Luiz Inácio Lula da Silva's narrow victory over Jair Bolsonaro in the Brazilian presidential election provided a small note of encouragement to those of us who hang onto the hope that humanity will soon react as one to the approaching climate catastrophe. The Amazon rainforest is one of the most important remaining sinks for carbon dioxide, and its accelerated destruction for cultivation of soya and for mining interests under Bolsonaro is one of the worst examples of ecological vandalism. Not only are the trees no longer taking up CO2 but also their stored carbon is largely being released and thus exacerbating global temperature rise.
The Amazon rainforest is an example of an ecologically balanced environment in which there is a sufficient variety of different animal, plant, fungal and microbial species for them all to live and reproduce sustainably, if not in harmony. They are sustained by the economy of nature, the provision of sunlight, water and soil minerals which allow them to get their nourishment largely by feeding on each other, as herbivores, predators, parasites, or saprophytes. The Amazon river provides a rich and diverse culture. The forest's destruction for agriculture leads to the development of monocultures, which require the use of pesticides and fertilisers.
The words culture and cultivate come almost unchanged from the Latin for the growth of crops and arrived in these islands with the Normans. From about the 17th century, they broadened their meanings to include intellectual growth and a characteristic of human education, and in the 19th century, with the discovery of bacteria, culture was used to describe their growth on nutrient material. In the 1950s, C P Snow wrote of science and the humanities as the 'Two Cultures' in apparent conflict, but I expect readers of Scottish Review
will recognise that these are complementary interests of rounded human beings.
The development of a monoculture, a 20th-century term, is usually quite insidious. In my youth in Britain, farms were generally rather small and employed many labourers. The fields grew in size, the workers and their horses were replaced by larger and larger machines, the hedgerows disappeared and, with them, so did birds and pollinating insects. Large tracts of the countryside became cereal monocultures sustained by fertilisers and pesticides, which were produced in large chemical factories and led to dependence on supplies of oil and ammonia, much of it imported and thus leading to vulnerability on world markets. Of course, this allowed an increasing population to be fed and the famine feared by Malthus to be avoided in the UK, though not in Ireland where the poor depended on a single crop.
There is a little-appreciated natural rule: nature abhors a monoculture
. Life, be it plant, animal, fungal or microbial depends on the interaction of species. We humans need bacteria as much as they need us, indeed much more so since they managed very well before we came onto the scene. Microbes have their own battles in the fight for survival.
I'll tell you a story. The common fungus, Aspergillus
, is an important if relatively infrequent cause of various diseases in humans and animals. You will have noticed one of its species at this time of year as black spots on fallen leaves. In the 1970s, I wondered why this one in particular, since we are exposed to many other fungal spores in the air all the time, breathing them in and out almost every breath we take when outside. Why was Aspergillus
the only one regularly to cause lung disease?
Our lungs contain cells called macrophages that creep around like amoebae to swallow inhaled bacteria and other harmful bits of matter. Our experiments showed that Aspergillus
had developed a means of protecting itself by paralysing them with a chemical it exudes, then using them as its own food. But Aspergillus
lives its life in the soil and its arrival in human lungs is of no biological advantage to it, so why had it developed this skill at avoiding being swallowed by human macrophages?
The answer was that, in the soil, other organisms (such as amoebae) creep around eating anything that looks tasty, and Aspergillus
had developed a defence that allows it to paralyse and feed on them itself. And, learning this, you will remember the story of the discovery of penicillin, when Alexander Fleming found that a fungus called Penicillium
on his culture of bacteria killed them off.
Streptomycin, the first effective anti-tuberculosis drug, was found similarly by soil biologists looking for a microbe that killed the TB bacterium. The soil is an immense culture of multiple organisms, all vying for their patch with each other and the plants and animals that interact with it, until intensive agriculture or climate change disturbs the balance. The crops grown influence the soil and vice versa, as all farmers know.
What I think is little appreciated is that we humans increasingly live as a global monoculture. We are the dominant animal species on the planet and depend on exploitation of plants and other animals. We have achieved this by our extraordinary intelligence and ingenuity. As our numbers have grown, we have developed means of using the planet's resources to the maximum but have become increasingly interdependent – as John Donne memorably wrote:
No man is an island entire of itself; every man
is a piece of the continent, a part of the main;
if a clod be washed away by the sea, Europe
is the less, as well as if a promontory were, as
well as any manner of thy friends or of thine
own were; any man's death diminishes me,
because I am involved in mankind.
And therefore never send to know for whom
the bell tolls; it tolls for thee.
This interdependence points to why the bell is now tolling for the monoculture we call civilisation. Monocultures are vulnerable to nature, which always fights back to restore the status quo
, as you may have noticed if you neglect your personal monoculture called a lawn. And nature has several ways of doing this, as we are now finding out. In principle, they apply across all life on the planet, including ours.
First, conflict and warfare. As different microbes in the soil fight for supplies of food and thus energy, to enable reproduction, so do different tribes of humans fight for oil, rice and grain to sustain their populations. As we see in Ukraine, war then has secondary effects on the world's supplies of these commodities and humans die from injuries and starvation.
Second, famine. If a species is deprived of its food supply by crop failure from lack of water or temperature change, it will die out unless it can migrate. Migration is almost impossible for some, such as polar bears (though some are trying to do so) and is becoming increasingly difficult for humans. Plant species do migrate, but this is constrained by temperature and weather bounds.
Third, infective disease. This is simply an example of the imbalance in terms of genetic mutation rates between different microbes and more complex organisms such as us. Genetic mutation allows adaptation to the environment and, as we know from Covid, bird flu, monkeypox, influenza, Dutch elm disease and ash die-back, the microbes mutate much more rapidly than do animals and plants. We rely on scientific ingenuity and political compliance to keep a short step ahead, and historically have often failed.
Fourth, inequality. Essentially, the strong win in nature. Weeds can easily take over your carefully cultivated lawn just as Homo sapiens
replaced H erectus
and H neanderthalis
. To be called wise does not ensure survival – we require to exhibit wisdom. Inequality has the potential to lead to economic breakdown, revolution and war, often via the arrival of dictators driven by ideology of extreme left or right.
Fifth, and most important, change in the climate. This has driven the great extinctions in geological time and is driving the current extinction of species that most people are hardly aware of. Already it is causing starvation, drowning, migration and death from heat stroke in members of our species and this will get worse. It will also on its path lead to revolution, war, further epidemics and widespread economic failure. Thus, we and our leaders must recognise that climate change is destroying, not the planet, but its ecology and is thus likely within this century to lead to breakdown of civilisation itself and unimaginable changes to all biological lifeforms on it.
Nature abhors monocultures
, including that of H sapiens
. To retain our civilisation, as with other threatened species, we need to adapt quickly. Adaptation means unity of purpose in moving to a sustainable lifestyle, more in harmony with nature and the Earth's resources. We must stop use of fossil fuels and change the way in which we grow and supply our food, especially in the developed world. We know what to do and, although there are serious institutional obstacles to action, we as individuals must all do our bit before it is too late. Think of our children and grandchildren.
Anthony Seaton is Emeritus Professor of Environmental and Occupational Medicine at Aberdeen University and Senior Consultant to the Edinburgh Institute of Occupational Medicine. The views expressed are his own