The Iron Age had arrived, thanks to charcoal, thanks to wood, thanks to the trees whose rare predecessors sheltered on the warm slopes of the Balkan forest. We were comfortable: cosy in front of a warm hearth in a wooden house, sitting on wooden furniture draped in the fur of forest animals, eating cooked meats and baked bread from a pottery bowl fired in a charcoal-heated kiln. If we were rich enough, we drank out of a charcoal-smelted glass beaker. Rare trees became common and then gave us our way of life.

  The forest limes, beech, hornbeams and oaks of Europe, and the radiata pine and blue gum trees that grow above Monterey Bay, all show how species that are rare at one time can become common at others. This has always been the way of nature. The majority of species that have ever become really important contributors to the Earth’s ecosystems have evolved in a relatively localized area first, before they spread more widely, and then their numbers have waxed and waned as conditions have changed. These examples also illustrate that rare species can go on to be of immense economic and social benefit to humans. Most of our carbohydrates come from plants that are descended from a few species of grasses that were restricted to small parts of the world before people arrived: maize, rice, the ancestors of wheat, and so on. Cattle and pigs were not particularly rare, but nowhere near as common or as widespread as today, and sheep and goats and chickens were quite ordinary species that lived in different parts of southern Asia. They now provide most of the meat protein that nourishes the world’s human population, and they can be found nearly everywhere that people live.

  The list goes on when one considers all the good things that we have obtained from other unassuming plants (medicines, insecticides, carbohydrates), microbes (brewer’s yeasts, antibiotics, methanogens in bioenergy plants), and animals (honey, pets, meat, leather). Rare species made good is not just a feature of species that we actively use. Like the Bactrian house sparrows and house mice that originated in Asia, and humans in Africa, many other animal species started off living in a small part of the world but have since taken the Earth by storm. Similarly, European herbs that used to live in a few small mountain ranges or ravines now grow widely across parts of North America, after people transported them there.9 Mount Etna Senecio–transformed into Oxford ragwort–now populates every British town.

  Huge changes in the commonness and rarity of different species are a feature of the entire history of life. Now, we are seeing changes again as humans alter the world. Some rare species have become common, while lists of the world’s endangered species highlight those that are increasingly rare and may be lost entirely.

  The inevitable ups and downs of different species that take place when the environment changes, and as they colonize new locations and evolve new characteristics, dictate that we will ultimately fail if we attempt to keep things exactly, or even roughly, as they are. This dynamic perspective of biological change might sound like capitulation, but, in fact, it releases us. The Earth was not in some perfect or final state before humans pitched up. Life is a process, not a final product. So we need a conservation philosophy that is based on natural change, with humans centre stage: partly because we have already brought about so many changes to the world that cannot be ignored, and partly because humans evolved naturally and we are part of the natural system.

  Such a philosophy has four overarching principles.

  The first principle is to accept change. Deviations from the past state are not all ‘worse’. We must recognize that the diversity of life on Earth is determined by the balance between gains and losses, and it is just as legitimate to maximize gains as it is to minimize the rate of loss.

  The second principle is to maintain flexibility for future change. There is no single way to achieve this, but, although it might seem paradoxical, the most important contribution we can make is to save the world’s existing species–within reason (a topic that I will return to shortly). We can think of them as currently rare species that may in future become common–the Earth’s spare parts that might be needed in the future, when new events unleash the next stages of environmental change.

  The third principle is that humans are natural within the Earth system, so anything we do is also a natural part of the evolutionary history of life. We can be adventurous and use whatever technological or other strategies might be available to us to ensure that we hand an operational Earth on to future generations, without fear that we will somehow make the world less natural.

  And the fourth principle is that we still have to live within our planetary bounds. We know that we cannot expect the bounty to continue if we carry on killing animals faster than they can breed or cut forests down faster than they grow. This strategy failed when our ancestors drove most of the world’s largest land animals to extinction, and it has played out in the last few centuries as whale and fish populations have collapsed under the pressure of over-harvesting.10 We need a resilient and sustainable approach. We should aim for maximum efficiency, by which I mean that we should pursue strategies that fulfil all human needs–and, where possible, desires–of every citizen on Earth while generating the least possible collateral damage to the global environment.

  Converting this philosophical quadrumvirate–accept and promulgate ‘good’ change; maintain flexibility; use any means available because human actions are natural; live within our planet’s bounds–into agreed practical strategies and actions is far more difficult, not least because individual people and societies will differ in their preferences. I will just touch on a few of the options.

