Colin Tudge asks why it matters and what we can do
to achieve it

Let us, for starters, banish the word “environment”. Let us speak instead of “the biosphere”. Environment, after all, simply means “surroundings”, which in practice in the present Zeitgeist is equated with “real estate”. The term is intrinsically anthropocentric – human-centred. It implies that we, human beings, are and should be right at the heart of things, while the rest of the world is our stage, our playground – a smorgasbord of “natural resources”, for us to consume, mould, or obliterate at will. Even worse: the plunder is not in practice, as we are given to understand, for the benefit of all humanity. Only a minority truly benefit and, it seems, not for much longer.

The term “biosphere” has quite different connotations.

The idea of the “biosphere”

“Biosphere” means “the living world”. It does not, like “environment”, imply that the world is our own personal cornucopia. We are part of the whole, like atoms in a molecule, or cells in an organism, or members of a family. The whole is our life support, and we are beholden to it. Other creatures, as St Francis said, only in part metaphorically, are our brothers and sisters. Or we could simply say, as mystics from all traditions have often said, “All life is one.”

Clearly, the term “biosphere” (at least as used here) has connotations both literal – matters of science and natural history – and metaphysical. In particular, apparently since humanity first began, many and probably most people have felt that there is more to the world in general, and certainly more to the living world, than meets the eye or can ever meet the eye. The world and perhaps especially the living world has a transcendent dimension (as discussed in section VI.1.1); or, as the German theologian Rudolf Otto put the matter in the early 20th century, it is “numinous” – a term derived from the Latin numen meaning “divine presence”.

The science of the biosphere – and some at least of the accompanying metaphysics – has been evolving stage by stage over the past 200 years or so. It properly began in the late 18th century with James Hutton.

Stage 1: First stirrings of modernity: James Hutton

James Hutton (1726–1797), alongside David Hume and Adam Smith and an honourable shortlist of others, was a pillar of the Scottish Enlightenment, often called “the father of modern geology” (although his successor, Charles Lyell, is sometimes afforded that title). As he describes in his monumental Theory of the Earth of 1795, Hutton studied the rocks and landscapes mainly of Scotland and its islands and sought to understand why things are as they are; why there are mountains and valleys and gorges and plains and beaches. For Hutton as for Aristotle the question “Why?” is multi-layered. He seeks to discover the physical forces that have shaped the world but he also wants to know what they are all for:

… the whole presents a machine of a peculiar construction by which it is adapted to a certain end. We perceive a fabric, erected in wisdom, to obtain a purpose worthy of the great power that is apparent in the production of it.

Thus he conceives that the world is planned – “erected in wisdom”. He also assumes, at least as a working hypothesis, that the source of this wisdom would not do anything gratuitous. Everything – surely? – must be for some purpose, contributing to the whole, and yet, he says, we don’t always know what that purpose is. Hence:

The laws of electricity and magnetism have been well examined by philosophers; but the purposes of those powers in the oeconomy of the globe have not been discovered.

Hutton wrote this some decades before Michael Faraday began his researches into electricity and magnetism (Faraday wasn’t born until 1791) and a very long time before James Clerk Maxwell (born 1831) started out on the road that led Einstein to relativity. So, ignorant scribbler that I am, I am not at all sure what was really known before Hutton’s day (although Luigi Galvani had done his stuff by then and Alessandro Volta was well into his stride). Be that as it may, he goes on to tell us that:

Subterraneous fire, again, although the most conspicuous in the operations of the world, and often examined by philosophers, is a power which has been less well understood, whether with regard to its efficient or final cause. It has hitherto appeared more like the accident of natural things, than the inherent property of the mineral region.

“Efficient” cause, in Aristotle’s physics, refers to the immediate reasons why things change – the forces at work; and “final” cause refers to the reason behind those forces: what is the goal? Although Hutton professes ignorance on both counts he does throw light on the final cause. For, as he goes on to show, volcanic eruptions help to build mountains and the general stirrings of the “subterraneous fire” lift the sea-bed to the mountain-tops – which is how and why there are sea-shells at high altitudes.

So, he says, volcanism is:

a great power acting a material part in the operations of the globe, and an essential part in the constitution of the world.

Once the mountains are built, however, they begin immediately to erode. Yet again we see that such destructive forces have a positive side too. For without erosion there would be no plants on land – and without plants there would be no terrestrial life of any kind. Thus:

A solid body of land could not have answered the purpose of the habitable world; for a soil is necessary to the growth of plants; and a soil is nothing but the materials collected from the destruction of solid land. [He does not mention the organic content of the soil.]

Therefore, the surface of this land, inhabited by man, and covered with plants and animals, is made by nature to decay, in dissolving from that hard and compact state in which it is found below the soil …

But there’s a snag. For once it is formed:

the soil is necessarily washed away, by the continual circulation of the water, running from the summits of the mountains towards the general receptacle of that fluid.


by the agitation of the winds, the tides and currents, every moveable thing is carried farther and farther along the shelving bottom of the sea, towards the unfathomable regions of the ocean.


If the vegetable soil is thus constantly removed from the surface of the land, and if its place is there to be supplied from the dissolution of the solid earth, as here represented, we may perceive an end to this beautiful machine; an end, arising from no error in the constitution of the world, but from the destructibility of its land which is so necessary in the system of the globe, in the “economy of life” and vegetation.

We are, therefore, to consider as inevitable the destruction of our land, so far as effected by those operations which are necessary in the purpose of the globe, considered as a habitable world.

Intuitively, though, he cannot bring himself to believe that the wisdom that created the Earth would simply allow that great creation – “this beautiful machine” – to run down. He also infers that sedimentary rocks, formed by compression from layers of silt and sand, must have taken many millions of years to form. In fact he cannot conceive that the Earth, which has clearly been here for such a long time, should ever end:

the natural course of time, which to us seems infinite, cannot be bounded by any operation that may have an end, the progress of things upon this globe, that is, the course of nature, cannot be limited by time.

In passing we might note that at the time Hutton was writing this, scholars still tended to accept the calculations of Archbishop James Ussher of Armagh who in the 17th century inferred from the chronology of the Bible that the Earth must have been created in 4004 BCE.

Much more to the point, Hutton then argues as follows:

We have now considered the globe of this earth as a machine … But is this world … merely a machine? Or may it not be also considered as an organized body? such as has a constitution in which the necessary decay of the machine is naturally repaired, in the exertion of those productive powers by which it has been formed.

If no such reproductive power, or reforming operation, after due inquiry, is to be found in the constitution of the world, we should have reason to conclude, that the system of this earth has either been intentionally made imperfect, or has not been the work of an infinite power and wisdom.

There is so much in this passage. As many have pointed out, the idea of the Earth as “an organized body” anticipates the 20th century idea of Gaia. Note, too, that Hutton is led to infer that the Earth must be possessed of some “reforming operation” by which its constituents are “naturally repaired” – what today is commonly called “regeneration” – largely on metaphysical, not to say theological, grounds. Hutton does not use the word “God”, at least in the opening chapter of Theory of the Earth from which the above quotes are taken, but he is driven by a sense of an underlying “wisdom” that is able to “obtain a purpose worthy of the great power that is apparent in the production of it”. So he infers that the world must be able to regenerate, or the grand plan behind it would be flawed – which surely cannot be the case; and this is a metaphysical argument. But he invokes science too, for he infers from his own studies, not least of sedimentation, that the world will last forever – and if this is so then the forces of erosion, of decay, must be countered. So we see theology/metaphysics and science in concert. As John Hedley Brooke of Oxford and Lancaster Universities explored at length in Science and Religion in 1991, the idea that science and religion are necessarily at odds is too crude by half. The relationship between the two has often been synergistic and sometimes – far more often than might be supposed – theology has taken the lead and suggested the agenda that science then follows. In Hutton’s work we see an example of this (and in Darwin too, though that’s another story).

Anyway, on the strength of all this, Hutton sets out his agenda:

In what follows, therefore, we are to examine the construction of the present earth, in order to understand the natural operations of time past; to acquire principles, by which we may conclude with regard to the finite course of things, or judge of those operations, by which a world, so wisely ordered, goes into decay; and to learn, by what means such a decayed world may be renovated, or the waste of this habitable land upon the globe repaired.

In “what follows” Hutton does indeed look at some of the regenerative forces, including the general turmoil of the Earth that produces new mountains and the circulation of water by evaporation and rain. Now, of course, his intuition that the forces of volcanism cannot simply be destructive is vindicated beyond all reasonable doubt by the new science of plate tectonics. The convection currents in the molten magma beneath the crust shuffle the re-solidified crust above, and the crust is split into a series of “plates” on which float the lighter rocks that form the land. The constant jostling of the plates causes earthquakes and tsunamis but it also makes mountains – and ensures on the grander scale that almost all land everywhere has migrated all over the globe over the past few billion years, sometimes tropical and sometimes polar, sometimes part of continents and sometimes isolated, with huge consequences for the history of life. Convection of the magma too ensures that the minerals of which the surface is composed are constantly recycled: welling up from the fissures along the ocean beds where the plates split apart, and carried back into the depths at the edges of the continents where the plates of the ocean bed dive under the continental plates.

