Step outside on a sunny afternoon. You’ll feel the warmth on your face, perhaps notice the way the light flickers through leaves or hear the thrum of insects. What you won’t notice (what you can’t) is that this ordinary scene is carrying on a conversation that began billions of years ago.

We usually describe DNA as if it were a kind of personal instruction manual. A code or blueprint, the spiral staircase that explains why you look and act the way you do. That’s true enough but it is also misleading, because our DNA isn’t just ours. Inside those twisting strands are traces of a much larger story: one about ancient interplanetary collisions, the origins of teamwork in cunning microbes and the importance of breath in cycles of sustenance and decay. Your body is less a solitary text than a well-thumbed anthology.  

That is the case made in The Forgotten Teachers, a book that argues our genes are a library of old lessons: six elemental ‘teachers’ that have shaped not only human beings, but life itself.

Once upon a time, the Ocean taught life how to begin. The lesson began somewhere warm, like the shallow waters of a calm bay, or the billowing broth of a hydrothermal vent. In these places, warm water provided enough energy to link up chemicals that normally stayed apart. Rings of carbon, called “nucleotides,” clumped together just the way letters do to make words. And while most of the clumps formed nonsensical tangles, some formed babbling threads of an early genetic text called “RNA.”

With Ocean’s encouragement, a chain reaction began; instead of dissolving back into the sea, chemicals began to fold into delicate structures that enabled even more chemical reactions to take place. As a result, we are all descendants of LUCA (the Last Universal Common Ancestor), with no breaks or gaps of any kind. This lineage connects us directly to the beginning of life, and four billion years later, these shared ancient lessons still travel with us, wherever we go. 

Each breath of Air we take connects us to an ancient cycle of growth, sustenance, and decay, a series of teachings scientists call “the fast carbon cycle.”  

The cycle begins with growth. Plants, self-sufficient at the base of the food chain, use water, soil, sunlight and Air. Though they may seem to grow only from soil and water, their form actually comes from Air. Through “photosynthesis” – sunlight (“photo-”) driving the building (“-synthesis”) of new chemical shapes – plants grow and release oxygen. They spin carbon dioxide into sugars, forming fruits, leaves, even DNA, which feed other creatures.  

Photosynthesis, then, opens a portal between formlessness and form. Through photosynthesis, carbon dioxide swirling in Air collects into a tangible plant, which we can touch and smell. Since nearly all food comes from the sugars and starches of Plants, we too are made from Air. 

Every four seconds, Air reminds us that we are not separate from the world but made from it and sustained by it. Through our breath, we participate in Air’s currents, expanding our presence beyond our bodies, perhaps through a hum or a joyous shout. 

Four-and-a-half billion years ago, back when Earth was still hot and new, Theia, an ancient planet about the size of Mars, slipped into Earth’s orbital path.   

The two planets collided, creating an impact so intense that it knocked Earth onto a tilt and sent it spinning on its axis toward the Sun. As the molten rock of these fused planets cooled, the leftover pieces formed the Moon, and all of Earth’s most dependable rhythms began. Earth’s spin brought day and night, Earth’s tilt brought the seasons, and the Moon brought light to the night sky and pulled the tides, marking months.  

As our ancestors experienced Earth’s rhythms drumming across millions of years, many rhythms also entered the genetic stories of our DNA. In the case of Earth’s spin, these stories are called “circadian rhythms,” and they describe patterns of behaviour and biological activity that follow the 24-hour cycle of day and night. Like dancers, we move to this rhythm, inspired by its timing but not locked to it.   

Our ancient ancestors learned to sense time from these earthly cycles of temperature and light: when to sleep, when to eat, when to set out on a journey of migration. But none of these cycles would have been the same without one of the most forgotten teachers of all: Theia. 

This is an adapted excerpt from The Forgotten Teachers: How Nature Wrote the Story of Life by Brian Isset and Claudia Biçen, published by Unruly, an imprint of Enchanted Lion Books.