  The first principle is to accept change because this is the natural way that the biological world responds when the environment changes. Accepting change is not the same as a laissez-faire approach. It is instead about considering the pros and cons of possible alternatives, knowing that ‘no change’ is not an option. It is about prodding the world in a desired direction as effectively and efficiently as possible.

  Being efficient usually means that it is a far greater priority to address the underlying causes of environmental change, such as generating energy without causing climate change, or obtaining sources of protein in the human diet from the minimum possible area of land and sea, than to patch the world up afterwards. For example, once we are able to produce laboratory-grown animal muscle economically and generate ‘meat substitutes’ from plant and fungal material that people really like as much as meat, killing living animals to derive our sustenance might become socially unacceptable. This could potentially be achieved rather soon, by which I mean within fifty years to a few centuries. At that point, the pressure to convert more land into pastures would be greatly reduced.

  If the cause cannot be rectified, there needs to be an extremely good reason to embark on an indefinite treatment of symptoms. We need to be able to justify keeping unstable ecosystems in their current state or saving species that are
no longer viable. We might decide to put in the effort, as New Zealand currently is, to protect pedestrian birds and crawling bats on account of their cultural and scientific interest,11 but if we decide that they fail the ecological and evolutionary triage of modern life, the future trajectory of our biological world will not be altered in any important way. Our aim should be to maintain robust ecosystems (however different from those that exist now or existed in the past) and species, rather than to defend an unstable equilibrium. We can let change happen.

  At present, our default position is to treat change as negative. The nations of the world have agreed that we should aim to save biodiversity, signing up to the overarching international framework of the Convention on Biological Diversity. The representatives of each nation go back home from their international congresses, charged with at least slowing the rate at which biodiversity is lost within their own country. This requires each country to establish what it already has.12 Loss has to be measured against something, so ‘the present’ (or recent past) represents a baseline against which any future change can be measured. That seems sensible. If any ‘native’ species or ‘natural’ habitat declines within a country, it triggers concern.

  The convention has been immensely beneficial, but the setting of baselines for species and habitats, and the calculation of trends separately for each country, has had a very negative side-effect. It has formalized a no-change-is-best framework for conservation throughout the world, when we know that dynamism is how species ultimately survive periods of environmental change. By saddling our assessment to fixed baselines within national boundaries, all changes, including gains of new species that arrive from other countries, represent deviations from the baseline that has been set. A decline of a species in one country registers on our biological accounts as negative, and its arrival in another country is likely to be either ignored or counted as negative (as a biological invader, which is also recognized as a problem within the convention), even if the overall international status of the species is unaltered. This can’t make sense.

  It is difficult to understand why any particular moment in the continuous passage of time should have special significance. Why are the dates of conservation congresses in the late twentieth and early twenty-first centuries superior to other baselines? Why not go back 130,000 years ago for a model of how the human-free world should be? This was the last time the Earth had a similar climate to today, in the period before modern humans had emerged from Africa and killed off the large animals. The fundamental flaw of baselines–or backwards-facing conservation–can be appreciated once one realizes that every ecological and evolutionary gain that took place prior to a particular baseline date is defined as desirable, whereas all the gains that took place afterwards are likely to be dismissed, disliked or repelled (equally, losses before the baseline are accepted, but those after it are not). Arbitrarily move the baseline to an earlier date, and more of the gains are deemed undesirable. Baseline reasoning makes no logical sense when life on Earth is a dynamic process.

  It is enormously helpful to understand and draw inspiration from the past, and I have repeatedly done so in this book, but going back to it is not on the table, as we saw in the abandoned landscape that surrounds the now-defunct Chernobyl nuclear reactor. Many of the biological changes of the human epoch are already permanent. We should be informed by the past, but not circumscribed by it. We can only go forwards, and that means dealing with species moving to new locations, with evolutionary change in those species, and with new species that come into existence.

  The second principle is to maintain flexibility for future generations, in the knowledge that we cannot predict the future with any accuracy. It is no easier for me to imagine the world that my descendants will inhabit 150 years from now than it was for my great-grandparents to have imagined the transformations that have taken place between the 1860s and today. How can we tell what new politics, social attitudes, construction, transport, pollutants, means of obtaining our food and drink, biomedical products, diseases, artificial life, artificial intelligence, robotics, energy sources, weapons systems and unknown unknowns will represent new global norms by the second half of next century? Nor can we know how we and the biological world will respond to these changes. This is sobering when we consider questions such as whether, when and how we might deliberately intervene to protect nature. While it is perfectly acceptable to make short-term decisions that will bring pleasure, health or other benefits to those of us alive today, an underlying philosophy of conservation is for us to act as custodians of the natural world for future generations.