Overall, Hutton established what is perhaps the key principle of all ecology: that the economy of the Earth is cyclic. Circularity is all. Thus he was indeed the father of geology – and also the father of ecology. In both he was guided by observational science and intuitive metaphysics in more or less equal measure. In truth, science always has a metaphysical underpinning and in Hutton, unburdened by 20th century minimalism, the metaphysics is clear to see.

Stage 2: The concept of ecology: Ernst Haeckel

Ernst Haeckel (1834–1919) belonged to the German Romantic tradition of biology, which again, very clearly, has both metaphysical and scientific roots. Like all great movements, German Romanticism led its disciples in many different directions, some of them most pleasing, but also leading some towards Nazism. This shows us that the inputs of metaphysics are not necessarily to the good – and also shows why it is that metaphysical assumptions must be made clear. As they say in maths exams, “Show your working!” (I still feel the chill).

Haeckel was a broad thinker and a great coiner of neologisms, including the essential biological concepts of “ontogeny” and “phylogeny”. He was also the first to speak of “The First World War” – clearly anticipating a sequel, even while the first one was in train. More to the point, in 1866 he coined the term ecology. It derives from the Greek oikos, which is usually translated as “household”, as of course does the word “economics”. Ecology may indeed be seen as the study of Nature’s economy – the sum total of all the interactions between all the players, and between living creatures and the physical world. Scrolling forward a little, in 1935 the English botanist Arthur Tansley (1871–1955) coined the complementary term ecosystem: the ecological relationships of all the creatures in any one community.

Ecology in our own brutal times is commonly seen as a minor player among the biological sciences. After all, it derives fairly seamlessly from the genteel pursuits of natural history and doesn’t look as difficult as the higher reaches of genetics, or molecular biology, and does not give rise to any immediately powerful and lucrative technologies, like genetic engineering. Yet ecology should surely be seen as the subtlest of all the sciences, and we neglect it at our peril. Ecology above all embraces the concepts of complexity and of non-linearity. The former means more or less what it says, while the latter acknowledges that within complex systems – which all ecosystems are – cause and effect cannot be simple, of the kind that Isaac Newton envisaged in his idealized mechanics. In nature there are so many variables and so many uncertainties that it is in theory as well as in practice impossible to predict the long-term consequences of any one change in conditions, whether or not the change is intended. Wildlife conservation, farming, gardening, and indeed clinical medicine – all of course can benefit enormously from science but none can ever be exactly predictive (which indeed is true of engineering too, although that is not always acknowledged until the bridge falls down or the aeroplane falls out of the sky). Ecologists, like physicians, live with the realities of non-linearity and with uncertainty. They acknowledge that nature is ultimately beyond our ken and cannot simply be tailored and re-conceived for our convenience, as the creators of GM crops and pesticides and herbicides and all the other “cides” evidently think it can. The idea that we can and should aspire to “conquer” nature is not only vile (and many would say blasphemous) but is also absurd, unless we equate conquest with obliteration.

Stage 3: The idea of the biosphere

The term biosphere was coined in the late 19th century by an Austrian geologist, an expert on the Alps, Eduard Suess (1831–1914). The idea of it was further elaborated the early 20th century by the Russian mineralogist and biologist Vladimir Vernadsky (1863–1945); the French philosopher and mathematician Edouard Le Roy (1870–1954); and the French Jesuit palaeontologist Teilhard de Chardin (1881–1955). Vernadsky is a hero of Russian science but is far less known in the west than he should be and Le Roy is not well remembered at all, but Teilhard has had a lasting impact the world over.

Eduard Suess at the University of Vienna proposed several ideas of lasting value including that of Gondwanaland, now more commonly called Gondwana, the huge supercontinent in the south. In Suess’s day this was very much conjectural but all the evidence now suggests that Gondwana did indeed exist, and was indeed huge (since it included all the land that now forms Africa, South America, Australia, New Zealand, India, and of course Antarctica). Suess introduced the term “biosphere” in his monumental Das Antlitz der Erde (The Face of the Earth), published between 1885 and 1901:

One thing seems to be foreign on this large celestial body consisting of spheres – namely, organic life.

But this life is limited to a determined zone at the surface of the lithosphere. The plant, whose deep roots plunge into the soil to feed, and which at the same time rises into the air to breathe, is a good illustration of organic life in the region of interaction between the upper sphere and the lithosphere, and on the surface of continents it is possible to single out an independent biosphere.

Then in the 1920s onwards Vernadsky, Roy, and Teilhard, working semi-independently (although they knew each other), developed the idea that the Earth evolved in three stages: first the geosphere (the structure of the Earth itself, including the lithosphere, hydrosphere, and atmosphere); then the biosphere; and finally the noosphere. “Noosphere” derives from the Greek nous, meaning mind, and is the world of conscious thought. Teilhard later said that he could not remember who first coined the word although he thought it was himself.

Teilhard spelled out the geosphere–biosphere–noosphere idea very clearly in his best-known and most important work, The Phenomenon of Man (Le Phénomène Humain). More broadly, he championed the idea of “orthogenesis”: the notion that evolution does not follow a random path (as some later biologists have insisted) but leads in particular directions, teleologically indeed, towards particular goals. Overall he saw the evolution of the whole universe as “an ascent toward consciousness” which would culminate in the “omega point” at which all Creation would be at one with God. Although we, human beings, are not the only conscious animals and do not have a monopoly on “mind”, it is we who have created the noosphere from which the omega point will arise. Thus, as Teilhard sees things, our own position in the grand scheme of things is very special indeed; we form the bridge between the material and the divine, and were designed for this role.

Teilhard was a fine palaeontologist, who helped in the discovery both of Peking Man and of Java Man, and was a subtle theologian. But he got a mixed reception both from scientists and from the Catholic Church. Many biologists dismissed his evolutionary musings out of hand – notably one of the all-time greats, the zoologist and immunologist Sir Peter Medawar, winner of a Nobel Prize, who wrote in the journal Mind that The Phenomenon of Man “for the greater part … is nonsense, tricked out with a variety of metaphysical conceits, and its author can be excused of dishonesty only on the grounds that before deceiving others he has taken great pains to deceive himself.” Richard Dawkins of course sides with Medawar and declared that The Phenomenon of Man was “the quintessence of bad poetic science”.

But other biologists, no less distinguished, were far more sympathetic. Sir Julian Huxley, co-author of “the modern synthesis”, which combines the ideas of Charles Darwin with those of Gregor Mendel, said that after Teilhard “The religiously minded can no longer turn their backs on the natural world … nor can the materialistically-minded deny importance to spiritual experience and religious feeling.” Theodosius Dobzhansky, one of the towering figures of 20th century evolutionary biology, who also helped shape the modern synthesis, was an admirer too. His famous comment that “nothing in biology makes sense except in light of evolution” echoes Teilhard’s observation that “nothing makes sense until you understand its history”.

At first the Catholic Church also took a dim view of Teilhard but, much later, sometime after his death, they changed their minds. Thus in 1926 Teilhard’s Jesuit superiors ordered him to stop teaching; and when he submitted The Phenomenon of Man to Rome for approval in 1941 he was told not to publish it (although the Vatican did not, as they might have done, place his great work on their Index Expurgatorius). But in 1981, on behalf of Pope John Paul II, Cardinal Agostino Casaroli wrote in the Vatican’s newspaper l’Osservatore Romano that Teilhard “was concerned with honouring both faith and reason, and anticipated the response to John Paul II’s appeal: ‘Be not afraid, open, open wide to Christ the doors of the immense domains of culture, civilization, and progress.’” The present pope, Francis I, has also expressed approval.

In truth, the world is still divided (and probably always will be). Some feel that Teilhard was a prophet of our age and some feel he was a crackpot, or as biologist Steven Rose put the matter, “little better than a charlatan”. For what my opinion is worth, I favour the former view. The hardline scientific opposition to Teilhard seems to me to reflect the hardline view of what science is, and of what it can do: of science as a ruthlessly materialistic, essentially logical-positivist inquiry that will, given enough time, effort, and money, lead us in effect to omniscience. But this, as argued elsewhere, is both dangerous and naïve. Science needs a metaphysical context that should be made explicit, and if it’s wisdom we seek, as it surely should be, then Teilhard’s admittedly poetic approach seems entirely appropriate. It surely is not the last word but then, this side of the grave, there isn’t one.

