When we ask, “What is life made of?”, we usually think of familiar answers: DNA, proteins, water, cells. But at its deepest level, life is a kind of recipe – a set of ingredients and instructions that has produced everything from microbes to human beings.
Scientists call those ingredients CHNOPS: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Together, these six elements form the architecture of every organism on Earth. They are the pigments on life’s canvas, the notes in life’s symphony.
Yet astrobiologists like Betül Kaçar, a bacteriology professor at the University of Wisconsin-Madison, remind us that this palette might not be universal. If life exists elsewhere in the cosmos, it could be painted with unfamiliar colors. As Kaçar puts it:
“If we are to discover life as we do not know it, we must challenge our deepest assumptions. We need to consider the very atoms that make life possible.”
Dallol, Ethiopia Hydrothermal chimneys, salt pillars, and terraces in Dallol, Ethiopia. This region has conditions analogous in some ways to the surface of Venus, including sulfur springs and extreme temperatures. Image: Electra Kotopoulou; Asa Stahl, “Rethinking the Atoms of Life,” The Planetary Society, Sept 8, 2025.
Beyond Carbon
Carbon is the great builder – capable of forming long, complex chains like the brushstrokes of a grand mural. But what if other elements could take on this role?
- Sulfur, which already powers certain Earthly microbes, might once have been a central ingredient in the origin of life.
- Boron is rarer but could provide scaffolding for exotic biochemistries.
- Silicon, beloved of science fiction, seems less likely to sustain life – but perhaps could serve as a collaborator alongside carbon.
For an artist, this is like imagining entire art movements crafted not from paint or stone, but from glass, fire, or sound. Each medium opens up new forms of expression; each element could shape a different kind of living world.
The Medium of Life
Every recipe needs not only ingredients but also a medium. On Earth, water is life’s universal solvent, dissolving and mixing molecules the way a studio brings together tools and light.
But astrobiologists are experimenting with other possibilities:
- Formamide, a liquid that may have supported Earth’s earliest chemistry.
- Liquid methane, pooling in Titan’s alien lakes, where life might encode information not in DNA but in electron counts or atomic patterns.
- Sulfuric acid (on Venus) and ammonia (on icy moons like Enceladus), which could support strange forms of metabolism unthinkable here.
It’s as though each world offers its own artistic medium: watercolor, oil, marble, or clay. Each one can give rise to entirely different masterpieces.
Ancient Recipes
Kaçar’s work is not only about imagining alien biochemistries but also about reviving the Earth’s lost ones. Using a technique called ancestral sequence reconstruction, her team resurrects fragments of ancient genomes, letting modern organisms express genes from billions of years ago.
This is like recreating a lost symphony or restoring a ruined fresco – not just to admire it, but to understand the creative process that shaped it. By reconstructing the chemistry of ancient Earth, Kaçar treats our planet’s past as if it were another world entirely – a living alien laboratory we already know exists.
A Universal Story
The search for life is not just a scientific project. It is also a cultural and artistic one, challenging us to think beyond Earth’s traditions of biology and to imagine the diversity of existence in the cosmos.
If we one day detect signs of life on a distant planet, they might not resemble us at all. And if we do not, then Earth becomes even more extraordinary – the single gallery in which life’s art is on display.
In Kaçar’s words:
“Ultimately, it will tell us more about ourselves. What better way to honor our own ancestors?”
Science here becomes poetry, and culture becomes cosmic reflection. To rethink the atoms of life is to expand both our imagination and our sense of belonging in the Universe.
Source: Asa Stahl, “Rethinking the Atoms of Life,” The Planetary Society, Sept 8, 2025.
