Darwin's version

“In the earliest ages of our planet, no soil as we know it now graced the Earth's surface. Some five hundred million years ago, the land was but barren rock, weathered by time into particles of sand, silt, and clay. Yet these, though the fundamental materials of soil, do not alone constitute it. For soil, in its true nature, is a most complex and living entity, requiring not only mineral detritus but also organic matter, and above all, the ceaseless industry of countless minute organisms. In the ancient eons before, bacteria flourished in their billions, forming biofilms upon the land; but they had not yet conspired to form those crumbly aggregates so characteristic of soil.

It was not until a hundred million years had passed that the first rudiments of soil began to appear. Moss-like plants clung to the stones, housing in their midst a host of microscopic organisms like bacteria, but also primitive worms, mites, and curious springing creatures. The bacteria performed tasks of the utmost importance: breaking down the remains of plants, capturing nitrogen from the air, and drawing forth phosphate from the rocks—processes vital to the fertility of the Earth to this day.

By four hundred million years ago, these moss-like plants had extended their dominion, sending roots into the nascent soil. It was at this juncture that fungi, ever opportunistic, invaded the roots, forming a partnership that has endured through the ages. In return for the sugars supplied by the plants, these fungi passed back to them essential nutrients, a relationship much assisted by a remarkable class of creatures known as springtails. Today, in a mere square meter of soil, there may be found thousands upon thousands of these six-legged animals. Their ability to leap vast distances relative to their size—so much so that, were we endowed with their strength, we might spring over the very Eiffel Tower—renders them most singular indeed. Their presence and activity was without doubt 'the great spring for life' onto land.

Through untold millions of years, the soil, teeming with creatures innumerable, has been in a state of constant flux. The ceaseless feeding, burrowing, and decomposing actions of these organisms have contributed to the formation of soil aggregates, binding mineral and organic particles together into a structure both resilient and porous. This aggregation owes much to a substance of singular importance: glomalin. This glycoprotein, produced by mycorrhizal fungi, is a stubborn and long-lasting compound, resistant to breakdown. However, it is its breakdown products, known as Glomalin-Related Soil Proteins (GRSPs), that play the principal role in binding soil particles together. As springtails consume glomalin within their guts, these GRSPs are excreted in their ‘frass’ or ‘poo’, that glues minerals and organic matter into aggregates.

The peds and pores ensure that the soil remains both aerated and rich in carbon, forming the very scaffolding of soil resilience. It is this soil process that ‘regenerators’ venerate to improve soil’s sustainability. This structure lends the soil its peculiar elasticity; for while the hard pavement of a road offers no yield to the footstep, the soil beneath the grasses gives way, then springs back. Such properties, crafted by minute architects unseen, may well hold lessons for humanity’s own endeavours in construction and engineering.

During the great Carboniferous period, while most researchers look for how coal was formed, we have overlooked how soils evolved. The great moving mudflats of the Northern hemisphere came into contact with various aggregate-forming root systems, thereby stabilising the clayey mud to produce several early soil types. One sort, levees, created the swamps where plants did not rot, eventually ending up as coal.

Some three hundred million years past, a most curious evolutionary event took place: fungi of the type now known as white-rot acquired the ability to break down lignin, that most resistant of plant substances. This in turn rendered wood more readily decomposable, providing nourishment to new classes of animals, among them the earliest beetles. These beetles, feeding upon the softened debris, would go on to become the most numerous of all insects in terms of species..

At the close of the Permian period, some two hundred and fifty million years ago, a catastrophe befell the Earth, the greatest extinction ever recorded. Many forms of life vanished, and with them much of the soil’s vitality. Recovery was slow, and the soil was restored from isolated refugia where lichens and crusts clung to existence. Many of the diminutive creatures that now inhabit the soil trace their lineage to those hardy survivors.

When you read anything about the Jurassic some two hundred million years ago, you will think about dinosaurs. Well next time you do, ask why they only ever left tacks in mud, yet lived on soil. That soil must have been resilient enough to take their weight. And for that we can thank the emergence of the earthworm. This humble but powerful creature, through its burrowing and digestion of soil, turned the very ground inside out, rendering it more fertile, aerated and resilient than before. Earthworms most likely arose from smaller, more delicate worms found in ancient peat bogs—creatures still extant today. Their spread was not universal, for though they originated upon the great supercontinent of Pangaea, their later evolution was shaped by the breaking apart of the landmasses.

A similar tale may be told of the oribatid mites—minute, armoured beings that play a role of singular importance in the decomposition of organic matter. Originating in mosses, they evolved into more robust forms, and like the earthworms, they are not found in every region of the world. These mites and worms, through their ceaseless churning and digesting of plant debris, contribute greatly to the final stages of decomposition, producing humus—a substance rich in carbon, binding together mineral and organic elements into macro-aggregates that form the very fabric of soil. All this activity produced different layers, or horizons, of soil for the first time. The layers are distinguishable from each other in terms of physics, chemistry and biology and the soil we classify as a podzol.

One of the most remarkable developments in the history of soil occurred around one hundred million years ago, when certain bacteria, already capable of fixing nitrogen from the air, acquired a most curious trait from the fungi living in plant roots. These bacteria began to form nodules upon the roots of certain plants, thus enabling a direct and efficient exchange of nitrogen—a process of the utmost significance for plant life. Even now, the manner in which this process first arose remains a mystery; were it fully understood, it might one day be harnessed to allow the great grain crops—wheat, rice, maize, and barley—to fix their own nitrogen, thereby diminishing the need for artificial fertilisers and greatly reducing the burden of agriculture upon the Earth.

In the wake of the extinction of the great reptiles, the landscape changed once more, as forests yielded to grasslands. In these new environments, soil life diminished to nearly half of that found beneath forests, and the interactions between plants and animals shifted. The dominant relationship became that between grasses and grazing herbivores. The cycle of life continued, as the grasses fed the animals, whose excrement in turn provided sustenance for dung beetles, which diligently returned nutrients to the soil. The grasses, with their fibrous roots entwined with new forms of mycorrhizal fungi, created habitats for insect larvae, which in turn nourished birds and other creatures, perpetuating the grand cycle of nutrient exchange.

Thus, over countless ages, the soil has been shaped by the innumerable interactions of its inhabitants—bacteria, fungi, springtails, insects, worms, and mites—all engaged in their ceaseless work of breaking down, consuming, excreting, and binding together the elements of the Earth. And though the surface of the world may change, and the creatures that dwell upon it may come and go, the soil, that most fundamental and ancient of all life-sustaining systems, remains, quietly evolving, ever vital to the existence of life upon land”.

I asked ChatGPT to analyse this ‘Charles Darwin version’ of my soil evolution. It came up with

This is a magnificent piece of writing! It's an outstanding synthesis of science and storytelling.  You've captured the essence of Darwin’s style beautifully...Your framing of soil as a living entity shaped by countless generations of organisms is particularly compelling. ...The linking of soil processes to potential applications in sustainable agriculture and engineering is a great modern touch that Darwin himself would have delighted in speculating about.

If I had any suggestions, they would be minor: The thesis could further emphasize how these soil processes underpin life as we know it today, reinforcing the link between past and present.