So the fourth stage:

Stage 4: Gaia: James Lovelock

James Hutton, at the end of the 18th century and the start of the modern era, conceived of the world as a very complex machine – indeed as “not merely a machine” but “an organized body”. He and the ecologists who came after him began to reveal what this implies: enormous complexity – a host of different players and a host of interactions between them, both synergistic and competitive; and in the end, circularity – nothing lost, nothing wasted, the ultimate exercise in what nowadays is crudely called “sustainability”. Indeed, as the English scientist James Lovelock (b. 1919) has described over the past few decades, the world as a whole and all its creatures behave, overall, very like an organism. The world isn’t an organism – or at least, that’s not the best way to look at it – but it does have many or most of the essential qualities of an organism. The complexity and the interdependence of all the components are a part of what’s implied by this. But also – which is Lovelock’s special contribution – the world as a whole (lithosphere, hydrosphere, atmosphere, and biosphere together) has the essential quality of homeostasis. Organisms strive above all to ensure that the conditions within their own bodies – what the 19th century French physiologist Claude Bernard (1813–1878) called the milieu intérieur – remain as constant as possible and, more importantly, that they remain within the limits needed to sustain life. So, it seems, does the world. Lovelock’s neighbour and friend, the novelist William Golding, suggested that the world conceived as a quasi-organism might be named after the Greek Goddess of the Earth: Gaia.

In a succession of books (there is no definitive account, he says) Lovelock presents many examples of many different kinds of Gaia in action – some, as is commonly true of ecosystems, of enormous complexity. Always two principles are to the fore: first, as Hutton first intimated, that all the materials that make up the Earth are constantly circulated, and nothing (or very little) is lost into the cosmos. Secondly – which some people in high places still apparently find hard to appreciate – living creatures do not simply camp on the surface of the Earth. By their machinations, they profoundly alter the composition and the nature of the whole caboodle: lithosphere, hydrosphere, atmosphere. Without life to soften the blows and to reconfigure its raw structure, the Earth would be a barren rock, its waters acrid, its atmosphere toxic, and all laid waste by cosmic radiation.

Sometimes the influence of life is easy to see. Thus there would be no oxygen gas in the atmosphere if it weren’t for photosynthesis, invented by cyanobacteria around two billion years ago and then commandeered by diatoms and plants. Obviously there would be no aerobic respiration – so no animals; no large creatures of any kind. Without oxygen gas too there would be no ozone layer, to protect us from cosmic rays. Neither would we see the red rocks that are such a feature of landscapes all over the world. The red is iron in its ferric, oxidized form.

Every schoolchild learns too that the great chalk cliffs and limestone seams that are such a feature of Britain and especially of England were made aeons ago by planktonic “protozoans” known as Foramenifera, or “forams”. Far less obvious is the phenomenon that Lovelock describes: that forams ensure that the salinity of the sea has remained more or less constant at least for hundreds of millions of years, at around 3.4 per cent.

Common sense suggests, after all, that the sea should be getting more and more salty – which is what old-fashioned textbooks said was the case. After all, the salt in the sea – 90 per cent sodium chloride, plus magnesium and sulphate, and a little calcium and bicarbonate, all in ionic form – is there because it washes off the land, and also wells up from the mid-ocean fissures between the tectonic plates: an estimated 540 million tonnes of it per year. If we know the total volume of the ocean, and the concentration of salt, and the rate at which salt is added by washing off the land, we can work out how long it must have taken to reach the present level of saltiness. But when we do the sums the answer comes out at 80 million years – and if we add in the salt that wells up from the sea-bed, it comes down to 60 million years. Yet the oceans have obviously been there for billions of years. If the salt had just gone on accumulating as common sense suggests it must, then the world’s oceans by now would be like the Dead Sea, super-saturated, and populated only by salt-loving (halophilic) microbes.

So what’s going on? Well, the forams extract calcium from the sea to make their calcareous skeletons, and other protozoans and sponges extract silicon to make their siliceous skeletons, and this upsets the electro-chemical balance of all the other ions in a way that makes it harder and harder for sodium and chloride and other ions to stay in solution. At the edge of the oceans the sea becomes more concentrated through evaporation and the sodium and chlorine combine to form sodium chloride, and then precipitate; and so we find great salt-beds all around the world, the spoor of seas long past. So the sea never gets too salty. This at least is the gist of the argument. In reality, as Lovelock describes in Gaia: A New Look at Life on Earth (OUP, USA, 2000) the chemistry is immensely complicated (as Medawar said in another context, though in his case it was ironic, “too much for my old head!”).

In the world as a whole, dozens of such mechanisms are at work. Many are immensely subtle and immensely complicated. To some extent the Gaia hypothesis is an extension of the Goldilocks hypothesis, which simply points out that if any of the forces at work in the universe were ever so slightly different – if gravity or the weak nuclear force or whatever were ever so slightly stronger – then the present universe simply could not exist, and it is hard to see how any other kind could either. The whole lot has to act in harmony. But Gaia says more than Goldilocks. It describes life interacting with life and with the fabric of the Earth itself, reformulating and in the case of rocks restructuring the geosphere – and overall the effect is homeostatic: life interacts with the geosphere in ways that make the geosphere fit for living in. The whole is indeed like an organism, always adjusting for its own benefit. Again, the connotations are both scientific (as Lovelock emphasizes) and metaphysical (which Lovelock prefers to play down). For my part, I see Gaia as one of the great insights both of modern science and of metaphysics.

One last development deserves mention:

Addendum: The Anthropocene

The International Union of Geological Sciences which has great sway in these matters has yet to decide whether or not the term “Anthropocene” should be officially adopted – but if it is, then it surely should be greeted with mixed feelings. The term seems to have arisen in the Soviet Union in the 1960s and was made popular in the west in the 1970s, and refers to the latest period of Earth history, in which human beings have had an obvious and significant impact.

On the one hand the term is welcome because it acknowledges reality. Over the past few thousand years, with ever-increasing vigour, human beings have hugely and to a large extent permanently changed the nature of planet Earth: the biosphere (with all the knock-on effects); the atmosphere (including climate); the chemistry of the hydrosphere; and the chemistry and structure of the lithosphere.

On the other hand, that reality is chilling. To accept the term “Anthropocene” is to acknowledge that the past really is past, and that what happens now and in the future must reflect human will and whim with all their imperfections and unintended side effects. Though some may feel that humanity itself has made progress (which to some extent we have: see I.3.1), our overall impact on the natural world has been one of devastation. On a trivial but nonetheless salutary note, strata of sedimentary rock dug up in a few million years’ time (if there is anyone to do the digging) may, alongside the fossils of ourselves and takeaway chicken wings, include petrified toothbrushes – though sometimes unfossilized: the plastic may still be pristine. Not ammonites and trilobites in future rocks, but millions on millions of flip-flops, now being lost on thousands of beaches. That might well be the reality but it is not a pleasing thought.

No-one can agree, though, on when the Anthropocene began. Some say it properly began around 10,000 years ago at the end of the latest Ice Age, the time of the “Neolithic Revolution” when agriculture truly got into its stride – enough to leave clear traces in the archaeological record. This would make the Anthropocene coeval with the already acknowledged Holocene. James Lovelock suggests that the Anthropocene can reasonably be dated from 1712 and the launch of Thomas Newcomen’s “atmospheric engine” – the start of the steam age. Others would begin as late as 1945 – the atomic age. On the grounds that it seems a shame to ditch the well-established Holocene, and 1945 is surely too late, Lovelock’s compromise, or thereabouts, seems fair enough. Perhaps around 1600 would be about right – the first convincing stirrings of industrialization.

Whatever the authorities decide, the fundamentals are undeniable. The changes that we have made have been profound and to a large extent are irredeemable. What’s gone is gone, and some of the processes we have set in train will take centuries to unfold, with no clear end point. In the face of all this, most of what now passes as world affairs and occupies the nightly news tends to feel rather trivial.

So what does it mean to say that the biosphere is “flourishing”?

A flourishing biosphere

Nature is not an idyll but, left to itself – without the conscious attempts of human beings to change it – it does pretty well. It has produced and supported wondrous diversity – surely many billions of different species since life first began on this Earth nearly four billion years ago. It has proved wonderfully sustainable – for Earthly life is almost a third of the age of the Universe. Life too has been continuous even though conditions have changed spectacularly these past few billion years (despite the best efforts of Gaia!). The acquisition of free oxygen gas, something over two billion years ago; continental drift, forming mega-continents and splitting them up again, spinning land masses on their axes, shuffling them from tropics to the poles and back again; a constant stream of new life forms, sometimes obliterating what was there before; fluctuating climate, not least because the Earth wobbles on its axis; and, every now again, a catastrophe – a mega-volcano or a giant asteroid, throwing the whole caboodle into confusion; all have created, at intervals, what in effect are quite new worlds. But although life has suffered some huge setbacks, including five mass extinctions, fresh suites of creatures have come surging back each time to replace what was there before. The biosphere as a whole, in short, has been wonderfully resilient.

To restore the biosphere to its former, pre-Anthropocene glory – or at least to halt and with luck reverse the present, headlong decline – we need, as ever, two ingredients. We need as far as possible to know what we are dealing with – what’s in the biosphere, and how it all works; and we need to give a damn. In other words we need a combination of good science, underpinning good technique – which in this case very obviously means the science of ecology; and we need morality, preferably underpinned by a sense of transcendence (though this perhaps is not vital – see below). As is always the case therefore, in all contexts, we need to be guided by the science of ecology on the one hand and morality (and metaphysics) on the other.