  Thinking beyond the direct and current needs of people who are alive today, any human-oriented conservation strategy must be about maintaining opportunities within the biological world of which we are a part. To be able to take full advantage of the world’s biological potential in future, we should keep alive the building blocks of the biological world. By building blocks, I mean those populations and species that will form tomorrow’s ecosystems. The more different kinds of species exist, the greater will be the chance that at least some of them will flourish under the new conditions (whatever they are), and it increases the chances that new evolutionary adaptations and hybrid forms will have properties that enable them to contribute to the Earth’s biological processes. This is not a preservationist strategy but a resilient, flexible approach that will fuel rather than prevent future biological change. Not only will existing species and their evolutionary descendants form future ecosystems, they will also be the sources of new discoveries. Such is the rate at which new biological technologies are advancing that we are probably entering a period of unprecedented growth in the ways in which we develop and use natural products from living animals, plants, fungi and microbes. If we care about the longer-term condition of humans on Earth, we should not ignore species that are unfamiliar or rare today. These may be species on which humans rely only a few generations hence, just as European civilizations relied on once rare Balkan trees and we now utilize previously rare Monterey pines and gum trees.

  Keeping as many species as possible alive is a momentous challenge, particularly when we realize that their future survival will not necessarily depend on them continuing to live in the places where they currently thrive. As the climate changes, for example, perhaps a quarter of all species will become climate refugees, surviving only outside their historical distributions, and nearly all species will live in at least some new places. Helping species to reach these new locations–promoting gains at the same time as minimizing global losses–is likely to become a major focus of conservation in the second half of this century. Keeping them alive somewhere on our planetary Ark is the challenge we face. This keeps our biological options open, even if we do not know precisely how each species will contribute to future ecosystems, or whether they will improve the wellbeing of future human generations.

  The third principle is that humans are natural within the Earth system, and so it follows that anything we do, or do not do, is a perfectly natural consequence of the evolution of a bipedal ape. We can intervene in ways that old-thinking would define as ‘unnatural’. We can be proactive rather than bowed over with regret that things are no longer as they were.

  The ginger-guzzling elephants I met in the under-storey of Borneo’s Danum Valley forest are a case in point. Imported from a now extinct population that most likely lived in Java, the island of Borneo now holds the world population of this genetically distinct form of Indian elephant. No one, as far as I know, is proposing to remove them–but if they could be proven to be ‘native’ to the island of Borneo after all, conservationists would then regard their presence as unambiguously beneficial.

  If we step back, does the answer to the question of whether they are ‘native’ really matter? It is difficult to see these elephants as bringing about ‘bad change’, provided we accept that humans are part of the new nature. Any unique genes13 that are held by these animals survive only because they were transport
ed from one island, where elephants died out, to another, where they have succeeded. Genes, like species, survive because they keep track of the changing world. With humans as part of the natural system (human-mediated dispersal is natural), the presence of elephants on Borneo now is natural, irrespective of however short or long their history in the region may be. There is no suggestion that they are driving Bornean species to extinction, and their presence may be beneficial by providing dung for beetles and generating small-scale disturbances for plants to regenerate, as well as water-filled footprints where damselflies can breed. It is true that a forest with elephants is going to be different from a forest without elephants, but the net balance of gains and losses is not necessarily going to come down on the side of debit.

  Such accidents pepper the world. All the many thousands of transported plants and animals that have established populations in new regions have demonstrated time and again that species may flourish outside their historical ranges. In doing so, they normally increase the total number of species that live in each region, they start to evolve into distinct forms and they sometimes hybridize and create new species. Eventually, they will increase the diversity of life on Earth. Unless one synonymizes change with loss, these events are not inherently bad, so why not use similar approaches in conservation? Moving threatened species to places where they will prosper could save them from extinction, as could the infusion of new genes from other populations or species. The critically endangered yellow-crested cockatoo, for example, is thriving as an introduced population in Hong Kong while continuing to decline in its Indonesian homeland.14 There are myriad opportunities, but the conservation world rarely countenances such thinking. There is a fear that projects of this type will cause yet more change, but change is going to happen anyway, whatever we do. If we are going to have new biological communities in any case, why should they not contain a smattering of rarities, rather than just the globe-trotting generalist species that will turn up on their own?