How a radical new view of life could reveal its origin – and aliens

Look around you wherever you are. Every living thing you observe—people, pets, birds, trees, flowers, mushrooms, and fish—exists due to interspecies unions. Common examples include lichens, which are typically combinations of algae and fungi, and corals, which consist of algae and animal components. However, these examples only scratch the surface of symbiosis.

In my book Togetherness, I argue that “living together” or symbiosis has been overlooked in biology and ecology. It’s not just its underappreciated importance; understanding symbiosis is crucial to understanding our own existence and origins.

All complex life, including everything you see, is the result of deep cellular symbiosis. Plants depend on symbiosis for growth and food production, a fact not widely recognized. Since before Darwin published his theory of evolution, and especially since, competition has been emphasized as the driving force behind evolution, overshadowing the significance of symbiosis.

As I researched my book, I discovered that this growing understanding of togetherness is reshaping our understanding of life’s beginnings, redefining what life is, and influencing the search for extraterrestrial life.

Deciphering the evolution of the earliest cells is a historical journey. Darwin, while reluctant to publicly speculate on life’s origins, wrote to Joseph Hooker in 1871 about the possibility of life beginning in a “warm little pond” with the right chemical conditions.

While the “warm little pond” idea has been appealing, it is now considered unlikely as the origin of life. Current interest is centered on deep-sea hydrothermal vents, where the contrast between hot alkaline vents and colder acidic seawater creates an electrochemical gradient that could drive biochemical reactions, essentially supporting life.

“The internal pores of the vents have cell-like structures with electrically charged catalytic surfaces, while the continuous flow gives continuous reactivity,” states Nick Lane, a leading origin-of-life researcher at University College London.

The fascinating aspect of this idea is its ability to transform insights from past scientific luminaries into a verifiable hypothesis. In 1866, Ernst Haeckel, known as the “German Darwin”, suggested life emerged from non-living inorganic substances. Later, Erwin Schrödinger wrote in 1944 about life’s evolution being tightly linked to its environment, and in the 1960s, Carl Woese speculated that life began in a community of protocells sharing molecules.

In 1985, physicist Freeman Dyson combined Schrödinger’s ideas with microbiologist Lynn Margulis’s work, which showed that complex cells in plants, animals, and fungi originated from a symbiotic relationship between two simpler cells. (In biology, symbiosis refers to two different species living closely together for a significant time.)

Life’s dual origins?

Dyson proposed that life began with two origins. Initially, protocells with metabolic processes emerged, providing energy. Subsequently, a method for storing genetic information, such as RNA strands, developed. He believed these two proto-life forms merged in a manner similar to symbiosis.

Today, these theories are being tested. I visited Lane’s lab to see how he and his team are recreating the conditions of life’s origin and creating their own protocells. Lane notes, “We’re searching for an environment where geochemistry naturally transitions into biochemistry,” bridging the gap between non-life and life.

In the laboratory, Feixue Liu is working to replicate one of the initial stages in metabolism: the reaction between carbon dioxide and hydrogen to create simple organic compounds like formate and acetate. She demonstrates the Y-shaped apparatus used to simulate a hydrothermal vent.

“We introduce ocean fluid on one side and vent fluid on the other,” Liu explains. “This setup mimics the ancient hydrothermal environment.” The experiment occurs in an oxygen-free chamber resembling Earth’s atmosphere 4 billion years ago. A chip detects any organic molecules produced.

A remarkable discovery in this field is the natural self-assembly of molecules, particularly the spontaneous emergence of metabolic processes even before life began.

Biochemists describe molecules as moving towards a thermodynamic minimum, or their resting state. This means molecules, even complex ones, can form because it is a natural tendency. For instance, the ingredients for RNA and DNA nucleotides can form spontaneously, even on asteroids, and complex metabolic pathways arise without genetic programming. These reactions are the early signs of life.

Spontaneous DNA formation

A significant discovery is that a metabolic pathway used by all life forms existed before the genes that code for it. Nick Lane explains, “We often think metabolism is genetically encoded, but recent work reveals it is spontaneous chemistry—a network of thermodynamically favored reactions.” The acetyl-coenzyme A pathway is the oldest and simplest energy source for cells and is used universally. Bill Martin from the University of Düsseldorf demonstrated that this pathway predates the enzymes and genes that encode it: the pathway came first, then the genes followed in its wake.