A matter of science

To begin with the ecology, how does the biosphere work? How – before our own species came along – did it remain in good heart for so long? Four qualities in particular stand out:

First, successful ecosystems in general are diverse. At least, when they are not, we can usually find special reasons why that is the case. In general over time ecosystems tend become more complex.

Secondly, all the creatures within any one community or ecosystem or the biosphere as a whole are inescapably interdependent. Sometimes their interactions are mutually beneficial, and then they are said to be mutualistic. (The word “symbiosis” is commonly taken to mean mutualistic, but really it just means “living together” without necessarily implying any benefit. The word that sounds like “symbiotic” and does mean mutualistic is “synergistic”.) Sometimes the different creatures compete with each other and are generally at odds and then the relationships may be agonistic. “Interdependence” is the key term. The relationships between creatures in any one time and place are both synergistic and competitive, but in the end, the net result is greater than the sum of the parts: a community, an ecosystem, Gaia.

For although Darwin apparently stressed, and modern economists and politicians certainly do stress, the need to be competitive, and nature obviously is highly competitive, it certainly is not as bad as Tennyson suggested – “red in tooth and claw”. Overall, though this may be less obvious, synergy prevails. Thus the vast majority of plants, including almost all trees, rely for their long-term survival on symbiotic – which in this case really does mean mutualistic – fungi known as mycorrhizas, or mycorrhizae, which live in and around their roots, and hugely extend the range and efficiency of root function. In exchange, the fungi exact a tithe of sugars from the plant, the product of photosynthesis, a skill that fungi have not mastered. Overall, such symbiotic relationships in many different forms are the norm. If it were not so, then all ecosystems, and communities, would surely fall apart, which they very obviously do not. The most virulent parasites and the most aggressive predators must make sure they don’t overdo it, and kill off all their potential hosts or their prey base, or they will die too; either that, or they must find new species to feed on.

In practice, predators and parasites don’t always exercise enough constraint. Many a wild population has been wiped out by some rampant disease. Many a predator has wiped out many a prey. Human beings kill off the creatures and the ecosystems that have supported them as a matter of course, and then move on. We, after all, are uniquely versatile, and can always adapt to fresh woods and pastures new. But we are running out of places to move on to. Interdependence is and must be the rule. Any creature that breaks the bounds and destroys its own prey base will destroy itself. The ecosystem as a whole, of which each creature is a part, will be impoverished, and must survive if at all in a different form.

Thirdly, although ecosystems do have leaky borders – they both donate to and receive from other ecosystems – the overall economy in any one ecosystem is circular: cyclic. The economy of the biosphere as a whole, the sum of all ecosystems, is definitely circular. The world does lose atoms into space – and gains a lot more, not least in the form of meteorites. It also of course relies absolutely on energy from the Sun, and to a lesser extent on geothermal heat, generated in the Earth’s own core. But for its raw materials (give or take a few meteorites) the biosphere as a whole is self-contained. We more or less are stuck with the materials we were doled out with 4.5 billion years ago, when the Earth first formed. Humanity too must devise a circular economy or else drive the world towards the ultimate form of disarray that physicists call entropy.

Finally, given that there are usually many players in any one system – many individuals, many communities, many species – there is an enormous, in fact an infinite, number of possible interactions between them; and each interaction, each relationship, may be very complicated, in the to-and-fro nature of a dialogue. Thus the interplay of ecosystems, and nature as a whole, is above all complex; and where we have complexity we have non-linear cause-and-effect, which contributes to the overall uncertainty. So even though ecosystems do sustain themselves, and are resilient against change, a nudge may send them off in weird and entirely unpredictable directions, and very often the nature of the nudge, the initial cause, is not at all obvious.

So let us look at these four essential features – diversity, interdependence, circularity, and complexity – one by one.


There are many measures of diversity: number of species; genetic variation within species; variety of habitats; variety of ecotypes – each ecotype being a creature that is adapted to a particular habitat; and so on.

Diversity of species

Conceptually the simplest measure of diversity is the number of species – but in practice, unless we wipe everything out in a given habitat with some sure-fire toxin, and then count the corpses (and don’t miss any), it’s impossible to know. Naturalists and scientists have been trying to assess what’s in the wild for several thousand years at least – and before anyone got around to making formal records tribal peoples the world over commonly had an extraordinarily broad knowledge of what’s out there – yet we still don’t know to within at least an order of magnitude how many species there really are. Fewer than two million have been formally described, although it’s clear that some of those species are really clusters of related types, while others almost certainly have been described more than once and named afresh each time. Much more to the point, it is clear from several highly intensive, concentrated studies of small areas, or of insects living on particular trees, or of the range of DNAs found in soil samples, that we know only a proportion of what’s out there. The true number of different species worldwide is conservatively estimated at five to eight million – but if we include microbes, which we should, then the true number could be 30 or even 100 million (though it’s hard to know what a microbial “species” really is, since they swap DNA so promiscuously). But it’s not just microbes we don’t know about. Every few years scientists discover some mega-species including, in recent years, a new species of river dolphin and a new kind of gibbon. Simon Bearder, too, of Oxford Brookes University, has been showing in recent years that although there are only about half a dozen species on the standard list of African bushbabies, the real number is probably around 40. The various kinds look very similar but modern studies of their DNA and of their calls show that what once were thought to be single species may be four or five different types. Bushbabies are nocturnal, after all, and recognize each other by their voices, rather than their looks.

In truth, however hard we try, we can never know the true number. One reason is theoretical: as J S Mill pointed out in the 19th century, no matter how much we know about anything, or think we know, we can never be sure that we haven’t missed something. But it is also impossible in practice to be sure of the numbers. The hills of Sicily for example are hot and dry, and generally hostile. It rains only occasionally, and briefly, and when it does, some flowering plants appear very rapidly apparently out of nowhere, though in truth of course from seeds or rhizomes or whatever beneath the ground; then flower and set seed; then disappear without visible trace. Few botanists spend much time on those hills (it’s not comfortable, and there aren’t many botanists to begin with) so it’s likely that a great many plants come and go without anyone knowing. Or then again, in tropical rainforests there may be 300 or so different species per hectare, and half a kilometre or more between two individuals of the same species; and different areas have different suites of species; and it’s very hard if you are standing on the ground to see which tree is which because all you can see is the trunk. The leaves and fruits, if any, are 20 metres up in the canopy and often obscured by the leaves of neighbouring trees and miscellaneous epiphytes. Again, too, although there are many brave souls studying tropical forest, and the native peoples have tremendous knowledge, there are few formal studies relative to the magnitude of the task. It is estimated that the Neotropics as a whole (from northern Mexico down to the north of Argentina) may contain 30,000 species of tree – about half the estimated number in the whole world – but nobody really knows.

Finally, alas, species are disappearing before our eyes before anyone has a chance to count then. Professor Bearder returns to Africa as often as he can to continue his studies of bushbabies and each time he finds that some woodland he’d studied previously has disappeared. Individual bushbaby species often have very limited ranges so if one wood goes it might take a whole species with it. The picture is much the same through much and probably most of the world, for all taxa. In short, we will never know what’s out there – or what had been out there just a few years earlier.

Some scientists and gung-ho politicians are keen to explore new planets beyond the solar system to find new life forms, spending billions of taxpayers’ dollars, pounds, and euros. But the life forms on Earth, part of our daily lives, are woefully neglected. The science and craft of naming species – taxonomy – is horribly underfunded. There surely are life forms on other planets but they are most unlikely to match ours in variety or complexity (although there are an awful lot of planets out there, so some conceivably might). In any case, in our studies of other worlds there is no urgency. Any life forms they may harbour should still be there in a thousand years, or 10,000, whereas those on Earth are disappearing by the minute. But then, space research is very big business, with military implications (including “Star Wars”), and wild creatures on the whole are not. Safaris and even smuggled ivory are not in the same economic ballpark, so those fixated on wealth don’t care – and the world is dominated by people fixated on wealth.

What matters most immediately though is not the total number of species in the world, but the total number in any one ecosystem – and again the uncertainties are huge. Whenever biologists of the right expertise apply modern methods of study to any ecosystem, intensively and over time, they almost invariably find that there is far more than expected. So it is that English suburban gardens studied over several years have sometimes revealed well over a thousand species of insects and other invertebrates. Study that included the diversity within the soil, with DNA probes to investigate microbes and fungi, would surely reveal many thousands more.

To be sure, some habitats and some taxa are very well studied. It would be very surprising if anyone were to find a new species of bird in Britain that is new to science (although it has only recently been shown that the Scottish Crossbill is different from the European kind). But much – most? – of the rest of the world, and most of the less charismatic taxa, are hardly known at all. Who knows, for example, what mosses or mites or nematodes are out there in the hills and cliffs of, say, Venezuela?

Diversity of genes

Number of species is only the preliminary measure. Very significant too is the genetic diversity within each species, and within each population. Genes of any one kind commonly and perhaps usually come in more than one form, each form known as an allele. All individuals of the same species contain the same general apportionment of genes (though in many species including humans the males and females each have their own special genes that determine sex). But different individuals of the same species usually contain different alleles, so no two individuals are genetically identical (unless they are cloned, which means that each is an exact genetic replica of the other). So although males and females of the same species contain the same general set of genes, they may pass on different variants of those genes – alleles – to their offspring. An individual that inherits different variations of the same gene (different alleles) from its two parents is said to be heterozygous for that gene. If an offspring inherits the same allele from each parent then it is said to be homozygous for that gene. Any one individual in a “normal”, or “wild” population will be heterozygous with respect to some genes, and homozygous with respect to others. Offspring of parents who are too similar to each other and so are highly homozygous, are commonly said to be inbred.

So we find two sources of genetic variation in any one population, or species. First, in some populations, many of the genes come in several allelic forms, so the population as a whole is genetically highly heterogeneous. In such populations, too, we are likely to find that most offspring are born to parents who are slightly different, genetically, so most of the offspring are heterozygous, at least with respect to many of their genes. But in some populations many or more of the genes come in one allelic form only, and then there is little or no variation to pass on to the offspring and so the population as a whole is highly homogenous, or, in English, uniform.

Secondly, populations whose members are highly heterozygous are likely to be more genetically various overall than those whose members are predominantly homozygous. We may note in passing however that although in practice in wild populations uniformity tends to imply homozygosity, uniformity and homozygosity are not inextricably linked. Hybrid crops, produced by crossing two highly homozygous parent lines, tend to be extremely heterozygous – but the population as a whole is more or less uniform. They are all heterozygous in the same way.

Populations generally are far more secure when they are genetically both heterozygous and heterogeneous. Animals (plants in general seem far more tolerant) commonly become sickly if they are too inbred, and therefore highly homozygous. The reason is as Gregor Mendel intimated in the mid-19th century: some alleles are dominant and some are recessive (though he did not use the word alleles). Thus a child who inherits a gene for brown eyes from one parent will have brown eyes even if his other parent has blue eyes, because the brown-eyed gene dominates the recessive, blue-eyed gene. The children of two blue-eyed parents cannot have brown eyes because neither of the parents can possess a brown-eyed gene (for if they did, they would not have blue eyes). But some recessive genes are damaging – deleterious; like the one that causes sickle-cell anaemia. The more inbred a population becomes, the more likely it is that offspring will inherit a deleterious allele from both parents. Quite a few aristocratic or otherwise isolated families have died out through inbreeding, and quite a few zoo populations too (before curators realized that they had to adopt strategies of breeding that conserved diversity).

Populations of all creatures, animals and plants, are far more prone to epidemic if they are genetically uniform than if they are genetically diverse. In general, it isn’t easy being a parasite, whether you’re a virus or a bacterium or a fungus or a mite or a protozoan or a worm. Unless the parasite is a foreign invader, which the native population hasn’t seen before, then the host species will have had plenty of time to adapt to its presence, and will have evolved all kinds of defensive mechanisms. Parasites can gain a foothold and cause an infection only if they can overcome all the defences. But if the host population is highly various, then no two host individuals will be quite the same. So a parasite might invade one host successfully but then find that the host’s neighbours have different tricks up their sleeves. So they find it difficult to spread from one to another. So it is that fungi such as rusts produce billions and billions of spores – all they do is produce spores – because they “know” that only a few will find hosts that their offspring can really get stuck into. Or at least that is true in the wild, where all the possible hosts are different, and not necessarily growing cheek-by-jowl. But if rust fungi find themselves in a field or a prairie with millions or billions of almost identical wheat plants, then once they get a hold on one they can spread to all the others with no trouble at all. Then the farmer reaches for the fungicide – or drenches the whole lot in advance to be on the safe side.

Anyway: genetic variation within populations is one of nature’s main protections against epidemic, and loss of variation makes animals and plants, whether wild or domestic, more and more vulnerable. As discussed in a later article, maintenance of diversity, both of species and of genetic diversity within species, is a key principle of agroecology – and again is almost precisely at odds with neoliberal–industrial farming, at least as generally practised.

But it is hard, going on impossible, to conserve genetic variety (genetic heterogeneity) within a population unless the population is large. Reproduction in any one generation is rarely 100 per cent efficient. Each parent passes on only half of its genes to each offspring and some alleles don’t get passed on at all. So in each generation there is likely to be a loss of alleles from the population as a whole – a phenomenon known as genetic drift. This doesn’t happen to any great extent if the population is large. If thousands of parents are passing on their genes in any one generation then most of the alleles do get passed on; and in a large population, too, there is plenty of opportunity to add to the genetic mix by mutation. But if the population is very small – say two fertile males and six breeding females, as can often be the case in the modern, beleaguered world – then a fair proportion of the alleles may fail to be passed on, and genetic drift takes a heavy toll. So then the whole population rapidly becomes uniform, and the individuals become highly homozygous. Sometimes – quite often, these days – wild populations become very rare for a time and then the numbers build up again and conservationists heave a sigh of relief. But they know that things can never be quite the same again, for during the time that the numbers are low there is tremendous loss of variation through genetic drift; and when the numbers pick up again the population is far more uniform and homozygous than it was before the lean period. The times when numbers are low and drift is high are called genetic bottlenecks. Cheetahs, wild dogs, elephant seals, bison, and latterly many populations of African lions are now dangerously uniform and homozygous, having been through genetic bottlenecks in the past. Many apparently flourishing populations in the wild are now skating on very thin ice.

In any one population, only some of the individuals will be able to breed – fit, fertile, and of the right age. There will also be youngsters and in some species (humans, elephants) some oldies as well, past breeding age. So the total number of individuals needed to ensure that enough of them are breeding to keep genetic drift to a minimum is far higher than it looks, since not all the individuals in a wild population are active players. A rule of thumb is that a wild population needs about 500 individuals at any one time to guarantee reasonable security (given that many individuals in the wild die before their time). Many populations of wild animals are now well below that number. Modern zoos try very hard, by arranged marriages, to ensure that their own animals are as diverse genetically as possible, even though individual zoo populations are inevitably small – usually well below 500! (but good modern zoos try to increase the effective number by judicious collaboration, so all the individuals of any one species, sometimes scattered in zoos all around the world, become one population). Breeders of elite livestock and crops tend to do the precise opposite: they produce genetically uniform and therefore very predictable animals or plants that contain only the kinds of genes that produce the most commercially desirable features. Thus agricultural breeders and conservation breeders must adopt completely different strategies.

Breeders of rare farm breeds are in a dilemma. On the one hand they want to produce commercially viable livestock, but on the other they need to conserve genetic variation, so as to preserve the whole breed with all its potential. Not easy. If all that matters is short-term commerce, which is now the case, the rare breeds must fail unless they have very rich and philanthropic patrons. Breeders of elite livestock in any one place do, however, seek to enrich the genetic variety from time to time by introducing semen from elsewhere, and so in recent years even Jersey cattle born and bred in Jersey and jealously protected, have been enriched by Jersey semen from the US. But still, breeders of livestock do not seek to maximize the genetic diversity of their herds in the manner of modern zoos. They want just enough diversity to protect their star animals against excessive homozygosity.

Diversity of habitats and ecotypes

Broadly speaking – though all generalizations about nature should be made with fingers crossed – living creatures are either generalists or specialists. Outstanding among generalists are carrion crows and brown rats. Archetypal specialists are giant pandas with their exclusive diet of bamboo (though in zoos they happily tuck in to omelettes and whatever is going, just like any bear. Polar bears, too, are more omnivorous than they usually have a chance to be in the wild, and these days as Alaska and Canada become more urban (relatively speaking) they are wont to indulge their omnivory by raiding dustbins).

All this leads to all kinds of false impressions. The Californian ecologist Michael Soule, co-founder of the Society for Conservation Biology, once told me that when he was a boy (he is now 80) the valleys of the chaparral around his home rang with birdsong. They still do. But the land has been built on and whereas the wild birds of his youth were of many different species – including many specialists – the kinds that are there now are all generalists: mocking birds and the like. Only a naturalist would know the difference. But the difference is real nonetheless. Despite general impressions, there has been a huge loss of diversity.

Similarly, some of the richest habitats in Britain in terms of number of species are the suburbs, including suburban gardens. Why? Because they contain a huge variety of habitats, at least in microcosm: ponds, woods, lawns, and cliffs in the form of houses. But again – though there’s the odd surprise – the cast-list is mainly of generalists. You won’t find many suburban capercaillies. Similarly, coppiced woodlands tend to be very species-rich, and for the same reason: at least in detail, the habitat is highly heterogeneous, and there is plenty of new growth. But a great many species miss out. Some need old trees, including post-mature trees, for example birds that nest in tree-holes, like woodpeckers. Many two-winged (dipteran) flies like high canopy, and cannot be doing with coppice. Some may say, “Who cares about flies?” The reasons are discussed below, but in passing we may note that dipteran flies are major pollinators. We might not miss them or even know they are there, but other species will. Or then again: although many species can put up with human beings once they get used to us, including polar bears and orang-utans, and of course urban foxes and muntjacs (and red kites and vultures (in Delhi)), many cannot. They need to be as far away from us as possible. Habitats that may seem easily big enough to accommodate the more reclusive species may in fact be too small because the shy types won’t go near the edges – and a small habitat is mostly edge. Edges in general are species-rich but they don’t suit everyone.