Moreover, under suitable conditions, like those in a hydrothermal vent, the energy molecule adenosine triphosphate (ATP) can form spontaneously. In all cells, ATP is the universal energy currency. These findings suggest that life’s processes align with naturally occurring reactions.

“It’s not what gets made, but how that potentially explains life’s origins,” says Lane’s colleague Stuart Harrison.

Dyson believed that metabolic processes in protocells paved the way for RNA “invasion.” However, Harrison, Lane, and their team propose a different perspective. They discovered that random nucleotides in protocells can serve as templates to create peptides, which are chains of amino acids forming proteins.

“Initially, the information is random, but it starts translating into function,” Harrison explains. In a protocell with metabolism and an energy source, the basis for a genetic code can develop automatically, leading to natural selection.

“If you have function and inherit that bit of information [via a gene], you might be more likely to survive, and natural selection starts to actually happen,” says Harrison.

Origin-of-life paradox

This approach addresses a classic dilemma in origin-of-life studies: the paradox of heredity. To pass on genetic traits, translation—a process converting genetic information into proteins—is necessary. Cells achieve this via a molecular machine called a ribosome, which manufactures proteins from amino acids. However, this system requires evolution, which cannot occur without heredity.

But what if there’s some form of translation occurring naturally, without enzymes, before this machinery, asks Raquel Nunes Palmeira from University College London. “Evolution can happen without the complete machinery.”

Nunes Palmeira, Lane, and their team have modelled this possibility and found that random RNA sequences can evolve into distinct genes encoding proteins with specific functions, like driving protocell growth. For natural selection to occur, heredity, variation, and differential success are needed, with RNA coding for protocell growth emerging first.

“Relating back to Dyson’s idea, here the RNA and the protocell are not separate individuals,” says Nunes Palmeira. The RNA is part of the protocell’s metabolic activity, not an invading entity.

This aligns with Woese’s vision of life’s origin, suggesting proteins could be created by random RNA fragments due to chemical affinities between nucleotides and amino acids.

While this framework is promising, it doesn’t mean we are close to recreating life’s origin in a lab. Even if we construct a functional, replicating protocell, it may not reveal life’s true origins, cautions Harrison. “There will always be a question mark,” he says. “Have we solved the origin of life, or have we solved an origin?” There are numerous hypotheses about life’s beginnings.

Extraterrestrial life

However, there is a way to validate protocols for creating protocells. “You can look on other planets,” suggests Nunes Palmeira, to see if similar chemistry leads to metabolism. There are alternative locations to explore as well.

In March, scientists analyzing asteroid Ryugu samples discovered all five nucleobases that make up DNA and RNA: adenine, cytosine, guanine, thymine, and uracil. This was reported as evidence supporting the idea that life on Earth might have been seeded from elsewhere, delivered by asteroids. But that’s not the most fascinating conclusion.

The presence of these ingredients aligns with the article’s premise: nucleobases—and potentially larger RNA and DNA molecules—form readily, ubiquitously. These essential life ingredients were also found on asteroid Bennu. “It looks to me more like these chemicals are just a thermodynamic minimum, perhaps at the universal scale,” says Harrison.

Even metabolic processes seem to reflect inherent chemical tendencies. Life can be seen as a biochemical process operating at a thermodynamic minimum. There’s no need for mystical origins or extraterrestrial delivery; life is simply a chemical process.

“Remarkably, starting from hydrogen and carbon dioxide, the formation of cellular biomass is thermodynamically favored,” says Lane. Life might be common across the universe, with potentially similar genetic building blocks. “All life in the universe could be eerily similar to us,” says Harrison. Saturn’s moon Enceladus, with hydrothermal vents akin to those on Earth, is a promising location for exploration.

The emerging picture is not precisely the symbiotic union of two entities as Dyson imagined. “However, there might be some kind of molecular cooperation among chemical reactions, RNA polymers, and early peptides,” says Harrison. “It depends on how loosely we define symbiosis.”

Strict symbiosis, defined as two species living together, may not have existed at life’s origin before species developed. I’m open to broadening the definition. Perhaps we should return to Woese’s idea of a communal, diverse array of primitive cells evolving collectively. The primordial soup was a community, and the ancient hydrothermal vent, still crucial to life and ecosystems today, was a place of togetherness.

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