All in all, then, apparent abundance and diversity may be very deceptive. Habitats that appear to be flourishing may in truth be falling far short of their pristine glory.

One last question:

Does diversity really matter?

Embedded in this are two kinds of question. The first is one of biology: “What does diversity contribute to the wellbeing of the biosphere?” The second is a matter of morality and metaphysics: “Why should we care about the biosphere anyway?” Here we’ll discuss the biology. The second question is addressed later, under “Attitude”.

Of course we might simply point out that diversity per se is desirable, so of course ecosystems with lots of species are better than those with few, and monocultures are worst of all. But suburbs are often very rich in species and they can hardly be seen as the world’s most desirable ecosystems. They are able to be diverse because they are so artificial – a pastiche of many different ecosystems brought gratuitously together: houses that resemble cliffs, roadside trees and garden shrubs that form a kind of woodland, and rich sources of nutrients from garden plants and rubbish. In nature, such a wealth of nutrients is found only in odd hotspots, like estuaries. Suburbs generally lack big forest trees and have no extensive grassland or bogs. The species that do well in the suburbs are mostly generalists like crows, or the more specialist kind (like goldfinches) that happen to have a penchant for one of the commodities that suburbs provide (in this case, small seeds). In short, the diversity of suburbs is pleasing but is also largely illusory – and is highly precarious because it is so subject to human whim. Of late, suburban creatures have been hard hit by the vogue for decking and paving.

What is the relationship between diversity and other features that reflect the wellbeing of the biosphere – like biological efficiency, total biomass, stability, resilience, and “sustainability”? Here the issues are far from simple. There are many “confounding variables”: relationships in nature are always non-linear – no simple cause-and-effect (of which more later); and there aren’t enough studies on a grand enough scale to tell us what we need to know. But here are a few pointers:

First, it does seem that diverse ecosystems in general have a greater biological efficiency than simpler ones – meaning that between them, different creatures working side by side, swapping materials between them, cooperating and competing, make better use of the available resources than fewer species could do. Intuition suggests that this is so and formal studies provide some confirmation. Laboratory studies with microbes show that judicious mixtures of species remove more nutrients from the medium more quickly than monocultures. In the same vein, the grasslands of Africa are grazed not simply by cattle and sheep like Britain’s uplands but by permutations of antelopes (including gazelles) from among the 70-odd species that live in Africa, plus buffalos, zebras, hippos, elephants, pigs, rodents and what you will. They all have slightly different grazing tactics and between them they do a very thorough job – to which the native plants are well adapted.

Greater efficiency in turn ought to lead to higher biomass. Again, though, things are not simple. Thus if the conditions are highly artificial – as in a commercial field that’s drenched in fertilizer, herbicide, and pesticide – then the total mass per unit area from a monoculture of wheat may be far higher than we would expect in any wild ecosystem, because the wheat is bred especially to cope with such conditions. Even then, though, we might find that the total mass would be even higher if the wheat was grown in an agroforestry system, when total yield includes the mass of the trees.

It surely is significant too that in the wild, ecosystems left to themselves become more and more species-rich as the years and centuries pass. The age of an English hedgerow can be judged at least to within a century by counting the number of species within it. Tropical forests contain many thousands of species of trees while boreal forests in any one continent have only about half a dozen – and one possible reason is that the tropical species have had more time to establish themselves. The boreal forests have grown up only in the past 10,000 years, since the last Ice Age came to an end – and 10,000 years can mean as few as five generations of boreal trees.

One final point. This whole subject (like all human discourse) is bedevilled by its terminology. Thus, “efficiency” in general means output / input. “Biological efficiency” (as I am using the expression here) means biomass produced / nutrient taken up (in a given time). But when manufacturers or industrial farmers speak of “efficiency” they mean “cash received / cash expended”. That is not the same thing at all. I once heard an industrialist of the gung-ho kind opine that irrigated soya on the Cerrado of Brazil is “the most efficient agriculture in the world”. Measured by any other yardstick other than money – social, ecological – it is of course a disaster – and it works in financial terms only so long as the freshwater holds out and oil prices are artificially low. But in some of the most powerful circles money is the only yardstick, or at least the only one that is taken seriously, and language is reinvented accordingly.

Then there’s the word “redundancy”. It implies duplication of effort, which businesses of all kinds seek to avoid. Labour in particular is stripped to the bone. Factories and supermarkets seek to operate on a “just in time” basis – goods delivered in exact amounts precisely when they are needed so that there is no need for storage space. Redundancy in any form is deemed to be “inefficient”.

But wild ecosystems to an enormous extent depend on what business calls redundancy. Thus Britain’s flowering plants are pollinated not exclusively by honeybees but also by a host of bumblebees and solitary bees (more than 200 species) and flies and beetles. This presumably is why our wildflowers and crops have not suffered as much from the recent slaughter of honeybees as many feared. A management consultant would surely have advised the gods of nature that since the solitary bees and flies and all the rest were largely duplicating each other’s efforts they were therefore largely redundant and therefore bad. But the resilience of nature with all its uncertainties depends largely on duplication, which means on apparent redundancy. Indeed, as Oxford biologist Tom Curtis points out, when efficiency is conceived as the lack of redundancy, efficiency and resilience are inversely related.

On the face of things, too, we might expect very diverse landscapes to be more stable than simpler ones, but again the matter is far from straightforward. True, ancient landscapes, undisturbed for many years, tend to be far more diverse than those that from time to time are wiped clean by ice or tsunamis or whatever. But tropical forests and savannahs which are rich in species are also very dynamic, with huge fluctuations over time. Many of their resident species are specialists and rapidly disappear if conditions move outside their comfort zone. The more species there are, the more they interact with each other, leading to complex interdependencies – so if any one disappears, a whole lot more are liable to go with it. None of this is what we normally mean by “stability”. Then again, very disturbed landscapes, like suburbs, may be very rich in species – though only because they represent the meeting point of different kinds of habitats, and so harbour many different ecotypes. It turns out, too, that some of the most stable ecosystems of all have very few species, like the great peat bogs of sphagnum moss that cover a million square kilometres of Siberia, or populations of clams on the sea-bed, which the fossil record tells us have not changed appreciably for tens or hundreds of millions of years. We need not assume, either, that very diverse landscapes are more resilient than simpler ones. Complex ecosystems that lose a lot of species in some catastrophe may well become complex again when normal conditions are resumed – but second time round they are likely to contain a different suite of species.

It is clear though, as noted earlier, that diverse ecosystems containing genetically heterogeneous creatures are far less susceptible to pandemic than monocultures, or to near-monocultures, with creatures that are more genetically uniform.

Taken all in all, then, there is no simple relationship between the diversity of species and all the other criteria by which we might judge the health of the biosphere. But almost all observations support the intuition that diverse ecosystems are more robust than simpler ones – more efficient biologically, with a higher biomass, and in the long term, other things being equal, more resilient, precisely because they have far more “redundancy”. Those wild ecosystems that seem very stable and resilient even though they have only a few species – boreal forest, sphagnum bogs, deep-sea clams – are all very special in their own particular ways.

Diversity, in short, is surely good for the biosphere. Why and whether we should care about the wellbeing of the biosphere is discussed later.

Of course, too, the more species there are in any one ecosystem, the more relationships there can be between the species; and the greater the scope for both competition and synergy, the more the different players become interdependent.


What matters most of all is how all the creatures in any one place interact, one with another – that, plus the many interactions between creatures in different ecosystems, often very far apart. Just to take two very simple examples: the oxygen we all of us breathe has largely been produced by diatoms in distant oceans, and the rain that makes it possible to grow crops in the southern United States is provided in large part by the Amazonian forest. In all this, the complexities are endless. Knowledge of what’s going on is already wondrous but compared to what there is to be known it is miniscule – and all of what we think we know, is uncertain. All that is certain is that the more we explore any one ecosystem the more players and the more interactions we will find, including many that are non-obvious. All scientific knowledge, always, is but an abstract of reality (as the mathematician and philosopher A N Whitehead pointed out in the early 20th century, and philosophers of science now take as read).

My favourite example of nature’s complexity is of the almendro tree of Central America, described to me in the forest of Panama by the scientist who has worked it all out, Egbert Leigh. The almendro is a legume, related to acacias and laburnums, and as such is a servant to all the plants around – fixing atmospheric nitrogen and increasing soil fertility. (Leguminous trees of many different kinds are key players in tropical forests.) Anyway, in due season – June/July – the almendro produces glorious cascades of pink pea-like flowers that are succeeded by hard wooden pods, each with a single seed inside. Many different animals flock to steal the pods and eat the seeds and a few of them benefit the tree by scattering the seeds without destroying them. Most important of these by far are the local fruit bats (not related to the Old World flying foxes). The bats carry the pods far and wide – and they do not eat the seeds themselves. They eat only the fleshy pulp around the seeds, and then let the seed fall to the ground.

Then along come the agoutis, larger relatives of the guinea-pig. They eat the seeds that the bats discard – but only some of them. The rest they bury, like squirrels, for use later. Hence the almendro trees are planted.

That is not the end of the story. In the dry season the agoutis raid their own little larders and if any seeds escape these forays, and germinate, then the agoutis eat the emergent shoots. So for the almendro it looks like bad news all round.

But there is one more player: the ocelots: middle-sized spotted cats. They eat many of the agoutis before they have a chance to dig up the seeds or eat the shoots. Hence, in the state of nature, the next generation of almendros sneaks through: dispersed by bats; planted by rodents; and protected by a cat that kills off the rodents (or a fair proportion of them) before they can snaffle the seeds that they themselves have planted.

Actually, there is one final player in the story. Ourselves. Ocelots are trapped for their beautiful spotted skins (the free market really cannot protect wildlife) so now there are more agoutis than there should be and more almendro seeds and seedlings get eaten. Furthermore, almendros don’t flower reliably unless the rainy season starts suddenly in April or May – they seem to need the shock – and because of global warming the rains are tending to come in fits and starts. So the almendros are producing fewer fruits. For both these reasons, says Dr Leigh, and doubtless more, the almendro population is dwindling. There are not enough replacements. (But it’s a decade since I visited Panama. I’m told that the ocelots are now coming back so perhaps there’s hope for the almendro after all.)

Closer to home, but equally intriguing, is the story of the large blue butterfly, once native to the grasslands of the west country. Its life story is remarkable. The eggs are laid on wild thyme or marjoram, on which the emergent caterpillars happily munch for the first three moults. At this stage the larvae resemble the grubs of the red ant, Myrmica sabuleti – whereupon, well-meaning worker ants cart them back to their own nest. There, the caterpillars feed on the ants’ larvae. They pupate in the safety of the ants’ nest until it is time to emerge as fully-fledged butterflies into the wide world, and begin the cycle again.

But large blue numbers diminished in the 1950s and in the 1970s the species was declared extinct – at least in Britain. Why? The answer was supplied by Dr, now Professor, Jeremy Thomas of Oxford University. The red ants on which the butterfly depends like warmth, meaning sunshine, and need the grass in which they live to be short. But in the mid-20th century grazing patterns changed – fewer sheep – and myxomatosis took its toll of the rabbits, and so the grass grew long and shady. So the ants did badly. No ants, no large blues.

Both these examples tell the same kind of story. Most obviously they tell us that the life stories of wild creatures (animals, plants, fungi, microbes) can be astonishingly complex – and, often, counter-intuitive. Thus the almendro in a state of nature depends for the scattering of seeds on three quite different animals with quite different life styles: fruit bats, agoutis, and ocelots; and the balance of agoutis to ocelots has to be just right. Yet the arrangement clearly works (if left alone) or there would be no almendro trees at all. But who would have thought it? Who would have thought that the fate of a forest tree depends, in the end, on the local cats? Who would suspect that a butterfly would pin all its hopes on the strangely obliging, self-immolatory behaviour of an ant? In both cases the details took many years of study to work out, and were finally clinched by particular individuals who are both accomplished and dedicated. In both cases, too, inadvertently, with their minds on other things, human beings at large managed to bring the species concerned to the point of extinction (although on the positive side, the large blue has been reintroduced to several prepared sites, apparently successfully, and the almendro could be protected by trapping agoutis after they have made their larders, or protecting ocelots, or simply planting almendro seeds, though I don’t know if this is happening).

Of course, many inter-species relationships in nature are far simpler than either of these examples – but many, too, are even more convoluted (including the pollination and dispersal of tropical figs by fig-wasps, with decisive input from nematodes, as described at length in my book, The Secret Life of Trees, aka The Tree). The subtleties may take years – decades – to unravel. Yet in a tropical forest, or an English meadow, and of course in nature as a whole, there are millions upon millions of possible interactions between different combinations of species in different circumstances. If all the biologists in the world became field ecologists, there still wouldn’t be enough time left in the life of the Earth to sort out everything that goes on. Besides, when we look at the whole picture we see that the sequence of cause and effect is decidedly non-linear: it is impossible in theory as well as in practice to predict the outcome of any one change in conditions, or any one intervention. In the end, then, nature really is beyond our ken, and will always spring surprises even if our own species is still here in a million years’ time. Yet scientists of a certain mindset – a mindset that is now very prominent – behave as if it were not so; as if we can indeed “subdue” nature as we choose, as Francis Bacon suggested at the start of the 17th century; or “conquer” nature as the makers of pesticides were apt to promise in the decades after World War II; or even to reconstruct other creatures (or even ourselves) by genetic engineering, according to the demands of the market. Politicians of a particular (and prominent) stamp are keen to encourage this conceit. It makes them feel they are in the vanguard, and it’s lucrative, and they feel that security lies in money.


It has become clear these past two-and-a-bit centuries that the world works just as James Hutton guessed it must: the materials of the world are constantly recycled. The Earth has gained fresh material since it first formed 4.5 or so billion years ago, in the form of meteorites; and hydrogen floats off into space; and radioactive isotopes decay and sometimes turn into other elements as they do so. But on the whole, although the present world is spectacularly different from how it was in the beginning, it has much the same overall chemical composition. Everything just circulates, round and round and round. The principal gases of the atmosphere, nitrogen, oxygen, and carbon dioxide (only a tiny proportion compared to N and O, but of key importance) at times are gases and at times are incorporated into all kinds of minerals and at times become the main ingredients of life. In essence, living creatures borrow the elements they need as they process from gas to salt to flesh and back again, their passage mediated largely by microbes. We just have to do the same: cash in on the circulating elements as they pass by us.

But that is not all we do. We in the Anthropocene have created the linear economy: take, use, discard. We do not physically destroy or transform the basic elements of the periodic table (apart from a few big recondite types, like plutonium) but we do scatter them far and wide so they can no longer, in practice, be recovered. Some of them, like cadmium and mercury, then become serious toxins. Phosphorus, vital for life in all kinds of guises, is thrown away in sewage and agricultural run-off and winds up in the sea, sometimes over-enriching and so polluting freshwater ponds and lakes along the way. Freshwater in general is simply being squandered at a horrendous rate (this needs serious discussion elsewhere); rivers, lakes, and aquifers drained or polluted; most of it finishing up, eventually, commonly polluted, in the oceans. Britain’s official answer to increased flooding is not to conserve the rainwater as it passes through, and make use of it, but to build mega-conduits at huge expense with commensurately huge profits and bundle it off to the sea with all possible haste. Topsoil, which at least in its present form has taken centuries (at least) to form, is allowed or indeed encouraged by modern farming and building to wash away when it rains or blow away on the wind when it doesn’t (which again needs separate discussion). The soil that does remain is robbed of carbon – organic material that adjusts the balance of air to water, and regulates the temperature, and doles out nutrients as needed, and makes fertility out of dirt. Organic farming worldwide is in essence designed to maintain soil carbon but receives very little support from officialdom worldwide relative to its importance. In Britain it is still in large part disdained.

There is no worthwhile strategy in Britain or the world at large for fossil fuels. Their price and distribution and hence the fate of the world is determined by oil sheikhs and oligarchs. Oil and coal could and should be treated as a gift that could help the human race to create a secure and agreeable – convivial – world and turn the Anthropocene into something to be grateful for; and not, as it threatens to be, a nightmare. Burning fossil fuel as everyone knows contributes to global warming – the physics was first worked out in the 19th century – and yet there are climate change deniers in high places, including some scientists who at least pretend to believe that there is no problem. But then, energy policy like everything else is driven by short-term profit – for only short-term profit is deemed to be “realistic”; and the most profitable course is to burn all that’s combustible as quickly as can be profitably arranged. In Britain, whether or not we create alternative sources of energy before the climate is wrecked will again depend primarily, if not entirely, on short-term accountancy.

The linear economy is, in truth, the economy of the March Hare, who took tea on a table of endless length and when one place was messed up, simply moved on to the next. So it is that Sir Martin (Lord) Rees, former Astronomer Royal and President of the Royal Society, recommends that we should focus with all zeal on space travel for then, when Earth becomes uninhabitable, we can go elsewhere (or a few selected and suitably trained NASA astronauts can). As he told Wired magazine in November 2016:

this might be the first step towards divergence into a new species: the beginning of the post-human era.

But he also says:

Development of self-sustaining communities remote from the Earth would also ensure that advanced life would survive, even if the worst conceivable catastrophe befell our planet.

“Post-human”, though, means just that. We can’t expect our own flesh and blood descendants to re-colonize the universe:

But don’t expect mass emigration from Earth. Nowhere offers an environment even as clement as the Antarctic or the top of Everest. It’s a dangerous delusion to think that space offers an escape from Earth’s problems. There’s no “Planet B”.

Perhaps in all this Lord Rees was being ironical – sounding a warning note by mooting such a vile scenario – but whether he was or was not, it’s clear that we, the human race, need as a matter of priority to acknowledge that the March Hare approach will not do. The tea-party is over. We need to do all that is possible, as quickly as possible, to introduce the circular economy: to create systems of farming and manufacture, and day-to-day living, that do not simply squander the fabric of the Earth, and run it down, but truly are sustainable (a horrible word, but it will have to do). For this we need new, appropriate technologies; but we also need an economy, quite differently structured, designed to support appropriate technologies. Taken all in all, the technology we have now is highly destructive. People in past ages never quite realized the need to take the biosphere seriously, and the present (neolib) economy is designed to make rich people richer in the short term, with a perfunctory nod to what Britain’s present prime minister calls “Ordinary Working Families”, and no worthwhile sense of the future. We will discuss the circular economy and what it may entail in section IV.2 (in the fullness of time). Some very good people are on the case, even if the powers-that-be are not.

The final outstanding features of the biosphere should really give us pause.

Complexity and uncertainty; the unknown and the unknowable

Truly modern scientists acknowledge – cheerfully! – that in the end, for several huge and incontrovertible reasons, the world and the universe are beyond our ken. The gung-ho scientists who are commonly perceived to be modern, and promise omniscience, and scorn all talk of transcendence, and promise that soon, with the appliance of science, we’ll be able to “conquer nature” and solve all life’s problems, may be very good technically but as thinkers they are seriously old-fashioned. But they say things that governments and industrialists are keen to hear, and they find common cause with neoliberal economists who offer the same kinds of cure-all formulae, and so are wont to become the public face of science. So it is that science, which should be wonderful, and should be seen as part of life’s great mission to know, insofar as knowledge is possible, becomes a threat: a crude view of the world, over-confidently acted upon. Scientists are apt to claim these days that they are fully trained. Indeed – but they, and all people in positions of influence, need to be educated, and that is not same thing at all. That implies, perhaps above all, that we all need to recognize the limits of our own understanding: what we know (as far as we can tell); what we don’t know (though we can’t logically know how much we don’t know); and what, this side of revelation, is unknowable (but can revelation be trusted?)

All this is preliminary to saying once more that nature is far too complex for us to get our brains around and even if we could make sense of all that we can see and measure we still could not be sure that what we can see and measure is all there is – and in fact can be fairly sure that it is not. For why should we be able to understand all there is? Our senses and brains have evolved as survival machines, to help us get through the day and, somewhere along the line, to reproduce. They are not designed or evolved to enable us to probe the deepest secrets of the universe – and the fact that we seem to know far more than is needed simply to say alive, is in itself mysterious. Science depends on empirical knowledge but even with our best and subtlest instruments our knowledge is always incomplete; and however much we know or think we know, there will always be more. Scientists claim and aspire above all to be rational, but rationality has its limits. It helps us to keep our thoughts straight but it does not tell us what is actually true. None of the formulae that the most rational philosophers have come up with to help us decide what is true are anything like sure-fire. Scientific theories can be disproved, but they cannot ultimately be proved. All our theories are partial and provisional. The ones that seem most definite and certain, like E = mc squared, are obvious abstractions, and abstractions are not the thing itself. For all such reasons, even the most rational of scientists are obliged to decide what to believe; and in the end they make their choices, as all human beings must, on the strength of their intuition. In the end we are forced to conclude that all our understanding is really just a story that we tell ourselves – the fashionable word is “narrative”. Truth in general is the story that comes closest to describing what really is the case. For each individual, truth is a story that we happen to find convincing.

One goal of science is simply to understand: to frame the best possible narrative; scholarship for its own sake, which was considered in some societies, including those of Ancient Jewry and China, to be the highest calling – a privileged insight, as the religiously-rooted western scientists of the 17th century felt to be the case, into God’s purpose. In addition, though, human beings have tried to use their scientific knowledge for practical purposes; to predict the vagaries of nature, including the weather; and to devise new technologies to help us control aspects of the world for our own benefit.

In societies like ours, science in practical guise has well and truly taken over from science in scholarly garb – and “practical” in these neoliberal times means “most liable to maximize wealth”. Those who aspire to gather “knowledge for the sake of knowledge” find it hard to find funding unless they can demonstrate some pay-off – which generally means pay-off of a kind that will maintain the status quo. Science in commercial mode must be gung-ho. The spoils of the market-place are not for the faint-hearted. So the caveats voiced by philosophers of science (who include a great many practising scientists!) are ignored. Those in control of policy and of the purse-strings take it as their premise that we can understand the world exhaustively (given enough time and resources to do the research); that we can predict to within fine limits what effect any particular change in conditions will bring; that if things do go wrong, then future scientists will be able to put things right (and devise lucrative technologies along the way to help them do so); and that therefore we can give ourselves carte blanche to manipulate the natural world at will, so as to create new industries that can “compete” in the global market, meaning that they can make more profit in a shorter time than anyone else. Immediate profit is all that is deemed truly to matter, or at least to be the sine qua non. In the latest six-monthly budget of the British government in March 2017 Chancellor Philip Hammond promised £300 million of taxpayers’ money to support biotech, which in practice largely means GMOs – not because they are likely to solve the world’s food problems, though he probably thinks they will, but because Britain is good at such things so it’s a good earner.

Hence industrial agriculturalists sweep aside natural ecosystems and replace them with what in effect is field-scale, ultra-simplified industrial chemistry; and genetic engineers seek to create new plants and animals and microbes that grow faster than traditional types, or have a higher vitamin A content, or whatever the market requirement may be. Those who urge caution, on whatever grounds, are written off as back-sliders, “Luddites” (in the pejorative sense) “anti-progress”, and all the rest.

Yet even a cursory appreciation of ecology tells us how crude and dangerous the gung-ho spirit that now prevails really is. Wild nature is endlessly complex, which means it can never be understood in more than outline. Even if scientific research could lead to certainty, there isn’t enough people power or time to do all the research that would be needed. Cause and effect are non-linear in spades, so the prediction of outcomes both of the natural course of events and of our own interventions is impossible even in theory. The al-fresco chemistry and genetic engineering of industrial farming are all very clever (credit where it’s due) and might in some contexts even do some good, but as the basis of global agricultural strategy they are naïve in the extreme. Those who perpetrate them with such zeal – which basically means all of the powers-that-be: the oligarchy of governments like ours, the corporates and financiers, and the large slice of academe that depends on them for grants – are at best seriously misguided, and at worst wicked, since some at least must know what risks they run.

Can we doubt that they run risks? Just look at the state of the world: the billion who are undernourished; the mass extinction; the gathering threat of global warming and all that goes with it. None of it was inevitable. All could have been avoided with good “appropriate” craft of the kind that already exists worldwide, supported by excellent, realistic science that was guided by a true desire to do good and was practised with humility, with the recognition of its own limitations.

Even with imperfect knowledge, however, we can still do a great deal to keep the biosphere in good heart and to undo some of the damage that’s already been done, if only the will is there. Many animals and some plants that once were rendered locally or nationally extinct have sometimes been successfully reintroduced – including the large blue butterfly to several specially prepared sites in south-west England; and the red kite, first to Berkshire and now widespread; and the white-tailed sea eagle to the Scottish Highlands and islands. Wildlife reserves the world over demonstrably make a huge difference. In Britain they include the various centres of the Royal Society for the Protection of Birds (RSPB) including the wondrous Minsmere, in Suffolk, home to a wide variety of wetland birds and other creatures, and woodland and grassland species too. Such places need not be confined to wild and woolly coastlands. The Wildlife and Wetlands Trust (WWT) has established the London Wetlands Centre – “just 10 minutes from Hammersmith” – with, among many other things, bitterns, a veritable symbol of wilderness, with their haunting, other-worldly “boom”. (But it’s funny how attitudes change. Whereas we, over-urbanized moderns, take the return of the bittern as a sign of hope – nature can fight back! – in 1770 Oliver Goldsmith in The Deserted Village tells us that the “Sweet smiling village” of his youth has fallen to “the tyrant’s hand”: its “glassy brook” is now “choaked with sedges”, and “Along thy glades, a solitary guest, the hollow-sounding bittern guards its nest.” For good measure, “Amidst thy desert walks the lapwing flies, And tires their echoes with unvaried cries.” Britain’s lapwings too are endangered now, of course. We might well mourn the days when there were enough lapwings to get on a poet’s nerves, and bitterns were seen as a symptom of desolation.)

Then again, although our knowledge must always be far less than perfect, we can nonetheless farm in ways – the ways of agroecology – that demonstrably are far less damaging than what is now “conventional”. Traditional knowledge and the craft to which it gives rise, intuition, and common sense can take us a very long way, especially when guided by appropriate science. The main thing going for us, however, is the resilience of nature itself. Nature is extremely vulnerable and often collapses locally for reasons no-one could have guessed. But (almost) all creatures seem to have a lust for life and given half a chance then sometimes, at least, they can come storming back.

What matters in the end – at least the sine qua non – is attitude. We need truly to care about our fellow creatures and the fabric of the Earth. This is a matter of morality which, I maintain, must be rooted in metaphysics.

Attitude to the biosphere is the subject of the next essay.

Colin Tudge, 16 March 2017